城市绿地中臭椿更新苗空间点格局及种间关联分析

[目的]探究城市绿地中臭椿更新苗的数量特征、存活情况及空间分布格局,为城市绿地生境下乔木的天然更新和人工干扰或促进更新提供理论依据。[方法]运用种群静态生命表,点格局分析法中的双关联函数G(r)、H(r)函数分析臭椿更新苗的生存状况,空间分布格局及各龄级间的空间关联性。[结果]更新苗种群结构存在波动性,存活曲线趋于DeeveyⅡ型,低龄级和中龄级个体数量丰富,个体死亡率和消失率在前期和后期较稳定,中期先减后增,超过第5龄级(8~10cm)后,个体死亡率和消失率出现高峰。[结论]一侧和两侧铺装样地在空间上都呈现出不同程度的聚集分布,聚集强度随尺度距离的增大呈减小趋势,一侧铺装样地在尺度接近3.7m处有转为随机分布的趋势。龄级间,小尺度内多表现为无关联,随着尺度增加呈正显著相关;两侧铺装有正关联的龄级组合比一侧铺装样地多;较大尺度上,用径级代表龄级的更新苗间相关关系越接近,正关联越强。     

北京雾灵山自然保护区核桃楸群落的优势种种间联结分析

为了解北京山区核桃楸种群的自然生长状况,于2007年8月对分布于北京雾灵山自然保护区核桃楸群落及其自然生境采用典型抽样的方法进行了研究。共设置面积为20 m×20 m 的样地6块,并把每块样地划分为16个5 m×5 m的小样方,在小样方尺度上,调查了核桃楸种群及其群落中占有一定优势地位的紫椴、黄檗、北京丁香和鹅耳枥的分布情况;用2×2列联表和χ2检验研究了核桃楸与紫椴、黄檗等在主林层、演替层和更新层的种内、种间联结性。结果表明:①主林层中核桃楸与演替层中的核桃楸呈显著正联结;与更新层中的北京丁香呈极显著负联结,且联结系数值较大;与其他物种在不同演替层间正联结种对数小于负联结。②演替层中核桃楸与不同林层间其他物种的正联结种对数大于负联结。      

高寒草甸牧草产量形成过程及与气象因子的关联分析

高寒草甸牧草产量的形成过程与生物量的积累过程和自然界各种生物种群消长规律一样,可用逻辑斯谛生长函数来描述。随着季节的进程,依环境条件的周期变化表现为有缓慢积累-快速增加-相对稳定-折损减少等4个阶段。对气象因子影响高寒草甸牧草产量灰色关联分析结果表明,高寒草甸地区降水量可基本满足牧草生长发育的需求,而温度因子则成为主要的限制因子。其气象因子影响程度大小的序次为：1月平均气温>5-8月平均气温>5-8月日照时数>5-8月水热综合配合(降水量与气 温的比值)>5-8月降水量>上年度末9-11月的降水量。在分辨系数取0.5的条件下,以上各因子所对应的关联度排列为：0.835>0.791>0.771>0.754>0.743>0.638。将上述各气象因子进行主成分处理后,建立评估或预报高寒草甸牧草产量的模拟模型方程：GW=a+aj覺j。其拟合及试报效果很好,可作高寒草甸牧草产量的评估或预测预报工具。     

Analysing farming practices to develop a numerical,operational model of farmers’ decision-making processes: An irrigated hay cropping system in France

Conventional water management in the Crau plain needs to be modified to ensure higher irrigation efficiency, better crop production and quality, and reduced environmental impacts. Because experimental approaches to test modifications of water management are difficult in relation to border irrigation, simulation may provide an alternative. We describe the development of a conceptual model of the decision-making process that determines the irrigation management of a cropping system, on which a simulation model is to be based. Interviews focused on water management were carried out, to understand how farmers manage their irrigation and how their decisions determine the technical system applied on the farm. These interviews were then analyzed using the “model for action” concept, to generate a conceptual model of the decision system, which is organized as a sequence of decision rules describing irrigation management. This model contains five elements: (1) spatial and temporal factors relevant to decision-making in terms of irrigation and hay cropping; (2) no interaction between the grassland cropping system and the sheep rearing system; (3) five rules to describe irrigation management in the cropping system; (4) major water distribution constraints; and (5) two inter-related operations, hay mowing and irrigation. The rules for irrigation decision-making are written as: “If <Indicator><Operator><Threshold> Then <Action1> Else <Action2>”. This conceptual model was used as the basis of a decision support system that includes models of grass growth and hydrology.     

