Posts Tagged ‘ecology’

It is a familiar sight in New England. An impassable trail, flooded over with stagnant pond water. In the evening beavers work away, patching a dam at the pond outlet with sticks and mud.


Beavers have earned a fitting reputation as nature’s engineers. Rivaled, perhaps, only by man, they have an uncanny ability to modify habitat to suit their needs. The beaver is an animal that is vulnerable on land. Their whole survival strategy is to provide themselves with easy access to their favorite foods, while spending as little time as possible on land. During the summer they live off the tubers that grow near the water’s edge, but for the harder winter months they must store away a cache of food (typically alder, maple and birch branches). These trees grow in an exhaustible supply around the edge of lakes and ponds, and as the beavers diminish the easily accessible supply at the water’s edge, they are left with two choices. Travel farther on land where they are vulnerable, or raise the water level.


Damming activities are simply a means to better access the necessary foods, but this very activity often puts them in direct conflict with people, who have a penchant for recreating close to the water’s edge. To enable our recreation we build access trails, often within the riparian zones of water bodies. Much attention has been paid to the damage human recreation does to these sensitive habitats, which have high ecological productivity and provide ecosystem services of incalculable value and necessity for life. As a result, many sustainability minded recreational organizations have begun the process of pulling away from shorelines.


The New York Department of Environmental Conservation recommends constructing trails and structures at least 150 feet from the water’s edge to minimize impacts on the riparian habitat. However, bridges are often necessary to traverse bodies of water, to get from point A to point B expeditiously. It is such infrastructure which seems to create the most opportunity for conflict between the interests of beavers and the interests of man.


A wilderness bridge must provide for safety of passage, while weathering the elements, while also impacting the environment as little as possible. Many times their are employed in wetlands, to minimize human impacts (such as the choose your own adventure style trails that emerge to avoid wet spots and muddy areas). However, these pieces of expensive and critical infrastructure are often placed in the areas where they are most susceptible to changes in the environment.


In recent years, attention has been paid to building structures with climate change in mind. In most cases this means building infrastructure in a way that is resilient to sudden deluges of water. This is the most common impact of climate change in the Northeast. Besides hotter temperatures, we are seeing storms that release unprecedented amounts of water in an exceptionally short duration of time. Construction designs increasingly rely on reinforced abutments and helical piers, that can withstand floods of greater severity. This leaves a foundation upon which to rebuild in the even of a washout. However, these designs do not consider longer term impacts, such as beaver flooding. It has become a necessity to address these longer term impacts, in order to ensure the sustainability of infrastructure, to minimize the cost to conservation organizations, associated with opening lands to the recreating public.


An anecdote comes to mind, associated with a land conservation organization in Western Massachusetts. The organization suffered flooding of a wetland boardwalk when beavers moved into the area. After the beavers  left the area returned to its previous state as a wet meadow and the old boardwalk was exposed again. The organization spent $20,000 to repair the old boardwalk, whereupon the beavers returned the next year to commence their water management actives again. The brand new boardwalk was flooded out, despite having been built upon helical piers and following the finest sustainable design recommendations.


This anecdote highlights the lack of foresight often involved in the planning process. As Woody Hasselbarth, Brian Vachowski and Mary Ann Davies suggest in the Forest Service’s Trail Construction and Maintenance Handbook, “good planning is stupidity avoidance.” If you have had beavers in the area in the recent past, it is safe to assume they may return, when conditions are again favorable. It is thus necessary to make considerations for this eventuality part of this process. A good deal of money, time and frustration can be saved by planning for eventual conflicts in infrastructure. While many organizations figure on placing expensive (and ineffective once silted) beaver deceivers in problematic beaver dams, to control water levels. Other organizations trap the beavers as pests, which strikes one as incompatible with a conservation based mission (even when that organization may be heavily recreation oriented). Beavers play an important role in disturbance cycles within the landscape of the northern forest, and this should be allowed to play itself out whenever possible. A small amount of planning can go a long way to solve this problem.


Best Practices For Sustainable Trails In Beaver Habitat:

  • Avoid placing trails within 150 feet of a riparian zone. Consider take trails uphill, to preserve the views and the habitat.
  • When it is not possible to avoid riparian zones, build boardwalks on sustainable structures like helical piers.
  • Instead of cutting off helical piers and placing the boardwalk on the top of the rods, consider using a clamping mechanism that can be adjusted by several feet, as water levels change.
  • Place permanent bridges down stream of a beaver dam, and high enough to avoid a washout from a breached dam. Beavers tend to use existing dams rather than building new ones, if an abandoned dam exists, it is relatively safe to assume they will return to repair the existing dam, as opposed to building a new one.


Planning for beaver activity can save a lot of headaches later and can prevent conflicts that often lead to the extermination of the beavers. As with all aspects of sustainability, it is important to plan for future eventualities in trail design, not just current conditions.


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While working on the Appalachian Trail, I realized that many of the campsites used year in and year out by Thru-hikers are growing in size and degree of impact. Yet, many of the organizations tasked with monitoring campsites keep records in paper form and have no tangible concept of the way impacts are adding up.

In the video above, I used ArcMap to enter in a hypothetical centerpoint for a campsite. I then compile polygons, representing monitoring trips. Ideally, this data would be collected in such a way as to contain monitoring metrics in the attribute table, so the symbology can be classified by the severity of impact.

The video shows how one campsite grows over time. Typically, however, campsites don’t exist in isolation. This technique can be expanded to show multiple campsites bleeding into each other.

The area data can be compiled in either excel or R, and used as an input to a linear regression analysis. This can be used to project, that if impacts continue at the current rate, they would result in campsites over ever increasing size, until you wind up with giant camping areas.

By finding trouble spots on the trail and analyzing them over a five year period, enough data can be compiled to extrapolate useful modelling, which can help inform better management decisions.

Currently management decisions are being made without data to show whether they are working or not. Anecdotally, the impacts appear to get worse every year. Management and monitoring need to go hand in hand. When a decision is made, the impacts of that decision need to be monitored and that data needs to inform future decisions. Otherwise, we cannot be said to be making rational decisions.

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In order to successfully conserve land, you must first understand what you are trying to conserve and why. Land Trusts typically spell out, in their mission statements, what their goals are. It is often better to be narrow, in this regard, than to try and “drink from a firehose.” There are, after all, many lands out there that need to be conserved, and not enough resources to conserve them. On the organizational level, this fact is most magnified.


In order to be successful, conservation organizations must be thoughtful about each step of the process. For instance, what grants should be applied for, will they build capacities for the organization’s mission or stretch the organization thin with new requirements. It is rare that a grant will cover an entire program. Often there is thee requirement that the organization receiving the money match it with a certain amount of their own fund-raising capacity. Grants come with requirements, so organizations do better to find grants with requirements they can easily meet, without building new capacities.


This is why it is important to define, as specifically as possible, what a conservation organization wishes to conserve. Many Land Trusts conserve land as wildlands, and others conserve agricultural land. It is more difficult to try and do both well. Many organizations that conserve wildlands, conserve forests, riparian zones, different types of wetlands, etc. Even in this regard, a degree of specificity is important. When trying to decide whether a particular tract is work putting resources into conserving, it helps to use Overlays. If any organization decides to preserve forested land, it can favor forested lands that are near other protected lands, in order to expand the conserved landscape. It may choose the favor those near riparian zones or wetlands. It may choose the favor those with endangered species habitat or certain soil types. All of these aspects can be represented spatially, and GIS can be used to better construct an effective overlay.


