Dynamics of greenhouse gas emission induced by different burrowing activities of fossorial vertebrates in the Qinghai-Tibetan Plateau alpine meadow ecosystem.

Plateau zokor (Myospalax baileyi) and plateau pika (Ochotona curzoniae) are endemic fossorial vertebrates in the Qinghai-Tibetan Plateau alpine meadow ecosystem. Their different burrowing activities together transform soil structure and then significantly change the landscape of meadow ecosystem. However, how their burrowing activities impact greenhouse gas (GHG) emissions and the pattern of GHG emissions between different types of tunnel burrowing still remain obscure. In this study, we conducted in situ measurements quantitatively investigating the impacts of the different burrowing activities of zokors and pikas on three main GHG CO2, CH4, and N2O from an alpine meadow ecosystem in southeastern Qinghai-Tibetan Plateau. Our results showed that zokor hummocks and pika burrows were sources of CO2 and N2O and sinks of CH4. Zokors burrowing increased N2O in the atmosphere, decreased CO2, and enhanced CH4 absorbing, while pikas burrowing increased N2O in the atmosphere and enhanced CH4 absorbing. Considering the controversial role of fossorial vertebrates in Qinghai-Tibetan Plateau, this study also shed lights on effective management of animal activities with the aim of stabilizing or increasing ecosystem carbon sequestration.

Nest-site selection analysis of hooded crane (Grus monacha) in Northeastern China based on a multivariate ensemble model.

Avian nest-site selection is an important research and management subject. The hooded crane (Grus monacha) is a vulnerable (VU) species according to the IUCN Red List. Here, we present the first long-term Chinese legacy nest data for this species (1993-2010) with publicly available metadata. Further, we provide the first study that reports findings on multivariate nest habitat preference using such long-term field data for this species. Our work was carried out in Northeastern China, where we found and measured 24 nests and 81 randomly selected control plots and their environmental parameters in a vast landscape. We used machine learning (stochastic boosted regression trees) to quantify nest selection. Our analysis further included varclust (R Hmisc) and (TreenNet) to address statistical correlations and two-way interactions. We found that from an initial list of 14 measured field variables, water area (+), water depth (+) and shrub coverage (-) were the main explanatory variables that contributed to hooded crane nest-site selection. Agricultural sites played a smaller role in the selection of these nests. Our results are important for the conservation management of cranes all over East Asia and constitute a defensible and quantitative basis for predictive models.

Phylogeographical analysis of a cold-temperate freshwater fish, the Amur sleeper (Perccottus glenii) in the Amur and Liaohe River basins of Northeast Asia.

The Amur sleeper Perccottus glenii (Perciformes, Gobioidei, Odontobutidae) is well known as an invasive fish in the river basins of Eastern and Central Europe, but its genetic background is unavailable across its native habitats in northeast Asia. In this study, we used the mitochondrial cytochrome b gene by sampling 19 populations of P. glenii across its native distributional areas of Liaohe and Amur River basins to explore its evolutionary history. Phylogenetic analyses identified three major clades within P. glenii, among which Clade A and Clade B were co-distributed in the Liaohe and Amur River basins, and Clade C was restricted to the latter. Molecular dating showed that the splits of Clades A, B and C have happened in the late Early-early Middle Pleistocene and the most recent common ancestors of these clades have been presented in the late Middle-early Late Pleistocene. The P. glenii showed very high levels of genetic structure among populations (ΦST = 0.801), probably due to the characters of its life histories with very limited dispersal ability. The admixture of different clades in some populations of P. glenii probably reflects historical secondary contact. These findings indicate that Pleistocene climatic oscillation and river capture were major determinants for genetic variations and evolutionary history of the P. glenii.

Delayed flood recession in central Yangtze floodplains can cause significant food shortages for wintering geese: results of inundation experiment.

