As the third pole of earth, the Qinghai-Tibet Plateau is an important ecological security barrier in China and an ecologically sensitive area of global climate change. The increasing climate change has posed a major challenge to its ecosystem function and stability. This paper first analyzes the spatiotemporal variation characteristics of the ecosystem pattern of the Qinghai-Tibet Plateau and its key functions including water conservation, soil conservation, windbreak and sand fixation from 2000 to 2020, clarifies the regional differences in ecosystem functions and their importance, and further evaluates the stability of ecosystem functions. And there is no doubt that the stable state will lay a scientific foundation for the plateau to build an ecologically civilized highland and launch protection and restoration projects. The results show that: (1) From 2000 to 2020, the wetland area of the study area increased and the grassland area decreased significantly. The water conservation and windbreak and sand fixation capacity were improved, and the annual change rates were 3.57 m³/(hm²·a) and 0.23 t/(hm²·a), respectively. However, the overall soil conservation showed a downward trend with an annual change rate of -0.16 t/(hm²·a). (2) The core areas of water conservation, soil conservation and windbreak and sand fixation accounted for 12.7%, 13.9% and 14.2%, respectively. The core water conservation barrier areas were mainly located in southeast Tibet, Sanjiangyuan and Ruoergai. The core windbreak and sand fixation areas were concentrated in the central and western parts of the plateau, and the core soil conservation areas surrounded the plateau. (3) From 2000 to 2020, the water conservation, soil conservation, and wind protection and sand-fixation functions have shown relatively high stability in the southeastern and central parts of the plateau, while relatively weak stability in the western part of the plateau. Combining stability assessment and ecological protection and restoration practices, we can divide the Qinghai-Tibet Plateau into three major categories of 16 ecosystem function zones and carry out differentiated ecological protection and restoration for different core ecosystem functions and zones.

Protecting the uniqueness, authenticity and integrity of the human ecosystem is an important path to achieve sustainable development of the Qinghai-Tibet Plateau National Park Cluster. The integrated evaluation method, coupling coordination model and equilibrium entropy index were comprehensively used to outline the spatial distribution pattern regarding the coupling coordination of human ecosystem in the Qinghai-Tibet Plateau National Park Cluster, and the main obstacle dimensions were clarified with the help of obstacle degree model. The results show that: (1) The sustainable production capacity of human ecosystem in the study area decreased from east to west, and each dimension presented the sequence characteristics of "harmony > openness > independence > vulnerability". At the national park level, the Zoige National Park, Shangri-La National Park-Pudacuo Area and the Giant Panda National Park scored the highest on the sustainable production capacity, while at the county level, the scores of sustainable production capacity in the central counties of the Giant Panda National Park ranked highly. (2) On the whole, the coupling coordination degree of the human ecosystem in the cluster showed the spatial characteristics of decreasing from southeast to northwest. The majority of counties involved in the national park cluster were in the primary or intermediate coordination state, and the human ecosystem in most of the national parks exhibited coupling and mutual feed-forward of internal structure. (3) At the level of national parks and the counties involved in national parks, the first obstacle dimension of coupling coordination of human ecosystem was openness, followed by independence. The main reasons are mostly related to the geographical location, location conditions, topographic characteristics and economic basis of national parks. Therefore, improving openness and promoting material circulation and energy flow between human ecosystem and the outside world are still the primary tasks for protecting the human eco-security of national parks in the future.

The extremely anoxic environment on the Qinghai-Tibet Plateau has a great impact on human and animal health. Studies of the contribution of vegetation to the atmospheric oxygen concentration on the Qinghai-Tibet Plateau are useful to clarify the environmental effects of changes in atmospheric oxygen concentration on human and animal health. Up to now, however, there are few such studies, and there is no spatio-temporal distribution map of the contribution rate. In this study, the vegetation net primary productivity was used to calculate the vegetation oxygen production on the Qinghai-Tibet Plateau, and the empirical equation of atmospheric relative oxygen concentration and the Ideal-Gas Equation were used to calculate the atmospheric absolute oxygen concentration, and then the ratio of the vegetation oxygen production and atmospheric absolute oxygen concentration was used to obtain the contribution rate. The results showed that the annual total vegetation oxygen production was 1.0353×10⁹ t on the Qinghai-Tibet Plateau in 2019. The theoretical upper limit value of the contribution rate of vegetation oxygen production to near-surface atmospheric oxygen concentration was 0.2788%/d on average over the plateau in 2019, but there were great differences across time and space (0.00 %/d to 4.62 %/d). In terms of temporal distribution, the change of contribution rate during the year is like a "∧" shape, the lowest value of the contribution rate in a year appeared during December through February of the next year, and the maximum value appeared in mid-August. In terms of spatial distribution, the contribution rate gradually decreased from southeast to northwest, with the lowest value in the northwest and the highest value in the southeast. From the perspective of vegetation types, the contribution rate per unit area from high to low was forest, cultivated vegetation, grassland, swamp wetland and shrub. From the perspective of altitude, the contribution rate per unit area gradually decreased with the increase of altitude. The spatial and temporal distribution map of the contribution rate was constructed in this paper, and the theoretical upper limit value of the contribution rate of vegetation oxygen production to atmospheric oxygen concentration on the plateau and its spatio-temporal variations were revealed. The results of this study can provide a reference for the studies on the changes of near-surface atmospheric oxygen concentration and its environmental effects on human and livestock on the Qinghai-Tibet Plateau.

