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本文引入模糊集论中基于模糊等价关系的模糊聚类的分析方法,将发病数量(病害强度)、空间和时间动态的相互关系联系起来,作为统一体,研究了杨树灰斑病(Coryneum populinum Bres)的流行动态,以平均病情指数((?))、聚集度指标((?)/M)和病叶率(p)作为群体动态的特征量度,将对病害流行系统的考察化成对若干亚系统(若干阶段)来研究,使复杂的系统得以简化。同时对该病短期预报、中期预报进行了研究,建立了短期和中期预报方程。 相似文献
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由于苹果品种多不抗斑点落叶病,目前国内外大都依靠化学防治来控制该病.但对其季节流行动态和爆发成因,以及在何种气象条件下使用农药才能获得最佳防治效果,尚缺乏系统研究.本研究以田间试验为主,通过对病害的逐日系统调查,将所得数据借助计算机进行统计分析,旨在明确生长季苹果斑点落叶病的季节流行动态和爆发成因(即病原菌大量侵染的决定性天气条件),为苹果生产提供可行的防治建议并为该病害的预测奠定基础. 相似文献
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苹果褐斑病是引起苹果树早期落叶的重要病害,本文选取平均病叶率,平均病斑数和病斑平均宽3个指标,应用灰色聚类法对苹果褐斑病在10个苹果品种上的感染程度进行了灰色综合评价,结果表明:富士、国光和翠秋等品种感染轻;金冠、青香蕉、 倭锦和美夏等品种感染中等;红玉、元帅、红星等品种感染重。 相似文献
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苹果早期落叶病的发生与防治 总被引:1,自引:0,他引:1
苹果早期落叶病的发生与防治靳爱荣,李淑恩(正定县林业局森检站050800)近两年来,苹果早期落叶病是石家庄市范围内苹果生产上的主要病害之一,它主要包括苹果褐斑病、灰斑病、圆斑病和轮斑病,其中生产上表现最为严重的是褐斑病和灰斑病,它能使叶片大量提前脱落... 相似文献
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采用分期调查病情与孢子捕捉的方法,通过引入模糊集论中基于模糊等价关系的模糊聚类分析,将发病数量(病害强度)、空间和时间动态的相互关系联系起来,作为统一体,研究了小黑杨灰斑病的流行动态。将其化分为SS_1、SS_2、SS_3、SS_44个亚系统提出了灰斑病发展的进程为:始期、始盛期、盛期、末期4个阶段,同时对多个因子进行了逐步回归筛选,选出了以病原基数、五月份降雨为关键因子的侵染期、发生期、发病始期、盛期、末期病情的预测模型。研究表明:自树木展叶后日降雨在1.2mm以上时为侵染期;侵染期加潜育期为发生期,即T=t_1+t_2。 相似文献
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在梅州市梅江区西阳镇、兴宁市径南镇和平远县长田镇3片油茶林(Camellia oleifera)采果后调查主要叶部病害种类、病情及其空间分布.结果表明:主要病害为炭疽病、软腐病、藻斑病、褐斑病,病情指数大小依次为:炭疽病(61.30)>软腐病(57.96)>藻斑病(41.36)>褐斑病(28.52),炭疽病、软腐病和藻斑病危害程度较重,褐斑病危害程度较轻;炭疽病、软腐病和藻斑病在油荼林皆呈均匀分布,而褐斑病呈聚集分布,聚集均数λ为4.635 1,大于2,该病由外界环境和其本身生物学特性相互共同作用引起. 相似文献
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采用扩散型指数法、回归模型分析法、FuzzyISODATA聚类分析和二维趋势面分析等方法,对油松毛虫幼虫种群中间格局的动态进行了分析。结果表明:自越冬幼虫上树后直至化蛹期间的中间格局皆属聚集型,种群聚集度系逆密度制约的,表现在时间序列上的总趋势是离心运动(扩散);幼虫种群空间动态系统可划分为4个阶段(亚系统),与之相对应的种群生物学阶段,分别是越冬幼虫刚刚完成上树期、幼虫稳定取食为害期、迁移扩散期和蛹期;m*(T,m)关系的二维趋势面方程对种群空间动态作出了客观的描述。此外,文中应时lwao的准则作了必要的补充,使之更趋完善。 相似文献
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本文应用多层次综合评判、模式识别、相似优选、Fuzzy聚类和Fuzzy非线性规划5种方法,从不同角度对河南省辉县油松(Pinus tabulaeformis Carr.)种子园规划设计中的3种可能方案进行了综合决策。其结果都是:C方案最优,B方案次之,A方案最劣。 相似文献
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通过对福建、江西和江苏等省17个县(市)的松树枯梢病的危害程度及发病特点调查,把松树枯梢病的发生区域归纳为:轻(无)度病害区、中度病害区和重度病害区三大类.感病程度与气象因子的相关分析表明,4、5月份的月平均湿度、月降水量和月降水天数,以及年平均湿度与病害发生关系较为密切.以上述气象因子为自变量,发病程度为因变量,建立了病害的回归预测模型:y = 98.60 13.54x1-9.33x2-3.62x3 0.07x4 0.07x5-11.97x6 3.26x7 (R=0.933 3).利用该模型对我国南方主要县(市)的病害进行了预测和划分,并提出了该病害的综合治理措施. 相似文献
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本文根据山东省省选12株毛白杨(Populus tomentosa Carr.)古树的38株无性系苗木资料,利用Fuzzy关系方程对苗高生长与7个形态性状进行模糊综合评判。结果表明,叶片长与苗高生长关系最密切。提出了应用形态性状估测苗高生长的GM(0,N)模型。 相似文献
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垂丝海棠品种数量分类研究 总被引:1,自引:0,他引:1
采用数量分类学方法对27个垂丝海棠品种的19个性状进行了聚类分析。R型聚类分析结果表明垂丝海棠品种用于形态分类学研究的多数性状具有相对独立性和稳定性。Q型聚类分析结果表明:枝条直立或下垂应作为垂丝海棠品种分类的第一级标准,花径、花型应作为第二级标准,叶色、花期等应作为第三级标准。 相似文献
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本文采用Fuzzy数学方法,对邢台县山区种植中华猕猴桃的适宜度进行了综合评判,结果为:好年份种植适宜度指数为1.415,正常年份为0.708,异常年份为2.413.在自然条件下,不宜普遍种植,小气候区可适当发展。 相似文献
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森林群落稳定性研究方法初探 总被引:43,自引:0,他引:43
在群落演替预测研究的基础上,结合比较分析,提出群落稳定性的测度方法,并对M.Godron法进行改进。以大青沟森林植物群落为例,探讨了上述两种方法在群落稳定性研究中的有效性。2种方法得出较为一致的结果,说明它们都适于森林植物群落稳定性的研究,可互相验证。但M.Godron法结果仅能提供群落稳定与否的信息,而演替与比较分析相结合的方法还可以说明群落的演替方向及趋势。因此,它有助于理解群落的动态过程,是研究森林植物群落稳定性较为有效的方法。 相似文献