It is important to identify a geographic region of importance. In this case, I have identified South Whitehall Township as an important area, because of its low percentage of total lands being conserved. (An organization can choose to value areas with a high level of conserved land instead). Since I have chosen South Whitehall, all the other layers will be clipped to focus on just South Whitehall.


Overlay Map2

Percent of Land Conserved


Lets say an organizations wish to favor forested properties, near protected lands, riparian zones and wetlands, with a presence of endangered species. One can make a model, taking land use layers, protected lands layers, riparian and wetlands layers and endangered species habitat layers. Each of these can be used to create a buffer (how close to the object should the protected land be). Again, this is derived by deciding how much certain layers should be valued. After making buffers, these can be merged into a single layer and joined to a tax parcel map. The join will maintain the geometry of the conservation layers, and tell you which properties are intersected by the conservation buffers, and thus a high priority for conservation. The output, in the example of South Whitehall Township, near Allentown, Pennsylvania, would look like this:

Overlay Map

The Green shows properties of potentially high conservation value.


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As I hiked Haystack Mountain in Pawlet, Vermont yesterday, I was impressed with the amount of diversity preserved in just a small tract of land. The North Pawlet Hills Natural Area preserves a little over 1,000 acres, yet from the trail it is possible to observe a strikingly large number of distinct habitats. Part of this is undoubtedly because the elevation changes so drastically, but it is also noteworthy that the Nature Conservancy intentionally focused on the preservation of land of high conservation value.

The conservation movement, over the years, has made strides in putting high value lands in the public trust, but it has also been a strategy with limits. This is why land trusts are so valuable. Land trusts can step in to conserve parcels  when there is not the political will to conserve the land in the public parks systems available.

When the government protects land, it protects lands that are valuable for recreation or for natural resources. Ecology is more often than not a secondary concern. The Forest Service manages forest resources for what it deems to be a sustainable timber harvest. In other words, a rate of timbering that does not degrade the forest in the long term. This is a useful strategy, seeing as we live in a society dependent on forest products. The Parks Service, on the other hand, manages lands for the recreational experience of National Park visitors. In the case of many of our previously wild parks, this has meant developing the kind of infrastructure that can handle the ever increasing (and under-educated in regards to leave-no-trace principles) visitorship. In both cases, governments have an anthropocentric management style, and this has resulted in a long term degradation of the resource, (barring the occasional, but rare wilderness area, where greater restrictions exist).

Even this anthropocentric management style has dried up in recent years. As budgets have become tighter, political will for conserving land has all but evaporated. This all during a time when the scientific community has raised concerns about biodiversity loss, due often to habitat fragmentation. As more land becomes developed for human interests, and the government fails to push back, land conservation has been left in a vacuum.

Fortunately, many non-profit land trusts have cropped up, in order to nickel and dime properties deemed to be of high conservation value, but often too small, or too lacking in recreational opportunities, to be of public interest. Often times, the trust will buy a tract in fee simple (meaning full ownership), but more often land trusts utilize scenic and conservation easements that spell out rights, restrictions and responsibilities of both the property owner as well as the land trust. Land trusts monitor the properties periodically to ensure the terms of the easement are met. Easements are backed by law, and there are legal ramifications for violating the agreed upon terms, however they are entered into voluntarily by private landowners interested in preserving  their property for future generations.

This is not a great strategy for large land acquisitions, but it has worked, piece-meal, to make additions to conserved lands, or fill in the gaps that the government is not willing to. For instance, in the Essex Chain of Lakes acquisition, in the Adirondacks State Park in New York State, it was uncertain whether the Department of Environmental Conservation would have the resources necessary to take over the property, which had previously been held by the timber company Finch Prine. As it became clear that the paper company wanted out, the Nature Conservancy acquired the parcel in fee and then sold it at a discount to the State of New York for admittance into the Adirondack Park. This process took years, but the Nature Conservancy was able to identify a parcel with high conservation value, and protect it.

Haystack, similarly is a property with high conservation value. As one walks up the mountain, you start in a typical example of Northern Hardwoood Forest, along rolling terrain that varies from wet to mesic, and often consists of Rich Northern Hardwood forest matrix communities. These communities are dominated by Sugar Maple, Beech and Yellow Birch. There is one point in the beginning of the trail, where a wetland is visible, though it is unclear whether it is a bog, fen or swamp (from the trail). However, with wetlands being home to immense biodiversity, being providers of essential ecosystem services, and being highly productive ecosystems, it is clear the area is of high ecological value.

Through the lower forest, one can hear an incredible diversity of bird life. From canopy birds like the blue-headed vireo to the elusive hermit thrush, it is well worth stopping to take the varied calls in.

There is also great diversity in the understory, from the common witch hopple, blue cohosh, jack-in-the-pulpit, blue-bead lily, red trillium, cranesbill and various ferns, to the poisonous nightshade.

As the elevation picks up, the change from wet northern hardwod foorest to mesic oak habitat becomes clear. The southern exposure is dominated by northern red oak and white pine, as well as a wide array of understory shrubs and plants. The herbaceous layer, once dominated by jack-in-the-pulpit and blue-bead lily, and blue nightshade, is now taken over by foam flower and witch hopple. As the elevation rises, the understory becomes thinner and there are more hemlocks, though the dry southern exposures still contain oaks.


White oak trunk, surrounded by maple leaves.

At the summit, there is almost an alpine meadow. Here there is only a stunted canopy of Northern Red Oak. Here and there there are speckled alders, but mostly there is an abundance of alpine bilberry, three-toothed cinquefoil and pale corydalis. There area few sedges lining the rocky escarpments, but the soil is very thin and dry at the peaks.


pale corydalis


View from  the summit of Haystack, Mt, Pawlet, Vt.

Just in the course of an hour, the trail traverses this entire diversity.

It is clear that the Nature Conservancy considered recreational value to the community in preserving the North Pawlet Hills property. However, the biodiversity preserved on the property is extensive, and provides an oasis of habitat for species that might otherwise be threatened by fragmentation, caused by extensive farming in the region. For its size, the preserve accomplishes a lot of positive goals.


There can often be public confusion at the decision of a land trust to preserve properties with low recreational value, as is the case with the Natural Lands Trust’s preservation of wetlands in western New Jersey. However, when you consider that the protected worm-eating warbler utilizes this habitat for nesting, and the wetlands are home to plants that are rare and endangered in the state, it becomes clear that the land has high conservation value. However organizations like the New York-New Jersey Trail Conference have been clamoring for more access and the right to build extensive trail improvements for the Highlands Trail through these habitats. Many in the hiking community cannot see why there is resistance from the land trust. However, this lays bare the argument in favor of protecting lands through the use of land trusts. The mission of the Natural Lands Trust is to preserve biodiversity, not improve recreational opportunities or garner public interest. Thus, land trusts such as this have the ability to resist public pressure, in order to do the right thing ecologically.


The benefits of land trusts are many. While sometimes those benefits align with public interest, often times they are able to take a longer view, for the purpose of serving the greater good. As the will to preserve large tracts of land continues to dissipate, it will become increasingly important to ensure the resources are available to protect the smaller habitat corridors, that enable extensive ecosystems like the north woods to function.

