我国薪炭材树种的热值与生态差异的研究

本文对木材热值的测定方法进行了研究。为了提高试验的精确度,改进了试样的容器;减少试样辅助添加剂引入的误差;考虑了含脂材挥发物对热值的影响,提出了一个实际通用的测试方法。通过对二十四种样木的测试,综合分析了测试误差、生态差异以及营林因子等的影响,对薪材热值的树种间差异和生态因子对热值变异时影响进行了研究。     

Assessing the perceived utility of wood resources in a protected area of Western Tanzania

To identify factors associated with interest in gaining access to protected wood resources in western Tanzania, I collected demographic, socio-economic and wood-use data for 240 households in three villages bordering Katavi National Park. Interest in accessing the protected wood resources was not associated with fuelwood needs, and did not fall along ethnic or demographic lines. Instead, logistic regression analysis identified material and land wealth as variables that increase households' interest in accessing wood resources in the Park, whereas intent to move in the near future and the interaction of material and land wealth were negative influences. These results suggest that resource-use interests are largely dependent upon expected individual gains, which vary according to household needs and ability to process resources for potential local sale or trade. This study considers the importance of distinguishing between people's conservation attitudes and their interest(s) in using specific resources, emphasizing the need to recognize intra-community variation in use interests.     

直干桉薪炭林萌发试验研究

对玉溪市直干桉薪炭林进行不同伐桩高度，不同砍伐方式，不同季节砍伐的试验研究表明，在玉溪地区经营直干桉薪炭林，砍伐可以提高薪炭林的产薪量，砍伐过的林分产量比对照提高１２．６倍，最高可达１６．９倍；伐桩高度在３０ｃｍ最好，砍伐方式以刀砍为主，伐后的产薪量也比锯的稍好；冬季砍伐比春季砍伐效果明显，平均树高可提高４８％，最大为５６％；采伐季节在林木休眠后，萌动前进行。该研究对指导玉溪地区经营桉类薪炭林具有重要意义。     

云南中部高原及干热河谷薪炭林经营模式探讨

经营模式，是建立在对森林的多种效益和社会功能的一定认识基础上的经营思想、经营格局和经营措施的总称。文中结合试验示范区薪炭林的实例对滇中高原、干热河谷薪炭林经营模式进行了探讨分析，为该地区薪炭林经营模式的构建提供了决策的参考依据。     

Wood and biomass production of Leucaena in subtropical Australia

Although only Leucaena leucocephala is widely used, most members of the Leucaena genus have potential as multipurpose species for tropical agroforestry systems. To investigate the wood and biomass production potential of the Leucaena genus, 116 accessions covering the 22 species were evaluated over a two-year period at Brisbane, southeast Queensland, Australia. Trees were planted into replicated line plots 5 m long, with rows spaced 3 m apart. Trees were initially planted at 0.5 m spacings within the plots, but were thinned to 1 m spacings prior to the evaluation period. The hybrid accessions, KX2 (L. pallida × L. leucocephala) and KX3 (L. diversifolia × L. leucocephala), were the most productive, yielding over 50 kg dry matter (DM)/tree. L. trichandra OFI53/88 and L. diversifolia CPI33820 were the most productive non-hybrid accessions producing total yields of 41 and 37 kg DM/tree, respectively. Cultivar Tarramba (26 kg DM/tree) was the most productive of the 26 L. leucocephala accessions assessed in the trial but all these accessions suffered from psyllid (Heteropsylla cubana) attack at this site. A series of non-destructive growth measurements was recorded every three months over the two-year evaluation period. Root collar diameter (RCD), stem number and plant height were found to be the most useful of the measurements for non-destructive assessment of accession agronomic characteristics. A relationship between yield and a growth index (calculated as RCD² × Height/1000), was derived from data from all accessions and could be used as a reliable predictor of yield (r ² = 0.94). The widespread use of the F1 hybrid leucaenas is currently limited by a lack of seed. Technologies to economically produce F1 hybrid seed on a commercial scale are required before the potential of these accessions in agroforestry systems can be fully realized. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nutrient use efficiency and biomass production of tree species for rotational woodlot systems in semi-arid Morogoro,Tanzania

Frequent nutrient removals accompanying wood and crop harvests from rotational woodlot systems may contribute to declining site productivity and sustainability because of soil nutrient depletion. However, selecting for nutrient-efficient tree species may well sustain productivity under this system. To test this hypothesis, a randomized complete block experiment was adopted to assess effects of five tree species on soil nutrients status, nutrient use efficiency and wood yield in semi-arid Tanzania. After 5 years rotation, top soils under Gliricidia sepium (Jaqua), Acacia polyacantha Willd. and Acacia mangium Willd. were the most fertile with soil organic carbon and exchangeable cation status raised close to those in natural Miombo systems. Soil inorganic N and extractable P levels reached sufficiency levels for subsequent maize culture. Wood productivity in tree fallows averaged three times higher than that of Miombo woodlands indicating the high potential of the woodlot system to supply fuelwood, and consequently relieve harvesting pressures on the natural forests. Acacia crassicarpa A. Cunn. ex Benth. produced the most wood (51 Mg ha⁻¹) at low nutrient “costs” presumably due to high nutrient use efficiency. Wood yield of this species was 42 and 120% greater than that of A. polyacantha and A. nilotica, respectively, but contained comparatively less nutrients (42–60% less for P, K, and Ca). Gliricidia sepium and A. polyacantha returned the largest amount of nutrients through slash at harvests. Of all test species, A. crassicarpa exhibited the most promise to sustain wood production under rotational woodlot systems due to relatively high productivity and low nutrient export at harvest.     

