Analysis of Landscape Connectivity among the Habitats of Asian Elephants in Keonjhar Forest Division, India

On the elephant trails: habitat suitability and connectivity for Asian elephants in eastern Indian landscape

Identifying suitable habitats and conserving corridors are crucial to the long-term conservation of large and conflict-prone animals. Being a flagship species, survival of Asian elephants is threatened by human-induced mortality and habitat modification. We aimed to assess the habitat suitability and connectivity of the Asian elephant Elephas maximus Linnaeus, 1758 habitat in the state of Odisha in eastern India. We followed the ensemble of spatial prediction models using species presence data and five environmental variables. We used least-cost path and circuit theory approaches to identify the spatial connectivity between core habitats for Asian elephants. The results revealed that normalized difference vegetation index (NDVI; variable importance 42%) and terrain ruggedness (19%) are the most influential variables for predicting habitat suitability of species within the study area. Our habitat suitability map estimated 14.6% of Odisha's geographical area (c. 22,442 km2) as highly suitable and 13.3% (c. 20,464 km2) as moderate highly suitable. We identified 58 potential linkages to maintain the habitat connectivity across study area. Furthermore, we identified pinch points, bottlenecks, and high centrality links between core habitats. Our study offers management implications for long-term landscape conservation for Asian elephants in Odisha and highlights priority zones that can help maintain spatial links between elephant habitats.

Spatial-temporal evolution and correlation analysis between habitat quality and landscape patterns based on land use change in Shaanxi Province, China

Regional habitat quality is an important reflection of ecosystem services and ecosystem health. Exploring the characteristics of habitat quality changes and revealing the vulnerability of regional ecosystems caused could provide reference for the improvement of ecological service functions and the protection of regional ecological environment. Based on remote sensing data of Shaanxi Province from 2000 to 2015, InVEST model and grid analysis were used to analyze the evolution characteristics of habitat quality and landscape pattern, and spatial autocorrelation was also used to analyze the spatial correlation and temporal evolution characteristics. The results showed: (1) Arable land, grassland, and forest land were the main landscape types in Shaanxi province, accounting for more than 94% of the total area, and the arable land and unused land showed a decreasing trend, while the grassland and forest land showed an increasing trend, and the proportion of construction land continued to increase with the rapid economic development from 2000 to 2015; (2) The spatial distribution characteristics of habitat quality was similar to land use cover change, which was "high in the southern and central forest areas, low in the northern sandy land and central urban agglomeration", and habitat quality value showed a steady increase, indicating that the habitat quality was getting better; (3) The landscape pattern index values of Guanzhong Plain urban agglomeration changed significantly, which tended to be fragmented, and the landscape types were more diverse and uniform; (4) There were obvious spatial correlation between habitat quality and landscape pattern, and the spatial differentiation of clustering was obvious, and the clustering effect of habitat quality and landscape pattern characteristics would weaken with the increase in urbanization degree. The analysis of the spatial association between habitat quality and landscape pattern could provide scientific support for ecological protection and landscape planning.

Gaps in mammal conservation in China: An analysis with a framework based on minimum area requirements

Climate change, habitat loss, and human disturbance are major threats to biodiversity. Protecting habitats plays a pivotal role in biodiversity conservation, and there is a global imperative to establish an effective system of protected areas (PAs) to implement habitat conservation and halt biodiversity decline. However, the protected patch size of habitat for a species is just as important for biodiversity conservation as the expansion of areas already under protection. In China, conservation management is often carried out based on administrative divisions. Therefore, here, an analytical conservation management framework was developed based on administrative divisions to assess whether the current network of PAs can effectively meet species' conservation needs using the minimum area requirements (MARs) of species as criteria for medium and large-sized mammals in China. This study found that the MAR of medium and large-sized mammals was larger in the northwest and smaller in the southeast, while taking the Hu line as the dividing line. Precipitation seasonality, elevation, annual mean temperature, and annual precipitation are the main environmental factors driving the distribution of a species MAR. Compared with MAR for each species, the maximum protected patch size of habitat is severely undersized in most provinces where those species primarily distribute, and this is particularly true for large carnivores and threatened species. The densely populated provinces of eastern China are particularly affected by this. The present study's framework can identify the provinces needing to expand PAs or implement other effective area-based conservation measures and habitat restoration. This analytical framework is also relevant for biodiversity conservation in different taxa and regions around the globe.

