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101.
人造板工业是我省林产工业的主体,近年来得到了迅速发展,形成了纤维板、胶合板、刨花板、竹材胶合板、饰面人造板(如保丽板、镁铝曲板)等板种。本文论述了我省人造板企业现状,并对各类产品及产品质量作了分析与评定,最后就人造板工业的发展提出了相应的对策。 相似文献
102.
103.
We investigated effects of silvicultural treatments (planting and subsequent treatments) on understory structure and plant
species diversity in managed Picea glehnii plantations (21–26 years old) in northern Japan. We evaluated the importance of each treatment (machinery site preparation,
planting, weeding, and thinning) in 19 plantations, with considerable variation among treatments overall. The understory had
98 vascular plant species; the most dominant species was a dwarf bamboo Sasa senanensis, followed by tree species Abies sachalinensis and Betula ermanii. Multiple regression analyses showed that thinning negatively influenced plant species diversity. Planting density showed
a strong positive correlation with density of seedlings (height <20 cm), but few independent variables were correlated with
density of saplings (height ≥20 cm and diameter at breast height <1 cm). The negative effect of thinning and the positive
effect of planting density seem to be related to the existence or reinitiation of dense cover of Sasa senanensis. We present possible mechanisms of response to treatments to generalize the results. We then suggest ways to improve current
treatments to meet the goals of wood production and biodiversity conservation in the region. 相似文献
104.
While riparian vegetation can play a major role in protecting land, water and natural habitat in catchments, there are high
costs associated with tree planting and establishment and in diverting land from cropping. The distribution of costs and benefits
of riparian revegetation creates conflicts in the objectives of various stakeholder groups, and elicitation of importance
weights of objectives and determination of rankings of a number of policy options by these stakeholder groups becomes critical
in decision-making. The analytic hierarchy process (AHP) is a multicriteria analysis technique that provides an appropriate
tool to accommodate the conflicting views of various stakeholder groups. The AHP allows the users to assess the relative importance
of multiple criteria (or multiple alternatives against a given criterion) in an intuitive manner. This paper presents an application
of AHP to obtain preference weights of environmental, social and economic objectives which have been used in ranking riparian
revegetation policy options in a small catchment (watershed) in north Queensland, Australia. The preference weights towards
environmental, economic and social objectives have been obtained for the various stakeholder groups (landholders, representatives
of local sugar mill staff, environmentalists, recreational fishers and the local community). The AHP technique has proved
useful in eliciting objectives and ranking policy options as well as in checking for consistency of the statements of stakeholder
groups. Implementation of this approach requires a complex data elicitation process. 相似文献
105.
Martina M. Backes 《Agroforestry Systems》2001,50(2):119-132
In order to precisely assess the role of agroforestry for the conservation of (agro-)biological diversity there is a need
to adjust sampling methods used in plant sociology. This study is on the contribution of agroforestry land use to the in-situ conservation of indigenous trees within a typical East-African smallholder farming system in Western Kenya. A modified approach
to measuring species richness and abundance is presented. The selection of tree-rich structures was done according to management
patterns rather than considering syntaxonomic classifications from the vegetation science point of view. This approach, which
is better suited to the strongly human-influenced vegetation of agroecosystems, employs between-management unit diversity
measures to help evaluate abundance and constancy of species in particular management units.
The predominant off-farm vegetation patterns are riverine forests, rocky hillsides, hedgerows, wooded grassland relicts, woodlands or colline forest
relicts and tree groves whereas the noticeable tree-rich on-farm management units are homegardens, homesteads, life fences, coffee- and banana-groves and annual cropping fields. 98% out
of all indigenous tree species known from Bungoma, occur in off-farm lands. 53% of the indigenous tree species occur in tree rich on-farm management units while 47% of the indigenous trees are dependent on the maintenance of off-farm lands. Hedgerows embody the most promising secondary vegetation structure that shows ample potential to accommodate a wide
range of indigenous perennial species outside the natural vegetation formations. The pattern of distribution of various vegetation
structures, and the mixture with diverse tree-based on-farm plots are interesting features in regard to floristic and eco-diversity on a landscape level. In this respect, three areas
that show different population densities and distinct agro-historical conditions were compared. In regions of particular high
population density the degree of association of various functional land use forms and woodland structures – each characterised
by its own floristic make-up – is comparatively high. In contrast, in regions with less population but that were settled at
a later date, one encounters fewer stands of woody plants with lower numbers of species.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
106.
新造林中防火隔离带分为天然防火隔离带;植物防火隔离带;防火林道,人工防火线等4种。在具体布设上则分为林中防火、林线防火、山脊防火、境界防火、铁路沿线、林区房屋隔离带6种。 相似文献
107.
A study conducted to assess the floor vegetation shows the presence of 17 species underPopulus deltoides in comparison to 28, 29 and 35 underAlbizia lebbeck, Dalbergia sissoo and mix-culture plantations, respectively. Further, the biomass and density of floor vegetation is considerably reduced underP. deltoides compared to other plantations. In addition, the indices for species richness, evenness, dominance and diversity are also
reduced underP. deltoides showing some inhibitory mechanism being operative under these plantations. Based on available literature, allelopathy is
speculated to be responsible for this reduction. 相似文献
108.
We present the results of field work and a series of interviews with Mayan beekeepers, in order to answer the following questions: (i) Which factors are relevant when establishing an apiary? (ii) How do Mayans choose the melliferous flora? (iii) How do Mayans manage the vegetation surrounding their apiaries? and (iv) What is their knowledge of flowering phenology and honey production cycle? Apiary establishment depends on: no apiaries established at a minimum distance of 3 km; water availability (i.e., “Haltunes”); direct access to roads; combination of old and young vegetation (particularly abundance of Gymnopodium floribundum). Melliferous flora is classified according to quality and quantitity of the honey produced; 34 species are considered important at different times of the year. Finest honey and arger quantities are obtained from G. floribundum, followed by Viguiera dentata; the worst honey is from Lysiloma latisiliquum. Management of vegetation is minimum, mainly cutting plants that could impede growing of important melliferous, or protecting ( = not cutting) the latter; nevertheless, some of the most important melliferous are dominant in the vegetation. Their knowledge of flowering phenology and production cycle are quite complex. We discuss the problems the beekeepers are facing in regards to forest clearing, commercialization of produces, etc. 相似文献
109.
110.
对位于祁连山南麓的青海省大通县退耕地人工植物群落的枯落物容水性能进行了研究。该地区从20世纪80年代初期陆续退耕还林的人工植物群落年龄虽只有10~27 a,但其枯落物层厚度已达2.9 cm,相当于天然植物群落(30~200 a)的56.9%;其枯落物容水量平均达4 mm,相当于天然植物群落的35.7%。研究表明退耕地植物群落的林龄越大,植物垂直层数越丰富,则枯落物干物蓄积量和容水率越大,枯落物容水量也越大。在人为去除枯落物层后,其地表径流速度较去除前增加了33%~35%,枯落物层的缓流、滞流作用十分明显。经逐步回归分析,影响植物群落枯落物容水量的因素99.8%的为枯落物干物的蓄积量、林龄、植物层数和枯落物容水率。 相似文献