Carex meadows are critical habitat for wintering geese in the floodplains of the middle and lower reaches of Yangtze River, China. These meadows follow a growth cycle closely tied to the seasonal hydrological fluctuation: as water levels recede in the fall, exposed mudflats provide habitat for Carex spp. growth. The seasonal growth of Carex overlaps the arrival of wintering geese and provides an important food source for the migrants. Recent alterations to the Yangtze's hydrology, however, have disrupted the synchronous relationship between water levels, Carex growth and wintering geese at Dongting Lake. In October 2012, we carried out an outdoor mesocosm experiment to investigate potential impacts of delayed water recession on the germination and growth of Carex heterolepis, the dominant Carex species at Dongting Lake, to understand how changes in hydrology might impact wintering goose habitat. Results showed that the delayed flood recession exerted significant impact on the first growth cycle of Carex growth. Prolonged inundation significantly lowered the intrinsic growth rate (P = 0.03) and maximum growth rates (P = 0.02). It also took significantly longer time to reach the peak growth rate (P = 0.04 and 0.05 for number of shoot and biomass, respectively). As a result, biomass accumulation was reduced by 45, 62 and 90 % for 10-day, 20-day and 30-day inundation treatments, respectively. These results indicate a severe risk of food shortage for wintering geese when water recession delayed. This potential risk should be taken into consideration when operating any hydrological control structures that alter the flood regimes in Dongting Lake.

Functional trait-based phytoplankton biomass and assemblage analyses in the pre-growing season for comprehensive algal bloom risk assessment.

Algal bloom (AB) risk assessment is critical for maintaining ecosystem health and human sustainability. Previous AB risk assessments have focused on the potential occurrence of ABs and related factors in the growing season, whereas their hazards, especially in the pre-growing season, have attracted less attention. Here, we performed a comprehensive AB risk assessment, including water trophic levels, phytoplankton biomass, functional trait-based assemblages, and related environmental factors, in the pre-growing season in Dongting Lake, China. Although mesotrophic water and low phytoplankton biomass suggested low AB potential, toxic taxa, which constituted 13.28% of the phytoplankton biomass, indicated non-negligible AB hazards. NH4+ and water temperature were key factors affecting phytoplankton motility and toxicity. Our study establishes a new paradigm for quantitative AB risk assessment, including both potential AB occurrence and hazards. We emphasize the importance of phytoplankton functional traits for early AB warning and NH4+ reduction for AB control in the pre-growing season.

Optimized Small Waterbird Detection Method Using Surveillance Videos Based on YOLOv7.

Waterbird monitoring is the foundation of conservation and management strategies in almost all types of wetland ecosystems. China's improved wetland protection infrastructure, which includes remote devices for the collection of larger quantities of acoustic and visual data on wildlife species, increased the need for data filtration and analysis techniques. Object detection based on deep learning has emerged as a basic solution for big data analysis that has been tested in several application fields. However, these deep learning techniques have not yet been tested for small waterbird detection from real-time surveillance videos, which can address the challenge of waterbird monitoring in real time. We propose an improved detection method by adding an extra prediction head, SimAM attention module, and sequential frame to YOLOv7, termed as YOLOv7-waterbird, for real-time video surveillance devices to identify attention regions and perform waterbird monitoring tasks. With the Waterbird Dataset, the mean average precision (mAP) value of YOLOv7-waterbird was 67.3%, which was approximately 5% higher than that of the baseline model. Furthermore, the improved method achieved a recall of 87.9% (precision = 85%) and 79.1% for small waterbirds (defined as pixels less than 40 × 40), suggesting a better performance for small object detection than the original method. This algorithm could be used by the administration of protected areas or other groups to monitor waterbirds with higher accuracy using existing surveillance cameras and can aid in wildlife conservation to some extent.

A multilocus phylogeny of Asian noodlefishes Salangidae (Teleostei: Osmeriformes) with a revised classification of the family.

A group of small and transparent Asian noodlefishes (Osmeriformes: Salangidae) are commercially important fishery species, however, interrelationships among these fishes remain unresolved in previous studies using mitochondrial markers. We re-examine phylogenetic relationships of Salangidae by including complete taxon sampling, based on seven nuclear loci and one mitochondrial gene using a multilocus coalescence-based species-tree method. Our results show a well-resolved phylogeny of Salangidae that does not agree with previous hypotheses. The topology test suggests that our hypothesis represents the most likely phylogeny. Using the inferred species-tree as criterion, we recombine the rank of subfamilies and genera in the Salangidae, and erect a new genus Neosalangichthys. Our revised classification of Salangidae is well supported by reinterpreting previously proposed diagnostic characters. Finally, re-defined synapomorphic characters are used to erect a key to the genera of Salangidae.

