Impacts of sedimentation and nitrogen enrichment on wetland plant community development

Abstract

Many factors influence which plant species are found in a particular wetland. The species pool is composed of the species present in the seed bank and species able to disperse into the wetland, and many abiotic and biotic factors interact to influence a species performance and abundance in the plant community. Anthropogenic activities produce specific stressors on wetland systems that alter these abiotic and biotic interactions, potentially altering species composition. We simulated three common wetland hydrogeomorphic ͑HGM͒ subclasses in a greenhouse to examine the effects of two stressors-sedimentation and nitrogen ͑N͒ enrichment-on the performance of 8 species grown in artificial communities. Species establishment, height, biomass, and foliar N and P concentrations were measured to explore species responses to stressors and competition, as well as the potential impacts of changes in species composition on ecosystem processes. Species were affected differently by sedimentation and N enrichment, and there were differences in overall community sensitivity to stressors between wetland subclasses. Sedimentation generally reduced seedling establishment, while N enrichment produced variable effects on height and biomass. Interspecific competition had little effect on establishment but significantly reduced most species biomass. Sedimentation generally lowered community biomass, diversity, and richness, while enrichment increased community biomass. Establishment, biomass, and foliar nutrient concentrations significantly differed between many species, suggesting that shifts in species composition may impact ecosystem processes such as nutrient cycling and carbon storage. Phalaris arundinacea, an aggressive clonal graminoid, universally dominated all wetland subclasses. This dominance across a range of environmental conditions ͑sedi-mentation, fertility, and hydrology͒ has important implications for both restoration and predicting the impacts of human activities on species composition. Our results suggest that, in regions where P. arundinacea is common, restoration projects that establish communities from seeds and human activities that cause vegetation removal are likely to become dominated by P. arundinacea.

Gravel pads of powerline towers as human-made habitats for ruderal vegetation in some Mediterranean wetlands of Egypt: Implications for management

“…Such spatial configuration of benched and graveled pads may facilitate the invasion and spread of ruderal plants into the intersected wetlands. In addition, the installation of these terrestrial barriers in water may induce sediment deposition and nutrient enrichment which change plant community development and create appropriate microhabitats for the establishment of non-native plants in wetlands (Miller and Zedler, 2003;Mahaney et al, 2004;Dube´et al, 2011).…”

Human Land-Use and Soil Change

“…Freeland et al (1999) found that there were higher rates of deposition in wetlands adjacent to cultivated fields in North Dakota. Sediments and nutrients deposited in wetlands impact the vegetation and hydrology of the systems (Mahaney et al 2005;Preston et al 2013).…”

Assessing the relative vulnerabilities of Mid‐Atlantic freshwater wetlands to projected hydrologic changes

“…), via changing hydrologic patterns, sedimentation, and nutrient enrichment (Wardrop and Brooks , Mahaney et al. , ).…”