安宁八街薪炭林树种营造技术的定量选择研究

１９９２年７月按裂区试验要求和修改后的造林设计布置了整地方式与树种选择、密度与树种选择两个田间试验，主要供试树种为：圣诞树（ＡｃａｃｉａｄｅａｌｂａｔａＬｉｎｋ），黑荆（ＡｃａｃｉａｍｅａｒｎｓｉｉＷｉｌｌｄ．），直干桉（ＥｕｃａｌｙｐｔｕｓｍａｉｄｅｎｉＦ，Ｖ，Ｍ，），蓝桉（ＥｕｃａｌｙｐｔｕｓｇｌｏｂｔｉｌｕｓＬａｂｉｌｌ．），洋槐（ＲｏｂｉｎｉａｐｓｅｕｄｏａｃａｃｉａＬ，），山樱桃（Ｃｅｒａｓｕｓｃｏｎｒａｄｉｎａｅ（Ｋｏｃｈｎｅ）ＹｕｅｔＬｉ），桤木（ＡｌｎｕｓｃｒｅｎａｓｔｏｇｙｎｅＢｕｒｋ．），藏柏（ＣｕｐｒｅｓｓｕｓｔｏｒｕｌｏｓａＤ。Ｄｏｎ），麻栎（ＱｕｅｒｃｕｓａｃｕｔｉｓｓｉｍａＣａｒｒｕｔｈ．），毛叶山合欢（Ａｌｂｉｚｉａｍｏｌｌｉｓ（Ｗａｌｌ．）Ｂｏｉｖ．）等１０种，加上其它供试的树种共计２５种。经选择，圣诞树、黑荆、桤木、直干桉、蓝桉为入选树种，用入选树种结合选择出来的造林技术，最后找出入选树种的最佳造林技术。通过对１０个供试树种的检验，并用这种方法和标准核对了在八街等地相似立地条件下生长的相应树种，符合实际，可操作。     

滇中高原及干热河谷薪材树种热值研究

１９９１年以来，对安宁、玉溪、东川、元谋４个试验基地的供试树种和部分乡土树种，共计３５个树种，用ＧＲ～３５００Ｂ微电脑热量计对薪材热值进行了分析。结果表明，滇中高原直干桉，赤桉、黑荆、圣诞、木荷、麻栎、锥连栎、苦刺等８个树种为优质薪材树种，每千克薪材的热值达１８８５０ｋＪ以上，与褐煤的热值相当，其次为大叶桉、蓝桉、山樱桃、桤木等９个树种，薪材热值在１６７５０～１８８５０ｋＪ之间。干热河谷区赤桉、直干桉、巨桉、黑荆、圣诞、马占相思、苏门答腊金合欢、刺槐等８个树种为优质薪材树种，其次为柠檬桉、银合欢、念珠相思等１１个树种。     

Can stumps tell what people want: Pattern and preference of informal wood extraction in an urban forest of Nairobi, Kenya

Detailed patterns and preferences of informal wood extraction were investigated in an urban forest used by slum inhabitants of Nairobi, Kenya, as such information determines the sustainability of resource use. Instead of asking the people what they had secretly cut, a survey was conducted of the stumps and trees left in the forest to (i) evaluate how accessibility and patrolling affected spatial patterns of resource use, and to (ii) estimate a broad spectrum of species and species-specific size preferences. Both probability and size of cutting increased with better accessibility (represented by distance from the slum), and stump size exceeded that of living stem size around 1.7 km from the slum, which suggested magnified impact of tree cutting near the slum. Patrolling (represented by distance from ranger stations) had little effect in reducing the probability of cutting but was effective in reducing cut size. With the use of random effect models, a broad species preference spectrum (including less abundant and non-preferred species) was estimated, which indicated trends in vegetation change. Smaller stems were preferred for most species presumably used for domestic fuelwood, but major exploitation of large Brachylaena huillensis stems traded in the woodcarving industry was also revealed. Such detailed information on informal wood use can help forest managers to understand threats to the forests as well as the needs of local communities. This is a first step to redefining ‘acceptable’ resource use by the local community for their increased role and responsibility in sustainable forest management, especially when conventional controls of informal activities (i.e. exclusion and penalty) are not functioning well.     

Burning biodiversity: Woody biomass use by commercial and subsistence groups in western Uganda’s forests

Woodfuels are the most heavily used energy source in sub-Saharan Africa. We analyzed the ecological impacts and modes of access of five user groups (domestic consumers, gin distillers, brick manufacturers, charcoal producers, and tea companies) drawing biomass energy from natural forests in western Uganda. While domestic consumers use the most species for fuelwood (>50), their consumption is likely sustainable because they generally harvest fast-growing species from fallows on their own land or their neighbors’. Charcoal producers prefer old-growth hardwood species and are responsible for the greatest loss of natural forests. They access forests by finding landholders who, either willingly or through coercion, allow trees on their lands to be cleared. The impact of charcoal production is exacerbated by a license system that undervalues natural forests and rewards rapid harvests across large areas. The tea industry consumes mainly eucalyptus wood (Eucalyptus spp.) from corporate plantations, but they indirectly create pressure on natural forests by hiring immigrants who subsequently settle in and clear forest remnants. If such practices continue, forest remnants will soon be exhausted, leaving Kibale National Park as the last natural forest in the region. Forest remnants are a vital source of water, medicinal plants, and energy for local citizens and to protect them from over-exploitation, policy makers should target the charcoal and tea industry for reform. Support for local land management institutions governing access to fallows and successional forests will inevitably enhance the policy interventions.