Encouraging the application of sustainable timber harvesting practices: A review of policy tool use and effectiveness in the eastern United States

States use a variety of approaches to encourage landowners and loggers to apply ecologically-sustainable timber harvesting practices, the latter generically referred to as timber harvesting guidelines. A survey of 37 state forestry agency administrators in the eastern U.S. (defined as a contiguous region with the northwest and southwest borders being North Dakota and Texas, respectively) was conducted in 2000 to assess the extent and nature of state guideline programs and the various methods by which states encourage their use. The study found states in the eastern U.S. use a variety of policy tools to promote guideline use, with certain policy tools more common for certain target audiences (e.g., loggers) as well as the types of resources (e.g., wildlife habitat) addressed by the guidelines. Eighty-three percent of the programs directed at encouraging forest landowners in the eastern U.S. to use the timber harvesting practices identified in their state guidebooks are technical assistance, educational, or cost-share programs. Technical assistance and education programs are the most common policy tools used to assist loggers in applying sustainable harvesting practices. Technical assistance and cost-share programs consistently rank among the most effective policy tools for encouraging loggers and landowners to apply the guidelines. Comparing the level of program investment to perceived benefits, assistance programs and education programs rank most efficient landowner programs, whereas premium prices for products and preferential access to contracts are the two most efficient programs directed at loggers. The paper concludes with an assessment of emerging trends and additional information needs associated with encouraging the application of sustainable timber harvesting practices.     

Effectiveness of forestry streamside management zones in the sand-clay hills of Mississippi: early indications

During the past decade, compliance with initiatives to promote forestry best management practices (BMPs) has been monitored in most states of the southern U.S. and suggests an excellent level of acceptance throughout the region. However, effectiveness of these practices to protect water quality and aquatic habitat in streams that are potentially impacted by forest management activities has not been as thoroughly documented as the degree of compliance. The objective of this study was to determine effectiveness of streamside management zones (SMZs), a key element of BMPs designed for protection of water quality, aquatic habitat, and macroinvertebrate communities, in low-order streams within a region of north central Mississippi that is subjected to intensive forest management. Three SMZ treatments (undisturbed reference, clear-cut logging with an SMZ designated by forest managers, or clear-cut logging with no SMZ) were evaluated using a study with three replications of each treatment. Response metrics including water quality parameters, mineral soil exposure and net deposition/erosion within riparian zones, stream habitat indicators, and aquatic macroinvertebrate communities were comparable between streams receiving SMZs and undisturbed reference streams at all sampling intervals during the first year after treatment. Furthermore, significant elevation of streamwater temperature, decline in habitat stability rating, and increase in density of macroinvertebrates occurring in streams without an SMZ in comparison to reference streams provides additional evidence of SMZ effectiveness during the initial year after harvesting.     

干旱区防风固沙林建设与管理的进一步思考

根据干旱区的典型特点,突出"水"的问题,结合已有成果的经验,针对目前新疆防风固沙生态林建设与管理中存在的问题,就造林树种选择、林带结构、造林密度、用水方式等问题,从恢复生态学的理论高度提出一些供参考的想法。     

干旱区荒漠植被的特点及恢复问题的研究--以塔里木河流域胡杨林生态系统为例

干旱区除存在唯一的真正森林-胡杨(Populuseuphratica)林外,植被普遍极其稀疏,以降水稀少,蒸发显著为特点的干旱区,荒漠植被的存在对于生态环境的保护和良性发展起到极大的作用,干旱区的荒漠植被表现出特有的生理特征,本文研究塔里木河流域胡杨林的特征及对生态环境的适应规律,进一步提出了扩展荒漠植被的可能性及其措施。     

