Integrating supply and demand factors for estimating ecosystem services scarcity value and its response to urbanization in typical mountainous and hilly regions of south China.

In the process of rapid urbanization, the decline in ecosystems' physical supply value is a direct result of the increasing demands of human development. The ecosystem services value combined with supply and demand factors can be used to obtain the ecosystem services scarcity value (ESSV). These ecosystems with larger ESSVs warrant increased protection, or at the very least a development plan to ensure a balance between their continued existence and human usage. However, urbanization and other developmental effects have often caused the ESSV of those regions to be disregarded, which produces an imbalance in the ecosystem. This paper evaluated the spatial differentiation of ESSV based on heterogeneous units in the Yuebei region, China. Then, a spatial response analysis of the ESSV to urbanization according to the spatial correlation model and Getis-Ord Gi* was conducted. The results showed that the ecosystem service physical supply value declined due to urban sprawl in 1990-2015, but the ESSV increased sharply during the same time with its acceleration being particularly strong after 2000. Areas with higher ESSV were concentrated in the northern region due to a higher prevalence of woodland. Urbanization accelerated significantly after 2000, and it is found that similar tendencies of ESSV and urbanization occurred over the same period. Surprisingly, the ESSV was negatively correlated with urbanization in local regions, and their interaction continued to increase over time. The spatial hotspot map of the ESSV and urbanization also formed an opposite pattern. In addition, the grid number of High-Low and Low-High types is more than half of the total number of aggregated grids. According to the results, understanding the variation in the ESSV clearly due to urbanization and identifying their interaction in local regions can provide a more specific direction for future resource adjustment and ecosystem service improvements.

Spatial heterogeneous relationship between ecosystem services and human disturbances: A case study in Chuandong, China.

Goal 15 of the UN Sustainable Development Goals (SDGs) has highlighted the importance of maintaining a sustainable relation between ecosystem services and human activities. Ecosystem services are heterogeneous across landscapes. However, how human activities, which cause disturbances to ecosystem services, relate to such heterogeneity has not been well studied and thus necessarily constraining our ability to manage ecosystems sustainably. Based on land use/land cover data, this study addressed the research gap by running two inter-related analyses on the datasets of the study area, i.e., Chuandong, China. The first analysis involves identifying distinctive heterogeneous units of ecosystem service values using Getis-Ord Gi⁎. The second analysis involves measuring the impacts of human disturbances on ecosystem service values and their variations over every five years between 1990 and 2015, using linear regression and spatial regression models. The result of the first analysis identified heterogeneous ecosystem service units of hot-spots, cold-spots, and random areas. The hot-spots mainly clustered in relative inaccessibility land at higher terrain gradients in the east of the study area. The cold-spots overlapped extensively with built-up areas and farmland at lower terrain gradients in the west of the study area. Random areas distributed mainly in the middle part of the study area. This heterogeneity also existed temporally. Ecosystem service values in the study area decreased from 1990 to 2000 but reversed the trend after 2000. The result of the second analysis revealed that the impacts of hot-spots, cold-spots, and random areas on the relationship between ecosystem service values and human disturbances vary. Specifically, there was a negatively linear relationship between ecosystem service values and the integrated indicator of human disturbances, which was the strongest in random areas, followed by cold-spots and hot-spots. In addition, spatial spillover effect is explicit in the relationship between ecosystem service values and three specific factors of human disturbances, i.e., terrain index, population, and gross domestic product. They varied significantly between units: the terrain index had a positive externality on ecosystem service values with cold-spots and random areas but negative externality with hot-spots; population imposed a more negative externality on ecosystem service values when in proximity to random areas than cold-spots and hot-spots; the externality between gross domestic product and ecosystem service values exhibited irregular inverse 'U' shape, which was below the 'X-axis' in cold-spots but throughout the 'X-axis' in hot-spots and random areas. The findings of this study have potential policy implications in improving ecosystem sustainability through harmonizing the environment and human activities.

Impact of Urbanization on Ecosystem Health: A Case Study in Zhuhai, China.

The past decades have witnessed rapid urbanization around the world. This is particularly evident in Zhuhai City, given its status as one of the earliest special economic zones in China. After experiencing rapid urbanization for decades, the level of ecosystem health (ESH) in Zhuhai City has become a focus of attention. Assessments of urban ESH and spatial correlations between urbanization and ESH not only reveal the states of urban ecosystems and the extent to which urbanization affected these ecosystems, but also provide new insights into sustainable eco-environmental planning and resource management. In this study, we assessed the ESH of Zhuhai City using a selected set of natural, social and economic indicators. The data used include Landsat Thematic Mapper images and socio-economic data of 1999, 2005, 2009 and 2013. The results showed that the overall ESH value and ecosystem service function have been on the decline while Zhuhai City has continued to become more urbanized. The total ESH health level trended downward and the area ratio of weak and relatively weak health level increased significantly, while the areas of well and relatively well healthy state decreased since 1999. The spatial correlation analysis shows a distinct negative correlation between urbanization and ESH. The degree of negative correlation shows an upward trend with the processes of urban sprawl. The analysis results reveal the impact of urbanization on urban ESH and provide useful information for planners and environment managers to take measures to improve the health conditions of urban ecosystems.

