Low-quality Habitat Research Articles

Temporal and Spatial Changes of Habitat Quality and Their Potential Driving Factors in Southwest China

Climate change and human activities have considerably changed the spatial patterns and functional elements of regional habitats. Understanding spatiotemporal changes in habitat quality (HQ) and their potential driving factors is essential for maintaining ecosystem health and protecting biodiversity. To explore the effect of physical and human factors on HQ changes in Southwest China, we firstly analyzed the land-use change intensity (LCI). We then evaluated spatiotemporal changes in HQ based on the InVEST model and explored the spatial heterogeneity of the main driving factors of HQ changes based on a geographical detector and a geographical weighted regression model. The results showed that LCI had obvious spatiotemporal differences, and LCI from low-quality habitat to high-quality habitat (LCI1) was significantly higher than that from high-quality habitat to low-quality habitat (LCI2). The HQ improved steadily in Southwest China in 1990–2015, showing a trend of low–high–low from southeast to northwest. Moreover, there were twelve factors, including aboveground biomass, ecological land area ratio, population density, slope, etc., which had a significant impact on the spatial differences in HQ, and the effects of different factors on HQ had observable spatial heterogeneity. The effect of LCI2 on the spatial difference of HQ was greater than that of LCI1. These results suggested that the current ecosystem protection and management policy had a positive effect on improving HQ. Our study provides an important decision-making reference for sustainable land development and utilization and regional ecological protection and restoration.

Ecosystem services valuation using InVEST modeling: Case from southern Iranian mangrove forests

As one of the most fertile ecosystems on earth, mangrove forests provide many goods and services for humanity. Mangroves are located in the south of Iran on the coasts of Sistan and Baluchistan, Hormozgan and Bushehr provinces, which include two species of Harra (Avicennia marina) and Chandal (Rhizophora mucronata) The purpose of this study was to describe the condition of mangrove forests using the integrated valuation of ecosystem services and tradeoffs (InVEST) between 2010 and 2021 from the southern coasts of Iran. The INVEST model uses land use and land cover maps to estimate habitat quality. With the opinions of local experts, sources of threats, maximum impact distance, state of degradation, and sensitivity to threats were also estimated for each type of land use cover. Urban and rural areas’ development, roads network, piers, oil and non-oil industries, agriculture, and aquaculture activities, were identified as sources that threaten mangroves’ long-term viability. The output maps of the INVEST habitat quality model included degradability and habitat quality maps, which were classified into four categories: poor, low, medium, and high, to better understand quality changes. The results demonstrated that mangrove habitat quality has decreased considerably despite the increase in their area. The area of the target habitats has been increased by 586.45 ha while two first quality categories, including poor and low classes, increased. Based on a habitat quality assessment in 2010, two classes of poor, low habitat quality, were estimated to be around 0.72, and 8.42 ha, which changed to 3.04 ha, and 9.72 ha respectively in 2021. The output maps obtained in this study can help local managers and decision-makers to have an image of what happened to the quality of the target ecosystems and may help them to adopt more effective management strategies for the conservation of these ecosystems.

Territory and population attributes affect Florida scrub-jay fecundity in fire-adapted ecosystems.

Fecundity, the number of young produced by a breeding pair during a breeding season, is a primary component in evolutionary and ecological theory and applications. Fecundity can be influenced by many environmental factors and requires long-term study due to the range of variation in ecosystem dynamics. Fecundity data often include a large proportion of zeros when many pairs fail to produce any young during a breeding season due to nest failure or when all young die independently after fledging. We conducted color banding and monthly censuses of Florida scrub-jays (Aphelocoma coerulescens) across 31 years, 15 populations, and 761 territories along central Florida's Atlantic coast. We quantified how fecundity (juveniles/pair-year) was influenced by habitat quality, presence/absence of nonbreeders, population density, breeder experience, and rainfall, with a zero-inflated Bayesian hierarchical model including both a Bernoulli (e.g., brood success) and a Poisson (counts of young) submodel, and random effects for year, population, and territory. The results identified the importance of increasing "strong" quality habitat, which was a mid-successional state related to fire frequency and extent, because strong territories, and the proportion of strong territories in the overall population, influenced fecundity of breeding pairs. Populations subject to supplementary feeding also had greater fecundity. Territory size, population density, breeder experience, and rainfall surprisingly had no or small effects. Different mechanisms appeared to cause annual variation in fecundity, as estimates of random effects were not correlated between the success and count submodels. The increased fecundity for pairs with nonbreeders, compared to pairs without, identified empirical research needed to understand how the proportion of low-quality habitats influences population recovery and sustainability, because dispersal into low-quality habitats can drain nonbreeders from strong territories and decrease overall fecundity. We also describe how long-term study resulted in reversals in our understanding because of complications involving habitat quality, sociobiology, and population density.

