Posts Tagged ‘sustainability’

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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For the past six months I have been working on a “sustainable,” organic sugar bush. In that time I have seen a number of impacts, which seem like a necessary consequence of our activities, that certainly appear to impact the landscape. However, the industry maintains that when tapping is done right, the impact to the trees should be negligible and the woods should be preserved. In fact, one of the aspects my company brags about, is that the woods have been preserved from logging and development. While clearing the woods for logging or development may be more obviously impactful, there are still aspects of the process which should be more deeply investigated before we can call the industry sustainable.


The first (and probably most noticeable) impact which should be examined is the use of plastic piping to convey the sap down the mountain. Best practices suggest that the 5/16″ lateral lines be replaced every five years, drop lines every three to five years and one inch branches every ten to fifteen years. The plastic can sometimes be melted down and reused, but it is uncommon to see recycling of these materials on a large scale as of yet. Considering that we’ve used tens of thousands of feet of one inch piping and possibly hundreds of thousands of feet of 5/16″ lateral line, we are certainly creating untold tons of plastic waste, every few years. The University of Vermont claims that as many as 88 tons of maple tubing are replaced in the Vermont woods, per year, as of 2009. This number is surely higher by now, given that there are many more large producers taking up residence in the state. UVM then predicted that sugarmakers would make progress in recycling in the years to follow, and they have, but to what degree is not yet clear, and there is certainly still a large amount of waste being produced.


Waste is not the only question raised, when we consider sustainability in this industry. There is also the question of tree health. The industry claims that when tapped properly, sugaring should have no negative impact to the health of the tree, or at least negligible impact. Producers have been using smaller tap sizes to reduce the amount of dead transport wood created in the tree, but they have also started using vacuum systems to create a pressure differential, tricking trees into thinking their is higher atmospheric pressure, and thus that it is an appropriate time for sap to run. The impacts of vacuum are still an open question, as far as how trees are impacted. On a basic level, the vacuum has allowed syrup producers to collect more sap per tap. This alone should be a red flag. Trees use the sap we wish to collect to build new structures each spring. This includes the leaves needed to photosynthesize and reproductive organs. The greater the sap we succeed in pulling from the tree, the less it has for itself. While research done by UVM would suggest that there are no known impacts, it seems obvious that there must be at least some detrimental effects, and that perhaps we just aren’t seeing them yet.


Furthermore, there is the open question as to whether the scarring is expanded by draining more of the tree’s transport wood. In experiments conducted by UVM, the trees subjected vacuum did not show statistically significant impacts, compared to those tapped with gravity. I would consider the results of the 2007 study to be inconclusive and requiring further investigation. I would hypothesize that trees subjected to multiple years of 25″ Hg of vacuum would show advanced scarring, compared to gravity taps of the same size, but there is no available data yet.


Finally, sugar bushes fragment habitat, in woodlands considered by the companies tapping maple trees to be “conserved.” The larger the sugarbush, the more infrastructure and development is necessary to get the sap out. First roads are needed to make the installation possible. Second, branches are often cleared of brush to make the installation of one inch pipe and main lines easier. The installation of tubing further fragments the woods. Many involved in the installation of sugaring infrastructure anecdotally claim the impacts on wildlife to be negligible, but this seems highly unlikely. The use of noisy machinery like chainsaws and ATVs disturb wildlife and often chase them from the immediate area. The infrastructure installation fragments the areas where animals need contiguous habitat to range.


Study has been done on how sugarbush management compares with biodiversity management standards. However, there seems to be an open research question in verifying whether the practices in use are, in fact, impacting habitat. Simply using observed control species-area relationships vs. experimental species area relationships on sugarbushes could help to answer this question.


While the industry continues to claim it is operating in an environmentally sustainable manner, I feel there are many open research questions that need to be resolved before we can use the term sustainable. My hope is that research institutions like UVM will continue to investigate these questions, and that best practices can be improved within the industry. It will take cooperation between the private industry, research institution and governmental regulatory agencies to advance the cause of sustainability.

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