During the Holocene, human activities gradually intensified, resulting in significant interference and alteration of natural vegetation. Anthropogenic disturbance has been one of the most critical factors driving vegetation changes in some regions. The archaeological study illustrated that continuous Neolithic culture developed in Zhejiang during Holocene. However, the relationship between vegetation changes and human activities in this region remains unclear. Here, we collected 40 pollen records in Zhejiang and classified them into three groups, i.e., archaeological sites, peripheral sites and natural sites. After standardizing the chronology and taxonomy of those pollen data, we calculated the rate and pattern of vegetation changes (RoCs) by the R-Ratepol package and Biomisation. The results showed that the RoCs increased significantly at archaeological sites, with high variabilities during 9000-3000 cal a BP. The values of RoCs at peripheral sites were lower than that of archaeological sites but showed a dramatic increase after 3000 cal a BP. The RoCs at natural sites were the lowest and relatively stable before 2000 cal a BP; after 2000 cal a BP, it accelerated and outstripped that of archaeological and peripheral sites. The increased RoCs at both the peripheral and natural sites manifested that the spatial range of human impact on vegetation expanded significantly in the late Holocene. The vegetation change rates exerted by Neolithic human activities might be 2-3 times greater than that under the natural state. Furthermore, there was a certain deviation between the human-related and natural vegetation changes. The deforestation and cultivation of Neolithic ancestors led to the fragmentation of the terrestrial landscape. The residence time of biomes at archaeological sites was significantly lower than that in natural and peripheral sites. To sum up, long-term human activities in Zhejiang accelerated the regional vegetation changes and reduced the stability of terrestrial ecosystems. In pollen-based vegetation and climate reconstructions, and also in the practice of vegetation protection and restoration, the potential influence of long-term human activities must be considered.

The connection between Arctic Oscillation (AO) and net primary productivity (NPP) of vegetation in the Indo-Myanmar region during the period from 1981 to 2018 was quantitatively analyzed using regression analysis, composite analysis, and other methods based on AO index, vegetation NPP, and meteorological data. The results revealed that: (1) There is a significant in-phase relationship between winter AO and NPP in the Indo-Myanmar region, with a regional average NPP increasing (decreasing) significantly by 6.50 gC·m^-2, and the maximum increment (decrement) reaching 20.60 gC·m^-2 corresponding to a one standard deviation increase (decrease) of winter AO index. The correlation coefficient between AO and NPP time series reaches 0.57. (2) The AO primarily affects the atmospheric circulation over the Indo-Myanmar region through wave propagation, which in turn impacts precipitation and ultimately leads to abnormal NPP. During the positive (negative) phase of AO, a Rossby wave propagates eastward along the subtropical jet, resulting in anomalous cyclonic (anticyclonic) circulation in the mid-lower troposphere over the Bay of Bengal-Indo-Myanmar region. This tends to strengthen (weaken) the South-Branch Trough, which in turn enhances (weakens) the southwestward moisture transport and ascending motion ahead of the trough, both of which favor above-normal (below-normal) precipitation in the Indo-Myanmar region. With a one standard deviation increase (decrease) in the winter AO index, precipitation from five datasets significantly increases, with ERA5 and GPCC datasets showing a significant increase (decrease) of more than 12 mm at higher resolutions. The precipitation of anomalously positive AO years minus its negative ones can exceed 90 mm, and all of the correlation coefficients between the regional average precipitation and the AO index reach more than 0.50 (p < 0.01). Accompanied by a 1 mm increase (decrease) in precipitation, the NPP increase (decrease) exceeds 10.10 gC·m^-2, and the correlation coefficients of the two time series exceed 0.40 (p <0.01).