Effects of soil nutrient heterogeneity on intraspecific competition in the invasive, clonal plant Alternanthera philoxeroides.

BACKGROUND AND AIMS: Fine-scale, spatial heterogeneity in soil nutrient availability can increase the growth of individual plants, the productivity of plant communities and interspecific competition. If this is due to the ability of plants to concentrate their roots where nutrient levels are high, then nutrient heterogeneity should have little effect on intraspecific competition, especially when there are no genotypic differences between individuals in root plasticity. We tested this hypothesis in a widespread, clonal species in which individual plants are known to respond to nutrient heterogeneity. METHODS: Plants derived from a single clone of Alternanthera philoxeroides were grown in the greenhouse at low or high density (four or 16 plants per 27·5 × 27·5-cm container) with homogeneous or heterogeneous availability of soil nutrients, keeping total nutrient availability per container constant. After 9 weeks, measurements of size, dry mass and morphology were taken. KEY RESULTS: Plants grew more in the heterogeneous than in the homogeneous treatment, showing that heterogeneity promoted performance; they grew less in the high- than in the low-density treatment, showing that plants competed. There was no interactive effect of nutrient heterogeneity and plant density, supporting the hypothesis that heterogeneity does not affect intraspecific competition in the absence of genotypic differences in plasticity. Treatments did not affect morphological characteristics such as specific leaf area or root/shoot ratio. CONCLUSIONS: Results indicate that fine-scale, spatial heterogeneity in the availability of soil nutrients does not increase competition when plants are genetically identical, consistent with the suggestion that effects of heterogeneity on competition depend upon differences in plasticity between individuals. Heterogeneity is only likely to increase the spread of monoclonal, invasive populations such as that of A. philoxeroides in China.

Effects of Meteorological Factors on Waterbird Functional Diversity and Community Composition in Liaohe Estuary, China.

Functional trait diversity represents ecological differences among species, and the structure of waterbird communities is an important aspect of biodiversity. To understand the effect of meteorological changes on the waterbird functional diversity and provide suggestions for management and conservation, we selected a study area (726 km2) in Liaohe Estuary, located in northeast China. We explored the trends of the waterbird functional diversity changes in response to meteorological factors using fourth corner analysis. Our study demonstrated that temperature was a key factor that impacted waterbird functional diversity in spring, while precipitation had a greater impact in autumn. The population size of goose and duck was positively associated with temperature and negatively with precipitation, while that of the waders (Charadriiformes) showed opposite association trends. Herbivores and species nesting on the bare ground exhibited responses to meteorological factors similar to those of geese and ducks, while benthivores and waterbirds nesting under grass/shrubs exhibited trends similar to those of waterbirds. Waterbirds with smaller bodies, shorter feathers, and lower reproductive rates preferred higher temperatures and less precipitation than other waterbirds. In addition, we observed seasonal variations in waterbird functional diversity. In spring, we should pay attention to waders, herbivores, and waterbirds nesting on the bare ground when the temperature is low. In autumn, waders, benthivores, and omnivores need more attention under extreme precipitation. As the global climate warms in this study area, waterbird functional diversity is expected to decline, and community composition would become simpler, with overlapping niches. Biodiversity management should involve protecting intertidal habitats, supporting benthic macrofaunal communities, preparing bare breeding fields for waterbirds favoring high temperatures to meet their requirements for population increase, and preventing the population decline of geese and ducks, herbivores, and species nesting under grass/shrubs. The findings of our study can aid in developing accurate guidelines for waterbird biodiversity management and conservation.

Predictive model of hypoxemia after shoulder arthroscopy: A retrospective observational study.

