Little by little,inch by inch: Project expansion assessments in the Papua New Guinea mining industry

Social impact assessment (SIA) has traditionally been practiced as an ex-ante predictive tool in the context of regulatory approval by government agencies. This model of SIA developed by Burdge and others is based on ‘greenfields’ development, of a new project going in to areas where there are no, or relatively few, similar types of development. The International Principles of SIA signalled a conceptual shift in the practice of SIA where greater emphasis is placed on the assessment and management of social issues across the life-cycle of developments. In addition forms of cumulative impact assessment have been developed for contexts where more than one project is likely to impact on populations or communities. With these changes to the traditional models of impact assessment there is a need to clarify how and when dedicated phases of ‘assessment’ might be undertaken over the life-cycle of a development. In the context of the mining industry, SIAs are increasingly required by governments for incremental increases in the size or impact of these operations. This paper reviews the development and application of Project Expansion Assessments (PEAs) for two large-scale mining operations in Papua New Guinea. It argues that a different set of assumptions need to underlie the model of IA for such assessments, with more emphasis on trajectories rather than baselines, a critical evaluation and attribution of effects, and the incorporation of adaptive management tools into the process.     

Land use change and carbon exchange in the tropics: II. Estimates for the entire region

Determining the effect of tropical land use on the carbon dioxide (CO₂) content of the atmosphere requires: (a) estimates of the rates of land use change, (b) estimates of the difference between the carbon stored in forests and that stored in pastures and cultivated fields, and (c) a consideration of the fate of carbon stored in the cleared vegetation. The first article of this series analyzed land use in four tropical countries and estimated the carbon released to the atmosphere as a consequence of changes in land use. This article estimates the carbon released from the entire tropical region based on the two published studies of land use change for the tropics as a whole that distinguish between temporary and permanent land use: Seiler and Crutzen (1980) and Lanly (1982). We combine these estimates with two estimates of the difference in carbon storage between forests and fields derived from Whittaker and Likens (1975) and Brown and Lugo (1982), and the two scenarios of the fate of cleared vegetation, developed in the previous article, to produce several complete sets of data describing the necessary parameters to calculate carbon exchange. These data sets, entered into our model, produce a range of estimates of the annual release of carbon from tropical vegetation in 1980 of from 0.6 to 1.8 BMT/year, with the more likely range being 0.9–1.2 BMT/year. Our preliminary analysis suggests that the release from tropical soils due to land use change adds about an additional 0.3 BMT C/year, so that the total release is probably between 1.2 and 1.5 BMT C/year. Peng and others (1983) reported that new models of the oceanic carbon cycle can accommodate at least 1.2 BMT C/year in 1980 from forests and soils. Our results indicate that, given the uncertainties in the size of both the biotic release and oceanic uptake, the global carbon budget may be balanced if there is no significant release from nontropical ecosystems due to land use change and all mature ecosystems are in collective equilibrium with the atmosphere.     

Land use change and carbon exchange in the tropics: III. Structure,basic equations,and sensitivity analysis of the model

The rationale, assumptions, structure and basic mathematical functions of the model used to produce the simulation results reported in the first two articles of this series are described in detail. Sensitivity analysis indicates that the most important parameters in the model, and, presumably, in the carbon exchange between tropical forests and the atmosphere, are: (a) the conversion rate of forests to permanent pasture and agriculture, (b) the changes that are occurring and have occurred in the shifting cultivation system, and (c) the fate of cleared vegetation. Although it is not possible to validate the model against direct measurements of carbon exchange, the model has been proven robust when subject to a series of explicit analyses and comparisons with other assessments.     

Land use and management in the People's Republic of China

Widespread disregard for essential principles of sound environmental management and protection during the three decades of Communist rule prior to 1980 have exacerbated traditional shortages of good arable land and productive forest cover in the People's Republic of China. The government's policies have also drastically reduced valuable freshwater surfaces, caused extensive grassland deterioration and soil erosion, and brought about many local and regional climatic changes. However, new policies put into effect recently are attempting to reverse these trends with a sound ecosystemic approach to land management.     