CONCENTRATED FLOW BREAKTHROUGHS MOVING THROUGH SILVICULTURAL STREAMSIDE MANAGEMENT ZONES: SOUTHEASTERN PIEDMONT,USA1

ABSTRACT: Geomorphic characteristics and spatial frequency of ephemeral concentrated flow paths entering streamside management zones (SMZs) were evaluated to determine the efficiency of best management practices (BMPs) in preventing concentrated overland flow and associated sediment from reaching stream channels. Specifically, SMZs of 30 recently clearcut and site prepared commercial forestry units in the Georgia Piedmont were surveyed to find two types of locations: those where flow and/or sediment from the adjacent silvicultural site entered and moved through SMZs into stream channels (breakthroughs), and those where either flow and/or sediment entered SMZs without reaching stream channels or where no overland flow entered SMZs (successes). A total of 187 breakthroughs were identified on 3,773 total acres. On average, sites featured one breakthrough for every 20 acres of clearcut or site prepared area. The average hydrologic contributing area to a breakthrough was 1 acre. The percentage of the total clearcut or site prepared area contributing to breakthroughs was 5 percent. Approximately 50 percent of all breakthroughs occurred in areas of convergence (swales) and gullies, while 25 percent of all breakthroughs occurred where runoff from roads or skid trails was concentrated. Breakthroughs tended to occur in areas with large contributing area, low litter cover, and steep slopes. However, individually these variables did not differentiate well between breakthroughs and successes. The variables that discriminated best between successes and failures were the product of contributing area and percent bare ground, and the same variable multiplied by average slope. Fourteen percent of the breakthroughs traveled more than 100 feet through SMZs before reaching streams. Results imply that reduction of bare ground, better dispersal of road runoff, introduction of hydraulic resistance to likely flow paths, and targeted extensions of SMZ width may be warranted in improving BMPs on Piedmont forests.     

森林火险等级分布模拟--中小尺度动力学模式

通过在地形坐标系中建立考虑森林植被影响的三维大气-土壤耦合动力学模式,对神农架林区历史上几次重大森林火灾发生期的气象要素场进行了模拟,并在此基础上计算神农架林区高分辨率的森林火险等级分布状态,揭示了林火发生的一些重要规律。     

APPLICATION OF THE SNOWMELT RUNOFF MODEL USING MULTIPLE-PARAMETER LANDSCAPE ZONES ON THE TOWANDA CREEK BASIN,PENNSYLVANIA1

ABSTRACT: The Snowmelt Runoff Model (SRM) is designed to compute daily stream discharge using satellite snow cover data for a basin divided into elevation zones. For the Towanda Creek basin, a Pennsylvania watershed with relatively little relief, analysis of snow cover images revealed that both elevation and land use affected snow accumulation and melt on the landscape. The distribution of slope and aspect on the watershed was also considered; however, these landscape features were not well correlated with the available snow cover data. SRM streamflow predictions for 1990, 1993 and 1994 snowmelt seasons for the Towanda Creek basin using a combination of elevation and land use zones yielded more precise streamflow estimates than the use of standard elevation zones alone. The use of multiple-parameter zones worked best in non-rain-on-snow conditions such as in 1990 and 1994 seasons where melt was primarily driven by differences in solar radiation. For seasons with major rain-on-snow events such as 1993, only modest improvements were shown since melt was dominated by rainfall energy inputs, condensation and sensible heat convection. Availability of GIS coverages containing satellite snow cover data and other landscape attributes should permit similar reformulation of multiple-parameter watershed zones and improved SRM streamflow predictions on other basins.     

峨眉山环境现状研究

峨眉山是世界名山，其主要风景林－－冷杉出现大面积衰败和死亡。本文概述了峨眉山的地理和气候特点，研究了土壤、植被、大气环境及旅游现状；为深入研究峨眉山冷杉衰亡的原因提供基础资料，为恢复和建设峨眉山的生态环境提供思路和参考。     

PREDICTING TEMPORAL AND SPATIAL FLOOD DYNAMICS USING A PRECALIBRATED MODEL1

ABSTRACT: A large storm in December 1990 allowed the evaluation of flood predictions from a hydrologic model (TOPMODEL) that had been previously calibrated on the West Fork of Walker Branch Watershed, a gauged 37.5 ha catchment near Oak Ridge, Tennessee. The model predicts both hydrograph dynamics and the spatial distribution of overland flow using an index based on topography. Maximum extent of overland flow during the storm was determined from patterns of leaf litter removal from valley bottoms. Both the flood hydrograph and the extent of overland flow were accurately predicted using model parameters obtained from a three-month period of normal flow conditions during 1983.