Where is this place? The Hemlock Forest

Where is this place I've been calling the Hemlock Forest?. The map below should help. Open up Google Maps and view the Saratoga Springs (NY) area (terrain view is best). The park is a prominent feature south of the city.

Map from Google Maps. The Hemlock Forest area is the park area (darker green) on the right. The orange lines show the trails and the marker is at the location of the parking area.

Of particular interest to me are the ecological communities present within the park and surrounding areas and the 2009 Park Master Plan includes a map of Park's ecological communities (You can view it here). Overall, Spa State Park is more developed than many others, but it also incorporates forested areas and a number of significant wetlands including an unusual Perched, Swamp White Oak, swamp.

The designation of ecological communities is based on both the landscape and the plant and animal communities that are present. The New York State Natural Heritage Program (run by the Department of Environmental Conservation) maintains a list of the community types found in New York State and where examples of those communities can be found. It's worth noting, however, that the classification of ecological communities is far from cut-and-dried. That's not a criticism, both the program and the website are well done and, for me at least, fascinating. But these designations are open to some interpretation and the communities change over time. It may be that new community types will have to be defined as natural systems adapt to changes resulting from human activity.

The potential for undesirable change is raised as a concern throughout the Park master plan which calls out the presence of invasive species -primarily plants and insects- as a significant threat to the natural heritage of the park. Several aggressive invasive wetland plants are present in the Hemlock Forest area (as they are throughout the park) and these plants pose a threat to native ecological communities. Two highly aggressive non-native plants -Oriental Bittersweet and Japanese Barberry- are now the dominant plant species in several areas of the Hemlock Forest. I plan to map these locations as part of surveying the state of the forest. Japanese Knotweed, another highly aggressive invasive species, is present near the parking area and that's worth watching. Once Knotweed gets going it is incredibly difficult to control.

Additional resources and information that you might find to be helpful.
Saratoga Spa State Park Master Plan
Saratoga Spa State Park Master Plan Map
Saratoga Spa State Park Master Plan Ecological Communities Map

Mystery Lines: What are those lines seen in the satellite images?

I love to visually explore an area using Google Earth (or similar software) and then go off and match up what is actually present on the ground with what I could see on the computer. Google Earth provides easy access to high resolution images but, if you are willing to dig a little deeper, there are many other sources of spatially referenced data that can be analyzed to learn about areas we want to study.

But let's talk specifics. Looking at satellite images of the Hemlock Forest area I noticed that there are some odd looking parallel formations present in one area of the forest. You can just make them out in the image from Google Earth (Image One). What are they? What process created them?

Image One: The lines are seen in the center of the image running at a 45 degree angle from upper right to lower left. The straight line that runs from top to bottom is a stone wall. Source: Google Earth, Historic imagery from April 1997.

Viewed in Google Earth I couldn't see enough detail to come up with a plausible explanation for what the lines represent or how they were created. But, for locations in New York State, other options exist including the very high resolution orthoimagery available from the New York State GIS Clearinghouse (NYSCG). Orthoimagery is a fancy name for aerial photographs; pictures taken from airplanes using high resolution cameras and techniques that minimize distortion. When you take pictures of the earth from a satellite the distance between the satellite and the ground pretty much ensures that the camera is at a right angle to the ground. So there is little or no distortion of the image. When you take those same pictures from an airplane, if the camera is not perfectly parallel with the ground, the images are distorted.

The imagery available from the New York State GIS Clearinghouse (NYSCG) covers (nearly) all of New York State and is available to the public via the NYSGC website. The catch is that there are thousands of files and they are big files. And, once you find the right images, you need a way to view them. These images are geo-referenced meaning that using the right software you can view the images and they will line up correctly with other map-based data layers. The software you use is commonly referred to as GIS; an acronym for Geographic Information System. Loaded into a GIS these geo-referenced images can be analyzed using a variety of methods. They can also be used to provide a base layer on which you overlay other data. This is much like what you do when you view satellite imagery in Google Earth and then add points or lines or outlines (polygons) on top.

