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Highlights • Biodiversity-productivity relationship in the grasslands of QTP varied along the spatial scales. • Species richness positively related to above- and below-ground biomass at landscape scale. • Shannon–Wiener index positively related to above- and below-ground biomass at landscape scale. • Pielou evenness index negatively related to above- and below-ground biomass at landscape scale. • Plant biomass partitioning between root and shoot was independent of plant diversity at all scales. Abstract There is no consensus about the relationship between plant species diversity and productivity in grasslands. Lack of consensus might be caused by different diversity metrics used and different spatial scales examined. In particular, the impacts of different biodiversity indices on the plant diversity–plant productivity relationship of alpine grasslands at different spatial scales of the Qinghai–Tibetan Plateau (QTP) require investigation. We investigated the relations of multi-dimensional diversity indices (species richness, Shannon–Wiener diversity, and Pielou evenness) with aboveground and belowground plant biomass in the alpine grasslands of the QTP by linear mixed model (LMM). We assessed the plant diversity and biomass of alpine meadow, alpine steppe, and alpine desert steppe from 5 sites across the vast landscape of the QTP by using 6 randomly placed plots in each site and 27 replicated quadrats in each plot. The species richness of the studied alpine grasslands ranged from 2 to 35, aboveground plant dry biomass ranged from 17 to 838 g m−2, and belowground plant dry biomass ranged from 398 to 3945 g m−2. The species richness and Shannon–Wiener indices were positively correlated with aboveground plant biomass and belowground plant biomass at the landscape scale, whereas the Pielou evenness index was negatively correlated with aboveground plant biomass and belowground plant biomass at the landscape scale. Less than 20% sites showed significant relationships between plant diversity indices and plant biomass at site scale. Plant biomass partitioning between the root and shoot was not correlated with the species richness, Shannon–Wiener and Pielou evenness indices at all scales. The plant diversity–biomass relationships of the alpine grassland ecosystems in the QTP depend on both the type (or dimension) of the biodiversity index and the spatial scale of sampling. Thus, the design and implementation of plant diversity conservation should consider different dimensions of plant diversity. It is not enough to increase species richness only in the process of grassland restoration and conservation, but also to reduce species evenness so as to promote productivity more fully, for example, in planting artificial grassland. [ABSTRACT FROM AUTHOR]

• Restoration actions improved community species richness, target species richness and target species aboveground biomass, not community biomass. • Community species richness was impacted by the restoration strategies. • Community biomass was impacted by the mean annual precipitation and temperature. • Recovery performance of target species was impacted by all the influencing factors. Ecological conservation and restoration projects in Three-river Headwater Region (TRHR) have been implemented to respond to the serious degradation of alpine meadow ecosystem. Compared with the substantial amount of studies on the recovery of plant communities, soil quality and ecosystem services, few studies have focused on the restoration performance of target species. Therefore, we conducted this study to analyze the dynamics and underlying mechanisms of species richness and aboveground biomass of plant communities and target species. The results showed that restoration actions (grassland cultivation and fencing) did not significantly improve the community aboveground biomass of the degraded alpine meadows, while the actions did significantly promote community species richness, target species richness and target species aboveground biomass. Community species richness (20%-45%) was significantly impacted by the restoration strategies, and community aboveground biomass (31%-53%) was impacted by the mean annual precipitation and mean annual temperature. The species richness (57%) and aboveground biomass (63%) of the target species were directly and indirectly impacted by restoration actions, climatic factors, biotic factors and soil factors. The implications of this study stress that target species should be highlighted in assessing the restoration success of degraded alpine meadows. Integrating climatic factors, target species and other biotic and abiotic indicators could help us better understand and evaluate restoration actions for degraded alpine meadows in the TRHR or other similar regions worldwide. [ABSTRACT FROM AUTHOR]