The study is aimed to establish a predictive model of hypoxemia after shoulder arthroscopy. The predictive model was based on a retrospective study with 756 patients who underwent shoulder arthroscopic surgery in Sichuan Orthopaedic Hospital from June 2019 to December 2020. Independent risk factors of hypoxemia in the post-anesthesia care unit (PACU) were screened out by the binary logistics regression and the primary predictive model was completed, which was evaluated by the receiver operating characteristic (ROC) curve and Hosmer-Lemeshow goodness-of-fit test. A separate cohort of 324 patients in the PACU from January 2021 to June 2021 was enrolled to validate the predictive model. Seven hundred fifty-six patients and 19 variables were enrolled in the binary logistics regression and 324 patients were validated by the primary predictive model. Logistics regression showed that application of irrigating solution ≥20 L, age, body mass index, and number of B-lines were independent risk factors of hypoxemia in the PACU (P < .05). The risk predictive model of hypoxemia in the PACU was established according to those factors. The model was validated by the Hosmer-Lemeshow test and the area under the curve of ROC was 0.823. The model area under the curve of external effect subject ROC was 0.870. The risk predictive model established in our study can predict the risk of hypoxemia in the PACU well and have good efficacy.

Indirect herbivore biomanipulation may halt regime shift from clear to turbid after macrophyte restoration.

Eutrophication transforms clear water into turbid water in shallow lakes. Current restoration techniques focus on re-establishing the clear-water state rather than on its maintenance. We investigated the response of submerged macrophytes to temporary grass carp (Ctenopharyngodon idella) and scraping snail (Bellamya aeruginosa) introductions. We also explored the impacts of herbivores on underwater light conditions to identify their long- and short-term potential to halt regime shift from clear to turbid after clear-water state reestablishment. Herbivores reduced both the biomass of submerged macrophytes and accumulated nutrients in the tissue of submerged macrophytes. This potentially avoided the pulse of endogenous nutrient release which would have exceeded the threshold required for the regime shift from clear to turbid. However, herbivores had a non-significant impact on submerged macrophyte-reduced light attenuation coefficient, which has a positive linear relationship with water chlorophyll a. Further, grass carp and snails enhanced the inhibition ratio of submerged macrophytes to phytoplankton by 3.96 and 2.13 times, respectively. Our study provides novel findings on the potential of herbivore introduction as an indirect biomanipulation tool for halting the regime shift of shallow lakes from clear to turbid after the restoration of submerged macrophytes.

Monitoring air quality can help for lakes excessive proliferation of phytoplankton control.

Previous studies assessing excessive proliferation of phytoplankton (EPP) in lakes are generally based on single investigation and focused on limited environmental factors; meanwhile, less attention has been paid to lakes susceptibility to EPP. Here, we identify the priority of lakes for EPP control in a basin by assessing EPP in multiple lakes and identify the key factors related to lakes' vulnerability to EPP. Field measurements, as well as multi-source survey data acquisition were conducted for 63 shallow lakes in the middle-lower Yangtze River basin. Resource-use efficiency by phytoplankton (RUE) was then used to represent lake susceptibility to EPP. Generalized linear models were used to assess the relative importance of environmental factors for RUE. We found that most lakes (76.19 %) were not suitable for recreation, due to health concern attributed to irritative or allergenic risk caused by EPP. Phosphorus was the primary limiting nutrient for EPP (74.60 % of lakes) which should be limited to < 0.09 mg/L. The linear model that included latitude, particulate matter 10, and precipitation explained 27.60 % of the variation of RUETP among lakes. In contrast, the linear model that included ozone, Secchi depth, and wind speed explained 19.41 % of the variation of RUETN among lakes. The key factor related to RUETP and RUETN was particulate matter 10 and ozone, respectively, both of which potentially increase RUE or reflect it. Our results suggest that integrating multiple survey datasets is critical for lakes EPP assessment in a basin, while lakes impacted by air pollution are a high priority for EPP control.

Effects of air quality and vegetation on algal bloom early warning systems in large lakes in the middle-lower Yangtze River basin.