Land use changes and net primary production in the Georgia,USA, landscape: 1935–1982

Land use since 1935 was quantified for Georgia, USA, and for a sample of 20 counties from the major physiographic regions within the state. Statistical data on crop production, pasture productivity, and forest growth were used to estimate net primary production. Appropriate harvest indices (ratio of crop yield to total plant production) were used to correct crop yield data for different decades. Net primary production (NPP) of the Georgia landscape increased from 2.5 to 6.4 tonnes/ha from 1935 to 1982, but varied considerably among land uses and physiographic regions. NPP in the piedmont and mountains reached a plateau between 1960 and 1982, but the upper and lower coastal plains showed a continued linear increase in NPP. In all regions, NPP rose most between 1960 and 1982, coinciding with increases in inputs such as fertilizer and irrigation. Natural ecosystem NPP for Georgia is approximately 16–18 tonnes/ha, and the estimated actual NPP is thus considerably less than the potential. Spatial and temporal patterns of NPP may be a useful basis for evaluating the biological performance of a landscape.     

Long-term dynamics in land resource use and the driving forces in the Beressa watershed, highlands of Ethiopia

Land degradation in the Ethiopian highlands is considered to be one of the major problems threatening agricultural development and food security in the country. However, knowledge about the forces driving the long-term dynamics in land resources use is limited. This research integrates biophysical information with socio-economic processes and policy changes to examine the dynamics of land resource use and farmers' livelihoods in the Beressa watershed for over 40 years during the second half of the 20th century. It was found that there have been substantial dynamics in land resource use in the area. The natural vegetation cover has been extensively cleared, although most of the cleared areas have since been replaced with plantations. Grazing land has expanded remarkably at the expense of cropland and bare land. However, the expansion of cropland was minimal over the 43-year period despite a quadrupling of the population density. Yields have not increased to compensate for the reduction in per capita cropland, and the soil quality appears to be not that good. Though the farmers perceived it otherwise, the long-term rainfall pattern has improved. In response to soil degradation, water shortage, socio-economic and policy changes, farmers have tended to gradually change from annual cropping to tree planting and livestock production to cope with the problems of soil degradation, water scarcity and smaller farms. Income diversification through the sale of wood and cattle dung is becoming a major livelihood strategy. Apparently, however, little attention has been paid to investments in soil and water conservation (SWC) and local soil fertility amendments. In particular, increased erosion and related high nutrient losses in sediments, as well as the removal of potentially available soil nutrients through the sale of manure threatens to damage agricultural sustainability in the area.     

Land Use and Land Cover Change Analysis and Prediction in the Upper Reaches of the Minjiang River,China

Scientists have aimed at exploring land use and land cover change (LUCC) and modeling future landscape pattern in order to improve our understanding of the causes and consequences of these phenomena. This study addresses LUCC in the upper reaches of Minjiang River, China, from 1974 to 2000. Based on remotely sensed images, LUCC and landscape pattern change were assessed using cross-tabulation and landscape metrics. Then, using the CLUE-S model, changes in area of four types of land cover were predicted for two scenarios considering forest polices over the next 20 years. Results showed that forestland decreased from 1974 to 2000 due to continuous deforestation, while grassland and shrubland increased correspondingly. At the same time, the farmland and settlement land increased dramatically. Landscape fragmentation in the study area accompanied these changes. Forestland, grassland, and farmland take opposite trajectories in the two scenarios, as does landscape fragmentation. LUCC has led to ecological consequences, such as biodiversity loss and lowering of ecological carrying capacity.     

