Effects of disturbances on aboveground biomass of alpine meadow in the Yellow River Source Zone, Western China

Abstract

A field experiment quantifies the impacts of two external disturbances (mowing‐simulated grazing and number of pika) on aboveground biomass (AGB) in the Yellow River Source Zone from 2018 to 2020. AGB was estimated from drone images for 27 plots subject to three levels of each disturbance (none, moderate, and severe). The three mowing severities bear a close relationship with AGB and its annual change. The effects of pika disturbance on AGB change were overwhelmed by the significantly different AGB at different mowing severities (−.471 < r < −.368), but can still be identified by inspecting each mowing intensity (−.884 < r < −.626). The impact of severe mowing on AGB loss was more profound than that of severe pika disturbance in heavily disturbed plots, and the joint effects of both severe disturbances had the most impacts on AGB loss. However, pika disturbance made little difference to AGB change in the moderate and non‐mowed plots. Mowing intensity weakens the relationship between pika population and AGB change, but pika disturbance hardly affects the relationship between mowing severity and AGB change. The effects of both disturbances on AGB were further complexified by the change in monthly mean temperature. Results indicate that reducing mowing intensity is more effective than controlling pika population in efforts to achieve sustainable grazing of heavily disturbed grassland.

A bibliometric analysis of research trends and hotspots in alpine grassland degradation on the Qinghai-Tibet Plateau

“…Continuous grazing causes a decrease in vegetation height and an increase in weed growth, triggering a large increase in plateau zokors and pikas, which further exacerbate grassland degradation by digging and gnawing on the turf ( Li-Zhi et al, 2002 ). Yan, Jay & Brierley (2022) found that the combined effects of sage-grouse and grazing disturbance reduced aboveground biomass, and that the greater the sage-grouse population, the more intense the competition for food and subsistence space, leading to more biomass loss from these animals nibbling on the soil substrate. In addition, the synergistic effects of grazing activities and pika burrowing affect plant composition, soil properties, and spatial patches in alpine grasslands ( Cao et al, 2021 ; Du & Gao, 2021 ; Wang et al, 2020 ).…”

Spatiotemporal Variability of Alpine Meadow Aboveground Biomass and Sustainable Grazing in Light of Climate Warming

“…In spatial terms, pika inhabit the flat areas close to water resources at the valley bottom, they do no damage to vegetation elsewhere (Wu et al 2019). Shi et al (2022) showed that controlling pika population had little effect on increasing AGB if grassland was grazed, especially in severely degraded alpine grassland. Livestock and pika have coexisted for thousands of years in the alpine grassland (Badingquiying et al 2018).…”

“…On average, an adult pika devours 77.3 g of fresh grass per day (Fan et al 1999), equivalent to 11.37 kg of dry matter per year (P 1 ). P 2 is the biomass loss caused by pika-induced grassland degradation (e.g., no AGB is produced on bare ground) and its annual value is about 1.6 kg of dry matter per pika (Shi et al 2022). D is the active burrow density recorded in the field (D = 380 active burrows per ha), and b is the burrow coefficient (Active burrow/pika population = 4.68 for moderately disturbed areas) (Liu et al 2003; Sun 2008).…”

“…dry matter per pika ( Shi et al 2022 ). D is the active burrow density recorded in the field (D = 380 active burrows per ha), and b is the burrow coefficient (Active burrow/pika population = 4.68 for moderately disturbed areas) ( Liu et al 20 03 ; Sun 20 08 ).…”

Variability in soil nematode communities across recovery patches in degraded Alpine meadows of the Yellow River source region

“…In past few decades, the degraded alpine meadow in the source region of the Yellow River was ecologically restored by banning pika activities (Sun et al, 2023). Currently, numerous research projects have been carried out on plant community biodiversity (Wu et al, 2014;Liu et al, 2020), primary productivity (Che et al, 2017;Zhang et al, 2019a;Shi et al, 2022) and soil microbial biodiversity (Che et al, 2019; in relation to ecological restoration of patch alpine meadow. While some studies have been conducted on underground soil fauna and their species composition, there is a scarcity of research on the ecological function of the underground microfood web in grassland restoration (Wang et al, 2022b).…”