The Type and Quantity of Plant Litter Influences the Plant Functional Group Growth in an Alpine Meadow

Plant functional group (PFG) diversity in a grassland is an important measure of productivity and health. Litter is known to be major driving factors of soil-grass feedbacks in natural grassland. The shift in PFG composition is a significant change that can result many ecological consequences such as litter composition and dynamics (Dong et al., 2019). Decomposition of litter can affect the nutrient and allelochemicals cycling of soil, which affects seed germination and establishment of seedlings (Yuan et al., 2015). Furthermore, PFG characteristics can vary via inputs of the quality or quantity of litter (Galvánek & Lepš, 2012). These compositional changes can result in variation heterogeneity of community PFG composition. More recently, alpine grasslands have undergoing retrogressive succession of spread and dominance by unpalatable noxious weeds, accumulating large amount of litter (Tang et al. 2015). However, quantitative tests of their importance in community dynamics are lacking, and their effects on the PFG characteristics of this special ecosystem are unknown. In this study, we investigated the effects of three species litter representing different successional stages of grassland on dynamics of PFG structure. Our aim was to elucidate the potentially interactive relationships between litter mass and litter species of different stage at PFG characteristics that can provide insights for sustainable management of grasslands

Legacy Effects of Herbivory Trampling on Soil Organic Carbon via Soil Properties, Plant Biomass and Functional Traits

Herbivores are important for ecosystem biogeochemistry, including soil carbon pools. Non-trophic interactions between herbivores and soil processes have recently gained attention, but remain underexplored. They include both direct and indirect effects of herbivore behaviour and physical soil disturbance by herbivores (e.g., trampling) causing compaction, and therefore probably influence historical contingency; however, little empirical data on the persistent impact or legacy effect of trampling and subsequent drivers of shifts are available. To address the knowledge gaps described above, we investigated whether the soil organic C (SOC) is driven by the legacy effect of sheep trampling intensity (0, 40, 80 and 120 footsteps m-2) in a typical steppe on the Loess Plateau. Cessation of trampling for two years, typical of historical trampling intensity, had positive effects on plant Shannon, Simpson, Pielou index, belowground biomass (BGB), soil available N (SAN), soil bulk density (SBD), community-weighted mean trait values of phosphorus (CWM_P) and SOC, but had negative effects on AGB, litter biomass (LB), CWM_C and soil moisture (SM). The effect of trampling increased with increased trampling intensity. LB, BGB, CWM_C, CWM_P, SBD, SAN and SM were the main drivers of trampling-mediated SOC. From the results of this study, trampling at 40 footsteps m−2 caused by sheep managed at a stocking rate of 2.7 sheep ha−1. This appears to be compatible with rangeland adaptive management. Ecosystem function can be maintained with high stocking rates by providing adequate deferment to re-establish sufficient cover and allow natural processes to restore soil processes

Enclosure Rather Than Topography Enhances the Soil Ecological Stoichiometry in Typical Steppe on the Loess Plateau, China

Grassland is one of the largest terrestrial ecosystems in the world, a large part of which is distributed in varied topography. And grazing and enclosure are the main ways to use this part. Grazing changes the soil structure through feeding, trampling and excreta return, thus affects the soil nutrients. The aspect mainly affects soil temperature and moisture by affecting solar radiation. The slope affects soil nutrients by affecting surface runoff. Water and temperature are the main factors affecting soil nutrients. We carried out to explore the effect of enclosure years and topography on soil ecological stoichiometry. The results showed that: soil organic carbon density, soil nitrogen density and soil phosphorus density increased with the increasing enclosure years and decreased with the increasing slope. Soil N/P (ratio between soil nitrogen density and soil phosphorus density) increased with increasing the enclosure years and the slope while soil C/N (ratio between soil organic carbon density and soil nitrogen density) decreased. Soil C/P (ratio between soil organic carbon density and soil phosphorus density) increased with the increasing enclosure years, however the trend with slope change was not obvious. The enclosure of sunny slope is more beneficial to soil nutrient accumulation

Community Asynchrony Increased Its Stability by Mediating the Relationship of Diversity–Stability Relationships in Loess Plateau, China

Extreme weather such as heavy rainfall and drought are threatening the global grassland and its potential to mitigate climate change. Therefore, understanding the drivers that promote the stability of grassland ecosystems is considered to be critical to mitigate the adverse effects of climate change on grasslands. Here, we use precipitation addition (PA) + grazing experiment to explain how species richness, aboveground biomass, species asynchrony, functional group level stability, drought tolerance and grazing tolerance can maintain grassland productivity stability. The results showed that grazing counteracted the promoting effect of rainfall on vegetation to a certain extent, and weakened the sensitivity of species of grazing tolerant functional group to rainfall. Rainfall and grazing affect the asynchrony of the community through the influence of drought tolerance and grazing tolerance functional groups, and then affect the stability of the community through the mediation of the relationship between aboveground biomass and species richness. This effect was significantly correlated with the differences of vegetation characteristics and resource acquisition strategies, but not with the community species richness. This study provides more explanations for the maintenance mechanism of community stability

Fe and MN Concentrations in Plants Correlated Negatively With Air Temperature Precipitation in Three Types of Grassland

Alpine meadows, typical steppe, and deserts are globally important grassland ecosystems. We investigated the seasonal trends in Fe and Mn concentrations in the dominant species and community of plants from diverse grassland types in northwest China. It was found that seasonal Fe and Mn concentrations in most plant species were negatively correlated with seasonal precipitation, biomass, and temperature. Additionally, seasonal Cu concentrations in Reaumuria soongorica was significantly correlated with seasonal precipitation. The seasonal mean temperature explained more of the seasonal variation of the Fe and Mn concentrations in the plant community of these grasslands than precipitation, except for the concentrations of Mn in typical steppe vegetation. However, there was almost no significant correlation between these factors and the seasonal Cu and Zn concentrations. These results provided a scientific basis for the assessment of plant trace elements in alpine meadows, typical steppes, and deserts around the world

The Role of Alfalfa and Forage Resources in Crop-Livestock Systems in a Rain-Fed Region of North-Western China

Western China has been facing the challenges of both environmental sustainability and economic development. Current government policies and interventions support the development of integrated crop-livestock production systems for enhancing food security and environment sustainability. Compared with traditional grain-based faming systems, integrated systems have better resource utilisation, however annual forage supply deficits estimated at 1.37 t DM forage/farm are experienced in the region, especially in late winter and early spring. Accordingly, optimising the use of available forage resources is a priority for regional researchers and extension officers, with research seeking pathways for better fodder conservation and greater and more effective use of fodder sources to close the spring feed gap. This paper presents relevant research activities relating to alfalfa (Medicago sativa L.) and winter wheat (Triticum aestivum L.) management in integrated crop-livestock production systems. As the planting of alfalfa is strongly encouraged in northern China, alfalfa species selection and optimised harvesting management are essential to ensure the full benefits of alfalfa are available for livestock intensification. The capacity for a prevalent grain crop, winter wheat to be managed as a dual-purpose fodder and grain source shows potential as a means to alleviate deficits of animal feed supply. The present information expands our understanding of integrated forage-livestock production in rain-fed areas, exploring options that can improve productivity in small-farm households leading to income generation