落叶松人工林林分极限密度确定方法的研究

为研究林分密度动态变化规律提供一个理论参考水平，且为合理经营森林提供一咱确定林分极限密度的较佳方法，本文对长白落叶松人工林为研究对象，在设置的３６块标准地上采用重复抽样的方法，每块标准地随机抽取２０个样方，在保证各样方株数分布为正态分布的前提下，引入顺序统计量分布的理论。采用抽象化的方法确定各标准地的林分极限密度。利用Ｒｅｉｎｅｋｅ公式ｌｎＮ－Ｋ＋     

毛竹林分结构与毛竹枯梢病的关系

据福建省 2 32块毛竹枯梢病 ( Ceratosphaeria phyllostachydis Zhang)林分病情样地调查分析 ,表明病害发生发展与林分结构关系密切 .并由 96块有代表性的样地推导出毛竹枯梢病感病指数与林分结构中的林龄、胸径、整齐度、均匀度、林分组成以及当年新竹占各度竹比例等因子的数学模型为 :Y=43.5 2 64- 1 6.3338C11- 1 1 .6346C12 - 8.1 5 4 6C2 1- 3.8438C2 2 - 8.40 96C3 1-3.7837C3 2 - 5 .5 81 5 C41- 3.774C42 - 0 .1 1 1 1 C51+ 1 .432 8C52 - 2 .1 5 1 9C61- 2 .6970 C62 ,其偏相关系数为 :0 .75 97、 0 .4668、 0 .5 4 78、 0 .2 780、 0 .1 5 2 9、 0 .2 2 4 2 ,复相关系数为 0 .91 66.用此模型对福建省 1 989～ 1 997年设置的 5 6块样地的应用判别准确率为 70 .3% .提出该病害林分病情辅助测报技术和以改善林分结构为主的防治技术     

免疫酶组化法对病料中多杀性巴氏杆菌定型的研究

本文采用自制的 B、A、D、E 定型酶抗体及由其组成的全价酶标抗体,以免疫酶直接法染色检查了20株多杀性巴氏杆菌及10株其它对照细菌感染致死小鼠脏器标本触片.并与脏器标本触片的免疫酶间接法染色,常规染色法及细菌分离培养鉴定等方法作了比较.建立了多杀性巴氏杆菌诊断和定型的一种特异快速的方法.     

桤柏混交林能量代谢中能量吸收,固定,积累和损耗研究

本文通过桤柏混交林气体交换测定研究了能量代谢基本过程。结果表明：桤柏混交林吸收的太阳辐射能大部分损耗子蒸腾作用中，桤木和柏木用于生长呼吸中损耗的能量最多．其中桤木南面时则用于维持呼吸中损耗能量最多，其能量固定建立在内部节律基础上，柏木能量积累大于桤木．     

Intestinal establishment and reproduction of adult Trichinella spp. in single and mixed species infections in foxes (Vulpes vulpes)

Intestinal establishment and reproduction of adult Trichinella spiralis, Trichinella nativa, Trichinella britovi and Trichinella pseudospiralis were examined as single species or mixed species infections in foxes. This is the first study of intestinal dynamics of Trichinella spp. in a carnivore model and the results suggest that the intestinal phase is relatively short as only very few worms were recovered 10 days post-inoculation (dpi). In mixed species infection with equal doses of T. nativa and T. spiralis, molecular typing demonstrated that 64% of the intestinal worms and 78% of the muscle larvae were T. nativa. Conversely, T. spiralis dominated in the mixed species infections with T. pseudospiralis, constituting 66% of the intestinal worms and 94% of the muscle larvae. Although, the individual recoveries of intestinal worms were only up to 5.6% on day 1, and up to 1.5% on day 4 post-infection, the muscle larvae establishment was comparable to other fox studies. Infectivity, measured as muscle larvae burden did not differ among the four species of Trichinella, which is in contrast to other models with mice, rats, pigs or herbivores. Although statistically significant differences in intestinal worm burdens were found for some days, no distinct species were recovered in consistently higher numbers than the others.     

