Ecohydrology最新文献

The relationship between biodiversity and ecosystem function has always been one of the hot issues in the field of ecology. With the acceleration of global warming, the precipitation pattern has become one of the main drivers of biodiversity loss, which has a profound impact on ecosystem functional services and stability. However, the studies on the effects and mechanisms of plant community diversity and ecosystem productivity under precipitation changes in desert steppe are still unclear. According to the change rate (−41.1% to 39.2%) of precipitation in the study area in recent 50 years, five precipitation gradients (i.e., −40%, −20%, CK, +20% and +40%) were set to simulate the possible future precipitation pattern changes. Aboveground biomass increased with the increase of precipitation. Compared with CK, the aboveground biomass increased by 22.81% with +40% and decreased by 80.71% with −40%, and the negative impact of precipitation decrease on aboveground biomass was more significant. Through multiple stepwise regression analyses, species diversity, functional diversity and phylogenetic diversity were identified as the best models of aboveground biomass. The results showed that the aboveground biomass changes could be explained by 51.3%, 81.6%, 32.6% and 60% respectively. Combined with plant community diversity, the final index model was obtained through multiple stepwise regression analyses, which could explain 88.3% of changes in aboveground biomass. In this model, The average coefficient of specific leaf area and leaf thickness had a very high significance level, and these two functional traits of dominant species had a greater explanatory power for ecosystem system function. There was a nonlinear correlation between precipitation and aboveground biomass, and drought had a more significant negative effect on aboveground biomass. Compared with species diversity and phylogenetic diversity, plant functional traits can better explain ecosystem productivity. Selection effects are the main maintenance mechanism of desert steppe community productivity under the background of precipitation change.

Sphagnum mosses are a keystone peatland species whose ecohydrology governs carbon sequestration processes in many peatlands. Globally, there are ~380 Sphagnum species that occupy a wide range of ecohydrological niches (microforms) based on their ability to grow at or above the water table, broadly grouped by hummock (furthest from water table), lawn, and hollow (closest to water table) microforms. The further from the water table a given species can grow is controlled by the ability to effectively retain and transmit water to the capitula (growing surface) during dry periods. However, Sphagnum species can have a relatively plastic ecohydrological niche, often occupying different niches (microforms) in different environments. We used numerical modelling parameterized by previous field and laboratory studies to compare the hydrological function between Sphagnum hummock, lawn, and hollow microforms. We determined (a) how two different organizations of a hummock of Sphagnum fuscum and (b) a lawn or hollow of S. magellanicum (S. divinum/S. medium) or S. rubellum differed between two different overarching climates (sub-humid boreal and humid temperate). The hydrological function, expressed as the cumulative water fluxes, was similar between species and ecohydrological microform (water table position) when water was plentiful, despite differences in soil hydraulic properties of the same species, but began to diverge during a prolonged simulated dry period (30-day drought). These results suggest a single species of Sphagnum moss can exhibit a wide range of soil hydraulic properties (i.e., sphagnum morphology) but have essentially the same consequential hydrology. Only the S. fuscum from the sub-humid climate was hydrologically stressed enough to show differences in the simulated evaporation rates. This study highlights the need for more physical research to determine the sensitivity of Sphagnum spp.'s soil hydraulic properties to overarching hydroclimatic factors so that we can more effectively incorporate these processes into large-scale numerical modelling efforts.

Reservoirs fulfil several societal needs, including water storage, energy production, flood control and recreation. However, the interruption of the river continuum may cause water quality declines that compromise water use. The surrounding landscape is a key driver of water quality variation in space and time, both across and within catchments. Therefore, understanding how landscape composition, structure and functioning influence reservoir water quality can help address management challenges. Here, we aim to investigate the current use and predictive capacity of landscape functioning indicators for reservoir water quality prediction. First, we carried out a literature review to investigate which landscape factors are most frequently studied as drivers of water quality in lentic systems. Then, we tested the predictive capacity of landscape functioning indicators in four reservoirs in Portugal using linear mixed models and multi-model inference. The literature review shows that most studies assess the effects of landscape composition while landscape functioning is rarely included. Our test using four reservoirs suggests that landscape functioning indicators, namely greenness and brightness, can complement landscape composition and structure indicators, improving the capacity to predict total suspended solids, chlorophyll-a, and total phosphorous. Landscape functioning indicators portrayed temporal variability in ecosystem dynamics that was not encompassed by landscape composition or structure indicators and may be relevant to predict specific water quality parameters. Our results show landscape functioning indicators can improve modelling of landscape contributions to water quality and thus have great potential to contribute to monitoring, modelling and forecast systems for water quality and ecological status.

Reservoirs have experienced varied degrees of eutrophication in recent years as the effects of climate change and human activities on reservoir ecosystems have intensified. This study looked at the patterns of integrated nutrient status and total phosphorus (TP) concentration in 30 reservoirs in major reservoirs across Fujian Province. Significant connections were identified between TP concentration, trophic status, and total phytoplankton density. 88.9% of the reservoirs were at the middle trophic level by the nutritional status (EI). The average EI of the 25 reservoirs with water supply functions is 39.2, eight reservoirs in coastal areas having EI values more than 45.0. The EI of the Baisha Reservoir in Jiulong River Basin reached 50.3, indicating modest eutrophication. TP concentration levels in the 30 reservoirs of Fujian Province range from 0.01 to 0.08 mg·L⁻¹, representing different functional categories. Algal bloom is more likely to occur in a reservoir with a high nutrient status value. The N/P mass ratios of the 30 reservoirs were all significantly greater than 7.0, with the minimum is 11.0 and the maximum is 136.0, which indicating that these reservoirs were typically phosphorus-limited.