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Hawk Migration on the Kittatiny Ridge and Climate Change


By Glenn Nelson



ABSTRACT: Much has been recorded about the phonological changes in the migration cycles of birds, as related to climate change. These studies typically focus on modeling for future changes in migration dates for a given range of species. However, there appears to be little focus on recording the change in numbers of birds seen in migration, as they relate to temperature and weather phenomena. This study hopes to find first, whether climate change is observable over time in a given location, and second, whether those changes appear to have a correlation with the total number of migrating hawks. Anecdotally, it has been noted that certain species will stay in their breeding ground as long as there is food source availability. Thus, we hypothesize that as temperature rises, fewer birds will get the impulse to migrate during the typical migration season, (or in warmer years at all), lowering the number of birds observed during the migration period. Initial results from a statistical analysis of NOAA weather data and migration data from Hawk Mountain suggest that there is a likely correlation between warming regional climate and lower than average hawk flights, particularly since the 1980s, which has been a period of increasingly rapid warming. There are a few possible explanations for this change. While this study hypothesizes fewer birds are migrating, it is also possible they are using thermals instead of the updrafts found along the mountain ridges. Whichever explanation accounts for the observed changes, it still represents a change in migration behavior, which could have ecological consequences.





Hawk migration has long been seen as a harbinger of seasonal changes, associated with the coming winter. However, less attention has been paid to how the phenology of hawk migration may change over time, on the various hawk watches in North America. While still politically debated, the scientific community has come to a consensus that the world is warming and that this effect is likely anthropogenic.[1] However, the warming effect is not universal, and climates are changing in a variety of ways. Thus it is important for this study to establish a trend in temperature within the given study years, as a primary goal, before trying to understand the relationship between temperature and hawk migration.

The usual volumes associated with hawk watching in the northeast, such as Pete Dunne’s Hawks In Flight and Jerry Ligouri’s Hawks From Every Angle, generally chart when to expect high flights of certain species.[2] (An example of such migration time tables can be seen in Figure 1.1).[3] Looking at these charts, the question arises as to whether such projections change and whether any changes are associated with climate change.


Fig: 1.1



There is a good deal of available research which has produced projections about the changing timetable for raptor migration, but the available research focuses more on the changing dates of a specie’s migration, as opposed to whether the total numbers changed as well. For instance, a 2012 study by Josh Van Buskirk, asserts that:

“The migratory period has become more extended, especially for short-distance migrants. Opposite responses during the two seasons had the effect of extending time spent to the north of the study area, by up to 30 days in some species since the early 1970s. These phenological shifts—potentially related to climate change— are causing dramatic changes in the annual cycle of North American raptors.”[4]

Another study, conducted in Europe by Mikael Jaffre, (et al), resulted in similar findings.


“We found that when the temperatures increased, birds delayed their mean passage date of autumn migration. Such delay, in addition to an earlier spring migration, suggests that a significant warming may induce an extension of the breeding-area residence time of migratory raptors, which may eventually lead to residency.”[5]


Yet, a change in total numbers should also be concerning for two reasons. First, hawk migration data is often used to estimate the health of a species population. This fact is highlighted in a forest service study by Kyle McCarty and Keith Bildstien. Their study points out that, “One particularly cost-effective method for monitoring populations of these birds is to sample regional and even continental populations at traditional migratory bottlenecks and concentration points.”[6] Second, even if the population remains healthy but the migration numbers change, it could signal a change in habits that may have detrimental effects to a species, or other ecological repercussions within the bird’s traditional range. For instance, if a species lingers too long in their breeding range, they may stress available resources in the breeding area, or be surprised by a rapid change in weather such as an unusually cold year. Furthermore, prey species may suffer from exponential population growth in areas that were in the hawks’ previous migration and southern range. Similar relationships have been noted in lower trophic levels, when keystone predators are removed from ecosystems.[7]

Inevitably, there are a number of factors that complicate the results. First, the period of acceptable data has been shortened to control for DDT. As was evidenced by Rachel Carson, the spraying of DDT had an effect on migratory bird populations, including raptors.[8] From 1934 to 1972, DDT spraying was allowed in the United States, (as well as in the migration range countries, where DDT still sometimes persists). DDT has since been illegalized in the United States, (1972).[9] It is clear that numbers jump drastically between the 1960s and the 1970s, as the DDT ban was enacted and conservation efforts for migratory raptors were put into place, (fig 1.2). Since there is no effective way to control for this effect, data prior to the illegalization of DDT was discarded.



Fig: 1.2

Decade Averages

Decade 1=1950


There are also issues in the standardization of the data, since the period of the hawk watch varies from year to year, and from weather and other factors. From 1943-to1945 no hawk watch was conducted, due to World War 2. More telling results could be gleaned from comparing population numbers to the percent of migrating birds, but systematic data on that topic does not currently exist, and collecting it would present logistical challenges.

Other issues must also be raised as possible factors. I had been informed, and since found anecdotal accounts in both Jerry Liguori’s Hawks From Every Angle, as well as Don Heintzelman’s Guide to Hawk Watching in North America, as well as research from Tarra E. Gettig, that hawks have a tendency to fly in advance of and behind certain frontal systems.[10] Since the number of frontal systems affecting this area per year is difficult to accurately calculate, it is not a factor included in this study. However, it is something that should be looked at in the future, in order to glean the full picture of what weather processes are affecting migration.

There is also research to suggest that hawks may be using thermals if the temperature is high, or if wind is unavailable. When hawks use thermals, they soar much higher, and are thus harder to observe. This is what is posited in Michael J. Lanzone’s study “Flight responses by a migratory soaring raptor to changing meteorological conditions This offers an alternate explanation for changes in migration numbers.”[11]

Overall, this study hypothesizes that, first, climate change will be observable in the temperature data, and may be observable in the rainfall data. I expect that this will affect migration numbers negatively and residency numbers positively, though the effect is likely gradual, requiring a large data set, or decade means, to see the trend.



Fig: 2.1

Decade Averages



This study is designed firstly to establish whether climate change is occurring in the Lehigh Valley area of the Kittatiny Ridge. To this end, climate summary data for the study period was requested of and provided by NOAA, for the Allentown weather station, ______ miles East of Hawk Mountain. All data were collected for the period of the fall hawk watching season on Hawk Mountain, between August and December. This data was used to establish decade means and charted as the dependent variable, while the decade functioned as the independent variable. (fig 2.1) Temperatures were measured in degrees Fahrenheit, in order to be more relatable to a domestic audience. As can be seen in figure 2.2, the decade mean for temperature generally rose, excepting one anomaly. The temperature for the period of the 2000s was 53.6 degrees (f), about a degree above the period average.


Fig 2.2:

Average Yearly Temp


Yearly hawk totals from Hawk Mountain Sanctuary in Kempton, Pennsylvania were then plotted as the dependent variable, (fig. 2.3). This showed us both the average flight, as well as the trend over the study period.



Fig 2.3

Hawk Per Year Decade Average


Precipitation data was collected similarly, and used as a stand in for weather variability.

Fig 2.4

Average yearly rainfall


The data were then compared using standard deviation to show variability, and pearson’s correlation coefficient, using the following equations:



Standard Deviation:



Pearson’s Correlation Coefficient:





Finally, data were collected from the Winter Raptor Survey results from Pennsylvania Birds Magazine.[12] The data are only available during the 2000s, and are thus of limited applicability, but can be used to suggest a possible explanation for the observed phenomena.