Evolution of Habitat Quality and Its Response to Topographic Gradient Effect in a Karst Plateau: A Case Study of the Key Biodiversity Conservation Project Area of Wuling Mountains.

Habitat quality (HQ) is widely considered to be a proxy indicator for biodiversity. Assessing the dynamic changes in HQ induced by land-use and land-cover (LULC) changes could provide a scientific perspective for regional sustainable development, especially in the ecologically fragile karst plateau mountainous areas. We selected nine landscape metrics to examine LULC dynamics in the Key Biodiversity Conservation Project Area of Wuling Mountains in Guizhou province, China, based on the land-use data for the 1990-2018 period. HQ was evaluated using the InVEST model and the topographic gradient effect on HQ was analyzed using the topographic position index. The results showed that the dominant land categories in the study area were arable land, grassland, and forestland. Land transformation was mainly characterized by a shift from cultivated land to construction land and forestland, and a mutual conversion between grassland and forestland. The changes improved landscape heterogeneity and the degree of fragmentation. The HQ of the study area was high, although exhibited a declining trend from 1990 to 2018. The eastern and western parts had relatively high HQ, whereas the southern and northern parts had low HQ. The topographic gradient had a significant effect on spatial patterns of HQ. High HQ distribution was consistent with that of forestland and was dominant along the topographic gradient, while low HQ distribution was consistent with that of construction land and cultivated land and was dominant along the topographic gradient.

Strategies for Restoring and Managing Ecological Corridors of Freshwater Ecosystem

Along with accelerating urbanization and associated anthropogenic disturbance, the structure and function of freshwater ecosystems worldwide are substantially damaged. To improve ecosystem health, and thus enhance the ecosystem security of the urban ecosystem, numbers of management approaches and engineering projects have been applied to mitigate the degradation of freshwaters. Nevertheless, there is still a lack of comprehensive and systematic research on the ecological corridor restoration of freshwater ecosystems; especially for Suzhou Grand Canal, one section of the world's longest and ancient Grand Canal which is inclined to severe ecosystem degradation. Through investigating the adjacent land use characteristics, habitat quality, vegetation cover, instream water quality, and habitat composition, we aimed to: (i) assess the water quality of the Suzhou Grand Canal; (ii) evaluate the ecological characteristics of the canal ecosystem; (iii) develop strategic countermeasures to restore the ecological corridors for the mitigation of ecological problems. The results demonstrated: a large built area, a smaller ecological zone, a low habitat quality and habitat connectivity, and a high degree of habitat fragmentation within the canal corridor, also a simplified instream habitat composition, and greater nutrient and COD concentrations in the surface water-especially in the upstream and midstream canal. All urbanization-induced multiple stressors, such as land use changes, altered hydrology, and the simplified riparian zone et al., contributed synergistically to the degradation of the canal ecosystem. To alleviate the ecosystem deterioration, three aspects of recommendations were proposed: water pollution control, watershed ecosystem restoration, and ecological network construction. Basically, building a comprehensive watershed ecological network-on the basis of associated ecosystem restoration, and the connection of multi-dimensional ecological corridors-would dramatically increase the maintenance of aquatic-terrestrial system biodiversity, and improve the regional ecological security pattern and watershed resilience toward stochastic future disturbances. This study contributes to the understanding of the ecological challenges and related causes of the canal ecosystem. The integrated strategy introduced in this study provides policymakers, water resource managers, and planners with comprehensive guidelines to restore and manage the ecological corridor of the canal ecosystem. This can be used as a reference in freshwater ecosystems elsewhere, to improve ecosystem stability for supporting the sustainable development of urban ecosystems.

