Background: Grazing is an important land use in northern China. In general, different grazing intensities had a different impact on the morphological and physiological traits of plants, and especially their photosynthetic capacity. We investigated the responses of Leymus chinensis to light, medium, and heavy grazing intensities in comparison with a grazing exclusion control. Results: With light grazing, L. chinensis showed decreased photosynthetic capacity. The low chlorophyll and carotenoid contents constrained light energy transformation and dissipation, and Rubisco activity was also low, restricting the carboxylation efficiency. In addition, the damaged photosynthetic apparatus accumulated reactive oxygen species (ROS). With medium grazing, more energy was used for thermal dissipation, with high carotene content and high non-photochemical quenching, whereas photosynthetic electron transport was lowest. Significantly decreased photosynthesis decreased leaf C contents. Plants decreased the risk caused by ROS through increased energy dissipation. With high grazing intensity, plants changed their strategy to improve survival through photosynthetic compensation. More energy was allocated to photosynthetic electron transport. Though heavy grazing damaged the chloroplast ultrastructure, adjustment of internal mechanisms increased compensatory photosynthesis, and an increased tiller number facilitated regrowth after grazing. Conclusions: Overall, the plants adopted different strategies by adjusting their metabolism and growth in response to their changing environment.

The adaptation of plants to drought through the adjustment of their leaf functional traits is a hot topic in plant ecology. However, while there is a good understanding of how individual species adapt to drought in this way, the way in which different functional types adapt to drought along a precipitation gradient remains poorly understood. In this study, we sampled 22 sites along a precipitation gradient in the Inner Mongolia grassland and measured eight leaf functional traits across 39 dominant species to determine the adaptive strategies of plant leaves to drought at the species and plant functional type levels. We found that leaf functional traits were mainly influenced by both aridity and phylogeny at the species level. There were four types of leaf adaptations to drought at the functional type level: adjusting the carbon-nitrogen ratio, the specific leaf area, the nitrogen content, and the specific leaf area and leaf nitrogen content simultaneously. These findings indicate that there is the trade-offs relationship between water and nitrogen acquisition as the level of drought increases, which is consistent with the worldwide leaf economics spectrum. In this study, we highlighted that the leaf economic spectrum can be adopted to reveal the adaptations of plants to drought in the Inner Mongolia grassland.

Background: Vegetation succession is one of the major driving processes of grassland degradation. Stoichiometry significantly contributes to vegetation dynamics. However, a knowledge gap exists in how soil nutrients and root enzymes influence the stoichiometric ratio to affect vegetation dynamics. Methods: To address these questions, we selected a dominant species (Leymus chinensis (Trin.) Tzvel.) and a degraded-dominant species (Artemisia frigida Willd.) under different management regimes (enclosure and grazing) on the Inner Mongolia steppe. We measured (i) plant nutrient concentrations, (ii) root enzymes and (iii) soil nutrients to investigate how the selected plant species responded to grazing. Results: The results show that: (i) N and P concentrations and the C:N:P ratio in different organs are significantly affected by grazing, and there is variation in the plant species’ response. Grazing significantly increased N and P in the leaves and stems of L. chinensis and the stems and roots of A. frigida. (ii) Grazing significantly increased the activities of glutamine synthase but decreased the activities of acid phosphatase in L. chinensis. The nitrate reductase and acid phosphatase activities significantly increased in A. frigida under grazing conditions. (iii) Grazing decreased the total nitrogen, total phosphorus, and available nitrogen, but increased the available phosphorus in the soil. Conclusion: We conclude that A. frigida is better adapted to grazing than L. chinensis, possibly because of its relatively increased stem and root growth, which enhance population expansion following grazing. Conversely, L. chinensis showed increased leaf and stem growth, but suffered nutrient and biomass loss as a result of excessive foraging by livestock, which severely affected its ability to colonize. Root enzymes coupled with soil nutrients can regulate plant nutrients and stoichiometric ratios as an adaptive response to grazing. Thus, we demonstrated that stoichiometric ratios allow species to better withstand grazing disturbances. This study provides a new understanding of the mechanisms involved in grazing-resistance within a plant-soil system.

This study was carried out to evaluate the vulnerability of the herders in the grassland areas of Northern China. The results showed that, as a consequence of less capital accumulation, the herders in this area were vulnerable as a whole, and that gender, grassland area, livestock numbers and net incomes have significant effects on the vulnerability of grazer households. The families with female householders tended to be more vulnerable and they were characterised as owning less grassland, smaller houses, fewer or no vehicles, fewer young livestock and numbers of livestock slaughtered annually, whereas the families with low vulnerability had a higher net income. Geographically, household vulnerability showed a decreasing trend from west to east in Northern China at the county or region scale, which was positively correlated with grassland productivity. Social resources played a less important role than natural resources in decreasing the herders’ vulnerability. Educational level of the household members and the household labour capacity played important roles in reducing vulnerability. Increasing the enrolment rate and the education background in grassland regions may decrease the vulnerability of the herders. It is argued that the use of vulnerability indices can be helpful to increase the herders’ adaptation to climate change and to improve the sustainability of rural pastoral regions.

Land use intensity is an important indicator of human activities, so we quantified the land use intensity and five ecosystem services (soil conservation, water conservation, carbon storage, net primary productivity (NPP), and crop production) in 13 subbasins of the Tabu River Basin in an agro-pastoral ecotone in central Inner Mongolia. Furthermore, we analyzed the relationships among ecosystem services and the responses of the services to the impact of land use intensity. The primary conclusions were as follows: (1) All five ecosystem services gradually diminished from the upper to the lower reaches of the Tabu River Basin; (2) Water conservation exhibited a trade-off relationship with soil conservation, NPP, and crop production, but it exhibited a synergistic relationship with carbon storage. There were also synergistic relationships between soil conservation, carbon storage, NPP, and crop production; (3) As land use intensity increased, soil conservation, NPP and crop production monotonically increased. In contrast, water conservation exhibited a monotonically decreasing trend, and carbon storage followed a unimodal curve; (4) In this region, suitable ecosystem services were sustained at a land use intensity of approximately 3.95.