Species Distribution and Patterns in a Forest-savannah Ecotone: Environmental Change and Conservation Concerns

Understanding the dynamics and patterns of biodiversity in transition forests is vital in promoting conservation and addressing environmental change issues.This work focused on elucidating the diversity,structure,and carbon potentials of a forest-savannah ecosystem.To achieve this,8 forest plots that measured 50 m×50 m each was set up in a forest-savannah landscape and used to identify and measure tree species≥10 cm diameter at breast height(DBH measured at 130 cm).Species importance value was used to summarize the biodiversity patterns and the aboveground carbon estimates were elicited with the allometric equation.43 species within 22 families were enumerated and the diversity was generally low(ranging from 1.82-2.5).Species such as Daniellia oliveri(Rolfe)Hutch.&Dalziel,Py-rostria guinnensis Comm.ex A.Juss,Dialium guineense Willd.and Margariteria discoidea(Baill.)G.L Webster were the dominant species,and had the highest importance values of 113.06,55.13,28.16 and 16.95,respectively,while Allophlus africanus P.Beauv.,Annona senegalensis Pers.,Anthonatha macrophylla P.Beauv.,Ficus capensis Thumb.and Lecaniodiscus cupanioides Planch had the least importance values of 0.16 each.Carbon estimates ranged from 16.43172-42.9298 t/Ha.Most frequent species with higher basal areas no doubt contributed much to the carbon esti-mates,but did not have higher capacities in storing carbon.Managing the ecosystem with more carbon-dense species was seen as a suitable strategy for addressing environmental change in the ecosystem and region.

Changes in Ecosystem Service of Soil Conservation Between 2000 and 2010 and Its Driving Factors in Southwestern China

Human activities significantly alter ecosystems and their services; however, quantifying the impact of human activities on ecosystems has been a great challenge in ecosystem management. We used the Universal Soil Loss Equation and county-level socioeconomic data to assess the changes in the ecosystem service of soil conservation between 2000 and 2010, and to analyze its spatial characteristics and driving factors in the southwestern China. The results showed that cropland in the southwestern China decreased by 3.74%, while urban land, forest, and grassland areas increased by 46.78%, 0.86%, and 1.12%, respectively. The soil conservation increased by 1.88 × 10^(11) kg, with deterioration only in some local areas. The improved and the degraded areas accounted for 6.41% and 2.44% of the total land area, respectively. Implementation of the Sloping Land Conversion Program and urbanization explained 57.80% and 23.90% of the variation in the soil conservation change, respectively, and were found to be the main factors enhancing soil conservation. The 2008 Wenchuan earthquake was one of the factors that led to the degradation of soil conservation. Furthermore, industrial adjustment, by increasing shares of Industry and Service and reducing those of Agriculture, has also promoted soil conservation. Our results quantitatively showed and emphasized the contributions to soil conservation improvement made by implementing ecological restoration programs and promoting urbanization. Consequently, these results provide basic information to improve our understanding of the effects of ecological restoration programs, and help guide future sustainable urban development and regional industrial restructuring.

The conservation patterns of grassland ecosystem in response to the forage-livestock balance in North China

Being a key ecological security barrier and production base for grassland animal husbandry in China,the balance between grassland forage supply and livestock-carrying pressure in North China directly affects grassland degradation and restoration,thereby impacting grassland ecosystem services.This paper analyzes the spatiotemporal variation in grassland vegetation coverage,forage supply,and the balance between grassland forage supply and livestock-carrying pressure from 2000 to 2015 in North China.We then discuss the spatial pattern of grassland ecological conservation under the impacts of grassland degradation and restoration,and livestock-carrying pressure.Over the last 16 years,the total grassland area in North China decreased by about 16,000 km^(2),with vegetation coverage degraded by 6.7%of the grasslands but significantly restored by another 5.4%of grasslands.The provisioning of forage by natural grassland mainly increased over time,with an annual growth rate of approximately 0.3 kg/ha,but livestock-carrying pressure also increased continuously.The livestock-carrying pressure index without any supplementary feeding reached as high as 3.8.Apart from the potential livestock-carrying capacity in northeastern Inner Mongolia and the central Tibetan Plateau,most regions in North China are currently overloaded.Considering the actual supplementary feeding during the cold season,the livestock-carrying pressure index is about 3.1,with the livestock-carrying pressure mitigated in central and eastern Inner Mongolia.Assuming full supplementary feeding in the cold season,livestock-carrying pressure index will fall to 1.9,with the livestock-carrying pressure alleviated significantly in Inner Mongolia and on the Tibetan Plateau.Finally,we propose different conservation and development strategies to balance grassland ecological conservation and animal husbandry production in different regions of protected areas,pastoral areas,farming-pastoral ecotone,and farming areas,according to the grassland ecological protection patterns.

