Effects of the hummock–depression microhabitat on plant communities of alpine marshy meadows in the Yellow River Source Zone, China

Abstract

Aims Our objectives are to examine the effects of hummock-depression spatial heterogeneity on plant communities and soil properties, and to understand the process of maintaining and adjusting microtopography-mediated hydrological inputs and their spatial fluctuations that produce obvious micro-habitats. Methods We set up 36 plots (1m×1m) and sampled 45 plant and 225 soil samples in flooded and non-flooded hummocks and depressions of the marshy, and the surrounding non-wetland meadows as well as in the Yellow River Source Zone, west China. We evaluated whether the alpine marshy wetland has a fertile-island effect by the comparison method. Important Findings Our results show that hummock presence can increase the spatial heterogeneity of the microhabitat and promote the plant diversity and soil fertility of the Kobresia tibetica community. Plant height, coverage, above-ground biomass, species richness and diversity were significantly higher in the flooded and non-flooded hummock microhabitat than in the areas between hummocks and surrounding non-wetland meadows. Compared with broad alpine meadows, the hummock-depression complex provided a microhabitat favourable to the growth of Cyperaceae. In the 0-50 cm soil layer, the closer the soil layer was to the ground surface, the higher its soil organic carbon and total nitrogen contents. Thus, in deeper layers, the gap between soil nutrients in wetland hummock-depression microhabitat and in the surrounding alpine meadows become smaller. Hence, the wetland hummock-depression microhabitat formed a fertile-island pattern. Therefore, these results contribute towards improving our understanding of ecosystem restoration in alpine marshy meadows.

A Novel Approach to Detecting the Salinization of the Yellow River Delta Using a Kernel Normalized Difference Vegetation Index and a Feature Space Model

“…The relationships between the green normalized difference vegetation index (TGDVI) and soil salinity were significantly different between time and space. They were highly sensitive to factors such as the geomorphological characteristics, the vegetation type, and the geographical environment [25]. However, most of these study areas were located in coastal areas, which demonstrated climate change characteristics including dry-wet alternations; therefore, they could not ensure the stability of the vegetation index [26].…”

“…Figure 3 shows the spatial distribution of point groups at different salinization levels in the KNDVI-SI feature space. There are significant differences in the spatial distribution was prepared to determine the soil salinity [25]. Finally, the mean value of every 5 soil sampling points was taken as the observation value of the soil measurement unit Among them, the treatment of the soil samples and the determination of the water and salt content were carried out by the analysis and test center of Shandong University of Technology.…”

“…The collected soil samples were naturally air-dried and crushed, and other intrusions were removed; they were then sieved with a 1 mm sieve and mixed evenly. A quartering method was used to create a 200 g sample, and a 1:5 soil/water ratio extract was prepared to determine the soil salinity [25]. Finally, the mean value of every 5 soil sampling points was taken as the observation value of the soil measurement unit.…”

Variations and Factors Characterizing Ecological Niches of Understory Herbaceous Species in Plantation Forests

“…However, species with a larger niche overlap usually had a larger niche breadth [35]. Species with a high niche overlap also occurred among species with narrower niche widths due to the high spatial heterogeneity of the resources of different species and the different capacity of each species to use the resources [36]; these species included Gypsophila licentiana, Stipa grandis, Hedysarum alpinum, and Setaria viridis. No obvious linear relationship was found between the population niche width and niche overlap.…”