Studies of algal bloom early warning systems have rarely paid attention to the dynamics of excessive proliferation of phytoplankton (EPP), which occurs prior to algal blooms, or to the sensitivity of a lake to EPP based on multiple environmental factors. In this study, we investigated EPP dynamics in large lakes and identified major factors that influenced the lake's vulnerability to EPP, to improve algal bloom early warning systems. High temporal moderate resolution imaging spectroradiometer (MODIS) images and multi-source daily site monitoring data of large lakes in the middle-lower Yangtze River basin were analyzed. Then, the floating algal index (FAI) and resource use efficiency (RUE) by phytoplankton were used to investigate the EPP dynamics and lake's vulnerability to EPP, respectively. Moreover, generalized linear models were used to assess the relative importance of environmental factors on RUE. The results indicate that the lakes freely connected (FC) to the Yangtze River (Dongting Lake and Poyang Lake) had lower FAIs but higher RUEs than the non-connected lakes (NC; Chaohu Lake and Taihu Lake). The key factors affecting RUE-FC were standard deviation of water level within 30 days(WL30), particulate matter <10 µm(PM10), and relative humidity(Hum), which explained 15.91% of the variations in RUE. The key factors affecting RUE-NC were ozone(O3), basin normalized difference vegetation index standard deviation(BNDVISD), and dissolved oxygen(DO), which explained 35.28% of the variations in RUE. These results emphasize the importance of air quality in influencing or reflecting EPP risks in large lakes. In addition, basin vegetation and hydrological rhythms can influence NH4+ through non-point source loading. Algal bloom early warning systems can be improved by routine monitoring and forecasting of potential environmental factors such as air quality and basin vegetation.

Assessing hydrodynamic effects of ecological restoration scenarios for a tidal-dominated wetland in Liaodong Bay (China).

Estuarine wetlands have experienced a variety of ecological and environmental problems caused by natural and anthropogenic factors. China has proposed a series of measures and made great efforts to control coastal degradation; however, decision makers still urgently need to know which measures to implement and how they will influence the estuarine environment and functions. This study used field observations, a hydrodynamic model, and statistical methods to investigate the effects of potential restoration scenarios on hydrodynamic conditions in the tidal-influenced estuarine wetland system, Liaodong Bay (China). Results reveal that the average total phosphorus, organic carbon, available phosphorus, pH, total nitrogen content, and moisture content in the soil and sediment environment were 0.04 ± 0.003%, 0.84 ± 0.25%, 16.3 ± 4.7 mg/kg, 8.3 ± 0.1, 0.07 ± 0.02%, and 44 ± 2%, respectively, exhibiting an overall trend of degradation. A series of restoration scenarios in regards to hydrodynamic regulation and tidal inputs were used to preserve the ecological value of the estuarine wetland. Model simulations indicate that the significant improvement of hydrodynamic fields (inundation depth and flow velocity) is more likely to occur when the tidal amplitudes reach around 2 m, while relatively weak responses can be observed when the tidal levels are lower than 1 m. Additionally, the construction of floodgates may play a key role in determining the tidal inputs and flowpaths across the wetland. The modifications in micro-topography of the wetland may play a complementary role in enhancing the connectivity condition via increased creek depth of 0.5 m and width up to around 20 m. This work represents a first attempt in exploring hydrodynamic effects of restoration scenarios for a tidal-dominated wetland. An improved understanding of the estuarine system also highlights that the design and implementation of wetland restoration projects should use more comprehensive measures to achieve long-term landscape management, connectivity planning, and ecological sustainability.

Land cover alteration shifts ecological assembly processes in floodplain lakes: Consequences for fish community dynamics.

Habitat degradation is expected to alter community structure and consequently, ecosystem functions including the maintenance of biodiversity. Understanding the underlying abiotic and biotic assembly mechanisms controlling temporal and spatial community structure and patterns is a central issue in biodiversity conservation. In this study, using monthly time series of fish abundance data collected over a three-year period, we compared the temporal community dynamics in natural habitats and poplar plantations in one of the largest river-lake floodplain ecosystems in China, the Dongting Lake. We found a prevailing strong positive species covariance, i.e. species abundance changes in the same way, in all communities that was significantly negatively impacted by higher water nutrient levels. In contrast to species covariance, community stability, which was measured by the average of aggregated abundance divided by temporal standard deviation, was significantly higher in poplar plantations than in natural habitats. The positive species covariance, which was consistent for both wet and dry years and among habitat types, had significantly negative effects on community stability. Furthermore, our results demonstrated that the ecological stochasticity (i.e. community assembly processes generating diversity patterns that are indistinguishable from random chance) was significantly higher in natural sites than in poplar plantations, suggesting that deterministic processes might control the community composition (richness and abundance) at the modified habitat through reducing species synchrony and positive species covariance observed in the natural habitats, leading to significantly lower temporal ß-diversity. When combined, our results suggest that habitat modification created environmental conditions for the development of stable fish community in the highly dynamic floodplains, leading to niche-based community with lower temporal ß-diversity.

