Description: WAP 2015: Lakes and Ponds
We developed a mapped classification of lakes and ponds based on variables that structure lacustrine natural communities and that could be mapped consistently across Northeastern US. The classification was built upon four key attributes: water temperature, trophic state, alkalinity, and depth. Water temperature was mapped into three classes (very cold, cold, and warm-cool) to reflect the requirements and limits of aquatic organisms. Trophic states, representing the productivity of a lake, were mapped into two classes (oligomesotrophic -mesotrophic and eutrophic- hypereutrophic). Alkalinity was grouped into three classes (high, medium, low) to reflect how well the lake system was buffered from acidification. Depth was divided into two classes (lake, pond) based on a light penetration zone, using maximum depth and trophic state as a proxy for this zone. A steering committee of state and regional experts contributed sampled data with measured values of these and other variables for waterbodies in their states. To create the mapped classification, we compiled the location of every waterbody in the region (n = 36, 675) , and for each waterbody we generatedover 300 descriptive attributes including: morphology, dams, climate, soils, geology, conservation lands, landforms, and land cover in the buffer zone or watershed. We used Random Forest software to develop a predictive model for each classification variable class based on the sampled data points and the descriptive attribute variables, and we then extrapolated the model to the unsampled waterbodies to estimate their class. After estimating each variable class, all waterbodies were assigned to one of 18 classification types based on the combination of 3 variables, temperature + trophic + alkalinity class. These types can be further subdivided into lake or pond categories to yield mapped occurrences, for example: cold, oligo-mesotrophic, low alkalinity, lake. The 18 primary lake and pond types are described in the addition to the “Northeast Terrestrial and Aquatic Habitat Guide”, December 2015.