Supply of tree-holes limits nest density of cavity-nesting birds in primary and logged subtropical Atlantic forest

Tree cavities are proposed to limit populations and structure communities of cavity-nesting birds. Although the greatest diversity of cavity-nesting birds is found in tropical and subtropical moist forests, little is known about how tropical logging affects the abundance of cavities or cavity-nesting birds. We compared the abundance of cavities and cavity nests between primary and selectively-logged subtropical moist Atlantic forest in Argentina, and conducted the first before-after controlled nest-box addition experiment to determine whether nest sites limit the breeding density of cavity-nesting birds in tropical or subtropical moist forest. Visual inspection of 86 cavities identified through ground-surveys revealed that only 19% were suitable for nesting birds, suggesting that cavity abundance may be overestimated in the literature on tropical forests. Suitable cavities were found in fewer than 1% of 1156 trees <60 cm dbh but 20% of 20 trees >100 cm dbh. Logged forest had half the basal area of primary forest, one third the density of large trees, nine times fewer cavities suitable for nesting birds, and 17 times fewer active nests. When we added nest boxes, nesting density increased on treatment plots but not on control plots in both logged and primary forest, suggesting that cavity supply can limit nest density even in relatively undisturbed forest. This is the first experiment to show how reduced cavity supply in logged tropical forest can limit breeding density of cavity-nesting birds. International initiatives such as forest certification should promote tropical timber management strategies that conserve large live cavity-bearing trees.     

集材50A拖拉机搭载板升降机构的改进研究

对集材５０Ａ拖拉机搭载板升降机构进行牵引力及升降阻力的力学分析，揭示了原机构动力性与经济性不佳的设计问题，本着原机构变动不大的原则，把两只ＹＧ１１０／４０型液压油缸，改为一只ＨＳＧ１００／５Ｏ型油缸；把ＣＢ４６型油泵。改为ＣＢ－３２型油泵。改进结果表明简化了机构，优化了动力性，提高了牵引效率，每年可以使林业生产节约大量经营费用。     

木材采运环节中木材检验的控制

本论述了木材采运环节中，木材检验的过程以及检验质量的控制方法和经验，做到木材检量准确无误。     

“天保”工程实施后森林采伐的探讨

国家实施天然林保护工程,作为森工企业存在不同程度的采伐。“天保”实施后,如何执行森林采伐。本文作者以方正林业局为例,谈了自己的见解。     

零散可采森林资源生产工艺的改革实践

可采森林资源日趋零散,旧的生产工艺已远远适应不了经济发展的需要,工艺改革势在必行。本文分析了旧生产工艺的种种弊端,提出了“移动式机库存车,移动式宿营车住宿,随车液压吊装原条”的新生产工艺模式,并着重介绍了按这一模式进行实践的效果,证明了新工艺具有一定的先进性和可操作性。     

Density and distribution of the endemic Seram cockatoo Cacatua moluccensis in relation to land use patterns

The endemic Seram cockatoo, Cacatua moluccensis, was placed on Appendix I of CITES in response to declining trade statistics but in the absence of population data. We conducted population surveys and collected data on habitat structure at seven sites on Seram in 1998. Cockatoo densities ranged from 0.93 to 17.25 birds/km² and averaged 7.9 birds/km² across sites. We classified habitat into three types but found that cockatoo densities did not correspond closely to habitat differences across sites. Cockatoo abundance was significantly associated with presence of potential nest trees and strangling figs. Analysis of forest cover and landuse indicates that while most of the island is still covered in lowland forest, only 14% of these forests are protected and almost half the island is classified as logging concession. Conservation recommendations include better information and enforcement of laws protecting Seram cockatoos and resolution of boundary conflicts between parks and logging concessions.     

Logging pattern and landscape changes over the last century at the boreal and deciduous forest transition in Eastern Canada

Forestry practices associated with the industrial era (since ~1900) have altered the natural disturbance regimes and greatly impacted the world’s forests. We quantified twentieth century logging patterns and regional scale consequences in three sub-boreal forest landscapes of Eastern Canada (117,000, 49,400 and 92,300 ha), comparing forestry maps depicting age and forest cover types for early industrial (1930) and present-day (2000) conditions. Results were similar for the three landscapes, indicating large-scale forest change during the twentieth century. In 1930, previous logging activities had been concentrated in the lowlands and along the main hydrographical network, as compared to a more even distribution over the landscapes in 2000, reflecting a decreasing influence of the environmental constraints on forest harvesting. In 1930, old-aged forests (>100 years) accounted for more than 75% of the unlogged areas of the three landscapes, as compared to less than 15% for the present-day conditions. Logging practices have thus inverted the stand age distribution of the landscapes that are currently dominated by young and regenerating stands. The 1930 forest cover types showed a clear relationship with elevation, with conifers located in the lowlands and mixed and deciduous stands restricted to the upper slopes. Between 1930 and 2000, 58–64% of the conifer areas transformed to mixed and deciduous forests, such that no clear altitudinal relationships remained in 2000. We conclude that twentieth century logging practices have strongly altered the preindustrial vegetation patterns in our study area, to the point that ecosystem-based management strategies should be developed to restore conifer dominance, altitudinal gradients, as well as the irregular structure inspired from old forest stands.     

皆伐炼山对华西雨屏区杉木人工林碳库的影响

人工林生态系统的C储量是陆地生态系统碳库之一,皆伐炼山所造成的环境负效应值得深思.本文以华西雨屏区28 a生杉木人工林为研究对象,旨在阐明皆伐和炼山对杉木人工林生态系统C库的影响.结果如下：（1）皆伐所造成的干材C转移量为85.9（±7.6）t·hm-2、（2）炼山所造成的采伐剩余物、林下层植物和凋落物C量损失分别为8.8（±0.3）t·hm-2、0.19（±0.02）t·hm-2和2.80（±0.08）t·hm-2、（3）炼山能显著降低0 ～60 cm层的土壤有机碳含量,其C损失量为39.5（±1.0）t·hm-2.炼山造成的采伐剩余物、林下层植物、凋落物和土壤有机质燃烧所释放CO2量为188.1 t·hm-2.在全球气候变化情景下,人工林皆伐炼山所造成的环境负效应不容忽视.     

经济转型期国有林业采育场的发展对策

根据福建省国有林业采育场的现状,分析了目前国有林业采育场所处的发展时期以及造成国有林业采育场陷入“两危”(资源危机和经济危圉)的原因。阐述了采育场发展产业经济的必要性。并在此基础上对企业的发展提出几点对策。     

中芬采运技术比较与经济分析

本对中芬的木材生产工艺流程、经营方案，生产劳动组织以及不同采运方式做了技术和经济分析。