  1. Results:


The following data tables represent the results from the statistical analysis at hawk mountain, (Tables 3.1 – 3.3) and (Figures 3.1-3.2)



Table 3.1

Decade Averages Temp Rainfall Number of Hawks BW SS RT
50 50.8 19.4 15535 8600.63 2858.55 2539.09
60 51.3 16.9 16162 9729.82 2187.18 2788.82
70 52.2 20.4 21513 11011.82 5535.55 3393
80 52 17.6 22042 8220.82 7190.09 4035.18
90 52.5 18.7 18631 6426.27 5316.36 3676.64
00 53.6 20.5 17971 7052.55 4397 3090.36
correlation 0.3788 0.1126 -0.4651 0.4459 0.4260
correlation from 1980s -0.8336 -0.8725 -0.4645 -0.9179 -0.9972
correlation from 1970s -0.852923146 -0.399197261


Fig. 3.1: X= Temperature, Y=Hawk Migration Numbers




Fig. 3.2: X=Rainfall, Y=Hawk Migration Numbers




Table: 3.2

Year 1950-1960 1960-1970 1970-1980 1980-1990 1990-2000 2000-2010
Average Temp. (F) 50.8 51.31 52.15 52 52.46 53.63
Average Rainfall (In) 19.44 16.9 20.41 17.62 18.71 20.53
Average Number of Hawks 15535 16162 21513 22042 18632 17971
Sharp-shinned 2859 2187 5536 7190 5316 4397
Broad-winged 8601 9730 11012 8221 6426 7053
Red-tailed 2539 2789 3393 4035 3677 3090
Standard Deviations
Temp. 1.14 1.36 1.69 1.44 1.49 1.53
Rainfall 3.75 2.87 4.28 4.81 4.37 4.92
Number of Hawks 3008 2170 8679 4202 4105 3606
Sharp-shinned 800.3763319 564.5103751 3155.206788 1997.933055 1146.100543 1057.040586
Broad-winged 2443.611642 1709.996188 6480.008084 3327.400451 3009.409214 2702.533158
Red-tailed 714.1127998 633.1852522 1010.681651 839.4813659 889.580606 861.2376295


Table 3.3

Year Winter hawks RT Temp Rainfall
2010 5915 2665 53.1 19.96
2009 5789 2275 53.3 20.13
2008 5634 2390 52.3 21.68
2007 4948 2218 55.2 19.68
2006 5359 2184 54.9 18.5
2005 4512 2610 55 23.22
2004 3959 2052 53.6 26.01
2003 2374 1182 54.4 29.64
2002 2539 1399 52.8 19.75
2001 2192 1141 55.1 10.55




Statistical data do not always tell their own story (or they tell multiple stories depending on how they are interpreted). As has been shown over the years by the climate change debate, data can be less or more convincing, depending on how it is analyzed. This study looks at total hawks per year, averaged over a decade. It can be said that this was done to improve R2 values, in order to strengthen certain conclusions. Certainly, when looked at on a closer scale, like taking yearly averages as individual anomalies and running a correlation, the R value is reduced. However, this was not our justification for looking at means.

The justification for using decade averages has to do with the high degree of variability in individual anomalies, concerning hawk migration data. As has arisen in the climate debate, you may have hot years and you may have cold years, but individual anomalies do not establish a larger trend. In the case of looking at long term trends, relationships can be obscured by scaling too close, and what may be only a small change from year to year presents itself as quite pronounced over time.

When looking at hawk data (fig 3.3) this is particularly pronounced. You have good years and bad years, and there don’t appear to be any particular reasons for the individual anomalies. However, the means help to smooth out the often pronounced outliers, (such as 1979, which had more than 40,000 hawks, in what is the single biggest year in Hawk Mountain’s history).

If we go back as far as 1930, and we look at the lowest outliers, there is certainly a linear improvement. However, the number of days on the lookout has also improved, as has the reliability of the count’s protocol. This is a problem with the Winter Raptor Survey data as well, since in recent years count hours have gone up, alongside the number of resident hawks.


Fig: 3.3



There are a number of problems with looking at the data in this kind of resolution, since there are changes in variables, through a number of periods during the study. The charted data showed lower than average flights through most of the DDT period. In the period immediately following, there appears to be a bump, followed by a gradual decline. The polynomial trend line does a much better job of expressing the shifting periods, than does the linear trend line. This helped to separate the data by three distinct periods. The DDT era, the post-DDT recovery, and a notable decline.

The first period was defined as 1946-1974, since this period was dominated by the effects of DDT, as a limiting factor to hawk populations. In this period we see far fewer than average hawk flights, at 15,458 birds per year. We also see below average precipitation and temperatures. Despite that fact, there is a warming trend present, even in these years. Between 1950 and 1970, the average decade temperature increased by nearly 2 degrees (f). In this period, the correlation coefficient for temperature was -0.25. This aligns with the hypothesis, that as temperature increases, fewer birds would migrate, though, during this period the effect is slight. Furthermore, the correlation coefficient for precipitation is .011, which is too weak to suggest any relationship.

The next period, 1974 to 1992, represents what would appear to be a recovery from DDT and a relative temperature stagnation. These two phenomena transpired to produce higher than average flights for the period at 22,933 per year, on average. The correlation between temperature and hawks for the period was

-0.068, which is too weak to suggest any relationship. What is more, the -0.14 coefficient for precipitation suggests that there is a weak inverse relationship between rainfall and hawk numbers.

The final period looked at, was between 1980 and 2014. While there is an overlap with the previous period, there seemed to be certain trends in the charts, which needed to be followed back to 1980. In this period, mean birds per year fell to 19,540, which is 225 below the average for the whole study period of 19,765. Furthermore, both average temperature and average rainfall were higher during this period. Both temperature and precipitation correlation coefficients increased their previous trends to -0.097 and -0.227 respectively. Both of these trends remain slight, but suggest a very gradual, possible relationship, where both temperature and rainfall adversely effect hawk flights.

Finally, the data was broken up into decade averages between 1970 and 2010. By zooming out on the data, certain trends did emerge as more apparent. First, through the 1980’s bird numbers are on an increasing path, which suggests that there has been a certain level of success in conservation efforts. However, the 1990s and 2000s show a marked decline in those averages. The averages remain higher than they had been in 1950, but suggest an alarming trend. Furthermore, by averaging, we can see a steady rise in temperatures, though there appears to be three segments. Temperatures rise into the 1970s, stagnation for a decade, and then rising rapidly (by 1.1 degree (f)) between the 1990s and 2000s. In that same period, average hawks per decade drop off by 340. While, if we look at the correlation coefficient for the averages of each decade since 1950 we get the slightly positive .0379, if we look at it just spanning the high point in the 1970s, up to 2010, we get a more alarming coefficient of -0.85. The precipitation averages also rise in this period, and amount to a coefficient with hawk numbers of -0.4. These numbers are suggestive of a strong relationship between high temperatures, high rainfall and fewer hawk flights. While the temperature relationship relates closely with the hypothesized results, the precipitation data seems somewhat less suggestive of a relationship between variable weather and hawk flights.

While over the study period the story appears to be a slight linear positive, a closer examination of recent trends is more alarming. By putting the data into three periods we can see the gradual changes, but by averaging the decades and examining the relationship more closely, we can see a more startling trend, which appears to establish a strong relationship between rising temperature and lower average hawks per decade. Overall, 72.25% of the variation in average fall hawk numbers by decade can be described by a negative linear relationship with temperature. Only about 16% of the variation can be described by a linear relationship with precipitation in inches.

Finally, in looking at the decade of data from the Winter Raptor Survey, we can see a that hawks observed per year is rising, though with negligible correlation to fall temperatures. While the data is incomplete, and can’t be fully analyzed into decade means, there are a few emergent trends worth noting. First, 2010 saw 5915 hawks observed, which is 1,593 birds more than the period average of 4,322. There is a P = -0.26, which is a bit below statistically significant and suggests that only about 6-7% of the variation in hawks can be described by the fall temperature anomaly. This result may be more significant if averaged out.