The Hemlock Forest orthoimagery (Images Two and Three) (viewed using Quantum GIS) reveals a lot more detail and those curious lines now take on a distinctly man-made look. Particularly telling is the track that comes in from the left and crosses the formation (Image Three). They look like tire tracks but when taking measurements in the GIS I found that the lines in main set are about 50 yards apart. That made me think that they might be ditches created using a tractor or bulldozer. It is also more apparent from the orthoimages that the formations are filled with water. The dark color seen in the formations is the same as the color of small ponds and streams present in nearby areas.

Image Two: The lines are in the center of the image running at roughly a 45 degree angle to the top of the image. The red lines represent the boundary of the State Park. The park boundary is a separate layer viewed on top of the images in the GIS. Source: New York State GIS Clearinghouse.

Image Three: Zooming in for a closer view the structures and the "track" coming in from the left have a distinctly man-made look. Source: New York State GIS Clearinghouse

Still, I had to wonder why someone would create ditches -about 50 yards apart- through the forest at this place. That left only one solution: field trip. From the Hemlock Trail parking area twenty minutes by trail and another half hour winding my way through the swampy forest brought me to the place pictured in Image Four. This, clearly, was one of the ditches seen in the orthoimagery and it was also immediately apparent that these are ditches that someone dug.

Image Four: The ground view of one of the water courses seen in the aerial photos. Filled with debris and leaf litter these were probably a few feet deep when created. The surrounding area is a swampy, nearly level. The entire area has very poor drainage. So it seems likely that someone dug these ditches to provide drainage for some type of agriculture.

The ditches are roughly 50 yards apart and run in straight lines through the forest for two to three hundred yards. What was not apparent from the aerial imagery is that the area where these ditches are found is very flat and very swampy. A few larger and older trees are present but most of the trees are roughly the same size (and age). Based on the size of the trees I estimated that this area was probably in use for some type of farming 50 years ago.

But something was still missing. The surrounding areas were all clearly used for agriculture in the past but this area is very wet and it is surrounded by swamps. My visit took place in late November and it had been generally dry, and even so, every depression in this area is filled with water. During wetter parts of the year this area would likely be flooded. The trees that are present are types that you find in a hardwood swamp or floodplain forest.

However, after poking around a bit more, a possible explanation appeared. One of my interests is in how invasive species compete against native species so I'm always on the lookout for invasive plants and trees. And I noticed the presence of a number of small, stunted, trees interspersed among the common species. Being late November, with the leaves down, I couldn't tell right away what those trees were. Then, one of them gave up its' secret, on a branch I spotted a small apple. The stunted trees are apples trees and now I could see that someone had tried to drain the area to create an orchard.

It appears that that plan did not work out very well. Apple trees prefer well drained soil and perhaps the farmer was unaware that this area is notable for lying over a layer of impermeable clay. Not too far away that clay, combined with the nearly flat topography, has produced a type of wetland known as a "perched" swamp. A perched swamp is a wetland where the water on the surface is not connected to the local water table but where the drainage is so poor that you get a swamp anyway. In most swamps the water level rises and falls along with the local water table but this is a place where the water doesn't drain through the soil and runoff is slow or non-existent. Creating an orchard here was never going to be easy. Which may be why we now have this wonderful little wild area to explore and enjoy.

Resources:
New York State GIS Clearinghouse Orthoimagery

A little Wild: The Hemlock Forest

Things are changing. The way people think is changing. The natural world around us is changing. Everything is changing. This has always been the case; change happens. But one thing is different now. We humans are altering the global environment at a pace and scale that from the perspective of geologic time looks a lot like the great natural cataclysms of the past. Think in terms of huge super volcanoes that shook entire continents or the asteroid that killed of the dinosaurs. We are the human asteroid. We are in effect running a giant experiment on how the earth reacts to change at scale and lots of data is coming in. Our instruments and satellites capture immense amounts of data every day. Leaving us with the questions: "what can we learn?" and "what should we do?". That's the context for this blog.