Combining modern tracking data and historical records improves understanding of the summer habitats of the Eastern Lesser White-fronted Goose Anser erythropus.

The Lesser White-fronted Goose (Anser erythropus), smallest of the "gray" geese, is listed as Vulnerable on the IUCN Red List and protected in all range states. There are three populations, with the least studied being the Eastern population, shared between Russia and China. The extreme remoteness of breeding enclaves makes them largely inaccessible to researchers. As a substitute for visitation, remotely tracking birds from wintering grounds allows exploration of their summer range. Over a period of three years, and using highly accurate GPS tracking devices, eleven individuals of A. erythropus were tracked from the key wintering site of China, to summering, and staging sites in northeastern Russia. Data obtained from that tracking, bolstered by ground survey and literature records, were used to model the summer distribution of A. erythropus. Although earlier literature describes a patchy summer range, the model suggests a contiguous summer habitat range is possible, although observations to date cannot confirm A. erythropus is present throughout the modeled range. The most suitable habitats are located along the coasts of the Laptev Sea, primarily the Lena Delta, in the Yana-Kolyma Lowland, and smaller lowlands of Chukotka with narrow riparian extensions upstream along major rivers such as the Lena, Indigirka, and Kolyma. The probability of A. erythropus presence is related to areas with altitude less than 500 m with abundant wetlands, especially riparian habitat, and a climate with precipitation of the warmest quarter around 55 mm and mean temperature around 14°C during June-August. Human disturbance also affects site suitability, with a gradual decrease in species presence starting around 160 km from human settlements. Remote tracking of animal species can bridge the knowledge gap required for robust estimation of species distribution patterns in remote areas. Better knowledge of species' distribution is important in understanding the large-scale ecological consequences of rapid global change and establishing conservation management strategies.

Construct social-behavioral association network to study management impact on waterbirds community ecology using digital video recording cameras.

Studying social-behavior and species associations in ecological communities is challenging because it is difficult to observe the interactions in the field. Animal behavior is especially difficult to observe when selection of habitat and activities are linked to energy costs of long-distance movement. Migrating communities tend to be resource specific and prefer environments that offer more suitability for coexisting in a shared space and time. Given the recent advances in digital technologies, digital video recording systems are gaining popularity in wildlife research and management. We used digital video recording cameras to study social interactions and species-habitat linkages for wintering waterbirds communities in shared habitats. Examining over 8,640 hr of video footages, we built tetrapartite social-behavioral association network of wintering waterbirds over habitat (n = 5) selection events in sites with distinct management regimes. We analyzed these networks to identify hub species and species role in activity persistence, and to explore the effects of hydrological regime on these network characteristics. Although the differences in network attributes were not significant at treatment level (p = .297) in terms of network composition and keystone species composition, our results indicated that network attributes were significantly different (p = .000, r 2 = .278) at habitat level. There were evidences suggesting that the habitat quality was better at the managed sites, where the formed networks had more species, more network nodes and edges, higher edge density, and stronger intra- and inter-species interactions. In addition, we also calculated the species interaction preference scores (SIPS) and behavioral interaction preference scores (BIPS) of each network. The results showed that species synchronize activities in shared space for temporal niche partitioning in order to avoid or minimize any potential competition for shared space. Our social network analysis (SNA) approach is likely to provide a practical use for ecosystem management and biodiversity conservation.

Phylogenetic position of the enigmatic Lepidogalaxias salamandroides with comment on the orders of lower euteleostean fishes.