Rice ＋ Fish Farming in Homesteads： Sustainable Natural-Resource Management for Subsistence in Arunachal Pradesh, India

Understanding the attributes of traditional, location-specific land-use systems will provide insights for improvement of such systems and design of new ones for wider applicability. The integrated rice ＋ fish system developed by the Apatani tribe of Ziro valley, Arunachal Pradesh, Northeastern India is such a unique system. Faced with shortages of their staple food items （rice and fish）, these subsistence farmers developed this ingenious system--in preference to the wide-spread shifting cultivation in the region--by capitalizing on the good water supply （from rainfall supplemented by natural flow from hills surrounding the valley）. Two rice crops are grown annually and fish is reared in paddy fields during the main rainy season. Crop residues and animal wastes are the sources of nutrients to crops, chemical fertilizers and insecticides are not used. Over the years, rice yield has been stable at about 3,700 kg.ha-1.year-1. Recently, UNESCO has tentatively added the valley as a ＂world heritage site＂ recognizing its ＂extremely high productivity＂ and ＂unique＂ ecological preservation. The resilience and the sustainability of the system could be attributed to efficient nutrient cycling and nutrient input through water seeping in from surrounding hills, which have not been, but deserve to be, quantified.

Effects of Sand-Harvesting on River Water Quality and Riparian Soil Physico-Chemical Properties

The widespread distribution of river sand-harvesting activities continues to degrade river water quality and the surrounding riverine environments. This study determined practical effects of sand-harvesting on two rivers in Kakamega County Kenya. Water samples were tested for turbidity and total suspended solids (TSS). For riparian soils, nitrogen (N), phosphorus (P), pH, organic carbon (OC), moisture content and textural class were determined on composite samples obtained from the field. Two control sites not affected by sand-harvesting were also used for comparison. Results indicate TSS concentrations increased during the rainy season when sand-harvesting was occurring, with significant differences between the control and sand-harvesting sample groups. Between seasons—dry and wet—in natural circumstances, the riparian soil moisture and phosphorus contents increased significantly. The study shows that river sand-harvesting degrades the aesthetic value of riparian areas, and makes rivers prone to bank erosion, and silt. This increases river water turbidity. The study concludes that sand-harvesting does not directly affect the riparian soil moisture content, total N, P, pH, OC or textural class, but reduces productivity of riparian land and puts the riverine ecosystems at risk.

The net ecosystem services value in China's Mainland

Protection of the ecological environment is an effective strategy for maintaining ecosystem health,improving provision of ecosystem services,and increasing human well-being.However,traditional calculations of the value of ecosystem services(VES)provide weak guidance because they ignore the costs of these services,leading to economically inefficient strategies.To understand the difference between VES and the net ecosystem services value(NES,after subtracting costs from VES)and to improve evaluations of ecosystem services,we estimated NES for China's Mainland(including farmland,grassland,forest,and wetland).NES totaled 10.0×10~3RMB ha^(-1)yr^(-1)in 2014,which is only 35.1%of the corresponding VES.Grassland NES was–0.7×10~3RMB ha^(-1)yr^(-1),in contrast with a positive grassland VES.NES of farmland,grassland,forest,and wetland in2014 totaled 7.2×10^(12)RMB,accounting for 27.0%of China’s GNP.Recent Chinese planning based on VES emphasizes forest conservation and ignores the conservation of other important ecosystems,such as grassland,leading to a continuing loss of China’s natural capital.Due to regional differences in economic conditions,resource endowments,and geographical characteristics,VES and NES differ among regions.To maximize the ecological benefits from conservation,it is necessary to account for these differences by comparing strategies based on NES,thereby choosing projects that maximize both economic and ecological benefits.To maintain the ecological balance,ecological restoration and socioeconomic activities should account for the costs of providing ecosystem services.This is essential to minimize the costs and maximize the benefits of projects.

Impacts of Non-farm Employment of Rural Laborers on Agricultural Land Use:Theoretical Analysis and Its Policy Implications

During rapid urbanization and industrialization process, non-farm employment of rural laborers has emerged as a prevalent phenomenon in rural areas of China and become an important driving factor for changes in agricultural land use. This article attempts to theoretically analyze the impacts of non-farm employment of rural laborers on agricultural land use based on economic frameworks. As rational agents, farmers aim to maximize their income and follow equilibrium principles when they decide how to allocate their labor forces（or working time） in two departments（farm and non-farm） and how to use their agricultural land with different quality and location. The income earned by non-farm employment is higher, and there exists a comparative advantage between labors, as a result the quantity and quality of labor input in agricultural land use decreases. With the limitation of labor input during agricultural land use decision-making of farm households, on the one hand, land with higher quality is still utilized by farmers. On the other hand, poor quality land will be less well managed and is more likely to be abandoned. Non-farm employment of rural laborers and the rising of opportunity costs will result in abandonment of poor quality land, and great importance should be attached to this by policy makers.