Habitat quality assessment of wintering migratory birds in Poyang Lake National Nature Reserve based on InVEST model.

Poyang Lake National Nature Reserve (PLNNR) is an important resting place for wintering migratory birds on the East Asian-Australasian Flyway (EAAF). In recent years, due to human activities and climate change, the area of wetlands has shown a downward trend, and the number and habitat of wintering migratory birds have been threatened. It is urgent to evaluate the habitat quality of wintering migratory birds in PLNNR. Therefore, the InVEST model and landscape index were used to evaluate the habitat quality of wintering migratory birds, and the grey correlation theory was used to reveal the response of typical wintering migratory bird population to habitat quality. The results showed that the habitat quality of the PLNNR was still at a high level, but showed a downward trend, with the average index of habitat quality decreasing from 0.872 to 0.817. The area of the highest quality habitat decreased by 3394.92 hm2, the area of the lowest, low, and medium quality habitats increased by 3112.11 hm2, and the area of the high quality habitat remained stable. The lowest, low, and medium quality habitat expanded from the middle to the south of the PLNNR mainly because of the expansion of construction land and cultivated land. The area with deterioration in habitat quality was 10,477.53 hm2, mainly concentrated in the center and south of the PLNNR. The area with restoration in habitat quality was 6148.26 hm2, mainly concentrated in the Bang Lake and Dacha Lake. The area with no change in habitat quality remained stable. The fragmentation degree and shape complexity of highest and high quality habitats increased, dominance degree and connectivity decreased, and the landscape pattern of habitat quality showed a downward trend. Typical wintering migratory birds have a strong correlation with highest, high, and low habitat quality, and there is a downward trend with the deterioration of habitat quality. Finally, this paper puts forward constructive suggestions on the degradation of habitat quality caused by land-use change.

Land use system, invasive species and shrub diversity of the riparian ecological infrastructure determine the specific and functional richness of ant communities in Mediterranean river valleys

The Riparian Ecological Infrastructure (REI) is defined by the ensemble of natural and semi-natural woody and herbaceous vegetation patches located contiguously to water courses. Freshwater environments and the associated REI provide habitat for many species, acting as corridors linking landscapes at a wider scale.Focusing on ants, a ubiquitous and diverse group of insects that provide a large number of ecosystem roles, we address the relative importance of REI-related local and landscape factors that drive the species and functional richness of ant communities.The study was conducted in 2019, at 100 sites in central Portugal, in Tagus and Sorraia irrigated valleys, comprising three landscape systems, namely, Forest production, Agroforestry and Irrigated cropland. Four major types of variables were used to characterize the sampling patches, including the landscape system, patch typology, spatial configuration and habitat quality. Ants were collected using pitfall traps and species composition was used to classify functional groups. Using an extensive survey, machine learning methods were used to identify the relative importance of REI-related variables in explaining ant specific and functional richness.Results indicated that ant biodiversity was primarily explained by the ‘Landscape system’ and the ‘Argentine ant abundance’. Nevertheless, ‘Shrub richness’ was selected as an important variable to enhance ‘Animal community regulation’ and ‘Plant community regulation’ functional groups, while herbaceous patches appeared to be relevant for the ‘Decomposition through scavenging’ group.The highest ant biodiversity was found in the Forest production ‘Landscape system’, where patches were larger, more complex and less fragmented, showing high habitat quality associated with a reduced abundance of the invasive Argentine ant. Contrarily, the lowest was expected in the Intensive cropland ‘Landscape system’, where the REI is highly fragmented, showing low habitat quality and suffering from a high Argentine ant invasion, as a result of high human pressure. The Agroforestry ‘Landscape system’ showed moderate ant biodiversity, mainly associated with patches characterized by low strata complexity and shrub cover densities, due to understory clearing and grazing activities.

