decrease in population

decrease in population的基本解释

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人口减少

与decrease in population相关的网络例句 [注：此内容来源于网络，仅供参考]

Because of the decline of growth potential and quantitative decrease in population, as well as deficiency in young seedlings, the community of Liriodendron chinense is now at the senescence phase.

从鹅掌楸种群的生势衰退和数量削减以及幼龄个体的贫乏来看，目前这个群落已处于发育过程的衰老阶段。

The main achievements of the project are as follows: 1 the hypothesis that a decrease in seed mass causes an increase in mean dispersal distance has been tested based on the experiments of weed dispersal by wind. The experimental results partly support the hypothesis. The results will help farmers to make an optimal strategy of weed control; 2 a statistic method for inferring probabilistic distribution function of a random variable has been developed, by which probabilistic distribution functions of weed species dispersal have been determined; 3 the reproduction structure of Bromus sterilis has been studied; 4 a more complex CA model with 25 neighborhood cells were built, which can simulate spread of a weed population. This work promotes developments in both theory and application of CA models; 5 the "mean law" in weed control has been proposed. Accordingly, the algorism of patch spring may be calibrated; 6 the "patch" and "true patch" have been mathematically defined so that herbicide can be efficiently applied; 7 simulation validates that initial configurations of weed will affect dispersal of its population and strategies of controlling it, or its distribution patterns affect its dispersal progresses.

主要完成的工作和取得的成果有：1）用实验证实了重量较轻的杂草种子并不一定飞得比较重的远，其结果有助于农民制订杂草的优化控制策略；2）发展了一种推断随机变量分布函数的统计方法并用它来获得了几个杂草种的扩散分布函数；3）对杂草Bromus sterilis的繁殖结构进行了研究；4）建立了一个具有25邻的较复杂的能模拟杂草扩散的CA模型，并在理论和应用方面促进了CA模型的发展；5）在杂草控制方面提出了&平均法则&，据此可对按块施药方法进行校正；6）精确地定义了&块&和&真块&以便在杂草控制中能更有效地使用除草剂；7）模拟证实杂草种群的初始配置影响其扩散和控制策略，或者格局影响过程。

The results showed that: 1 The survival curve of the population conformed to the type of Deevey-Ⅲ; 2 With an increase in the population mortality ratio and a decrease in the survival rate, the mortality ratio greatly increased in ages 0-40 years, reaching 89.7%; 3 There existed two peaks of mortality in the lifespan, one was from seedlings to young trees (0-40 years) and the other in the adult stage (180 years).

结果表明：1岷江上游林线地段岷江冷杉种群存活曲线趋於Deevey-Ⅲ型。2林线地段岷江冷杉种群生存率呈单调下降趋势，生存率下降趋势前期高於后期，说明岷江冷杉种群幼苗死亡率高，种群后期比较稳定。3林线地段岷江冷杉林整个生长期中出现了两个死亡高峰期，一个出现在幼苗向幼树过渡时期（0~40年），另一个出现在中龄时期（180年）。