Fig: 3.4





In the process of conducting this study, a number of questions have arisen. First there has been the problem of accounting for the DDT period and the period immediately afterward, (which appears to exhibit a recovery). While this is a very important finding, it is not helpful to the study, because the exceptionally low number of hawks in the DDT period creates an artificially low floor, while the recovery due to conservation efforts presents an artificially high ceiling. In many ways, it shows that human effort has helped to solve a human problem, which is optimistic for future challenges. The idea that we can overcome our mistakes once they are identified is encouraging, but the problem of identifying the problem remains.

There were certain trends, which appeared from the data to be correlative, that emerged when looking at the data from the height of the recovery period (1970) into the present. First, temperatures, which had stagnated during the recovery period rose after 1980; at first gradually and then rapidly after the year 2000. Furthermore, there appeared to be greater disparity in the scatter in rainfall data in the current period. These trends are magnified when examined by decade.

The increase in climate change related measurements, and a significant drop in birds per year, appears to have a significant, if gradual relationship. This relationship may have significant ramifications ecologically. First, as the paper by ____ notes, migration data is one of the cheapest ways to monitor hawk populations. If migration is occurring less frequently, or differently, it will be more difficult to monitor populations. Birds that stay in their breeding range to the north longer would likely effect both their breeding habitat and their wintering habitat, by stressing prey populations in one and not limiting them enough in the other. Even if that is not the correct assumption, and hawks are just travelling at higher altitudes on thermals, as ___ suggests, this is still significant, as it impedes our ability to monitory the populations of migratory raptors. This study also has ramifications for phenology, as hawk migration is seen as a harbinger of the changing seasons.





While I can see that there may be concerns that the decade averages could be construed as an alarmist manipulation of statistics, I believe that it was necessary to view the data on such a scale, in order to establish long-term trends. While the overall trends show a growing number of migrating hawks since the 1930s, which do not correlate with climate change, (when plotted in a linear regression model)—the polynomial projection suggests a different relationship; depending on what period you are focused on. Averaging decades and discarding data that presented too many variables provided an amplified and simplified window for comparison. I was able to observe how higher and lower numbers, in each category, were skewing the mean in different periods. Furthermore, the patterns that appeared gradual, in a year over year analysis, emerged in a more pronounced manner. The years where DDT likely effected hawk populations were particularly apparent, as were the recovery years. The recovery years appear to be aided by a stagnation in temperature, as well. However, as the world economy began growing again in the 1980s, and greenhouse gas emissions rose precipitously though the 1990s (citation needed), many of the gains made by conservation efforts in the 1970s have been lost. The relationship between higher temperatures and lower decade averages of hawk numbers, since 1970, is thus an alarming one.

When we look at the data we see this process, but it occurs gradually, as indicated by the polynomial line on figure ______. There are waves of both progress and setbacks, that cannot be shown by a simple linear projection, even in the decade means. It is important to isolate the current period, one which is nearly a degree Fahrenheit warmer than the study average, and which has risen at a faster rate, from periods where other factors were likely dominant. Even when we look at the yearly averages, (instead of the decade averages) the correlation exists, but it is not as drastic, because we see it spread out over time. The decade averages isolate each period, and make a vague picture clear.

I think it is important to acknowledge how gradual this process has been, and that the low rate of change certainly effects the correlation coefficient. That said, the data set does tell a story. For instance, there have been 21 years in which high temperatures correlated with low flights, 11 of them occurring in the period of rapid warming after 1980. Higher than average precipitation correlates with lower hawk flights for 23 of the study years, but only 8 since 1980. Meanwhile, there has been an increasing frequency of higher than average temperatures since 1980, with 24 higher than average years, including every year since 2001. This compares with 13 before 1980. In that time, there has only been one year significantly below average. In the same period, there have been 14 years with higher rainfall than average. The frequency appears to have accelerated since the year 2000, with half those years occurring in that period. The number of lower than average rainfall years since 1980 have also increased from 5 in the previous 46 year period to 5 in just 34 years, with 2 since the year 2000. This is suggestive of more extreme and variable weather. There have been 15 years with lower than average hawk flights in this period, 10 of them since the year 2000. These numbers are why I think it is important to focus heavily on this period.

When we look at the R value between temperature and hawk migration numbers between the decades of 1970-2000, the value is a statistically significant -0.8529. When that is couple with a 0.73 R2 in a linear regression model, with a slope of -2434.419, it is clear that there is a strong relationship with temperature, that cannot be ignored. While there can be a number of explanations for this trend, all of the explanations have to acknowledge this relationship. The probability exists that 72.25% of the variation in hawk migration numbers can be described by the hypothesis of y= 2434.4x + 148029. In other words, there is a high probability that temperature is affecting hawk migration. This cannot be said with more certainty, because there are too many variables, and hawk migration itself is extremely variable.

We still have a net positive picture, as even the decade averages show. The decade of the 2000s has better hawk flights than that of the 1950s, when DDT was an active problem. If we plot the data in a linear manner, we have an upward trend. However, since the 1980s that trend has reversed, and that reversal has accelerated in the 2000s, in correlation with temperature and to a lesser degree rainfall.

I believe that this evidence is suggestive, then, of a change in migration that is likely due to climate change. The process is gradual, and it would be expected to be, but it appears to be occurring. While there are certain ways that this study could be strengthened, I think it shows that this understudied area would benefit from a greater intensity of study.


Appendix 1: Hawk Migration Data from Hawk Mountain Sanctuary and Weather Data from NOAA.