Identifying Migration Routes of Wild Asian Elephants in China Based on Ecological Networks Constructed by Circuit Theory Model

Humans overlap with Asian elephants, resulting in frequent costly human-elephant conflicts, which disturb and even threaten local residents. In this study, we treat provincial and national nature reserves where Asian elephants still exist and other alternative habitats suitable for Asian elephants in southern Yunnan, China, as ecological patches. By using this approach, we can treat the terrain and surface state factors that hinder the migration of Asian elephants as a form of ecological resistance surface. We can then use a circuit theory model and remote sensing data to construct an ecological network, which allows us to identify ecological corridors and ecological pinch points. Herein, the possible migration routes of wild Asian elephants were identified. The main results are as follows: (1) In the study area, dense forests with steep slopes and high altitudes, cultivated land, and building land have greater migration resistance, while the gently undulating shrubs, bamboo forests, and grasslands far away from the city have less migration resistance. (2) There are three ecological corridor groups in the study area, mainly composed of shrub and grassland. The ecological corridors identified in this paper are the most likely migration routes of wild Asian elephants in China, and areas with higher simulated current densities reflect a higher probability of Asian elephants passing through. (3) According to the analysis, the ecological pinch points in the study area are 602 km2 in total, and woodland and grassland account for 89.2% of the total ecological pinch area. The areas where the pinch points are located have a high probability of Asian elephants passing through and a narrow space. Our findings can provide suggestions and solutions for the current conservation of wild Asian elephant species, alleviate human-elephant conflicts, promote the harmonious coexistence between humans and nature, and provide reference for biological protection and biological reserve planning.

Male mastodon landscape use changed with maturation (late Pleistocene, North America)

Fossil remains usually reveal little about lifetime landscape use beyond place of death, but ever-growing tusks of American mastodons (Mammut americanum) record this fundamental aspect of paleobiology. Using oxygen and strontium isotopes from a serially sampled male mastodon tusk, we reconstruct changing patterns of landscape use during his life. We find clear shifts in landscape use during adolescence and following maturation to adulthood, including increased monthly movements and development of a summer-only range and mating ground. The mastodon died in his inferred summer mating ground, far from landscapes used during other seasons. Mastodons had long gestation times, and late Pleistocene populations lived in harsh, rapidly changing environments. Seasonal landscape use and migration were likely critical for maximizing mastodon reproductive success.

Under harsh Pleistocene climates, migration and other forms of seasonally patterned landscape use were likely critical for reproductive success of mastodons (Mammut americanum) and other megafauna. However, little is known about how their geographic ranges and mobility fluctuated seasonally or changed with sexual maturity. We used a spatially explicit movement model that coupled strontium and oxygen isotopes from two serially sampled intervals (5+ adolescent years and 3+ adult years) in a male mastodon tusk to test for changes in landscape use associated with maturation and reproductive phenology. The mastodon’s early adolescent home range was geographically restricted, with no evidence of seasonal preferences. Following inferred separation from the matriarchal herd (starting age 12 y), the adolescent male’s mobility increased as landscape use expanded away from his natal home range (likely central Indiana). As an adult, the mastodon’s monthly movements increased further. Landscape use also became seasonally structured, with some areas, including northeast Indiana, used only during the inferred mastodon mating season (spring/summer). The mastodon died in this area (>150 km from his core, nonsummer range) after sustaining a craniofacial injury consistent with a fatal blow from a competing male’s tusk during a battle over access to mates. Northeast Indiana was likely a preferred mating area for this individual and may have been regionally significant for late Pleistocene mastodons. Similarities between mammutids and elephantids in herd structure, tusk dimorphism, tusk function, and the geographic component of male maturation indicate that these traits were likely inherited from a common ancestor.

Identifying Connectivity Conservation Priorities among Protected Areas in Qinling-Daba Mountains, China

Mountain biodiversity is under unprecedented threat due to climate change and excessive human activity. Although protected areas (PAs) are the cornerstone of nature conservation, it is increasingly hard for isolated PAs to maintain the species and ecological processes they depend on in the long term. Linking nature reserves to form a large and connected conservation network is regarded as the optimal measure, but research in this field is lacking in China. We mapped PAs in the Qinling-Daba Mountains in China and identified corridors among PAs and the corridors’ key nodes using a least-cost analysis and circuit theory to model an ecological connectivity conservation network for the region. The results showed that this large ecological network has 46 habitat patches connected by 88 corridors, with 69 pinchpoints, 86 barriers and 37 stepping stones in and around the corridors. In this study, 34.86% of suitable habitats have little or no protection and, in the future, these areas should be developed with caution, with more emphasis on protecting their ecological connectivity. This study used connectivity analysis to construct large ecological corridors based on PAs, providing a framework for connectivity conservation at the biogeographic scale and a scientific reference for further, subsequent conservation actions.