• Responses of different functional groups to overgrazing and overgrazing with N deposition varied. • Overgrazing and overgrazing with N deposition provided a favorable living environment for forbs. • Overgrazing with N deposition obviously promoted forbs dominance both directly and indirectly. Alpine grasslands are sensitive to grazing and atmospheric nitrogen (N) deposition. Despite increases in N deposition, few field studies have assessed the effects of grazing in conjunction with increased N deposition on alpine grassland vegetation. In this two-year field study, we examined the effects of overgrazing and overgrazing plus N deposition on eco-physiological processes of alpine grassland plants at the functional group level. We found that both overgrazing and overgrazing plus N deposition altered species composition and the dominance of three plant functional groups (grasses, sedges, and forbs) in an alpine meadow and alpine steppe. In the overgrazing and overgrazing plus N deposition treatments, forbs dominated the plant community. Grass and sedge dominance decreased substantially, relative to a ungrazed treatment. The underlying eco-physiological processes that led to the forb-dominated plant community differed between the overgrazing and overgrazing plus N deposition treatments. Overgrazing plus N deposition increased forb dominance both directly by selective herbivory and indirectly by enhancing forb photosynthetic rates. Our results suggest that overgrazing concomitant with increases in N deposition will likely shift the plant community composition of alpine grasslands on the Qinghai-Tibetan Plateau from grass/sedge communities to forb-dominated communities in the future. [ABSTRACT FROM AUTHOR]

• No functional traits connected both phylogeny and environmental factors. • N addition at 8 kg N ha-1year−1 filtrated the species of the gramineae. • N addition at 72 kg N ha−1 year−1 filtrated the species of non-gramineae. • Potassium in normal year and phosphorus in warm year were main factors of environmental filtering. Nitrogen (N) deposition and warming leads to environmental gradients that shape plant communities and ecological diversity, space is treated as an equally important variable as the environmental variables in the environmental gradients. The Qinghai-Tibetan Plateau (QTP) is very sensitive to large increases in N deposition rates and warming. Environmental gradients caused by N deposition and spatial factors act as environmental filtering in community assembly by affecting plant functional traits and phylogeny. To investigate the effects of environmental filtering caused by N deposition on the community assembly in alpine meadows, we randomly placed and fertilized at 6 levels of N addition (no N addition, 8 kg N ha-1year−1, 24 kg N ha−1 year−1, 40 kg N ha−1 year−1, 56 kg N ha−1 year−1 and 72 kg N ha−1 year−1) both in a normal (normal precipitation and normal temperature) year and a warm (normal precipitation and warm) year. We used the fourth-corner analysis and extended RLQ (R stands for a matrix of environmental variables by samples, L stands for a species-cover-by-samples matrix and Q stands for a species-by-traits matrix) through multiple factors (soil factors, spatial heterogeneity, species traits, phylogenetic factor) to examine the effects of environmental filtering on the community assembly in alpine meadows. The results demonstrated that all soil variables showed a clear gradient and were affected by simulated N deposition; N addition at 8 kg N ha-1year−1 can filtrate the species of the gramineae, but N addition at 72 kg N ha−1 year−1 can filtrate the species of non-gramineae, the main factors of environmental filtering were potassium in normal year and phosphorus in warm year. With the increase of N deposition rate in alpine meadow of QTP, non-gramineous plants will be favored first, but eventually gramineous plants will occupy the dominant position in the QTP. Rational mitigation strategies should be developed for different climate change scenarios of alpine grasslands on the QTP according to their responses to the N addition gradients and climate change scenarios in the future. [ABSTRACT FROM AUTHOR]

Over the last 40 years, a burrowing mammal eradication policy has been prevalent on the Qinghai–Tibetan Plateau (QTP). This policy is based on similar burrowing mammal eradication programs in other areas and is justified on the assumptions that burrowing mammals compete with livestock for forage and contribute to grassland degradation. However, there is no clear theoretical or experimental evidence supporting these assumptions.This paper synthesizes the ecological functioning of small burrowing mammals in natural grasslands and discusses the irrationality and consequences of burrowing mammal eradication for sustainable livestock grazing and grassland degradation.Past burrowing mammal eradication efforts have failed because increased food availability for the remaining rodents and reduced predator populations led to rapid population rebounds. Herbivores differ in diet, and there is clear evidence that burrowing mammals, especially plateau zokors Myospalax baileyi, have a different diet than livestock. In QTP meadows, burrowing mammal eradication induces a shift towards plant communities with fewer species preferred by livestock and more species preferred by burrowing mammals. Thus, eradicating burrowing mammals has the opposite effect, a reduction in livestock preferred vegetation. We suggest that the policy of poisoning burrowing mammals needs to be reconsidered and revoked as soon as possible.We argue that incorporating density‐dependent factors such as predation and food availability are essential for maintaining a low burrowing mammal density. For degraded grasslands, we suggest that the optimal sustainable approach is to decrease the intensity of livestock grazing. Lower grazing induces changes in vegetation structure and plant species composition that increases predation on burrowing mammals and decreases the abundance of plants preferred by burrowing mammals. Such a nature‐based grassland management system maintains the density of burrowing mammals at a low stable density while minimizing human management and interventions. [ABSTRACT FROM AUTHOR]