Year Temp Percipitation BW SS RT # of Hawks
1934 50.9 22.83 3 1703 5426 7874
1935 50.3 20.01 3873 4168 3214 14681
1936 50.7 15.45 6990 4406 3162 16083
1937 50.8 14.85 4343 4791 4932 15446
1938 52.1 18.16 10754 3105 2228 17007
1939 51.4 10.84 5736 8620 6208 22488
1940 49.5 17.45 3159 2406 4725 11228
1941 53.3 11.68 5170 3908 4698 15424
1942 50.5 25.71 4362 3200 2378 11014
1943 49.8 17.06
1944 50.6 14.41
1945 50.2 20.88
1946 52.8 14.62 2886 2382 2306 8729
1947 52.3 13.12 6664 1726 1680 11366
1948 52.3 16.07 15026 1650 2343 20483
1949 52.5 17.02 9579 2963 2749 17092
1950 50.8 16.19 5305 2667 3674 13366
1951 50.8 22.5 10997 3008 2307 17890
1952 51.5 26.45 12603 3566 2754 20737
1953 53 16.87 7247 2791 2051 13542
1954 51.6 20.44 5956 3183 2070 12606
1955 51.1 24.19 9542 4709 3764 19867
1956 51.8 16.7 8734 2048 1525 13469
1957 52.4 15.11 8935 2662 2730 15858
1958 49.9 15.58 8880 1752 2951 15128
1959 53.8 19.99 5301 2825 1904 11585
1960 50.6 19.83 11107 2233 2200 16832
1961 53.5 12.5 8642 1723 2566 14716
1962 49.1 20.59 8254 2181 2772 14651
1963 50.9 18.4 9791 1518 3402 15900
1964 51.7 11.62 10180 1259 2626 15202
1965 51.7 15.12 9235 3103 3297 17371
1966 51.4 18.73 10110 2883 2126 16582
1967 49.8 16.37 8000 2330 1854 13604
1968 52.5 16.38 14041 2253 3765 21789
1969 50.2 17.85 8515 2670 3566 16176
1970 53 18.6 9153 1906 2503 14960
1971 53.8 24.17 5603 2135 1781 10536
1972 50.8 22.24 8131 2233 3463 15285
1973 54 20.17 6404 3347 3098 14448
1974 51.3 24.03 9146 4477 3658 18519
1975 53.1 22.75 10390 5354 2880 20121
1976 48.1 18.48 8461 5376 3694 18941
1977 51.7 25.78 13009 10612 3504 29123
1978 51.8 19.18 29519 6826 2852 40576
1979 53.1 19.1 11173 10306 4175 27639
1980 53 10.01 10141 8319 5715 26495
1981 50.3 11.95 8660 9464 3939 24890
1982 52.8 16.54 7163 4541 5025 18742
1983 52.4 22.53 6922 6517 3954 19681
1984 54.3 14.27 13619 3796 3157 22343
1985 52.3 23.6 3415 5766 2895 13931
1986 50.9 19.46 13996 9239 3305 29200
1987 51.2 24.07 8409 6776 4215 22366
1988 51.2 14.1 5944 6714 4687 20034
1989 49.8 16.5 7504 9832 3710 24700
1990 53.8 20.78 4656 8127 3785 20084
1991 53.3 14.41 5858 5678 2970 17219
1992 50.6 17.68 10661 4629 3288 21125
1993 52 26.26 3592 5449 3744 15829
1994 53.7 17.34 3513 4934 4433 15713
1995 51.3 16.68 10077 6217 4854 24363
1996 52.2 24.85 1809 4468 2734 11589
1997 51.4 15.81 5519 4218 2402 15533
1998 54.6 12.6 9935 5835 4331 24238
1999 54 22.75 8634 4416 4999 22491
2000 50.2 16.68 6435 4509 2903 16767
2001 55.1 10.55 3843 4817 3741 16137
2002 52.8 19.75 12228 3211 3499 22212
2003 54.4 29.64 6134 3651 3385 16474
2004 53.6 26.01 6387 2958 2847 15027
2005 55 23.22 5273 4545 4551 18346
2006 54.9 18.5 11804 5480 3898 24940
2007 55.2 19.68 7836 5099 2426 19495
2008 52.3 21.68 4289 3358 1807 12205
2009 53.3 20.13 6640 4299 1762 15590
2010 53.1 19.96 6709 6440 3175 20492
2011 55.7 40.07 13323 4447 1697 22902
2012 54.2 18.97 8394 5222 2876 20078
2013 52.4 21.41 6430 3772 2030 15271
2014 53.8 12.7 6369 4772 2266 17415



[1] UN climate report.

[2] Ligouri: pg 11, Heintzleman: pg 79-80.

[3] Hawk Mountain

[4] Buskirk: pg 1. http://www.zora.uzh.ch/70159/1/auk%252E2012%252E12061.pdf

[5] Jaffre, et al: pg 1.

[6] McCarty and Biddlestein: pg 718. http://www.fs.fed.us/psw/publications/documents/psw_gtr191/psw_gtr191_0718-0725_mccarty.pdf

[7] environmental sustainability

[8] (citation from Silent Spring).

[9] Citation needed

[10] Liguori: pg 10, Heintzleman: pg 77-84, Gettig (http://www.gammathetaupsilon.org/the-geographical-bulletin/2010s/volume53-2/article2.pdf).

[11] http://rsbl.royalsocietypublishing.org/content/8/5/710

[12] PA Ornithological Society

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Boreal forests represent the largest undisturbed eco-systems in the world, accounting for about a third of all forest cover, or 12 million square kilometers. About half of the Boreal Forest is undisturbed, primary forest. It is known for its vast expansive of conifers, (largely Spruce/Fir forests), but this biome also consists of bogs, fens and shallow lakes, which hold vast quantities of fresh water. Species that live in the Tiaga are specialized to withstand long winters, (for instance, the conical shape of Spruce trees, designed to shed snow and ice, or the snowshoe hare, which sheds its brown summer coat for a white winter one). Perhaps most impressive, however, is the role these forests play in the carbon cycle. Trees are known to uptake carbon through photosynthesis, and store it in their biomass as carbohydrates. The average carbon content is generally 50% of the tree’s total volume. Old growth forests, like those in the Boreal Forests, are capable of storing carbon for up to 800 years in the live mass of trees. Since Boreal Forests represent the largest portion of old growth forest, they are responsible for storing more carbon than any other biome at 703pg. The nearest biome is the Tropical Rainforest at 375pg. However, this living carbon sink is particularly vulnerable—first, because temperatures are rising faster in the adjacent arctic region, and second because a change of just 1.5 degrees Celsius would cause climate zones to migrate north at rate of 5 kilometers per year, far outpacing the migration rate of trees. Even if the biome could migrate quick enough, the carbon from dying trees in the southern extent of their range would release much of the carbon they have been responsible for storing, thus accelerating the greenhouse effect. This effect is consequential not just for the healthy functioning of the ecosystem, but also for the health of the entire planet.

I. The Boreal Biome:
The Boreal Forest is the northern most forest type, occurring just south of the Arctic Tundra, and transitioning from the northern hardwoods of the Temperate Broadleaf forests to the south. Boreal forests overlay areas formerly covered by glaciers and permafrost. The vegetative biodiversity is relatively limited, with most of the forest existing in patches of subclimax plant communities. The Boreal Forests of North America are primarily composed of Balsam and Douglas Fir, White and Black Spruce, Hemlock, Cedar and other conifers, but also include some populations of deciduous trees such as, Sugar Maple, Speckled Alder, Yellow and Paper Birch, White Ash and American Beech.

Winters are long in the Boreal Forest: typically up to six months of below freezing temperatures. The growing season is also very short: between only 50-100 days without frost. When the sun is near the horizon, during winter, the angle of incidence at which energy is received in the Boreal Forest is lower than it is in the tropics, causing more energy to be received by diffuse radiation as opposed to direct radiation. The species that live in this biome must develop adaptations in order to survive the strict economy of energy, during the winter. Many mammals are larger as a defense against the cold, and many hibernate through the coldest months to prevent starvation and freezing. While the nesting range of many bird species, like Cedar Waxwings, Red-winged Blackbirds, Hermit Thrushes, Boreal Chickadees and Common Loons, lie within the Boreal Forest, most migrate south for the winter. Conifers dominate the northern extent of the forest due to their adaptation to snow and ice loading. The broader shape of hardwoods make them more susceptible to ice loading, and the premature shift of sap from the roots to the trunk and branches in spring can cause the trees to crack in a late frost. However, conifers have capillaries that have evolved to be able to turn water movement on and off, depending on conditions. They also have stronger cell walls, and can better withstand ice expansion.

While the Boreal Forest may seem inhospitable, it is, in fact, a vital ecosystem. Between carbon capture and storage, water filtration, waste treatment, biodiversity maintenance, pest control and other services, the Boreal Forest provides ecosystem services estimated to be worth about $250 billion per year. The boreal forest has been described as “a giant carbon bank account.” Boreal Forests “store an estimated 67 billion (tons) of carbon in Canada alone – almost eight times the amount of carbon produced worldwide in year 2000.” Globally, the Boreal Forest contains about 1/3 of the world’s vegetation and soil carbon.

It is important to remember, however, that carbon uptake and carbon storage are vastly different, and the slow rate of primary production in the Boreal Forest acts as a limit to the forest’s ability remove carbon from the atmosphere at a rate that could combat our use of fossil fuels. That said, the destruction of the forest causes carbon that has been stored for hundreds of years to be released, acting as a positive feedback to global climate change. What is particularly disturbing about this fact is that the Boreal Forest may be in decline as a result of global climate change, as well as contributing to it.

