These maps are from a recent paper by JF Lapierre et al. that compared the factors that control lake CO2 at the continental scale. He found that the spatial patterns in lake pCO2 driver‐response relationships translated into the formation of spatial clusters of pCO2 “regulation” that are shown in map (e) even though there is little apparent regional pattern in pCO2 itself (shown in (d)).

 

The above figure legend reproduced here: 

“The spatially varying relationships of (a) Color, (b) alkalinity, and (c) Chl a with pCO2 in U.S. lakes. Colored dots on Figures a–c represent significant relationship between the proxy and pCO2 based on geographically weighted regressions. Colors indicate classes of t values (slope of the regression divided by standard error of the estimate), with red denoting a positive effect, blue denoting a negative effect, and white denoting no statistically significant effect on pCO2. Despite an absence of spatial pattern in (d) pCO2, the spatial patterns in lake pCO2 driver‐response relationships translated into the formation of (e) spatial clusters of pCO2 “regulation.” Clusters include lakes with comparable response of pCO2 to Chl a, Color, and tAlk (see Table ). Note that the map displays the boundary of U.S. territories, not just the land area.”

This map is from this article by Sarah Collins et al. It clearly shows how spatial patterns in TP and TN alone do not lead to similar patterns in the ratio of TN:TP.  Also, spatial pattern in TN and TP are similar, but not identical and there are some interesting outliers, e.g., Michigan lakes.  See the article for details on these cool patterns.

 

Emi Fergus et al. published a recent paper that describes the complex features of the freshwater landscape. These maps are very compelling in that they show that there are very different patterns between freshwater ABUNDANCE versus CONNECTIVITY.

FIGURE DESCRIPTION (Figure and text from Fergus et al. 2017): Freshwater abundance and connectivity maps by system type. Freshwater abundance is quantified as the total proportion area or stream density within the Hydrologic Unit (HU) 12 spatial unit for lakes (a), wetlands (b), and streams (c). Abundance values are binned as quantiles. Freshwater connectivity for lakes (d), wetlands (e), and streams (f) is represented by connectivity cluster groups determined by k‐means cluster group using principal components analysis (PCA) scores from lake, wetland, and stream connectivity metrics at the HU12 spatial scale. Dominated is in reference to where spatial units plotted on the PCA axes using relative proportion connectivity metric values. The solid black line represents the estimated boundary of the Wisconsin glacial period—north of the line is glaciated area and south of the line is unglaciated area.

This is a map of the full spatial extent of the LAGOS-US database that is currently being built by the Continental Limnology Research Team.