Impacts of wise grazing on physicochemical and biological features of soil in a sandy grassland on the Tibetan Plateau

Abstract

Desertification is a serious environmental problem on the Tibetan Plateau and various strategies, such as long‐term fencing and grazing management, have been implemented in that region to control the soil degradation. However, little is known about the role of interactions among the soil aggregate, microbial communities, and nutrient traits in the soil restoration. In this study, we compared the effects of different restoration strategies on the formation of aggregates, the amount and distribution of soil nutrients, as well as the abundance and diversity of bacteria in a sandy soil of grassland at the Tibetan Plateau. The results demonstrated that both the grazing exclusion (GE: artificial planting and nutrient addition) and wise grazing (WG: artificial planting and nutrient addition with controlled grazing) treatments significantly increased the proportion of macroaggregates (4.0‐and 5.2‐ times, p < 0.05) compared with the control. Increased soil organic carbon, total carbon, total nitrogen, and total phosphorus were found in the aggregates of WG treatment, but not in the GE samples. In addition, WG significantly changed the bacterial composition and increased bacterial abundance in soil. This study evaluated WG as an efficient management for restoration of degraded sandy grassland in the Tibetan Plateau because it significantly enriched the soil nutrients, improved the soil structure, and increased bacterial abundance. This is the first study to relate the aggregates with nutrient accumulation and bacterial community during the soil restoration in the Tibetan Plateau.

Change of soil physicochemical properties, bacterial community and aggregation during desertification of grasslands in the Tibetan Plateau

“…Our results revealed that the soil nutrients were positively correlated with soil aggregation, and the SOM contributed to the aggregation (Figures 5 and S2), which is similar to the results of previous reports (Bronick & Lal, 2005; Obalum, Chibuike, Peth, & Ouyang, 2017; Yang, Lv, & Li, 2015). The low soil nutrient content in the FMi of a sandy grassland of the Tibetan Plateau might explain the weak influence of FMi on soil aggregation (Zhang et al, 2019). The increase in the soil pH during desertification was also similar to that of previous studies reviewed by Six et al (2004) and might be related to the release of metal ions combined in the aggregates during their degradation.…”

“…Over the last three decades (1981–2010), this area has had a mean annual temperature of 1.7°C (from −9.0°C in January to 11.2°C in July) and mean annual potential evaporation of 1353.4 mm. The annual precipitation is approximately 615 mm, fluctuating greatly every year, of which 80% occurs during summer and autumn (Tian, Tian, Ka, & Du, 2015; Zhang et al, 2019). This area is an alpine meadow with aeolian sandy soil (Dong et al, 2010), corresponding to the Cambisols and Cryumbrepts in the WRB and USDA soil classifications, respectively, which are highly susceptible to wind erosion.…”

“…Primer sets 338F (5 0 -barcode-ACT CCT ACG GGA GGC AGC AG-3 0 ) and 806R (5 0 -GGA CTA CHV GGG TWT CTA AT-3 0 ) were used to amplify the V3-V4 region of the bacterial 16S rRNA gene (Srinivasan et al, 2012). PCR amplification was accomplished as described in our previous study (Zhang et al, 2019). A melting curve analysis was performed after each assay to ensure that only the products of the desired melting temperature were generated.…”

“…On the Tibetan Plateau, the area of desertified land increased in severity (207%) between 1975 and 1990, but decreased sharply after 2005, corresponding to the implementation of specific countermeasures (Hu, Dong, Lu, & Yan, 2015). Previously, various studies investigating the restoration of the degraded grasslands of different plateaus, including the Tibetan Plateau, have reported on the effects on soil microbes (Yao et al, 2018;Zhang et al, 2017Zhang et al, , 2019 and soil physicochemical properties (Zhang et al, 2019). However, the mechanisms behind grassland desertification and the interactions among soil aggregates, microbial communities and soil properties during the soil desertification process on the Tibetan Plateau are still poorly understood.…”

Simulated grazing and nitrogen addition facilitate spatial expansion of Leymus chinensis clones into saline‐alkali soil patches: Implications for Songnen grassland restoration in northeast China

“…For example, in China, more than 90% of the grassland have been degraded as a result of climate change, land use change, and unsustainable human management practices (Z. Zhang, Li, et al, 2019; Zhou et al, 2019). Degraded grassland restoration and vegetation reconstruction have been paid more consideration in the past several decades (Martin & Wilsey, 2006; Tölgyesi et al, 2019; N. N. Zhang, Sun, et al, 2019; F. Zhang et al, 2020; Zhou et al, 2019), and numerous recovery practices have also been successfully implemented to alleviate degradation and to increase the vegetation cover in degraded grasslands (e.g., K. Liu et al, 2020; Martin & Wilsey, 2006; Pykala, 2003; D. L. Wang & Guo, 2019; H. X. Zhang, Xiang, et al, 2019; L. P. Zhao et al, 2020). However, with widespread and accelerating degradation of grasslands, more efficient ecological measures are needed for the degraded grassland restoration.…”