II. The Effects of Climate Change on the Boreal Forest:
Boreal Forests are, by their very nature, extremely resilient. However, as the abstract to “Boreal Forest Health and Global Change” suggests, “(…) projected environmental changes of unprecedented speed and amplitude pose a substantial threat to their health.” Though the biome remains one of the largest on earth, “it faces the most severe expected temperature increases anywhere on Earth.” It is widely accepted that a warming of 1.5 to 2.5 degrees Celsius would increase the risk of major vegetation changes, including the loss of heat sensitive species in the Boreal Forest.

As this 2010 report from the U.S. Forest Service’s Northern Research Station suggests, “One of the big uncertainties of the global climate change phenomena is what will happen to the trees.” Many optimistic foresters predict that increased levels of atmospheric carbon dioxide will improve photosynthetic rates and thus accelerate tree growth. While there is evidence to support this prediction, there is also concern about what effect changes in temperature and precipitation patterns will have on forest and species distribution. Already, some research points to climate change contributing to advancing infestations of invasive and pest species such as the Hemlock and Balsam Wooly Adelgids, the Emerald Ash-borer, the Spruce Budworm, Mountain Pine-beetle and the Asian Longhorn Beetle. Many of these invasive insects cause forests to be more susceptible to pathogens, as Professor Tom Wessels notes in Reading the Forested Landscape of New England: “Beech-bark Scale Disease, Dutch Elm Disease, Chestnut Blight, and White Pine Blister Rust—are all caused by fungi, their spread often facilitated by insects.” In at least the case of the Hemlock Wooly Adelgid (HWA), cold winters can hamper the spread of the insect. It has been found that the HWA struggles when winter temperatures average less than negative 5 degrees Celsius, which has so far hampered their spread into the boreal forest. However, as Anna Szyniszewska writes on the Climate Institute’s website, “The impact of climate change and rising average world temperatures can have a profound influence on species’ geographical ranges that are often set primarily by climate…”

Professor Wessels also writes about the destructive potential of the HWA:
At the doorstep of central New England awaits another insect defoliator. Accidentally introduced from Asia and first discovered in Pennsylvania in the 1960s, the wooly adelgid has spread as far north as southern Massachusetts. Its tolerance to cold temperatures has researchers worried about the future of its host, the eastern hemlock.

It is largely expected that as climate changes, many damaging invasives will be able to expand their ranges, and this is expected to be very damaging to host trees in the Boreal Forest. As Roger Olsson notes in “Boreal Forests and Climate Change,”

The impact of insect damage in boreal forests is significant. In terms of area affected it exceeds that of fire. Spruce Budworm, for exampled, defoliated over 20 times the area burned in eastern Ontario between 1941 and 1996… Insect outbreaks are expected to increase in frequency and intensity with projected changes in global climate through direct effects of climate change on insect populations and through disruption of community interactions…

It is likely that both native and invasive pests will increase, and that the damage to forests will amount to billions of dollars, (in both crop loss in the forestry sector, and somewhat less directly in the loss of ecosystem services).

Invasives are not the only concern when considering the impacts of climate change on Boreal Forests, and animals are not the only species capable of expanding or contracting in range. As the U.S. Forest Service notes, “Tree ranges in ancient times certainly shifted according to changing climates, but the changes were relatively slow.” Northern Research Station scientist Christopher Woodall used existing data to analyze movement in the geographic distribution of current trees. His study found evidence that northern tree species “are exhibiting a northward migration,” and that, “Over 70 percent of this study’s northern species have mean locations of seedlings that are significantly farther north than their respective mean biomasses.” Woodall also recorded a number of species, which exhibited negative area changes, “that is the areas in which they thrived decreased.” Black Spruce, Bigtooth Aspen, Quaking Aspen, Balsam Fir, Paper Birch, Yellow Birch, Northern White Cedar, Striped Maple, Black Ash, Scarlet Oak, Eastern White Pine, Red Pine, Eastern Hemlock, Red Spruce, Sugar Maple, Sweet Birch, American Basswood, Hawthorn, Sourwood and Northern Red Oak, all lost area, while southern species “demonstrated no significant shift northward despite greater regeneration success in northern latitudes…” Woodall estimates that tree migration amongst northern species may accelerate to a rate of 100 km per century, which sounds like a small amount, but this rate will likely outstrip the rate at which southern species can take the place of northern species, potentially leaving a vast savannah, where once there was a Boreal Forest. As Dmitry Schepashenko, co-author of, “Boreal Forest Health and Global Change,” notes in an interview with the Canadian Broadcast Company, “The (southern) forests can’t go so far to the north. The speed at which forests can move forward is very slow, like 100 meters a decade.”

The decline in thriving habitat of many boreal species is likely due to temperature induced drought stress. As Roger Olsson suggests in “Boreal Forests and Climate Change,” “Some tree-growth declines are large and have been seen at different points across a wide area. Temperature induced drought stress has been identified as the cause in some areas.” He notes that studies of tree-rings have shown a negative correlation with temperature increases during the 20th century, and that growth decline occurred more often in the warmer areas of a species distribution, “suggesting that direct temperature stress might be a factor.” As temperatures increase, and drought becomes more common in the already arid biome, the destruction of habitat may become as widespread as Schepashenko suggests. To again quote Roger Olsson:

If global warming exceeds 2 degrees celsius the change of ecosystems in the boreal forest region may be even more far-reaching than outlined… Direct effects of warming on forest growth and distribution, combined with indirect effects of climate-induced changes in disturbance regimes may transform vast areas of boreal forest into open woodland or grassland… In regions where the boreal forest presently is succeed by continental grasslands in the south, a contraction of forest is projected due to increased impacts of droughts, insects and fires. With global warming of more than 2-3 degrees Celsius extensive forest and woodline decline in mid-to high latitudes is predicted.

Besides simply degrading forest aesthetics by replacing vast primary forest with anti-entropic, high growth, early successional habitat, there is one glaring problem that would result from the recession of an old growth carbon sink. With so much of the world’s untapped carbon reserves existing in the biomass of the Boreal Forest, it is daunting to think of the impact that releasing that carbon would have. If global warming negatively impacted the Boreal Forest, as it seems almost certain to, the carbon released would be a positive feedback into the carbon cycle, causing more warming, and thus more forest degradation.

The spectre of carbon cycle feedback was raised in a 2006 “Realclimate.org” article entitled, “Positive Feedbacks From the Carbon Cycle,” and suggested that warming could be accelerated between 25-75 percent. In Michael E. Mann’s summary of the IPCC’s findings entitled, Dire Predictions, he notes that current emissions due to deforestation amount to between 4.5 and 5.5 gigatons of carbon dioxide per year. The result may be that the forests we have known to be carbon sinks may no longer be providing us that service. Again, Roger Olsson suggests that, “Modelling results suggest that forest ecosystems in Canada shifted from a carbon sink to a carbon source around 1980… Projections for a hypothetical North American boreal forest landscape indicate that carbon losses from disturbances cannot be offset by increases in growth, if higher decomposition rates caused by altered disturbance regimes are taken into account.” Thus, even the successional habitat that is likely to replace the disturbed forest, even being anti-entropic (taking up exponentially more energy and nutrients, using energy to increase complexity over time), it will not be able to take up as much carbon as is currently stored in the Boreal Forest.