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Stem analysis data of 432 trees were obtained from even-aged, pure natural stands of Calabrian pine in the central Mediterranean Region of Turkey. Eight dynamic site equations derived with the Generalized Algebraic Difference Approach (GADA) were compared, based on autoregressive analysis and a thorough evaluation of the goodness of fit. We used generalized nonlinear least squares methods for model fitting. The adjusted coefficients of determination (0.9825–0.9842), root-mean-square errors (0.8004–0.8435 m), and Akaike’s information criterion differences (0–145) indicated a good fit of the eight site index equations. The Hossfeld equation (M3) provided the best result. The Durbin-Watson test statistic did not reveal an autocorrelation issue while the Hossfeld equation provided a satisfactory solution to the serial correlation problem in stem analysis data as time series using autoregressive modeling. This study presents new site index models for Calabrian pine forests in the central Mediterranean region of Turkey where it is the most important commercial tree species. The site index equation, based on the Hossfeld model is recommended for height growth prediction and site classification of Calabrian pine stands in the central Mediterranean region of Turkey, providing a new basis for growth prediction and yield estimation in these important forest ecosystems. 相似文献
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G. Della Rocca T. Osmundson R. Danti A. Doulis A. Pecchioli F. Donnarumma E. Casalone M. Garbelotto 《Forest Pathology》2013,43(3):211-221
Seiridium cardinale is regarded as the most important agent responsible for the disease of cupressaceous hosts referred to as Cypress canker. The fungus was first described in California and is currently reported in all continents. A recent study based on seven SSR loci has suggested that California populations may represent the source of the epidemic in the Mediterranean. In this study, 185 AFLP markers were used on an expanded sample size of 125 isolates to determine whether the Mediterranean population may indeed be derived from the California one and to compare the reproductive modes of populations in the two regions of the world. Additionally, amova , NJ, STRUCTURE, principal component analysis and β‐tubulin sequence analyses were employed to infer the presence of genetic structure within and between populations. The distribution of pairwise AFLP similarity coefficients suggests Mediterranean populations are reproducing only clonally, while California populations are reproducing both clonally and sexually. amova indicates Mediterranean and California populations are currently genetically isolated, but NJ and STRUCTURE analyses both suggest ancestral Mediterranean genotypes belong to the California population. No alleles were private to either population, and the presence of identical or quasi‐identical genotypes at large distances supports the notion that movement of infected cypress plants is responsible for the global spread of the disease. Surprisingly, STRUCTURE identified a second cluster of Mediterranean genotypes distinct from the basal mixed California–Mediterranean cluster. This second cluster either may have originated from the first one under the selection pressure imposed on the pathogen in the new Mediterranean environments or may be the result of a further introduction from California or elsewhere. Cumulatively, the evidence presented here suggests that S. cardinale may be native or long naturalized in California and that two genetically distinct groups are present in the Mediterranean, with obvious implications for further studies on this disease. 相似文献