There is still time to reconcile forest management with climate-driven declines in habitat suitability for boreal caribou

Many boreal populations of woodland caribou in Canada are declining, mainly due to the prevalence of anthropogenic disturbances which alter predator-prey dynamics. Climate change is expected to exert an additional negative influence on caribou populations in coming decades, but it is unclear whether or how human activities and climate change will interact to influence habitat suitability for caribou, and how important these agents of change will be relative to each other. In this study, we used the LANDIS-II forest landscape model to forecast boreal caribou habitat suitability across its distribution within the harvestable boreal forest in Québec for the period 2020–2100, under three increasing anthropogenic radiative forcing scenarios (baseline, Representative Concentration Pathways [RCP] 4.5 and 8.5), and two contrasting harvest scenarios (with and without harvest). Our simulations revealed that harvesting was the dominant agent explaining future variations in caribou habitat suitability, although climate change also decreased habitat suitability, especially under RCP 8.5. Climate-induced decreases in habitat suitability mostly originated from increases in wildfires that burned mature conifer-dominated forests, i.e., high-quality habitat for caribou. Habitat suitability by 2100 was also predicted to vary spatially, with the northeastern and northwestern parts of the study area supporting better caribou habitat conditions regardless of scenarios. We show that reducing harvest activities in areas where habitat suitability is currently high could help maintain high-quality caribou habitat even under the most intense climate change scenario. Our results also suggest that highly-disturbed regions which currently provide low-quality habitat may not improve in the future unless active habitat restoration is performed. Our study helps disentangle the potential future effects of forest management and climate change as threats to caribou habitat, emphasizing the urgency of reconciling forest management with the conservation of this species at risk in Canada.

The effects of landscape change on habitat quality in arid desert areas based on future scenarios: Tarim River Basin as a case study.

Human activities have caused spatiotemporal patterns of land use and land cover (LULC) change. The LULC change has directly affected habitat quality (HQ) and ecosystem functions. Assessing, simulating, and predicting spatiotemporal changes and future trends under different scenarios of LULC-influenced HQ is beneficial to land use planners and decision-makers, helping them to formulate plans in a sustainable and responsible way. This study assesses and simulates the HQ of the Tarim River Basin (TRB) using the future land use simulation model (FLUS), the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model, and partial least squares regression (PLSR). Since 2000, the TRB has experienced a declining trend in HQ from 0.449 to 0.444, especially in the lower elevations (740-2000m) and on sloped land (<10°). The decline will continue unless effective and sustainable plans are implemented to halt it. Agricultural and settlement areas have a lower HQ and a higher degree of habitat degradation than native habitats. This shows that the expansion of oasis agriculture (with an annual growth rate of 372.17 km2) and settlements (with an annual growth rate of 23.50 km2) has caused a decline in native habitat and subsequent habitat fragmentation. In other words, changes in LULC have caused a decline in the HQ. Moreover, there is a significant negative correlation between HQ and urbanization rate (p<0.01), and the PLSR also indicate that number of patches (NP), area-weighted mean fractal dimension index (FRAC_AM), percentage of landscape (PLAND), and largest patch index (LPI) were also important contributors to worsening the HQ. Therefore, the TRB urgently needs appropriate strategies to preserve its natural habitats into the future, based on the ecological priority scenario (EPS) and harmonious development scenario (HDS), which can help to maintain a high-quality habitat.

Spatio-Temporal Analysis of the Effects of Human Activities on Habitat Quality: A Case Study of Guiyang City, Guizhou Province, China

In recent years, regional habitat quality (HQ) has significantly degenerated, mainly attributed to human activities. Evaluating the spatio-temporal effects of human activities on HQ is crucial for maintaining regional ecosystem and conservation of landscapes. In this paper, taking Guiyang city as a case study, the spatio-temporal patterns of HQ and human footprint (HF) in 2000, 2010 and 2020 were respectively calculated by the HQ model and human footprint index (HFI). Then, the bivariate local Moran’s I was applied to measure the spatial relationship between them. Urban development zoning was conducted on the basis of the spatio-temporal relationship. The results showed that (1) in the past 20 years, HQ in Guiyang city was mainly dominated by relatively high value areas (moderately high and high), accounting for more than 60% of the total area. The proportion of low HQ area increased from 12.5% in 2000 to 18.5% in 2020, indicating that urban development has caused the continuous degradation of HQ. (2) The human activities in Guiyang city undergone apparent changes. The area of low HF decreased from 51.5% in 2000 to 46.7% in 2020, while the area with high-value increased from 2% to 5.8%. (3) There was a significantly negative correlation between HQ and HF in Guiyang city. The increasing correlation coefficient indicated that the impact of human activities on HQ has been strengthening. (4) Based on the spatial zoning scheme, the territorial space of Guiyang city was divided into four types, that is, the core development zone, the moderate development zone, the habitat conservation zone and the prohibited development zone. A series of corresponding strategies were proposed for the characteristics of each zone. Our findings can serve as guidance to urban managers and policy-makers for adopting suitable urban development plans and appropriate management of natural environment.

