Long‐term changes in marsh vegetation in Sanjiang Plain, northeast China

Abstract

Questions Is there a consistent change in species composition and species richness across the communities along the wetness zonation? Which species are sensitive to environmental changes? Has species richness increased or decreased? What are the relative effects of climate, geographical position and local environmental factors on the inland marsh community? Location Sanjiang Plain, northeast China (130–133° E, 45–48° N). Methods A total of 94 plots were re‐surveyed in 2012 and compared with data from 1973. Detrended correspondence analysis (DCA) and indicator species analysis were used to analyse the direction and nature of change in community composition between 1973 and 2012. Paired t‐test was used to test for change in species richness, water level and soil variables between the two surveys. Correlation and step‐wise regression analyses were used to test the relationship between vegetation change (species richness and DCA scores), environmental variables and geographic position. Results Vegetation has changed towards a drier state, with the greatest changes in the wettest Carex lasiocarpa community and the smallest changes in the driest Calamagrostis angustifolia community. The frequency and cover of hygrophilous species and species typical of oligotrophic wetlands decreased, while grasses and other non‐marsh species increased. Species richness per community and per plot increased over time. The dynamics within each community was only weakly correlated with biogeographic predictors: longitude, latitude, elevation and annual precipitation. Conclusions Hydrology was the main factor controlling changes along the marsh zonation, and was most likely in response to climate warming and land‐use changes. The different responses among the marsh communities along the zonation and between hydrophytes and other species imply that future protection and management need to be based on community type and plant functional types.

Response of Plant Height, Species Richness and Aboveground Biomass to Flooding Gradient along Vegetation Zones in Floodplain Wetlands, Northeast China

“…In addition, the negative correlation between species richness and water depth in two Carex communities indicated that species number per plot would show increasing trends with the habitat drying, similar to the result of Dwire et al [ 38 ], and confirmed by a long-term study by Lou et al [ 39 ]. Furthermore, this also demonstrated that the water table depth of the growing season is a significant predictor of species diversity for marsh vegetation.…”

“…Significantly, this is a pseudo-correlation statistically, and resulted from the fact that aboveground biomass increased as flooding depth decreased along the vegetation zone. So with the habitat drying resulted from human activity and climate warming in this region marshes [ 39 ], vegetation productivity and carbon sequestration in this temperate freshwater marshes would increase by species replace and community succession.…”

Modeling the Spatial Distribution of Three Typical Dominant Wetland Vegetation Species’ Response to the Hydrological Gradient in a Ramsar Wetland, Honghe National Nature Reserve, Northeast China

“…A water level decrease was the factor most clearly related to the changes along the marsh zonation. The temperature showed an increasing trend, while precipitation fluctuated without a trend; this would result in a decline in humidity [44]. These findings indicate that if the drying of wetlands in this region continues, then Carex lasiocarpa and Carex pseudocuraica marshes will gradually be replaced by Calamagrostis angustifolia wet meadows in the near future.…”

“…Hydrological conditions have been demonstrated to be the main factor controlling changes in vegetation community composition in the Sanjiang Plain [11,34,44]. How the probability of occurrence varies between different plant species in response to an increasing hydrological gradient may play an important role in the distribution of vegetation zones in these freshwater marshes.…”

Soil Degradation Effects on Plant Diversity and Nutrient in Tussock Meadow Wetlands

“…Variations of community characteristics, including community structure, species composition and plant diversity, are common ecological phenomenon in wetland ecosystem (Lou et al 2015(Lou et al , 2018. Previous studies have highlighted that plant diversity and community composition can change in responses to environmental fluctuations, especially with a variation of soil physiochemical properties (Ma et al 2017;Wang et al 2018a).…”