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These datasets represent aquatic cores and aquatic buffers, in combination with terrestrial cores and connectors they spatially represent the ecological network derived from the CTR LCD project. Data included in this download include: River and Stream Cores, Lake and Pond Cores, Aquatic Buffers (raster), and River and Stream Network (Stream Classes, The Nature Conservancy). River and Stream cores represent: 1) streams of relatively high ecological integrity across all lotic ecosystem types, emphasizing rivers and streams that are relatively intact and resilient to environmental changes. 2) headwater streams of relatively high current habitat value for brook trout, emphasizing streams that provide the best habitat conditions under current climate conditions; and 3) large and medium rivers that provide habitat for anadromous fish, including the portions of the main-stem and major tributaries of the Connecticut River from the mouth of the river upstream to the limit of passability for 5 additional fish species. Lake and Pond cores represent: lakes and ponds of relatively high ecological integrity, emphasizing lakes and ponds that are relatively intact and resilient to environmental changes due to their size and connectivity to similar natural environments. Aquatic Buffers spatially represent the areas estimated to have a strong influence on the integrity of the aquatic cores based on watershed processes. Specifically, the buffers represent areas hydrologically connected to the aquatic cores through surface runoff and instream flow processes, such that anthropogenic stressors within the buffers are likely to adversely impact the integrity of the aquatic cores. Unlike the cores the buffers do not necessarily represent areas of high ecological integrity. River and Stream Network is a classified version of the stream network in which streams are classified and mapped along centerlines, even through wetlands and lake and pond systems. This layer is provided for the sole purpose of facilitating the display and mapping of landscape design products, as it is easier to visualize vector features for narrow linear features.
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This dataset represents the selection index used to create aquatic ecosystem-based cores. The selection index is a continuous surface in which every cell is assigned a value (0-1) based on its relative ecological integrity within each HUC6 watershed. Specifically, the selection index is equal to the index of ecological integrity except in headwater creeks where it is the average of IEI and USGS's stream temperature tolerance index. Aquatic core areas are created, in part, by choosing cells above a certain index value and spreading from these "seed areas" through adjacent aquatic cells to build larger, buffered cores of relatively high ecological value.
This dataset represents Aquatic index of ecological integrity (IEI), which is a measure of relative intactness (i.e., freedom from human modifications and disturbance) and resiliency to environmental change (e.g., as caused by disturbance and climate change). Raw IEI is a composite index derived from 19 different landscape metrics that measure different aspects of intactness and resiliency. For the derivation of this layer, raw IEI is (quantile) scaled by ecological system and HUC6 watershed so that the poorest cell of each ecological system gets a 0 and the best gets a 1 within each watershed. Aquatic IEI, is provided for convenience in displaying the results of the aquatic conservation design but is otherwise equivalent to Weighted IEI except that it only has values for aquatic cells (all non-aquatic cells are set to nodata), is technically unweighted IEI. IEI is a major component of the terrestrial and aquatic core area selection indices and thus the terrestrial and aquatic network of core areas.
This dataset represents the aquatic vulnerability to development index, which reflects the likelihood of development occurring in places in the uplands that are likely to impact the aquatic cores. Specifically, aquatic vulnerability is the product of the aquatic buffers, which represent the areas estimated to have a strong influence on the integrity of the aquatic cores based on watershed processes, and the integrated future probability of development between 2010-2080. Cells with relatively low watershed influence on the aquatic cores have low vulnerability regardless of their risk of development, since the integrity of the cores will not be degraded too much if they get developed. Aquatic vulnerability is greatest where there is high watershed influence; i.e., uplands in close proximity to the cores as the water flows, and where there is also relatively high probability of development in the future.
This dataset represents a scaled version of the headwater stream temperature tolerance index based on a model developed by Dr. Ben Letcher and associates at the USGS Conte Anadromous Fish Lab, which is a measure of the relative sensitivity of stream temperatures to rising air temperatures. Specifically, sensitivity is measured by the slope of the linear relationship between air and stream temperatures during the spring season when air temperatures are rising. A steeper slope indicates that stream temperature responds faster to air temperature change, while a shallow slope indicates that stream temperature is more independent of air temperature change. Lower values (i.e., shallower slopes) are interpreted as being more tolerant under climate change, possibly because of groundwater influence or other factors. Conversely, streams with higher slopes are likely to be more impacted by increased air temperatures. In the layer provided here, the raw rising slope index is inverted and (quantile) scaled by HUC6 watershed so that the least tolerant headwater creek (steepest slope) gets a 0 and the most tolerant (shallowest slope) gets a 1 within each watershed.
This dataset identifies large and medium rivers within the Connecticut River watershed that provide habitat for five anadromous fish species: American shad, blueback herring, shortnose sturgeon, alewife, and sea lamprey. Habitat includes the mainstem and major tributaries of the Connecticut River from the mouth of the river upstream to the limit of passability for these species. This layer is derived from a product entitled "diadromous fish habitat in the Connecticut River watershed" developed in 2010 by The Nature Conservancy, Connecticut River Basin Program. Digital data updates were performed by Renee Farnsworth working with USFWS personnel through the NALCC. Specifically, river segments identified and known to be accessible to the five species listed above were extracted from the diadromous data layer, and each river segment was assigned a score from 1-5 indicating the number of species having known access to the segment. In addition, each segment was scored as “free-flowing,” “impounded” or “unknown.” All river sections with a score >0 for the five focal species are included in the final set of lotic cores.
This dataset represents opportunities to restore aquatic connectivity by upgrading culverts. Specifically, this product tabulates the results of a model in which each road-stream crossing is systematically upgraded (virtually) to a bridge having the minimum aquatic barrier score, one at a time, and the predicted improvement in aquatic connectedness from the upgrade is recorded. The delta, or difference, in the aquatic connectedness score, before and after the crossing upgrade for each cell within the affected neighborhood, is computed and multiplied by the average index of ecological integrity of the affected neighborhood. The weighting by the Index of Ecological Integrity emphasizes the potential ecological benefits of a crossing upgrade in an area that is otherwise in good condition but depressed by the crossing structure. Conversely, the score is lower where conditions are already so degraded that an upgrade would not improve local ecosystem conditions.
