Nitrogen (N) and phosphorus (P) deposition have increased rapidly during the past decades, which likely changes soil N and P availability. These soil resource variations will further affect N, P concentration and N:P ratio in different ecosystem pools (i.e., soil, leaf, litter, root, and microbe). Various pools may show different stoichiometric responses to nutrient enrichment, with a further influence on ecosystem nutrient cycling. However, few studies have been conducted to fully examine the stoichiometric responses of different pools and their nutrient relationships in a given ecosystem. Here we established a 2‐year experiment of N (10 g m−2 year−1), P (10 g m−2 year−1), and combined N + P addition in a temperate forest of Changbai Mountain. We found significantly different N:P stoichiometric responses among various ecosystem components under P addition, with the leaves showing a higher response than litter and root while microbe behaving the lowest response. The responses of N:P ratio to N + P addition were similar with those under P addition in all pools. In most cases, N addition did not significantly affect N:P ratio. These results indicate that N:P ratio response was mainly determined by changes in P rather than N concentration in this temperate forest ecosystem. Moreover, we found tighter N:P stoichiometric correlations than elements among diverse ecosystem components under nutrient addition. Overall, our research reveals different responses and tight links of element stoichiometric variations among various ecosystem components in face of nutrient enrichment. It calls our attention to considering stoichiometric changes in the whole ecosystem beyond individual plant organ or microbial component.

Studying the ecosystem service value is of great value for solving the contradiction between ecological protection and economic development in the Huaihe River Basin. The characteristics of land use change were studied by using the Landsat remote sensing image data of Anhui section and Henan section of Huaihe River Basin from 2010 to 2020. The equivalent factor method was used to estimate the ecosystem service value, and the spatial autocorrelation model was used to analyze the spatial distribution characteristics of ecosystem service value The GM-BP model was used to predict the land use change in 2025. The results showed that: (1) From 2010 to 2020, cultivated land and construction land dominated the land use in the study area, and the degree of land use change changed from severe to stable. (2) The value of ecosystem services is in the transition stage from low level (II) to medium level (III). (3) ecosystem service value has a significant positive spatial correlation, and the spatial distribution is generally high in the southeast and low in the northwest. (4) Compared with 2020, ecosystem service value will rise by 0.54 % in 2025.

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寒灌丛2003~2016年生长季(5~9月)CO 2 通量动态及影响机制, 结果对预测高寒灌丛生态系统碳平衡对未来气候变 化的响应具有重要参考价值. 结果表明, 总初级生产力(gross primary production, GPP)和生态系统呼吸(ecosystem respiration, Re)呈先增加后降低的单峰趋势, 净生态系统CO 2 交换(net ecosystem exchange, NEE