Professor Tom Wessels of Antioch University writes extensively on the topic of forest disturbance. He argues that complex systems like a forest ecosystem are self-organizing, meaning they, “take in energy and use it to increase their level of complexity through time.” He notes that, “A clear cut forest is left in a simplified state. In time it grows back to a forest with complex structure and a wide variety of organisms.” However, he also suggest entropy, “a process where things naturally move from a state of order toward disorder,” effects complex systems. He notes that all energy conversion is inefficient and that some diffusion results from all complex systems. However, he defines systems as anti-entropic if they take in more energy than they release, as is the case with early successional habitat. The goal of a forest ecosystem is to reach the dynamic equilibrium of an old growth, which would be defined as taking in as much energy as is released, and where nutrients are recycled across trophic levels. However, when ecosystems die they become highly entropic and release both stored energy and carbon dioxide. This is what is behind the aforementioned feedback. The high level of entropy of dying forests is greater than the anti-entropic effect of the savannah habitat that will likely replace the forests.
Professor Wessels points out that Global Climate Change is largely an entropy imbalance, and that positive feedbacks, like dying Boreal Forests releasing carbon, eventually cause bifurcation. He writes:

In a system with positive feedback, the feedback amplifies the system’s behavior in a directional, accumulative way… With sustained positive feedback the impacts eventually may build up to such a degree as to throw the system into a totally new mode of behavior. The point at which a complex system jumps into a new behavioral patter is known as a bifurcation event…Although the positive feedback leading up to bifurcation may be gradual, the change in system behavior is abrupt.

Global warming is essentially a gradual building of positive feedbacks related to a high level of entropy. To get under the hood of how the positive feedback works, defoliation from pathogens, pests, increasing acidity, drought and other climate related causes reduce the forest’s ability to photosynthesize. Reduced canopy means more radiation reaches and warms the forest understory. Warming on the forest’s floor increases decomposition rates, “a process that releases nutrients.” As Professor Wessels notes, “When photosynthesis drops and decomposition increases, the loss of nutrients from the ecosystem is accelerated…” Nutrient availability becomes greater, but because of the reduced photosynthesis, less is taken up. Eventually trees start to dieback. When a tree species is lost, the reverberation is felt amongst all the species that associate with it, and if there is not enough niche redundancy this results in a loss of biodiversity. Forest ecosystems are intensely interconnected, and such declines can have a snowballing effect.

What will the bifurcation eventually look like in northern forests? Professor Wessels suggests that:

For species of trees that don’t grow south of New England… the warming climate will most likely translate into an inability to germinate successfully… Drought sensitive trees like sugar maple and white ash will experience more dieback… Southern trees will take centuries to complete a northern migration to the region… Coupling these reductions with those already created by introduced forest pathogens and potential declines from atmospheric deposition, we see a very bleak picture of our future forests.

The complexity of the relationship between global climate change and the largest biome on earth is immense. Yet, there is one factor that unites the entire issue: the ecological interconnectivity of each of these issues. This is why declines in on part of the forest result in ecosystem feedback. For centuries the Boreal Forest has served as the largest carbon sink in the world. However, this appears to be changing, and concern is rising that, a decline in productive biomass in this biome, defoliation and deforestation, are releasing carbon and energy as a carbon source. Since the decline of the forest creates positive feedback in the global system, once decline starts, it is likely to escalate, causing both localized and global destruction. The habitat that will likely result from the shrinking or loss of Boreal Forests, though anti-entropic, is neither likely to be able to absorb the release of carbon and energy, nor to replace the ecosystem services currently provided. If the Boreal Forests transition from sink to source, as some research suggests has already happened, not only will it accelerate global climate change, but we would likely lose the last, largely undisturbed, functioning forest ecosystem in the world.

Bibliography To Be Added Later

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A list of all the flora and fauna I have spotted, during my summer in the Essex Chain. As would be expected, birds and wildflowers dominate this list. There were many more spotted in the Adirondacks and many that were unidentifiable by me. Inevitably, as my knowledge is incomplete, my list is flawed. But, it is a pretty good representation of what one could expect to find in a summer here.

Mammals: 9 species.

Beavers, Red Squirrel, Black Bear, White-Tailed Deer, Mink, Chipmunk, White-footed Mouse, Coyote, Moose.

Amphibians: 3 species.

American Toad, Green Frog, Eastern Newt.

Reptiles: 3 species.

Painted Turtle, Snapping Turtle, Garter Snake.

Birds: 49 species.

White-throated Sparrow, Eastern Phoebe, Northern Raven, Ruby-throated Hummingbird, American Robin, Wood Thrush, Black-capped Chickadee, Yellow-rumped Warbler, Common Grackle, Cedar Waxwing, American Crow, Turkey Vulture, Great Blue Heron, Common Loon, Barred Owl, Bald Eagle, Downy Woodpecker, Northern Mockingbird, Northern Cardinal, Blue Jay, Sharp-shinned Hawk, Canada Goose, American Black Duck, Song Sparrow, Dark-eyed Junco, Belted Kingfisher, Red-tailed Hawk, Broad-winged Hawk, Red-winged Blackbird, European Starling, Roughed Grouse, Yelow-bellied Sapsucker, Hermit Thrush, Black-throated Green Warbler, Wild Turkey, Mourning Dove, Red-breasted Nuthatch, Brown Creeper, Winter Wren, Black and White Warbler, Hairy Woodpecker, Gray Catbird, Pine Warbler, Eastern Towhee, Pine Siskin, Scarlet Tanager, Common Merganzer, Eastern Wood Pewee, Mgnolia Warbler.

Trees: 18 species.

Yellow Birch, Grey Birch, River Birch, Paper Birch, White Ash, Sugar Maple, Red Maple, American Beech, Spotted Alder, Quaking Aspen, Big-tooth Aspen, Black Spruce, Balsam Fir, White Pine, Red Pine, Northern White Cedar, Tamarack, Eastern Hemlock.

Shrubs: 7 species.

Witch Hopple, Striped Maple, Mountain Maple, Maple-leafed Viburnun, Sheep Laurel, Low-bush Blueberry, American Mountain Ash.

Ferns: 3 species.

Sensitive Fern, Bracken Fern, Internmediate Wood Fern.

Mosses and Lichens: 4 species.

Shining Club Moss, Tree Clubmoss, Big Redstem Moss, Old Man’s Beard.

Flowers: 64 species.

Jack-in-the-pulpit, Red Trillium, Gaywings, Partridgeberry, Starflower, Indian Cucumber, Solomon’s Seal, Yellow Violet, Common Violet, Canada Mayflower, Wild Stawberry, Indian Strawberry, Bluets, Painted Trillium, Goldthread, Common Mullien, Bunchberry, Pink Lady-slipper, Common Cinquefoil, Blue-eyed Grass, Sundrops, King Devil, Yellow Rocket, Hellbore, Small-flowered Cranesbill, Common Daisy, White Clover, Pinesap, Wood Sorrel, Twin Flowers, Blue Flag Iris, Viper’s Bugloss, Yellow Wood Sorrel, Blue Vetch, Bird’s Foot Trefoil, Yellow Hop Clover, Common Milkweed, Rough- fruited Cinquefoil, Hedge Bindweed, Indian Pipe, Selfheal, Swamp Milkweed, Common St. Johnswort, Herb Robert, Dewdrop, Shinleaf Pyrola, Marsh Skullcap, Pickerlweed, Day Lily, Water Hemlock, Bull Thistle, Tall Buttercup, Queen Anne’s Lace, Sweet Goldenrod, Grass-leaved Goldenrod, Evening Primrose, Jewelweed, Tiger Lily, Steeplebush, Fall Phlox, Black-eyed Susan, Virgin’s Bower, Cardinal Flower, Bladder Campion.

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