Model for predicting rainfall by fuzzy set theory using USDA scan data

This paper presents a fuzzy inference model for predicting rainfall using scan data from the USDA Soil Climate Analysis Network Station at Alabama Agricultural and Mechanical University (AAMU) campus for the year 2004. The model further reflects how an expert would perceive weather conditions and apply this knowledge before inferring a rainfall. Fuzzy variables were selected based on judging patterns in individual monthly graphs for 2003 and 2004 and the influence of different variables that cause rainfall. A decrease in temperature (TP) and an increase in wind speed (WS) when compared between the ith and (i − 1)th day were found to have a positive relation with a rainfall (RF) occurrence in most cases. Therefore, TP and WS were used in the antecedent part of the production rules to predict rainfall (RF). Results of the model showed better performance when threshold values for: (1) relative humidity (RH) of ith day, (2) humidity increase (HI) between the ith and (i − 1)th day, and (3) product (P) of decrease in temperature (TP) and an increase in wind speed (WS) were introduced. The percentage of error was 12.35 when compared the calculated amount of rainfall with actual amount of rainfall.     

长柄石笔木播种育苗试验研究

通过对长柄石笔木的种子采集处理、种子主要参数测定及育苗方法进行试验和对苗木观测调查,初步研究了长柄石笔木的育苗技术、苗期生长规律。结果表明:长柄石笔木大田育苗播种量以150 g/m2为宜,1年生苗高平均可达60 cm,地径平均0.58 cm,根系较发达,可出圃造林;苗高生长高峰在8月至9月上旬,期间应加强水肥管理,促进苗木生长。     

Progress on Mapping of Quantitative Trait Loci in Crops

Most important agricultural traits of crops are controlled by many genes. These traits have complicated genetic basis and are difficult for genetic analysis. Due to application of molecular marker techniques in the last two decades, genetic and molecular dissection of quantitative traits has become possible. In this paper, recent progress on mapping of quantitative trait loci in crops was reviewed.     

Species association in tropical montane rain forest at two successional stages in Diaoluo Mountain, Hainan

Species association is one of the basic concepts in community succession. There are different viewpoints on how species interaction changes with the progress of succession. In order to assess these relationships, we examined species associations in the tropical montane rain forest at early and late successional stages in Diaoluo Mountain, Hainan Island. Based on data from a 2 × 2 contingency table of species presence or absence, statistical methods including analysis of species association and X ² tests were applied. The results show that: 1) an overall positive association was present among tree species in the communities during the two successional stages and were statistically significant at the late stage. The number of species pairs with positive and negative associations decreased throughout the process of succession, while the number with null associations was greatly increased. The same trend existed among the dominant and companion species. The results indicate that the communities are developing towards a stable stage where the woody species coexist in harmony. 2) In the early-established and later invading species, all positive associations were not significant. Compared with positive and null associations, fewer negative associations were found. This implies that these species are inclined to coexist independently through portioning of resources. 3) Among the later invading species, positive associations were significant and no negative associations were found which suggest that these species have similar adaptive ability in the habitat and occupied overlapping niches in the community. __________ Translated from Biodiversity Science, 2007, 15(3): 257–263 [译自: 生物多样性]     

运用种间联结分析濒危植物白桂木在群落中的地位

在2×2联列表的基础上,运用2χ检验和联结系数(AC)调查并分析了白桂木(Artocarpus hypargyreusHance)在5个分布点与群落中的乔、灌木树种的种间联结.结果表明:2χ检验和联结系数(AC)测定的结果基本一致,白桂木与群落中的其它树种不存在显著关联,与其它树种的2χ值都小于3.841,与大多数树种的AC值在-0.2-0.2之间,说明白桂木在群落中具有较大的独立性和随机性,只是群落中的伴生种或偶见种.     

单体型关联分析方法研究进展

基于单体型的分析方法在当前的复杂疾病和数量性状候选基因的研究中扮演越来越重要的角色。本文综述了开展单体型关联分析研究的动机,单体型的生物功能及单体型的统计优势。介绍了单体型关联分析的回归分析模型,应用的局限和需要进一步的研究的领域。