Estimation of the impact of oil palm plantation establishment on greenhouse gas balance

Estimates of emissions indicate that if tropical grassland is rehabilitated by oil palm plantations, carbon fixation in plantation biomass and soil organic matter not only neutralises emissions caused by grassland conversion, but also results in the net removal of about 135 Mg carbon dioxide per hectare from the atmosphere. In contrast, the emission from forest conversion clearly exceeds the potential carbon fixation of oil palm plantings. Forest conversion on mineral soils to promote continued oil palm mono cropping causes a net release of approximately 650 Mg carbon dioxide equivalents per hectare, while the emission from peat forest conversion is even higher due to the decomposition of drained peat and the resulting emission of carbon oxide and nitrous oxide. The conversion of one hectare of forest on peat releases over 1,300 Mg carbon dioxide equivalents during the first 25-year cycle of oil palm growth. Depending on the peat depth, continuous decomposition augments the emission with each additional cycle at a magnitude of 800 Mg carbon dioxide equivalents per hectare. The creation of ‘flexibility mechanisms’ such as the clean development mechanism and emission trading in the Kyoto Protocol could incorporate plantations as carbon sinks in the effort to meet emission targets. Thus, for the oil palm industry, grassland rehabilitation is an option to preserve natural forest, avoid emissions and, if the sequestered carbon becomes tradable, an opportunity to generate additional revenue. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.     

Pollution-induced successions in forests of the Kola Peninsula

Trends of changes in the successional status of northern taiga forests exposed to technogenic pollution in the Kola Peninsula are discussed. Main studies of digression in spruce and pine forests are characterized on the basis of the dynamics of species composition of phytocenoses and chemical composition of atmospheric fallout, soils, and dominant plants.     

A Matrix‐Calibrated Species‐Area Model for Predicting Biodiversity Losses Due to Land‐Use Change

Abstract: Application of island biogeography theory to prediction of species extinctions resulting from habitat loss is based on the assumption that the transformed landscape matrix is completely inhospitable to the taxa considered, despite evidence demonstrating the nontrivial influence of matrix on populations within habitat remnants. The island biogeography paradigm therefore needs refining to account for specific responses of taxa to the area of habitat “islands” and to the quality of the surrounding matrix. We incorporated matrix effects into island theory by partitioning the slope (z value) of species–area relationships into two components: γ, a constant, and σ, a measure of taxon‐specific responses to each component of a heterogeneous matrix. We used our matrix‐calibrated model to predict extinction and endangerment of bird species resulting from land‐use change in 20 biodiversity hotspots and compared these predictions with observed numbers of extinct and threatened bird species. We repeated this analysis with the conventional species–area model and the countryside species–area model, considering alternative z values of 0.35 (island) or 0.22 (continental). We evaluated the relative strength of support for each of the five candidate models with Akaike's information criterion (AIC). The matrix‐calibrated model had the highest AIC weight (w_i = 89.21%), which means the weight of evidence in support of this model was the optimal model given the set of candidate models and the data. In addition to being a valuable heuristic tool for assessing extinction risk, our matrix‐calibrated model also allows quantitative assessment of biodiversity benefits (and trade‐offs) of land‐management options in human‐dominated landscapes. Given that processes of secondary regeneration have become more widespread across tropical regions and are predicted to increase, our matrix‐calibrated model will be increasingly appropriate for practical conservation in tropical landscapes.     

POSTFIRE SUSPENDED SEDIMENT FROM YELLOWSTONE NATIONAL PARK,WYOMING1

ABSTRACT: Wildfires in 1988 burned over 2000 square miles of the greater Yellowstone area in Montana and Wyoming in the largest fires in the history of Yellowstone National Park (YNP). A four-year postfire study to estimate fire-related changes in suspended sediment transport on the Yellowstone River and its principal tributary in YNP, the Lamar River, benefitted from a recently completed three-year prefire baseline study. Both studies took daily depth-integrated samples from April through September. Fire-related changes in suspended sediment were distinguished from natural climatic variations by two methods: comparison of forecast postfire sediment loads estimated with prefire sediment-rating equations to measured postfire loads; and by postfire changes in suspended sediment load expressed per unit volume runoff. Both methods indicated postfire sediment increases that varied according to season. The higher elevation Lamar River basin had little postfire increase in spring snowmelt season sediment but large increases in summer sediment load. The Yellowstone River had postfire increases in sediment load for the spring but did not reflect the large summer increases of its upstream tributary. The reasons for the difference in postfire snowmelt sediment response are unclear but may relate to basin elevation differences, the effects of unburned watersheds, and cooler postfire springs. The few high streamflow snowmelt events in the postfire period mitigated postfire sediment increases.     

试谈建立沱江源头水源保护区的必要性

本文根据沱江源头水源涵养林辽度砍代，导致源头蓄水量锐减，以及滥采乱控矿石，造成资源损失与灾害频繁的严峻现实，提出了建立沱江源头水源保护区的必要性。     

开化县外向型创汇林业的战略模式

我国森林资源少,消耗量大,林业建设资金短缺。如何发展当前的林业生产、筹集林业建设资金,开化县的外向型创汇林业为我们走出了一条具有中国特色的外向型林业建设道路。本文就开化县发展外向型创汇林业的优点、出口创汇的主要对策、主要商品、发展潜力及其前景进行了论述,对目前正在探索适合我国国情的、解决我国林业“两危”的战略对策提供了现实的典型范例。     

EVALUATION OF HYDROLOGIC MODELING TECHNIQUES FOR FOREST LAND MANAGEMENT PLANNING1

ABSTRACT: A growing concern for environmental quality paralleled with increasing demands on our forest resources has prompted the Washington State Department of Natural Resources to evaluate simulation modeling as a technique for analyzing management decisions in terms of their environmental effects. The evaluation focused on a system of integrated models developed at the University of Washington which simulate processes and activities within the forest ecosystem. A major part of the system is a hydrologic model which predicts changes in discharge, stream temperature, and concentrations of suspended sediment and dissolved oxygen based on information generated by other models representing intensive management practices. The evaluation consisted of applying the system to a 72,000 acre tract of forest land, validating the models with two years of discharge and water quality data from a 93,000 acre watershed, and determining the pertinence of hydrologic modeling for management purposes. Results show several potential uses of hydrologic modeling for forest management planning, especially for analyzing the effects of timber harvesting strategies on water quality.     

INFLUENCES OF A FOREST ON THE HYDRAULIC GEOMETRY OF TWO MOUNTAIN STREAMS1

ABSTRACT The influence of a forest on the formation of steps in two small streams of the Colorado Rocky Mountains was studied. Steps provided by logs fallen across the channel added to flow energy reduction. The streams required additional gravel bars to adjust to slope. Average step length between logs and gravel bars was strongly related to channel gradient and median bed material size. Based on the average number of log steps per 50 feet of channel, an average of 116 percent of gravel bars were added at Fool Creek and 60 percent at Deadhorse Creek. The latter had 52 percent more logs in the channel and therefore required less bed material movement than the former. Although these are “rushing mountain streams,” most flow velocities ranged between 0.5 and 2.5 f.p.s. Exponents of a function relating rate of change of depth or velocity to discharge indicated that dynamic stream equilibrium was attained. Implications for forest management are that sanitation cuts (removal of dead and dying trees) would not be permissible where a stream is in dynamic equilibrium and bed material movement should be minimized.