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11.
小兴安岭红松针阔混交林林分空间结构分析   总被引:1,自引:0,他引:1  
用角尺度、混交度、大小比数3个空间结构参数对黑龙江省凉水自然保护区的红松针阔混交林进行分析,用Hegyi竞争指数分析种内种间竞争关系,为制定合理的森林保护措施提供依据。分析结果表明:林木分布格局为随机分布;总体来看该林分处于强度混交向极强度混交过渡的状态,单一树种聚集在一起的情况较少,大多与其它不同树种混交;各树种在林木大小分化程度上存在很大差异,针叶树种较占优势,阔叶树种则分化严重,既有占优势树种又有受压树种;林分的种内竞争大于种间竞争。  相似文献   
12.
樟子松松针锈病病原菌——鞘锈菌(Coleosporium)的分类历来很乱。传统的分类方法都是依冬孢子形态和冬孢子寄主来进行的。但近年的研究表明1种鞘锈菌的春孢子可以侵染2种或2种以上的冬孢子寄主,所以按冬孢子寄主来划分鞘锈菌的种是不合理的。文中在病害症状观察和春孢子表面形态观察的基础上,首次对樟子松3种不同形态的春孢子的酯酶同工酶进行了分析,从而为鞘锈菌的分子分类学研究奠定了基础。  相似文献   
13.
This paper focuses on understanding human impact on landscape. Both ecological and human practices are analysed as interacting processes. An agent-based model integrating biological and historical knowledge is used to analyse the pattern of Scots Pine encroachment in a French Mediterranean upland. In the STIPA model, pine trees are autonomous agents and a cellular automaton simulates land-use. We test the effects of shifting cultivation on tree establishment at the landscape scale. This allows us to understand how agropastoral practices patterned this area from the 17th to 19th century: simulations show the importance of shifting cultivation in limiting woodland progression. Fallow duration linked to environmental heterogeneity is a significant factor for explaining pine dynamics and landscape patterning at the scale of the study region. We put this result in perspective with current rangeland management policies that often consider grazing as the most relevant tool for open landscape maintenance. Our results also show the importance of taking into account time-scale effects when linking landscape patterns to agricultural systems.  相似文献   
14.
Landscape geneticists can take considerable advantage of differences in the action of evolutionary forces (mutation, migration, selection, and drift) on different loci within the genome. Appropriate comparisons among loci allow researchers to isolate and study the effects of these processes. For example, the organelles are typically inherited maternally (but occasionally paternally), and so will experience migration only when females or seeds disperse (males or pollen in the paternally inherited organelles). Thus, the comparison with biparentally inherited loci allows inferences about the differential migration rates of male vs. female animals or of seeds vs. pollen in plants. Conversely, all biparentally inherited nuclear loci should experience the same levels of migration and drift. Thus, loci that show unusually large levels of variation across the landscape (as compared with the bulk of loci) may be reflecting the action of spatially varying natural selection (local adaptation). Such comparisons are conceptually straightforward, but are complicated by the high intrinsic variability of stochastic neutral processes. Careful statistical analysis is needed to avoid over-interpreting differences among loci. Inferences will be most robust when both genetic and non-genetic data can be integrated, and the collaboration of landscape ecologists with geneticists promises to be particularly fruitful.  相似文献   
15.
马尾松是中国主要的人工林树种,其蓄积量最大,分布地域最广.但由于富含树脂,其用途受到很大限制,因此松木脱脂成为提高其利用价值的重要手段.基于传统的脱脂方法不甚理想的状况,作者探讨了一种新的脱脂工艺方法——汽相法.该方法不仅能保证脱脂效果,而且大大降低了加工成本.  相似文献   
16.
松针叶绿素与脂溶性复合物的提取   总被引:1,自引:0,他引:1  
采用置换反应将松针中含镁叶绿素转变成水溶性叶绿素铜钠,用低浓度乙醇浸提并分离脂溶性部分,得到叶绿素铜钠速淀粉,其1%水溶液pH值为8-9,600倍稀释呈翠绿色,产品获得率为松针干粉的8%-10%,同时获得脂溶性复合物,其主要成分为VE。  相似文献   
17.
黄山御墅天筑山地别墅内原生态资源丰富,尤其是原生态黄山松保护性开发成为项目的重点,从现状调查、原因分析、解决实施三个阶段入手,通过规划设计、建造施工和养护管理,合理避让和利用,基地现场的黄山松90%保留,将项目不露痕迹的融合在自然景观里,成为尊重原生态,可持续发展的景观项目。  相似文献   
18.
马尾松胚胎发育的观察研究   总被引:2,自引:0,他引:2       下载免费PDF全文
在自然条件下,马尾松成熟花粉粒发育需6个月,授粉有效期在珠鳞展开的头5天,授粉后雌配子体游离核时期持续12个月,从游离核到细胞约需7天,颈卵器2-3个,受精作用发生在授粉后第13个月,原胚期约30天,幼胚期约40,成熟胚期约60天;从球花芽分化到种子成熟约需24个月,在形态发育的观察中,发现低温冻害会引起花粉在发育各阶段的形态异常及大量败育。  相似文献   
19.
A micro-feeding assay was developed for testing small amounts of synthetics and extracts as antifeedants for Hylobius pine weevils. We devised a simple setup consisting of 5×5-mm pieces of thin layer chromatography cellulose plates used in pairs for a bioassay involving choice. After application of 1.5 l solutions and evaporation of the solvent, each plate received a 5 l aliquot of 1 M sucrose as a feeding stimulant. The test period was 4 h at 25 °C with 6 days of starvation before the test, compared to just the 1 day sufficient for twig tests. Deprivation of water for 1 day at 65% RH before the test was critical because it increased feeding but not mortality. The combination of starvation and thirst reduced the relative variance (coefficient of variation) to below 50%. There was a good correlation of antifeedant activity in the microassay with the activity in a standard twig test. The microassay needs only several mg for a test series, whereas the twig test needs grams.  相似文献   
20.
Management of subterranean clover (Trifolium subterraneum L.) understory grown with loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) resulted in differences in both clover yield and pine diameter. Loblolly and slash pines were planted into a subterranean clover pasture in 1984. Suppression of warm season herbaceous vegetation by applying herbicides or disking the site in late summer resulted in significantly greater subterranean clover production than on the control site where no additional understory management was applied. Pine species had no effects on clover yield. The N content of the pine foliage on the blocks managed with herbicide application or disking generally was significantly greater than the control from the 5th through 7th growing seasons (1988–1990). The dbh of the pine trees in the disked and herbicide treatments was greater than the control after the 7th growing season (1990).  相似文献   
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