Feeds:
Posts
Comments

Posts Tagged ‘arcMAP’

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.

 

Advertisements

Read Full Post »

Dying Norway Maple

Over the last few years I have noticed that the Norway Maples in the Lehigh Valley were not looking so great. The most immediately apparent problem ¬†was the crown die-back, and increasingly completely dead trees. This stands in stark contrast to the way things looked when I was a kid. The Maple lined streets were lush and green then… So, what happened?

After reading up on Norway Maples and Crown Die-Back, and listening to several episodes of You Bet Your Garden on NPR, I came up with a number of theories. First, I though, as Mike McGrath often suggests on the aforementioned show that over-mulching was causing root girdling. Basically, how this occurs is, when you over-mulch it concentrates the water over too small an area. The tree’s roots concentrate in that area, instead of spreading into a wider radius, and eventually strangulate themselves. Another issue that came up was decline from road salt. This relationship has long been noted in relationship with the New England Sugar Maple population, and the symptoms typically include crown die-back. Finally, I came across evidence of a fungal blight that is found throughout the northeast called Verticillium Wilt.

Verticillium Wilt is a fungus that starts in the soil, enters the trees through its roots, and causes a blight in the pith wood. Amongst the common symptoms are stunted growth in the tree’s new growth, discoloration of pith wood and, of course, crown die-back. Because the blight offers several diagnosis points, I was able to study the trees in the area, and found they exhibited all three tell-tale symptoms.

Discolored wood fibers around a rotten pith, characteristic of Verticillium Wilt.

Discolored wood fibers around a rotten pith, characteristic of Verticillium Wilt.

On the left is stunted new growth, characteristic of Verticillium Wilt. Compare to healthy growth on the right.

On the left is stunted new growth, characteristic of Verticillium Wilt. Compare to healthy growth on the right.

Various states of die-back.

Various states of die-back.

So how is Verticillium Wilt spread and why are so many trees dying. After reading that Verticillium Wilt can survive in soil or mulch for ten years without a host plant, I had an ahah! moment. I now have a hypothesis about the vector for this disease. When a tree contacts Verticillium Wilt it is typically fatal. When these trees that die are in people’s yards, they call the tree removal service, and they come by and fell and remove the tree. Typically the tree is then mulched, and the mulch is sold to contractors to then mulch people’s yards. This then spreads the disease to more suburban trees, which then die and are themselves mulched and so on.

I have started to study this with the aid of GIS. I have a suburban sample, which is mulched and an urban sample which is not mulched. In the suburban sample 54% of the trees examined show signs of Verticillium Wilt. Meanwhile, in the urban sample I found no trees that exhibit clear signs of the blight. I then ran a correlation on diameter, to see if the age of the tree could be affecting the sample. However, I found a -0.62 correlation, which is a weak correlation between an increase in diameter and decrease in occurrence of the crown die-back. This suggests that there may be a resistance in older trees, that older planting methods were more effective, or that mulching may indeed play a role. I did find a 0.41 correlation between mulching and die-back. Again this is a weak correlation and will need more data to flesh it out. I am hoping to add a  forest plot to expand the available data.

This is the sample of the suburban neighborhood, where Verticillium Wilt is present.

This is the sample of the suburban neighborhood, where Verticillium Wilt is present.

Test Plot at Kutztown Park. Verticillium Wilt is not present and there is not mulching around the trees.

Test Plot at Kutztown Park. Verticillium Wilt is not present and there is not mulching around the trees.

Read Full Post »