Why Do We Need to Document and Conserve Foundation Species in Freshwater Wetlands?

Abstract

Foundation species provide habitat to other organisms and enhance ecosystem functions, such as nutrient cycling, carbon storage and sequestration, and erosion control. We focus on freshwater wetlands because these ecosystems are often characterized by foundation species; eutrophication and other environmental changes may cause the loss of some of these species, thus severely damaging wetland ecosystems. To better understand how wetland primary producer foundation species support other species and ecosystem functions across environmental gradients, we reviewed ~150 studies in subtropical, boreal, and temperate freshwater wetlands. We look at how the relative dominance of conspicuous and well-documented species (i.e., sawgrass, benthic diatoms and cyanobacteria, Sphagnum mosses, and bald cypress) and the foundational roles they play interact with hydrology, nutrient availability, and exposure to fire and salinity in representative wetlands. Based on the evidence analyzed, we argue that the foundation species concept should be more broadly applied to include organisms that regulate ecosystems at different spatial scales, notably the microscopic benthic algae that critically support associated communities and mediate freshwater wetlands’ ecosystem functioning. We give recommendations on how further research efforts can be prioritized to best inform the conservation of foundation species and of the freshwater wetlands they support.

Characteristics, Main Impacts, and Stewardship of Natural and Artificial Freshwater Environments: Consequences for Biodiversity Conservation

“…A phase of low rainfall is followed by a phase of rainfall concentration, when discharge increases result in a flood pulse [533] in catchments, and the waters flood and rise in low-land areas and results in the most typical freshwater feature in the tropical landscape, i.e., wetlands. According to some authors [534], tropical and subtropical ( Figure 1AF) freshwater wetlands (e.g., [50]) are dominated by (1) floodplains, (2) peatlands, and (3) swamps. The array of tropical freshwater habitats is completed by several (4) large river systems (e.g., [52]), and (5) lakes ( Figure 1AE).…”

“…The colonization by organisms with specific adaptations makes mires very important for nature conservation [351,356]. Generally, they are threatened by various direct impacts (e.g., land reclamation, peat extraction, drainage, organic pollution and eutrophication; [50,357,358]) that cause their fragmentation, loss of specialized organisms [359], or even complete destruction. One per cent of the land area of the planet is covered by peat bogs, and Europe has lost about 62% of this habitat type in recent decades [360].…”

“…A complex nature of fen and bog ecosystems, including multiple environmental gradients and successional trajectories, crucial effects of Holocene development, the great role of ecosystem engineers belonging to less known groups of organisms such as microorganisms including testate amoebae and diatoms, or bryophytes [50,343,395,396], and high representation of habitat specialists with less known ecological preferences, makes the prediction of the future of mires difficult. Further research should disentangle relationships between individual groups of organisms, and between organisms and their environment, in order to better understand these fascinating ecosystems and to find a way how to preserve them at the largest possible geographical and environmental extent.…”

“…We also briefly explore what can be done to protect or restore these ecosystems. We thus aim at addressing the multiplicity of still and running freshwater environments, from headwaters down to large rivers and lakes (papers published in the VSI are cited in the following): groundwater and dependent ecosystems, springs and spring-fed streams [40][41][42][43][44][45], headwaters [46,47], glacial streams [48], streams, large rivers, ancient and large lakes, high-mountain lakes, oxbow lakes, reservoirs, urban freshwater habitats (fwh) [49], mires [50], small wetland ecosystems [51], Boreal and Arctic fwh, Antarctic fwh, Mediterranean fwh, tropical fwh [52], arid-climate fwh ( Table 1; the ecosystem types addressed and flagship organisms are illustrated in Figures 1 and 2).…”

Development of the Wetland Condition Index (WCI) by Combining the Landscape Development Intensity Index (LDI) and the Water Environment Index (WEI) for Humid Regions of China

“…Wetlands are known to be essential providers of valuable ecosystem services and functions, including the provision of habitat and biodiversity, water quality improvement, flood abatement, carbon sequestration, the source of food, and support of recreational activities [1][2][3][4]. Unfortunately, due to various natural and human factors, such as climate change, water pollution, and reclamation, wetlands have suffered severe losses and degradation around the world [5][6][7][8].…”