Spatiotemporal Evolution of Ecosystem Services in the Wanhe Watershed Based on Cellular Automata (CA)-Markov and InVEST Models

The evaluation of habitat quality and its genesis is of great significance to ecological protection of the watershed. Based on land use data, Digital Elevation Model (DEM), and road network data and population data, the Cellular Automata (CA)-Markov model and InVEST model were used to analyzed the land use change in the Wanhe Watershed, predicting the land use in 2025. Based on this, the degree of the habitat degradation and habitat quality in 2000, 2005, 2010, 2015, 2020, and 2025 were predicted and analyzed, and combined with the particularity of the terrain in the study area, the topography was introduced. Landform relief gradient was used to discuss the relationship between habitat quality and topographic factors in the Wanhe Watershed, and to reveal the distribution law. The result shows that from 2000 to 2025, farmland and forestland are the main land use types in the study area, and the main change is due to the expansion of the construction land, whereby the area increased by 62.86 km2, with an increase of 34.41%, mainly from farmland and forestland. From 2000 to 2020, mainly due to the expansion in urban land and the reduction in forestland, the habitat degradation tends to be serious, and the habitat quality generally shows a downward trend, with areas with low habitat quality having had the largest increase from 452.67 km² in 2000 to 526.15 km² in 2025. The topography of the study area affects the distribution of natural landscapes and the intensity of human activities, resulting in significant differences in the landscape pattern of habitat degradation and habitat quality. The western mountains are relatively better. After 2020, due to the implementation of environmental protection policies, the habitat quality has tended to improve. This study can promote the adjustment of land use planning policies in the study area, maintain the biodiversity in the watershed, and realize the coordinated development of environmental benefits and social and economic development. The research results have theoretical significance and practical value for ecological environmental protection and land use layout in Wanhe Watershed.

Grizzly bear (Ursus arctos) movements and habitat use predict human-caused mortality across temporal scales

While the location of wildlife mortalities provides some insight on the cause of death, identifying the risk factors associated with mortality events and in which cases these factors result in death requires information on individual behaviour prior to death. With access to a long-term database of grizzly bear ( Ursus arctos L., 1758) GPS locations, we investigated how behaviour differed between individuals that died of anthropogenic causes and those that survived across different temporal scales. We analyzed movement (diurnality and daily displacement) and habitat use (modelled risk and habitat quality) of grizzly bears residing in Alberta, Canada, from 2005 to 2021 to determine whether grizzly bears that died and grizzly bears that survived differed in these behaviours 2–4 years, 1 year, and 1 week prior to death, and whether patterns changed over time. We found that diurnality increased in the last year of life, while displacement increased in the last week of life, with differences becoming greater nearer the day of death. Grizzly bears that died used high-risk and low-quality habitat at all time scales, and these behaviours increased as death approached. Our analysis suggests that grizzly bear mortalities do not occur randomly but happen at times when individuals exhibit high-risk behaviours. This information can be used to make management decisions related to habitat management, road use, and human access.

Land use contribution to spatiotemporal stream water and ecological quality: Implications for water resources management in peri-urban catchments