Quantifying the Impact of Grain for Green Program on Ecosystem Service Management: A Case Study of Exibei Region, China.

Evaluating the impact of an ecological restoration program on ecosystem services is crucial, given the role of such a program in boosting sustainable ecosystem management. This study examines the impact of one of the large-scale ecological restoration programs in China, the Grain for Green Program (GGP), on ecosystem service management in the Exibei region of China. This region is studied, as it is a key source water area with rich biodiversity and has been experiencing GGP for 20 years. To achieve the stated goal the changes of land use and ecosystem services value (ESV) and the ecosystem services scarcity value (ESSV) in the Exibei region were quantified and assessed based on remote sensing images from 1990, 1995, 2000, 2005, 2010, 2015 and field survey data. The results indicated that the expansion of construction land and the increase of water body were the dominant land use changes throughout the study period. Farmland, forestland and grassland decreased by 2.61%, 0.47% and 1.41% after the GGP, respectively. The ESV of the entire Exibei region increased slightly in response to land use change during 1990-2015, with an annual loss of 0.08% before the implementation of GGP and an annual growth of 0.03% after the implementation of GGP. Moreover, forestland was the dominant contributor to ESSV after the implementation of the GGP. Its annual growth rate was four times higher than before the commencement of GGP. The results of this study contribute to the protection of the Exibei region ecosystem, and more importantly, the future management of the ecosystem service in the hilly regions of southern China.

Patterns of land change and their potential impacts on land surface temperature change in Yangon, Myanmar.

This study used remote sensing imagery to characterize land use/cover patterns and to derive land surface temperature (LST) of Greater Yangon, the largest urban agglomeration in Myanmar, to provide insights into the association between land use/cover and seasonal, daytime, and nighttime LST change. Analysis of Landsat images from 1987 to 2015 showed urban expansion radiating from the city center and along prominent rivers, with major increases in built-up land (6.4%) and grassland (10.1%) and consequent decline in agricultural land (17%). Examination of MODIS LST showed that agricultural land was warmer than the city core during daytime in hot seasons, while in cold seasons, the city core was warmer than its rural surroundings during both daytime and nighttime. Correlation analysis revealed stronger association between built-up land and nighttime LST from 2000 to 2015, suggesting an increased surface urban heat island effect. Furthermore, this study highlighted two main differences from prior work on the influences of land use/cover on LST. First, the predominant land use/cover type that had great overall impact on LST was agricultural land, marked by its statistically significant correlation coefficients across all time periods of analysis. Such finding emphasized the influence of agriculture and related practices on the atmosphere and climate system. Second, the temporal analysis of LST highlighted a stronger and more complicated role water played because of its negative correlations with daytime LST and positive correlations with nighttime LST. The findings of this study underscored more complex effects of land use/cover on the spatial and temporal variations of LST in Yangon, compared to prior work that generally reported high LST in the urban areas. These insights improve the understanding of the land change consequences on the temporal dynamics of LST and can support sustainable land use planning for the better well-being of the inhabitants in Greater Yangon.

Assessing the role of landscape connectivity on Opisthorchis viverrini transmission dynamics.

Opisthorchis viverrini (Ov) is one of the most important human parasitic diseases in Southeast Asia. Although the concept of connectivity is widely used to comprehend disease dispersal, knowledge of the influences of landscape connectivity on Ov transmission is still rudimentary. This study aimed to investigate the role of landscape connectivity in Ov transmission between the human and the first intermediate snail hosts. Fieldwork was conducted in three villages respectively in Kamalasai District, Kalasin Province, Phu Wiang District, Khon Kaen Province, and Nong Saeng District, Udon Thani Province. Bithynia snails were collected to examine parasitic infections, water samples were analyzed for fecal contamination, and locations of septic tanks and connections between habitat patches with observable water movement were surveyed. Euclidean distance, topological link and distance, and graph measures were employed to quantify the connectivity between human and snail habitats. The findings showed that snail patches with higher fecal contents were generally located nearer to septic tanks. The statistically significant results for the topological link and distance measures highlighted the importance of water in functionally facilitating Ov transmission. Graph measures revealed differences in landscape connectivity across the sites. The site with the largest landscape component size and the most mutually connected snail patches coincided with the presence of Ov parasite, reinforcing its higher risk for human to snail transmission. The site with the dissected landscape structure potentially limited the transmission. This study underscored the potential effect of landscape connectivity on Ov transmission, contributing to the understanding of the spatial variation of Ov infection risk.

An ecological study of Bithynia snails, the first intermediate host of Opisthorchis viverrini in northeast Thailand.