云南省罗平县土地利用变化及驱动力研究

土地利用问题是实现生态脆弱区环境-经济协调发展的关键所在。选取喀斯特地区的罗平县作为研究对象，将遥感、GIS和多元统计技术结合运用于土地利用变化研究中，对罗平县1990～2001年的土地利用变化情况及驱动力进行了研究。结果表明，罗平县耕地逐年减少；影响耕地变化的主要驱动因子包括人口、经济和社会投资。     

Land use change and carbon exchange in the tropics: I. Detailed estimates for Costa Rica,Panama, Peru,and Bolivia

Our group, composed of modelers working in conjunction with tropical ecologists, 3 has produced a simulation model that quantifies the net carbon exchange between tropical vegetation and the atmosphere due to land use change. The model calculates this net exchange by combining estimates of land use change with several estimates of the carbon stored in tropical vegetation and general assumptions about the fate of cleared vegetation. In this report, we use estimates of land use and carbon storage organized into sixlife zone (sensu Holdridge) categories to calculate the exchange between the atmosphere and the vegetation of four tropical countries. Our analyses of these countries indicate that this life zone approach has several advantages because (a) the carbon content of vegetation varies significantly among life zones, (b) much of the land use change occurs in life zones of only moderate carbon storage, and (c) the fate of cleared vegetation varies among life zones. Our analyses also emphasize the importance of distinguishing between temporary and permanent land use change, as the recovery of vegetation on abandoned areas decreases the net release of carbon due to clearing. We include sensitivity analysis of those factors that we found to be important but are difficult to quantify at present.     

Impact of land use and land cover changes on the ambient temperature in a middle scale city, Takamatsu, in Southwest Japan

There is a lack of information on urban heat island impact on the thermal environment due to low populated urban sprawl, although densely populated urban sprawl impact has been identified by several researchers. The Takamatsu area has recently developed in a low populated urban sprawl style without any increase in population. This paper examined the impact of a low populated urban sprawl on the thermal environment through an analysis of the last 30 years data set and investigated the contribution of vegetation fraction and population density to the temperature trend. As a consequence, it was shown that one of the most significant causative factors of temperature increase is an expansion of non-vegetated area even without population growth. This result implied that vegetated zones should be maintained in urban areas in order to realize sustainable urbanization.     

Changes in Soil Aggregate,Carbon, and Nitrogen Storages Following the Conversion of Cropland to Alfalfa Forage Land in the Marginal Oasis of Northwest China

Maintenance of soil organic carbon (SOC) is important for sustainable use of soil resources due to the multiple effects of SOC on soil nutrient status and soil structural stability. The objective of this study was to identify the changes in soil aggregate distribution and stability, SOC, and nitrogen (N) concentrations after cropland was converted to perennial alfalfa (Medicago sativa L. Algonguin) grassland for 6 years in the marginal oasis of the middle of Hexi Corridor region, northwest China. Significant changes in the size distribution of dry-sieving aggregates and water-stable aggregates, SOC, and N concentrations occurred after the conversion from crop to alfalfa. SOC and N stocks increased by 20.2% and 18.5%, respectively, and the estimated C and N sequestration rates were 0.4 Mg C ha⁻¹ year⁻¹ and 0.04 Mg N ha⁻¹ year⁻¹ following the conversion. The large aggregate (>5 mm) was the most abundant dry aggregate size fraction in both crop and alfalfa soils, and significant difference in the distribution of dry aggregates between the two land use types occurred only in the >5 mm aggregate fraction. The percentage of water-stable macroaggregates (>2, 2–0.25 mm) and aggregate stability (mean weight diameter of water-stable aggregates, WMWD) were significantly higher in alfalfa soils than in crop soils. There was a significant linear relationship between total SOC concentration and aggregate parameters (mean weight diameter) for alfalfa soils, indicating that aggregate stability was closely associated with increased SOC concentration following the conversion of crops to alfalfa. The SOC and N concentrations and the C/N ratio were greatest in the >2 mm water-stable aggregates and the smallest in the 0.25–0.05 mm aggregates in crop and alfalfa soils. For the same aggregate, SOC and N concentrations in aggregate fractions increased with increasing total SOC and N concentrations. The result showed that the conversion of annual crops to alfalfa in the marginal land with coarse-texture soils can significantly increase SOC and N stocks, and improve soil structure.