Quantifying ecological filters: the relative impact of herbivory, neighbours, and sediment on an oligohaline marsh

Abstract

The objective of this experiment was to quantify the relative importance of herbivory, interactions with neighbours and sediment addition as filters in controlling the species present in an oligohaline marsh in southeastern Louisiana, USA. We planted 16 species of wetland plants in 3)3 m plots either inside or outside herbivore exclosures, with or without presence of established vegetation, and with or without added sediment. These species, representing 12 families and diverse morphologies, included herbaceous and woody plants. At the end of the growing season above-and below ground biomass were measured. In cleared plots (no neighbours) inside herbivore exclosures, 12 of the 16 species grew well, indicating that they could tolerate the physical conditions in the habitat. Competition significantly reduced the biomass of four of these species (A. calamus, C. occidentalis, P. hemitomon, P. cordata ), suggesting that it is the strongest species-specific filter operating in the marsh. These results confirm the general consensus that competition from existing plants is the strongest filter operating in high biomass habitats, and further imply that competition has the potential to remove 33% of the species from the community. Facilitation occurred for one species, R. corniculata. Herbivory had the largest general effect of reducing biomass, as determined in the full ANOVA model, but on a species-specific basis, significantly reduced the biomass of only two species (T. distichum, T. domingensis ). These results support the emerging view that herbivory is an important filter in coastal wetlands. Although several other studies have argued for the importance of sedimentation in controlling plant species composition in wetlands, we found no effect of sediment addition. Competition and herbivory appear to be two critical biological filters that control plant composition of coastal wetlands, and they must be considered in future studies and restoration efforts along the Gulf of Mexico.

Emergence of Summertime Hypoxia and Concurrent Carbonate Mineral Suppression in the Central Bohai Sea, China

“…However, a geographic information system‐based study (supported with satellite imagery analyses) suggested that coastal reclamation shortened the natural coastline of Bohai Sea from 1,397 km in 1990 to 561 km in 2014 (Hou et al, ). According to some researchers (e.g., Comín et al, ; Crumpton, ; Geho et al, ), these changes may decrease the nutrient filtration effect of coastal wetlands. Moreover, the local marine aquaculture yield increased by 20 times from 1985 to 2002, directly discharging a large amount of nourished sewage into the Bohai Sea (Cui et al, ).…”

Rates of local colonization and extinction reveal different plant community assembly mechanisms on road verges in central Spain

“…Species regional persistence is then governed through the processes of colonization, extinction and recolonization within patches of suitable habitat (Freckleton & Watkinson 2002). Habitat suitability is, in turn, determined by environmental filters, which involve both environmental adversity, in terms of habitat stress and disturbance, and species interactions, ranging from facilitation to competition (Geho et al 2008). The dual nature of environmental filters is particularly evident along stress-productivity gradients in which plant recruitment is limited physiologically at one end and by competition at the other, respectively (Grime 1979).…”

Performance and fate of tree seedlings on and around nests of the leaf-cutting ant Atta cephalotes: Ecological filters in a fragmented forest

“…In other words, we tested the potential of A. cephalotes nests to function as ecological filters. Nests would act as ecological filters if their presence benefits plant species different from those favoured in the undisturbed forest understorey following the concept of pools and filters (sensu Keddy 1992; Geho et al . 2007).…”