• Grazing reduced the temporal stability of ANPP. • Grazing increased the stability of productivity of functional group of forbs. • The response species to continuous grazing are mainly grasses. • The response species to rotational grazing are forbs. • Functional groups asynchrony stabilized ANPP under grazing in the Qinghai-Tibetan Plateau. The stability of grassland is pivotal in maintaining the grassland functioning and services. However, the knowledge about the consequences of grazing on stability of grassland productivity is limited. Based on a 3-year manipulated experiment with two grazing regimes (i.e., continuous grazing and rotational grazing) along four levels of grazing-intensity (0, 4, 6, and 8 sheep per hectare) on the Qinghai-Tibetan Plateau, we researched the responses of temporal stability of plant community and functional groups of alpine grasslands to different grazing management regimes. We found that grazing regimes, intensity and their interaction affected the temporal stability of aboveground net primary productivity of alpine grassland (ANPP), and intermediate rotational grazing significantly reduced the temporal stability of ANPP, whereas increased the stability of productivity of functional group of forbs. The response species to continuous grazing and rotational grazing are different, for grasses and forbs respectively. Rotational grazing and intermediate continuous grazing increased the diversity of response species. Structural equation modeling further revealed that functional groups asynchrony stabilized the productivity of the alpine grassland ecosystem under grazing in the Qinghai-Tibetan Plateau. These results showed that the rotational grazing and intermediate continuous grazing can maintain the productivity stability, and highlighted importance of regulating the relationships among functional groups for promoting the stability of alpine grassland under grazing management. [ABSTRACT FROM AUTHOR]

• The temporal stability of community biomass decreases with the time series. • The temporal stability of forb biomass increased with the time series. • Community asynchrony determined the temporal stability of plant community biomass. • Annual maximum and minimum temperature regulated the temporal stability of forb. Climate changes can affect the temporal stability of plant community biomass on the Qinghai-Tibet Plateau, but most studies were based on short-term field climate manipulation experiments. However, the response of biomass stability of natural alpine meadow remains largely unexplored. We conducted a 20-year experimental study monitoring aboveground biomass of plant functional groups (grass, forb and sedge) and community in eastern QTP, with linear regressions and a path analysis of: annual temperature, annual night minimum temperature, annual daytime maximum temperature, annual precipitation, annual daytime precipitation, annual night precipitation, biomass stability of grass, biomass stability of forb, plant functional groups asynchrony to assess the influence climate change and biological factors on the temporal stability of plant community biomass. We found that it was plant functional groups asynchrony rather than climate change that determined the temporal stability of plant community biomass. Our findings suggest that future climate change has a considerable uncertainty in the temporal stability of the plant community biomass in the alpine meadow and we should combine with both field climate manipulation experiments and long-term observational experiments to assess the influence of climate change on the temporal stability of plant community. [ABSTRACT FROM AUTHOR]

Integrating biodiversity and ecosystem services (BES) has been viewed as an appropriate approach to identifying conservation priorities. Taking Xishuangbanna tropical region in Southwest China, different BESs (habitat quality [used as a proxy for biodiversity], carbon storage, and water yield) were quantified using the InVEST model and conservation hotspots from 1976, 1990, and 2010 were identified by overlapping and ranking the service layers. Results showed that BESs areas were unevenly distributed. High habitat quality and carbon storage areas located in the eastern part of the region were mainly occupied by broad-leaved forest, while high water yield areas were covered by grassland and tropical forests. Recognized hotspots were primarily composed of the broad-leaved forest and shrub grassland. However, these habitat types declined by nearly 50% from 1.25×105 ha to 0.63×105 ha and became more fragmented during the study period. We also found that the sub-watersheds which decreased in BES had fewer hotspots distributed and suffered greater landscape fragmentation. Our study further explored the impacts of land-use conversion on BES, and illustrated the necessity and feasibility of BESs in identifying potential conservation areas. [ABSTRACT FROM AUTHOR]