Infection with the food-borne trematodiasis, liver fluke Opisthorchis viverrini, is a major public health concern in Southeast Asia. While epidemiology and parasitic incidence in humans are well studied, ecological information on the O. viverrini intermediate hosts remains limited. This study aimed to investigate the factors affecting the distribution and abundance of the first intermediate host, Bithynia siamensis goniomphalos snails. Water quality and snails were sampled in 31 sites in Muang District, Khon Kaen Province, Thailand from June 2012 to January 2013 to characterize the B.s. goniomphalos snail habitats. Species relative abundance and Shannon's diversity and evenness indices were employed to describe snail compositions and diversities across different habitat types. Statistical analyses were conducted to examine the extent to which the water quality variables and species interactions account for the relative abundance of B.s. goniomphalos snails. The results showed that the freshwater habitats of ponds, streams and rice paddies possessed significantly different abiotic water qualities, with water temperature and pH showing distinct statistical differences (P<0.05). Different habitats had different snail diversity and species evenness, with high B.s. goniomphalos snail abundance at rice paddy habitats. The differences in snail abundance might be due to the distinct sets of abiotic water qualities associated with each habitat types. The relative abundance of B.s. goniomphalos snails was found to be negatively correlated with that of Filopaludina martensi martensi snails (r=-0.46, P<0.05), underscoring the possible influence of species interaction on B.s. goniomphalos snail population. Field work observations revealed that rice planting seasons and irrigation could regulate snail population dynamics at rice paddy habitats. This study provides new ecological insights into the factors affecting Bithynia snail distribution and abundance. It bridges the knowledge gap in O. viverrini disease ecology and highlights the potential effect of anthropogenic irrigation practices on B.s. goniomphalos snail ecology.

Environmental determinants of Opisthorchis viverrini prevalence in northeast Thailand.

Opisthorchis viverrini infection is an important, human, parasitic disease along the middle and lower Mekong River of Southeast Asia. Despite vast efforts in epidemiological research, the wide geographical variation in O. viverrini prevalence remains unexplained. To investigate the potential influence of village location, prevalence data recorded during the year 2009 for 90 villages in northeast Thailand were analysed by a geographical information systems approach based on a digital elevation model for altitude determination. Land use compositions of village surroundings were derived from images produced by the Thematic Mapper of the Landsat satellite and landscape metrics were applied to quantify spatial patterns. Pearson's correlation coefficients were used to evaluate the associations between the environmental factors and O. viverrini prevalence. In spite of no statistical difference (P = 0.117), higher-ground villages generally had a lower level of opisthorchiasis than those situated lower down, while a significant negative correlation was detected between O. viverrini prevalence and the composition of farmland with low water content (P = 0.028), indicating the potential influence of agricultural lands with drought-tolerant crops. Strengthening this hypothesis, a significant positive association with O. viverrini prevalence was found for the combined land use classes of water and of farmland with high water content (P = 0.032), indicating that the dominance of a large land use patch capable of providing suitable habitats for the intermediate hosts might contribute to the disease. This study highlights the influence of landscapes on the epidemiology of O. viverrini infection and emphasises the need to incorporate land use planning into control strategies.

Asian primate species richness correlates with rainfall.

Previous studies of meta-analyses found significantly positive correlations between primate species richness and rainfall for Africa, Madagascar and the Neotropics, with the exception of Asia, leaving the open question whether that anomaly is the result of sampling bias, biogeography, or some other factor. This study re-examines the question using modelled data, with primate species richness data from the Southeast Asian Mammals Databank and rainfall data from the Climatic Research Unit. Data processing with Geographical Information Systems resulted in 390 sample points. Reduced major axis and ordinary least squares regressions were employed to examine the relationship for six regions, including the whole study area of Southeast Asia, and the subareas of Huxley West, Huxley East, Mainland Southeast Asia, Borneo, and Sumatra. The results showed a significant positive relationship between primate species richness and mean annual rainfall for Southeast Asia (r = 0.26, P<0.001). Comparing the results for the large islands and Mainland Southeast Asia showed that Sumatra had the highest correlation (r = 0.58; P<0.05). After controlling for the major biogeographic effect associated with Huxley's Line, our results showed that primate species richness is positively associated with mean annual rainfall in Southeast Asia. Our findings contrast to prior studies of meta-analyses that showed no relationship between rainfall and primate species richness in Asia, and thereby bring Asia into agreement with results showing significant positive correlations between rainfall and primate species richness everywhere else in the world. The inference is that previous anomalous results for Asia were result of sampling bias in the meta-analysis.

How do snails meet fish? Landscape perspective needed to study parasite prevalence.

We echo the viewpoints presented in the recent editorials and forums in ecohealth in 2009 and 2010 that understanding the links between water and health using biogeography can provide insights into the patterns of and the processes that give rise to the distribution of disease prevalence. In particular, we underscore the need to integrate disease ecology and biogeography using landscape ecological approaches. We use opisthorchiasis, a major public health problem in Southeast Asia, to illustrate our opinions.