• Seasonal variability confounds land-use source contribution in peri -urban streams. • No robust ecological improvement despite implementation of Nature-based solution. • Nematode-based stress index reveals impacts and benefits of wastewater effluents. • Contaminant-bound particles and other chemicals stressors may be overlooked. Climate change and intensifying agricultural production and urbanization are central factors driving the global freshwater biodiversity decline. To design sustainable green transition schemes and support urban planning, a deeper understanding of the numerous interacting physicochemical and biogeochemical processes and their relation to ecological quality becomes essential. This study thus aims to explore links between hydrological regimes and patterns evident for key water quality parameters and benthic invertebrate indicators in a peri -urban catchment that has undergone several stream restoration projects. Results indicate significant seasonal variability in discharge and physico-chemical parameters confounding the identification of sources behind detrimental impacts on ecological quality, which may lead to the implementation of inappropriate mitigation strategies. Notably, sampling at the sub-catchment level underlined the dynamic contributions of both agricultural and urban-like areas for nitrogen and phosphorus, while non-volatile carbon was mainly exported from agricultural lands. Multivariate statistical methods were used to classify benthic macro- and meioinvertebrate (specifically nematode) taxa showing poor-to-moderate and poor-to-good ecological quality, respectively. Poor ecological quality was mostly found in the upstream part of the catchment, driven by a combination of low habitat quality and periodically impaired physico-chemical conditions (e.g. dissolved oxygen, temperature, and suspended solids). In addition, the nematode-based stress index NemaSPEAR[%] (expressing the proportion of species-at-risk within a sample and specifically sensitive to the chemical contamination), indicated a TSS-related transport of contaminants to the sediment. It could also reveal both the negative impacts of different urban features (low ecological quality just downstream of combined sewer overflows), as well as the potential benefits of wastewater effluents (i.e. good ecological quality, via well-treated flow contributions and limited fine sediment accumulation especially in summer) on the stream ecosystem. Our results highlight that the use of this indicator, in combination with high frequency monitoring are promising techniques to better link the dynamic impacts of land use and spatiotemporal changes in ecological quality.

Exploring the spatial and temporal driving mechanisms of landscape patterns on habitat quality in a city undergoing rapid urbanization based on GTWR and MGWR: The case of Nanjing, China

Landscape pattern significantly impacts habitat quality, especially in cities undergoing rapid urbanization, where landscape patterns are changing dramatically. However, the spatial and temporal driving mechanisms of landscape pattern on habitat quality are still unclear, and the proposed methods of Geographically and Temporally Weighted Regression (GTWR) and Multiscale Geographic Weighted Regression (MGWR) provide possibilities for the exploration of these mechanisms. This study was conducted in Nanjing from 2001 to 2020. Landscape pattern indices indicating aggregation, connectivity, diversity and compactness were calculated using Fragstats from 2001 to 2020. The habitat quality was computed using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. By combining two new spatial measurement models, GTWR and MGWR, the spatial and temporal driving mechanisms of landscape patterns on habitat quality were explored. The results show that (1) as Nanjing’s land under construction has expanded, habitat quality has decreased significantly, and the overall landscape pattern has fluctuated drastically. (2) GTWR and MGWR are well-suited to such analysis and provide important insights. (3) Overall, aggregation and compactness were negatively associated with habitat quality in areas of low-quality habitat. Increased connectivity on low habitat substrates had a positive effect on habitat. The increase of diversity in proximity had a positive effect on habitat, while the opposite was true in high habitat zones. (4) As the urbanization level increases, the negative effects of aggregation expand, as do the positive effects of connectivity and diversity. (5) The extent of influence of landscape pattern effects are ranked from largest to smallest: compactness, diversity, connectivity, and aggregation, while the intensity of effects is reversed. Based on these findings, a reference point for urban planners is provided to plan urban landscape patterns in a sustainable and rational manner. It also provides a new means of integrating GTWR and MGWR into the study of landscape ecology.

Habitat suitability or female availability? What influences males’ home-range size in a neotropical montane lizard?

In many species, the shape, size, and location of home ranges depend on the spatial positioning of resources. Therefore, evaluating the resources and conditions related to the space use of individuals can provide crucial information on the species’ ecology and sociobiology. In this study, we evaluated factors shaping the use of space by the lizard Tropidurus montanus M.T. Rodrigues, 1987 and assessed how the distribution of resources can affect the size of the home range and how the quality of the male's home range can influence the number of associated females. We hypothesized that ( i) males with a larger body size would have a higher-quality home range, and ( ii) there would be a positive relationship between the home-range size and home-range quality of males and the number of associated females. Our results suggest that males, females, and juveniles adopt different strategies. While females and juveniles have relatively small home ranges located in more suitable locations, males invest in larger home ranges, including in lower-quality habitat patches. Our results suggest that males increase their home ranges to incorporate resources females prefer, enlarging the number of females in their harems.

