A six-year grazing exclusion changed plant species diversity of a Stipa breviflora desert steppe community, northern China

Abstract

Excluding grazers is one of most efficient ways to restore degraded grasslands in desert-steppe communities, but may negatively affect the recovery of plant species diversity. However, diversity differences between grazed and fenced grasslands in desert-steppe are poorly known. In a Stipa breviflora desert steppe community in Northern China, we established six plots to examine spatial patterns of plant species diversity under grazed and fenced conditions, respectively. We addressed three aspects of species diversity: (1) The logistic, exponential and power models were used to describe the species-area curve (SAR). Species richness, abundance and Shannon diversity values change differently with increasing sampling areas inside and outside of the fence. The best fitted model for SAR was the logistic model. Excluding grazers had a significant impact on the shape of SAR. (2) Variograms was applied to examine the spatial characteristics of plant species diversity. We found strong spatial autocorrelations in the diversity variables both inside and outside the fence. After grazing exclusion, the spatial heterogeneity decreased in species richness, increased in abundance and did not change in Shannon diversity. (3) We used variance partitioning to determine the relative contributions of spatial and environmental factors to plant species diversity patterns. Environmental factors explained the largest proportion of variation in species diversity, while spatial factors contributed little. Our results suggest that grazing enclosures decreased species diversity patterns and the spatial pattern of the S. breviflora desert steppe community was predictable.

Responses of Individual Plant Species, Functional Groups, <em>α</em>- and <em>β</em>-Diversity to Short-Term Grazing Exclusion under Severe Drought Episode in Long-Term Grazed Alfa-Steppes

“…This is consistent with the increase in mean richness at the transect level witnessed in the exclosures. Overall, this finding is in line with other studies that reported that the exclusion of livestock grazing can alter species composition and competitive relationships within plant communities (Jing et al 2013, Wang et al 2018b. Conversely, other studies have confirmed the role of grazing in the enhancement of fine-scale variability of species composition by increasing fine-scale environmental heterogeneity through selective grazing [sheep, in particular, are more selective than other herbivores (Tóth et al 2018)], trampling, deposition of excreta, and by acting as dispersal agents (Limb et al 2018, Wang et al 2018a).…”

Litter addition decreases plant diversity by suppressing seeding in a semiarid grassland, Northern China

“…Furthermore, abandonment or closure significant increases the accumulation of plant litter (Hosseinzadeh, Jalilvand, & Tamartash, ), which had stimulated effect (Eckstein & Donath, ; Rotundo & Aguiar, ) or inhibit effect (Jensen et al, ; Xiong & Nilsson, ) on plant species richness. Mowing and fire, which reduce the amount of plant litter (Davidson et al, ; Larreguy, Carrera, & Bertiller, ; Trammell, Rhoades, & Bukaveckas, ), usually have a significant positive impact on plant community diversity (Ibanez et al, ; Wang, Yang, et al, ). Therefore, there may be inconsistent responses of plant community species diversity or richness to litter addition and removal.…”

Litter accumulation alters the abiotic environment and drives community successional changes in two fenced grasslands in Inner Mongolia

“…However, although long-term fencing can facilitate the restoration of vegetation and soil in degraded grasslands (Liu, Wu, Su, Gao, & Wu, 2017;Wang et al, 2018), it can also create new issues. For example, long-term fencing results in excess litter accumulation on the soil surface, particularly in arid and semiarid grasslands.…”

“…Of all restoration methods, fencing appears to be an effective and practical method for restoring degraded grasslands, especially for those subjected to overgrazing (Jing, Cheng, & Chen, 2013;Wu, Du, Liu, & Thirgood, 2009). However, although long-term fencing can facilitate the restoration of vegetation and soil in degraded grasslands (Liu, Wu, Su, Gao, & Wu, 2017;Wang et al, 2018), it can also create new issues. For example, long-term fencing results in excess litter accumulation on the soil surface, particularly in arid and semiarid grasslands.…”