Tiny wetlands, big effects

This landscape in west-central Florida contains a diverse portfolio of wetlands that vary in size, shape, and connectivity. Many of these are geographically-isolated wetlands.

Good things sometimes come in small packages. Check out this article, that the Lewis Lab participated in, on the importance of small wetlands, high in landscapes, for big ecological functions. This work was led by Matt Cohen, at the Univ. of Florida, and emerged from an EPA-hosted working group.

Landscapes consist of a patchwork of many ecosystems, and they provide services such as the generation of biodiversity, maintenance of key plant and animal populations, storage of water to prevent flooding and ensure available water during dry spells, and the capture of nutrients and sediments to prevent pollution of rivers and bays. Analyses in this paper support the concept that the provision of these services by landscapes depends on a portfolio of many wetlands that vary in size, shape, and connectivity. A host of landscape functions, this paper argues, require the portfolio to include geographically isolated wetlands (GIWs). Owing to their landscape characteristics, these GIWs shelter organisms, sequester captured pollutants, and are connected to other ecosystems in landscapes through sometimes hidden avenues, such as through migration and groundwater flow. This finding has important implications for whether legislation and policies concerned with the quality and biotic integrity of larger rivers and bays should include protection of the many small GIWs that help regulate what materials escape landscapes and enter these waterways.

Geographically isolated wetlands tend to be smaller wetlands (solid black line in upper panel), and more circular. Larger wetlands tend to have irregular shapes (larger perimeter:area ratios; green dots) that deviate from circularity, which is important because many ecological functions happen on the edges of ecosystems where reactants and organisms can mix. Despite the irregular shape of large wetlands, it is small wetlands that provide most of the “edge” habitat in a landscape, as the bottom panel shows that as wetland size decline, area drops off before perimeter length does. (Modified from Cohen et al. 2016, PNAS)

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