Analysis of highbush blueberry (Vaccinium corymbosum L.) fruit growth with exponential mixed models

Blueberry fruit growth commonly exhibits a double-sigmoid pattern. The goal of this work was to characterize and compare fruit growth of cultivars differing in ripening time using exponential non-linear mixed models. Mixed-effects five-parameter exponential (Gompertz I and II; logistic; monomolecular) models were fitted to fruit diameter data from 2 years and three cultivars grown in the field in a cool temperate environment. Gompertz II mixed model provided the best fit to fruit growth data and was used for further analysis. In later ripening cultivars ‘Cape Fear’ and ‘Herbert’, clear-cut double-sigmoid patterns were observed, absolute growth rate models exhibited two marked peaks, and relative growth rate showed an initial decreasing trend, and a subsequent peak. The earlier cv. ‘O’Neal’ did not exhibit a defined double-sigmoid pattern. The time between relative extremes of absolute growth acceleration is proposed as an objective criterion for fixing stage boundaries within growth curves. Exponential mixed models accurately fitted blueberry growth patterns. These equations highlighted differences in fruit growth patterns between early and late ripening highbush blueberry cultivars.     

The mean tree mass–stand density index relationship for forest stands in China

Most traditional studies of mean tree mass (MTM)– density relationships focus on crowded stands, without considering stands characterized with canopy gaps. We developed a model to estimate MTM of closed and unclosed forest stands based on stand density index (SDI). Data were obtained from eight forest stands in China to test the generality of this model. MTM was accurately expressed in terms of SDI by combining the equations for SDI and Yoda's model, and exponents of the MTM–SDI relationship ranged from –2.23 to 1.93. Compared with density, SDI is a better predictor of MTM, regardless of the degree of canopy closure in the stands.     

青山湖森林公园针阔混交林大小比数的研究

该研究通过对青山湖森林公园内亚热带针阔混交林各树种的不同大小比数进行比较分析,得知以胸径和树高大小比数反映林木的大小分化程度较冠幅大小比数可靠,同时林木竞争过程中胸径和树高的分化程度最大。林分中的优势种马尾松的大小比无论在胸径还是树高上都优于其他树种。     

Testing the suitability of the Nepal-Somers stand table projection method for Eucalyptus grandis plantations in South Africa

This study presents an application of a stand table projection method for varying stand densities of Eucalyptus grandis in South Africa. The projections of diameter at breast height (dbh) class frequencies are compatible with future values of basal area and stem number per hectare. The application requires an individual tree dbh growth function, a current stand table, and estimates of future basal area, and tree survival. The resulting stand table is adjusted by an algorithm that guarantees that the future stand table is compatible either with observed or predicted values of basal area and stem number per hectare. The results, based on a relatively small experimental dataset, are satisfactory. However, further work based on a larger dataset is required to evaluate the general suitability of the method for stand table projection of Eucalyptus grandis in South Africa, especially regarding variable site conditions. The particular contribution of this study is the fact that we were able to demonstrate the suitability of the Nepal and Somers stand table projection method for a unique dataset from a very densitysensitive Correlated Curve Trend spacing trial. We also made an attempt to present a comprehensive example of a projection to facilitate practical application of this method in the KwaZulu-Natal coastal plain of South Africa.     

Spruce forest conversion to a mixed beech-coniferous stand modifies oribatid community structure

We investigated oribatid mite community diversity and structure in the managed conversion of coniferous stands into semi-natural montane forests that are composed of a small-scale mosaic formed by different age classes of silver fir, Norway spruce and European beech in the southern Black Forest area, South-Western Germany, using the space-for-time substitution method. The core hypothesis was that changing tree composition and management practice will affect functional structure and diversity of oribatid mite community through changing substrate quality and litter diversity. Three forest districts were selected within the research region. Four stand types representing the major stages of forest conversion were selected within each forest district: (i) even-aged spruce monocultures, (ii) species enrichment stage, (iii) forest stand structuring stage, at which fur and beech and other deciduous trees penetrate the upper storey of the forest and (iv) a diverse continuous cover forest respectively. Oribatid mite abundance, species richness and composition, biomass, ecomorphs and feeding groups relative abundance were determined. An overall increase in species richness moving from the spruce monoculture to a continuous cover forest was detected. However, the herbivorous and litter-dwelling mites were most sensitive to forest conversion demonstrating significant differences in abundance between conversion stages. Almost all changes in the oribatid community were associated with the properties of the changing litter layer. Abundance of soil-dwelling mites remained very stable what is in contradiction with the response of the other soil fauna groups found at the same sites. Overall oribatid community seemed to be more dependent on total microbial biomass than fungi. However, observed effects were overshadowed by considerable district-induced differences.