Vegetation and its spatial pattern analysis on salinized grasslands in the semiarid Inner Mongolia steppe

Abstract

We determined how the vegetation and spatial heterogeneity (spatial variation) in species richness and species composition in salinized grasslands are affected by soil salinity level, and whether the Grime's hypothesis regarding species richness is accepted, to understand vegetation on salinized soil. To address these questions, we surveyed three grassland sites in Inner Mongolia. All sites had been degraded heavily by livestock grazing, and had different salinity levels: heavy (electrical conductivity 1.18–8.15 dS m−1), intermediate (0.38–0.70 dS m−1) and non‐salinized (0.07–0.20 dS m−1). We set 50 square quadrats (0.25 m2 per quadrat), divided into four sub‐quadrats (0.0625 m2 each), along two 25 m transects in each site, and recorded all plant species in each sub‐quadrat. The species richness of the sites per 0.25 m2 was in the order: intermediate salinity > non‐salinized > heavy salinity. At the heavy and intermediate sites, the spatial heterogeneity of vegetation per sub‐quadrat was higher than expected from a random pattern, but not at the non‐salinized site. At the heavily salinized site, the spatial patterns of two halophytes with the highest occurrences drove the high spatial heterogeneity in species richness. In contrast, at the non‐salinized site, two low‐level halophytes with the highest occurrences determined the random pattern. The intermediate salinity site, where high‐ and low‐level halophytes could coexist in accordance with small‐scale spatial changes in salinity, had the highest species richness with relatively high spatial heterogeneity (which accepted the Grime's hypothesis). Our working hypothesis for remediating vegetation and soil in salinized grasslands is to inhibit grazing, and to grow species that accumulate organic matter in soil. For this, halophyte species with large spatial heterogeneity/body size would be effective.

Grazing enhances species diversity in grassland communities

“…The proposed grazing model integrated with a microhabitat locality model 22 should be sufficient as a canonical model with which to investigate the functional mechanisms of herbivore grazing effects mathematically. In terms of maintaining and increasing diversity, our results are in line with those of some empirical studies 2,15–18,27,28 . For example, Komac et al .…”

“…In Himalayan rangelands, moderate grazing increases diversity 17 . Heavy grazing indirectly influences species richness in Inner Mongolian grassland sites 18 . Thus, explanations of why and how an increase in grazing intensity promotes the coexistence of many more species are needed.…”

A System Analysis on Steppe Sustainability and Its Driving Forces—A Case Study in China

“…The other was that the driving forces of precipitation and air temperature were significantly stronger in semi-humid/humid area than semi-arid/arid area, while the driving force of sunshine duration were basically same in both type of areas. There were similar conclusions with the first point at the global and national scales in previous studies [7,22,54,97,98], while the driving forces on ecosystem productivity dynamics at smaller scales presented obvious spatial heterogeneity in different regions [58,69,93,[99][100][101][102]. The second point reveals that steppe sustainability is more susceptible to disturbances resulting from precipitation and temperature factors in semi-humid/humid area than semi-arid/arid area, but the effect of sunshine duration is stable in both type of areas.…”

“…The previous studies mainly focused on steppe degradation in arid and semiarid regions [51,52,54,58,[84][85][86]95]. However, we found the spatial diversity of steppe sustainability degradation distributed in all types of geomorphic regions as the Figures 2 and 3 shown.…”

The Application and Development of Statistical Technology in the New Times

“…The new normal of statistics [4] is inevitable when the economy enters the new normal state. When facing such a rapidly changing economic environment, the original statistical work attitude has been unable to adapt to the new situation of economic life.…”