Ecohydrology最新文献

Fluvial wetlands, such as floodplains, are particularly vulnerable to increasingly frequent extreme climatic events such as droughts because river flows are tightly coupled to atmospheric drivers such as precipitation. At the same time, these ecosystems can play a crucial role in supporting biodiversity resilience by providing refuge during regional droughts. The Paraná River Basin, the second largest in South America, has experienced unprecedented reductions in river flow since 2019. Here, we examine the effects of this multiyear hydrological and meteorological drought (2019–2024) on bird assemblages in the Paraná River floodplain. We compared two distinct hydrological contexts: a period with greater water availability in the floodplain (i.e., ‘wet’ period; 2011–2013) and another marked by drier and more recent conditions (i.e., ‘drought’ period; 2021–2024). Comparisons were based on point counts conducted at 60 sites along approximately 450 km. At each point, we also quantified habitat heterogeneity. Under drought conditions, regional and per-point species richness, total abundance and Simpson diversity increased markedly, with non–wetland-exclusive species showing the strongest response. Habitat heterogeneity also increased and was positively correlated with all bird metrics; however, drought effects remained significant after accounting for habitat variability. Beta-diversity analyses revealed reduced species turnover during drought, and indicator-species analysis identified 63 species associated exclusively with drought (22% wetland-exclusive; 78% nonexclusive). Overall, our results suggest that although river levels reached historical lows and assemblages became dominated by non–wetland-dependent species, the floodplain retained sufficient wetland refugia to sustain, and in some cases even enhance, populations of wetland-dependent species during the drought.

Faced with the dual pressures of global climate change and the intensification of human activity, sophisticated social–ecological systems (SES) are generating unprecedented challenges for sustainable development. Nevertheless, current research primarily emphasizes the dynamic variations of ecosystem services (ESs), with a specific focus on the dynamics of their supply, demand and flow, but with insufficient exploration of the complex mutual feedback mechanism between ecosystems and social systems. Network approaches have significant potential in the research of ESs, but their practical applications still require further exploration. This study selected the Shiyang River Basin (SRB) as a representative case and employs ESs as a bridging framework by introducing partial correlation networks, aiming to analyse how ESs are intricately linked with social–ecological factors (SEF). Results indicated that from 2010 to 2020, within the SRB, ESs demonstrated distinct spatial heterogeneity. Through network analysis, this study reveals the complex interrelationships between SEF and ESs in the SRB, identifying critical nodes and connecting pathways in the network. Among them, the importance and influence of precipitation in the network have gradually become prominent, with its node strength increasing from 0.92 in 2010 to 1.20 in 2020, becoming a key element driving the evolution of the network structure. Population density consistently served as a pivotal social factor throughout the study period, exacerbating the demand for multiple ESs. The persistent influence of human activities poses potential risks to SES. Additionally, the least absolute shrinkage and selection operator method eliminates over 50% of false connections, significantly enhancing the reliability of results. Furthermore, the study emphasizes that achieving sustainable development requires not only enhanced management of key elements but also greater attention to the relationships between SEF and multiple ESs, thereby establishing a systematic governance framework. This study not only provides a fresh angle to understand the complex interplay between ESs and SEF but also offers scientific foundations and practical guidance for ecological management in arid inland river basins.

Non-perennial streams are globally prevalent. These streams are vital components of ecosystems, yet their drying patterns and resulting impacts on hydrologic connectivity remain poorly understood at the watershed scale. Aridity is a dominant driver of stream drying, but its influences on hydrologic connectivity have not been fully explored. In this study, we investigated the role of aridity in shaping streamflow and connectivity patterns in non-perennial stream networks that span the continental United States aridity gradient. Using hydrologic models, we simulated daily streamflow and stream network connectivity under current and future climate scenarios. Our findings support previous research showing that aridity and streamflow are strongly linked. We also found that connectivity was related to aridity, although this relationship was weaker. Under the future climate scenario, mean runoff increased in most watersheds in the future, while mean connectivity decreased in the majority of watersheds. This difference is an indicator of the complex relationship between streamflow and connectivity. Aridity was a strong predictor of changes in very high and very low connectivity periods that resulted from climate change, but aridity did not predict changes in mean connectivity. Arid watersheds tended to experience more high connectivity days due to climate change while humid networks tended to have more low connectivity days. By modelling climate impacts at the network scale and across a broad hydroclimatic gradient, we highlight the importance of considering context-dependent changes in network connectivity in river flow management and watershed conservation plans.

Extreme climatic events can cause a high degree of impacts on forest carbon dynamics, particularly in more sensitive subtropical regions. We investigated the dynamics of carbon exchange, light use efficiency (LUE) and water use efficiency (WUE) in a subtropical forest ecosystem representing Central China's Yangtze River basin. The region is located at the East Asian monsoonal zone largely characterized by hot and humid summers and cold and dry winters. Using eddy-covariance measurements, we find that the climatically sensitive subtropical forest ecosystem acts as a robust carbon sink, sequestering carbon at an annual rate of 8.26 t C ha⁻¹, exceeding the average C sink of broadleaf forests. Despite favourable hydrothermal conditions in summer, excessive solar radiation and vapour pressure deficit (VPD) suppress carbon sink potential, highlighting the sensitivity of carbon exchange to extreme climatic events. The LUE of the subtropical forest exhibits a nonlinear relationship with leaf area index (LAI) as high as 2.6 m² m⁻², while water use efficiency (WUE) variability is strongly driven by VPD, reflecting the combined effects of environmental factors including temperature, precipitation and biological factors. In comparison, carbon exchange in the subtropical forest in YRB is highly sensitive to climate change, while LUE remains the most stable. The critical balance of water and thermal conditions for optimal carbon uptake of subtropical forests in YRB provides insights into the climatic extremities, as revealed by strong interactions among carbon exchange, LUE and WUE, highlighting the potentially important role in carbon offsets in the region.

Understanding the influence of vegetation on nitrogen transport is crucial for assessing the ‘nitrogen status’ of watersheds and advancing sustainable ecosystem management, particularly in vulnerable permafrost-affected regions. Daily riverine nitrogen data during the ice-free period (from 9 April to 26 October) in 2021 of a boreal forest watershed of the permafrost region in northeast China were investigated. Results showed that the nitrogen wet deposition during the growing season significantly exceeded the riverine nitrogen export. The vegetation (including trees, shrubs, herbs and mosses) significantly influenced the riverine nitrogen export during this period. The modified double mass curve and Pettitt's test were used to quantitatively assess the impact of vegetation on riverine nitrogen export. Runoff variations could explain 51.35% of the riverine nitrogen export in the non-growing season. However, vegetation attenuated the impact of runoff on riverine nitrogen export, thus ensuring a relatively stable relationship between runoff and riverine nitrogen export in the growing season. When daily runoff was below 1.40 mm (the daily runoff threshold at which riverine nitrogen export underwent a significant change), vegetation reduced nitrogen export by 31.89%. Above this threshold, the reduction increased to 60.51%. These results provide new mechanistic insights into the seasonal nitrogen dynamics of permafrost watersheds under climate change.