This study examines phylogenetic placement of the enigmatic Western Australian Lepidogalaxias, and extends previous studies by including eight new taxa to enable re-examination phylogenetic relationships of lower euteleostean fishes at the ordinal level, based on mitochondrial genomes from 39 ingroup taxa and 17 outgroups. Our results suggest that Lepidogalaxias occupies a basal position among all euteleosts, in contrast with earlier hypotheses that variously suggested a closer relationship to esocid fishes, or to the galaxiid Lovettia. In addition our evidence shows that Osmeriformes should be restricted Retropinnidae, Osmeridae, Plecoglossidae and Salangidae. This reduced Osmeriformes is supported in our results as the sister group of Stomiiformes. Galaxiidae, which is often closely linked to Osmeriformes, emerges as sister group of a combined Osmeriformes, Stomiiformes, Salmoniformes, Esociformes and Argentiformes, and we give Galaxiiformes the rank of order to include all remaining galaxioid fishes (Galaxias and allied taxa, Aplochiton and Lovettia). Our results also support a sister group relationship between Salmoniformes and Esociformes, which are together the sister group of Argentiniformes.

Lake productivity and waterbird functional diversity across geographic and environmental gradients in temperate China.

Geographical gradients in species diversity have long fascinated biogeographers and ecologists. However, the extent and generality of the effects of the important factors governing functional diversity (FD) patterns are still debated, especially for the freshwater domain. We examined the relationship between lake productivity and functional diversity of waterbirds sampled from 35 lakes and reservoirs in northern China with a geographic coverage of over 5 million km2. We used structural equation modeling (SEM) to explore the causal relationships between geographic position, climate, lake productivity, and waterbird FD. We found unambiguous altitudinal and longitudinal gradients in lake productivity and waterbird FD, which were strongly mediated by local environmental factors. Specifically, we found (a) lake productivity increased northeast and decreased with altitude. The observed geographic and altitudinal gradients were driven by climatic conditions and nutrient availability, which collectively explained 93% of the variations in lake productivity; (b) waterbird FD showed similar geographic and altitudinal gradients; the environmental factors which had direct and/or indirect effects on these gradients included climate and lake area, which collectively explained more than 39% of the variation in waterbird FD; and 3) a significant (p = .029) causality between lake productivity and waterbird FD was confirmed. Nevertheless, the causality link was relatively weak in comparison with climate and lake area (the standardized path coefficient was 0.55, 0.23, and 0.03 for climate, lake area, and productivity, respectively). Our study demonstrates how the application of multivariate technique (e.g., SEM) enables the illustration of complex causal paths in ecosystems, enhancing mechanistic explanations that underlie the observed broadscale biodiversity gradients.

Mapping the potential of mangrove forest restoration based on species distribution models: A case study in China.

Mangrove forests support numerous ecosystem services and contribute to coastal ecological risk reduction. However, they are one of the most severely threatened ecosystems in the world. China has carried out national mangrove restoration projects, but there is still insufficient scientific information for the strategic planning of this restoration. In this study, we carried out mangrove suitability assessments using the genetic algorithm for rule-set prediction (GARP) and maximum entropy (MaxEnt) models, and we mapped the restoration potential of mangrove forests in China for the first time. The restoration potential index (RPI), which combines suitability and land use data, is proposed as a rapid estimator method for locating theoretically available areas for restoration. The results showed that the MaxEnt model performed better than GARP in predicting potential mangrove distributions. Temperature was the most important environmental factor for determining large scale distribution of mangroves. The predicted northern limit of mangrove distribution was around 28°27' N-28°35' N. Using the RPI approach, 16,800 ha with the potential to restore mangrove forests was identified. According to both models, the largest area with restoration potential occurs along the Guangdong and Guangxi coast. Nationwide, about 75% of the potential area suitable for mangrove forests has been lost as a consequence of land use and is no longer available for restoration. Around 6400 ha of ponds is currently used for aquaculture, accounting for 38% of theoretically restorable areas. These areas can be a priority for mangrove forest restoration. In conclusion, our findings provide a better scientific understanding of mangrove distribution in China and can underpin strategic design and planning of mangrove restoration.