THE ECOLOGY AND GENETICS OF FITNESS IN FOREST PLANTS. I. ENVIRONMENTAL HETEROGENEITY MEASURED BY EXPLANT TRIALS
THE ECOLOGY AND GENETICS OF FITNESS IN FOREST PLANTS. I. ENVIRONMENTAL HETEROGENEITY MEASURED BY EXPLANT TRIALS
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森林植物适应性的生态学和遗传学。
DOI：
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发表时间：
1991
期刊：
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通讯作者：
M. Lechowicz
中科院分区：
文献类型：
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作者：
G. Bell;M. Lechowicz
(1)环境异质性有两个组成部分：一个区域内站点的总体方差，以及站点之间的方差随距离的变化方式。它可以通过测量环境的物理属性来间接研究，也可以通过生物体对环境的反应来直接研究。使用直接生物测定法的研究有两种：一种是种植研究，即植物在自然环境中生长；另一种是外植体研究，即植物在受控条件下在环境样本（如土壤芯）中生长。外植体研究给出了保守的异质性估计。(2)在加拿大魁北克省蒙特利尔市东南部一个50 m × 50 m的未受干扰的大叶fagus - saccharum森林中进行了外植体试验。采用了三种抽样方案：随机抽样，以产生无偏的方差估计；嵌套取样，以初步估计空间结构（即邻近地点的相关性）；网格采样，在50米、10米和1米的空间尺度上获得结构的详细信息。进行了两个系列的试验，一个是拟南芥的生物测定，另一个是普通Hordeum的生物测定。在每个试验的每个地点收集每个物种的两个基因型的两个复制土芯。在温室中将植物播种到这些核心中，并在每个核心上记录几个性状，包括收获时的干质量，这与繁殖成功密切相关。(3)随机抽样对大多数性状的环境方差给出了实质性和显著的估计，包括两种物种的所有干质量测量。干质量评分的环境相关性约为0.25 ~ 0.40。巢式抽样表明，方差总体上从10 ~ 1m尺度减小到0.1m尺度。栅格抽样结果表明，随着距离的增加，站点间的方差增大。对数方差对对数距离的回归是线性的，干质量分数的斜率约为0.15 ~ 0.25。即使在相距0.1 m的地点之间的1 m样方内，也可以用这种方法检测环境结构。(4)在所有空间尺度上，站点间的相关性随距离的增加而降低。此外，相关性结构不受空间尺度的影响，当距离表示为绝对距离除以网格维数时，在所有尺度上相关性下降的速度相同。在所有的空间尺度上，环境都是一样复杂的。
SUMMARY (1) Environmental heterogeneity has two components: the overall variance of sites within an area, and the way in which the variance between sites changes with the distance separating them. It can be studied indirectly through the measurement of physical attributes of the environment, or directly through the response of organisms to the environment. Studies using direct bioassays are of two kinds: implant studies, in which plants are grown in the natural environment, and explant studies, in which plants are grown in samples of the environment, such as soil cores, under controlled conditions. Explant studies give conservative estimates of heterogeneity. (2) This paper describes explant trials within a 50-m x 50-m area of undisturbed Fagus grandifolia-Acer saccharum forest situated south-east of Montreal, Quebec. Three sampling schemes were used: random sampling, to yield an unbiased estimate of variation; nested sampling, to yield preliminary estimates of spatial structure (i.e. correlation of nearby sites); and grid sampling, to yield detailed information on structure at spatial scales of 50 m, 10 m and 1 m. Two series of trials were conducted, a bioassay using Arabidopsis thaliana and another using Hordeum vulgare. Two replicate soil cores for each of two genotypes of each species were collected at each site in each trial. Plants were sown into these cores in the glasshouse, and several characters scored on each, including dry mass at harvest, which is closely related to reproductive success. (3) Random sampling gave substantial and significant estimates of environmental variance for most characters, including all measures of dry mass in both species. The environmental correlation for dry mass scores was about 0 25-0 40. Nested sampling showed that variance generally decreased from scales of 10 m through 1 m to 0.1m. Grid sampling showed that the variance among sites increases with the distance separating them. The regressions of log variance on log distance were linear, with slopes, for the dry mass scores, of about 0 15-0 25. Environmental structure was detected in this way even within 1-m quadrats among sites 0 1 m apart. (4) The correlation between sites decreases with increasing separation on all spatial scales examined. Moreover, the correlation structure was independent of spatial scale: correlation declined at the same rate at all scales, when distance is expressed as the absolute distance divided by the grid dimension. Environments are about equally complex at all spatial scales.