Habitat Quality Assessment and Ecological Risks Prediction: An Analysis in the Beijing-Hangzhou Grand Canal (Suzhou Section)

With the fast pace of global urbanization, anthropogenic disturbances not only lead to frequent disasters, but also cause direct and indirect ecological and economic losses. To reduce the adverse effects of anthropogenic disturbances as part of sustainable ecosystem management, assessments of habitat quality and ecological risk are necessary. The objectives of this study are to analyze environmental conditions of the Beijing-Hangzhou Grand Canal (Suzhou section) for evaluating habitat quality and habitat degradation, and to conduct ecological-risk early warning assessment in this section. The Grand Canal is the longest and first canal in the world to be artificially excavated from natural rivers and lakes. By evaluating habitat quality using the InVEST suite of open-source software models for mapping and valuing the ecosystem, it was found that the natural lands with high habitat quality such as wetlands, forests and lakes along the Suzhou section of the Grand Canal have gradually decreased, while construction lands such as roads and buildings have gradually increased; there is a clear trend of decreasing areas with high habitat quality and increasing areas with low habitat quality, which is likely the result of urbanization. It was also found that the region has a high habitat degradation index, meaning that areas located at the junction of different land types are vulnerable to the surrounding environment due to narrow buffer zones that allow areas with high habitat quality to be easily affected by areas with low habitat quality. In terms of ecological risks, it was found that the natural land area with high habitat quality in the downstream locations was declining, thereby increasing the risks of pollution and flooding events while reducing the ecosystem’s resilience. The valuation model used in this study can be used as an effective decision-support tool to prioritize important ecological areas for conservation in the Grand Canal, and can also be adapted for use in the ecosystem management of other regions.

Phylogenetic and functional structure of tree communities at different life stages in tropical rain forest fragments

Tropical rain forest fragmentation is considered one of the principal drivers of biodiversity loss worldwide. Fragmentation and defaunation of tropical rain forests affect the maintenance of their biodiversity in a myriad of ways. Old-growth forest plant and animal species are more likely to suffer from local extinction, not only because fragments frequently represent low quality habitats but also because of the loss of biotic interactions such as seed dispersal. In this study, we evaluated the maintenance of tree species diversity in the face of habitat fragmentation in southern Mexico using different approaches. Firstly, we used community phylogeny at different tree life stages (i.e., seeds, seedlings and adults). Secondly, we categorised plant species in different life stages into functional groups according to seed size (small seeds < 1 cm length and large seeds > 1 cm length) and, finally, by dispersal syndrome (predominantly primate dispersed). We searched for three sites of continuous forest as experimental controls where two important seed dispersers coexist, the howler ( Alouatta pigra ) and spider ( Ateles geoffroyi ) monkeys, and six forest fragments of similar sizes (ca. 3–6 ha). Three fragments were occupied only by howler monkeys, and three had no primates. We compared entire assemblages as well as assemblages of small-seeded and large-seeded species separately to determine the phylogenetic structure and patterns of species richness and the density of adult trees (> 10 cm dbh), seedlings (10–100 cm tall) and seed assemblages. Fragments and continuous forest differed in taxonomic species richness and density at all life stages when large-seeded species mainly dispersed by primates were solely considered, with numbers in unoccupied fragments being consistently lower than in continuous forests and occupied fragments. Phylogenetic clustering occurred in all habitats and for all life stages, predominantly for the seedling stage, indicating that the understory community is assembled via environmental filtering (including both biotic and abiotic processes). Habitats occupied by primates tended to present a higher phylogenetic clustering than unoccupied fragments, suggesting that primates select phylogenetically-related species in their diets and, importantly, that these foraging behaviours influence seedling recruitment patterns. The loss of taxonomic and functional biodiversity and the non-random extinction of tree species principally dispersed by primates, represents part of the evolutionary history that is being lost throughout fragmentation.