OK, setting that cheery opening aside, I'm planning to write about very specific places that I think are interesting. One of those places is a small (300 acres) forest that is part of Saratoga Spa State Park. I call it the Hemlock Forest though that name is completely made up. Before going any further, let's look at a map (Figures One and Two).

Figure One: The City of Saratoga Springs, New York and surrounding areas. The green outline represents the boundary of Saratoga Spa State Park. The Hemlock Forest is on the right wedged in between Rte. 9 and the I87 (the Northway). The park covers approximately 2800 acres and that includes a tree nursery two golf courses, a Hotel and an outdoor performing arts center that seats 20,000 people (SPAC).

Figure Two: The Hemlock Forest is outlined in red. This section of Saratoga Spa State Park covers about 300 acres. The forest is separated from the main body of the Park by Rte. 9 (on the left). The northern edge of the forest runs into the rapidly developing urban/'suburban fringe of the City of Saratoga Springs. The southern margin is mostly undeveloped with a connection to the Kaydeross Creek other nearby natural areas.  

There are several interesting things going on in this little bit of forest. One is the presence of wetlands of several different types including an uncommon "perched" swamp (perched referring to how the swamp interacts with the local water table). This particular wet area, though small, hosts an uncommon ecological community anchored by the presence of old growth Swamp White Oak trees. The forest also includes an old growth hemlock forest and good stands of American Beech trees that so far have held up against the Beech Bark Disease that has devastated Beech trees elsewhere. The State Park maintains a two mile long trail that loops through a 150 year old forest that includes hemlocks, White and Red Pines, and Oaks. The existing trails provides direct access to less than half of the total area though the un-trailed southern portion of the forest is hardly an untrammeled wilderness. The entire area is crisscrossed by stone walls, old farm and field tracks, and unofficial trails. Still, parts of the forest have a distinctly wild feel and the range of habitats present make this an important natural preserve.

I enjoy walking the area and capturing data that represents the "current state" of the ecological communities that are present there and that will be one of things I'll write about in this blog. This "Field guide to the Hemlock Forest" will also include information on technologies and methods that I use, and that anyone can use, to gather real data about places like this. I'm sure that some posts will start with something like "saw a  Barred Owl today", but my emphasis will be on acquiring and managing data that represents the ecological and environmental state for this area. My hope is that this data will be useful in the future. In particular, I'm interested in how invasive species interact with native communities and I'm hoping to capture a data set that can be used to learn more about how those interactions change over time.

When I was a kid I loved to read about the explorers and naturalists who traveled the world finding species not known to western science. Unless you are willing to spend a lot of time looking through a microscope it's unlikely that any new species will turn up in northeastern New York, but spotting the arrival of a species that has not been present in the past is a very real possibility. We have tools at our disposal that were unimaginable even 20 years ago. A smartphone with GPS, environmental sensors, and on-line identification guides doesn't match a tricorder quite yet, but that's where we are headed.

If you are reading this it might be because you live nearby and can visit these places. Or maybe you are interested in nature generally and my writing is not so bad as to ruin it for you. Or, maybe, and this is my hope, you want to do something like this where you live. I'll be writing about citizen science and how we can contribute data towards a better understanding of our world.

That's all well and good but you may get an inkling that the for me this is fun. The Forest is less than a mile from my house and I like to walk in the woods. I used to play golf but, to paraphrase Mark Twiain's famous quip, "that's a sure way to ruin a nice walk." There is a parking area with trail access on the northern edge of the forest (access is from Crescent Avenue). The trails are lightly used and I'm yet to see another person while wandering off trail. Much of the area is swampy so if you do go off trail you can expect wet feet. And I'm not worried that publicizing the area will bring in swarms of hikers. For much of the year the hemlock forest is well defended by armies of mosquitoes and ticks (beware: Lyme Disease, seriously I have captured many many Deer Ticks while walking in this area). For now the Hemlock forest is well protected.

Resources:
Saratoga Spa State Park Master Plan (pdf)
Saratoga Spa State Park Master Plan Map