Failed despots and the equitable distribution of fitness in a subsidized species

Abstract Territorial species are often predicted to adhere to an ideal despotic distribution and under-match local food resources, meaning that individuals in high-quality habitat achieve higher fitness than those in low-quality habitat. However, conditions such as high density, territory compression, and frequent territorial disputes in high-quality habitat are expected to cause habitat quality to decline as population density increases and, instead, promote resource matching. We studied a highly human-subsidized and under-matched population of Steller’s jays (Cyanocitta stelleri) to determine how under-matching is maintained despite high densities, compressed territories, and frequent agonistic behaviors, which should promote resource matching. We examined the distribution of fitness among individuals in high-quality, subsidized habitat, by categorizing jays into dominance classes and characterizing individual consumption of human food, body condition, fecundity, and core area size and spatial distribution. Individuals of all dominance classes consumed similar amounts of human food and had similar body condition and fecundity. However, the most dominant individuals maintained smaller core areas that had greater overlap with subsidized habitat than those of subordinates. Thus, we found that (1) jays attain high densities in subsidized areas because dominant individuals do not exclude subordinates from human food subsidies and (2) jay densities do not reach the level necessary to facilitate resource matching because dominant individuals monopolize space in subsidized areas. Our results suggest that human-modified landscapes may decouple dominance from fitness and that incomplete exclusion of subordinates may be a common mechanism underpinning high densities and creating source populations of synanthropic species in subsidized environments.

Interactive effects of multiscale diversification practices on farmland bird stress.

Farmland diversification practices (i.e., methods used to produce food sustainably by enhancing biodiversity in cropping systems) are sometimes considered beneficial to both agriculture and biodiversity, but most studies of these practices rely on species richness, diversity, or abundance as a proxy for habitat quality. Biodiversity assessments may miss early clues that populations are imperiled when species presence does not imply persistence. Physiological stress indicators may help identify low-quality habitats before population declines occur. We explored how avian stress indicators respond to on-farm management practices and surrounding seminatural area (1-km radius) across 21 California strawberry farms. We examined whether commonly used biodiversity metrics correlate with stress responses in wild birds. We used ∼1000 blood and feather samples and body mass and wing chord measurements, mostly from passerines, to test the effects of diversification practices on four physiological stress indicators: heterophil to lymphocyte ratios (H:L), body condition, hematocrit values, and feather growth rates of individual birds. We then tested the relationship between physiological stress indicators and species richness, abundance, occurrence, and diversity derived from 285 bird point count surveys. After accounting for other biological drivers, landscape context mediated the effect of local farm management on H:L and body condition. Local diversification practices were associated with reduced individual stress in intensive agricultural landscapes but increased it in landscapes surrounded by relatively more seminatural area. Feathers grew more slowly in landscapes dominated by strawberry production, suggesting that nutritional condition was lower here than in landscapes with more crop types and seminatural areas. We found scant evidence that species richness, abundance, occurrence, or diversity metrics were correlated with the individual's physiological stress, suggesting that reliance on these metrics may obscure the impacts of management on species persistence. Our findings underscore the importance of considering landscape context when designing local management strategies to promote wildlife conservation.

Population Dynamics and Determinants of Annual Fluctuations of the Endangered Smith's Blue Butterfly, Euphilotes enoptes smithi (Lycaenidae)

A mark-release-recapture study of the federally-listed Smith's Blue butterfly, Euphilotes enoptes smithi, was conducted in 1986 at Marina State Beach (Monterey County, CA) in coastal sand dune habitat. Demographic parameters estimated included daily and generation population numbers, residency, vagility, and emigration rates. Manly-Parr and Jolly-Seber analyses indicated an estimated 2,657 to 5,875 individuals comprised the 1986 generation, with average residence from 6.7 to 10.1 days (maximum 20 days). Average movements between consecutive observations on different days were 95.1 m for males and 91.0 m for females, while the longest lifetime dispersal observed was 1,230 m by a female. Emigration rates from areas of low quality habitat were as much as 8x greater than those from high quality habitat. Between 1997 and 2017 this butterfly was monitored yearly at three neighboring sand dune remnants in Sand City, CA to determine annual generation sizes. Transect counts of adults conducted during the 21 flight seasons, in conjunction with the frequencies of observed residencies from the 1986 study, indicated estimated generation numbers from 360 to 2,151 for the three sites combined. The observed year-to-year fluctuations in generation sizes were strongly correlated with annual numbers of flowerheads of this butterfly's Eriogonum foodplants, which in turn was correlated with annual precipitation.