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首页> 外文期刊>Forest Systems >Effects of different intensities of overstory thinning on tree growth and understory plant-species productivity in a semi-arid Pinus halepensis Mill. afforestation
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Effects of different intensities of overstory thinning on tree growth and understory plant-species productivity in a semi-arid Pinus halepensis Mill. afforestation

机译：半干旱松林不同强度的间伐稀疏对树木生长和林下植物物种生产力的影响。造林

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摘要

It is becoming more and more common in the Mediterranean basin to guard against forest fires by creating wooded firebreak areas by reducing the overstory density, pruning the remaining trees and slash mulching. Nevertheless, very few attempts have been made to analyse the effect of this practice upon tree growth and the productivity of the understory plant species in semi-arid areas by following a well defined experimental design over any length of time. To remedy this lack of information, during the spring of 2005 we thinned the overstory in a semi-arid Aleppo pine (Pinus halepensis Mill.) afforestation in SE Spain (planted in the winter of 1993-1994) from an initial density of about 1,500 trees per ha according to three different thinning regimes. The annual growth data of each stand (diameter at breast height, canopy cover and basal area) were measured in randomly situated plots of 20 x 20 m and the above-ground biomass of understory plant species was also harvested from quadrats of 0.5 x 0.5 m during the early summers of 2005 to 2009. Our results showed a positive and significant response from trees in thinned stands compared to the controls, in spite of periods of low-rainfall and plague stress that unfortunately occurred during the study period. There were also statistical differences in understory biomass production within the different areas of overstory thinning as a response to the new conditions. Nevertheless, this biomass was only a small fraction of the total above-ground biomass of the afforestation, which was much higher in control plots. These tree responses and structural changes to the afforestation could be of great interest because of their implications for forest management in the context of global change in an area where increases in temperature and reductions and irregularity in precipitation, together with higher fire risks, are forecast.
机译：在地中海盆地，通过减少过度的林木密度，修剪剩余的树木和砍伐覆盖物来创建树木繁茂的防火区，以防止森林火灾，这种情况正变得越来越普遍。然而，通过在任何时间长度上进行明确定义的实验设计，很少有人尝试分析这种做法对半干旱地区树木生长和林下植物物种生产力的影响。为了弥补这一不足的信息，在2005年春季，我们将SE（在1993-1994年冬季种植）在西班牙东南部的半干旱阿勒颇松（Pinus halepensis Mill。）造林中的表层稀疏，最初的密度为1,500根据三种不同的间伐制度，每公顷树木。在20 x 20 m随机分布的样地中测量了每个林分的年生长数据（胸高，冠层覆盖和基部面积的直径），还从0.5 x 0.5 m的四足动物中收获了地下植物物种的地上生物量。在2005年至2009年的初夏期间，我们的结果显示，尽管在研究期间不幸发生了小雨和瘟疫胁迫，但与对照相比，稀疏林中树木的反应积极而显着。作为对新条件的响应，在表层间伐稀疏的不同区域内，地下生物量的生产也存在统计差异。然而，这种生物量仅占造林总地上生物量的一小部分，在对照地块中要高得多。这些树木的响应和造林的结构变化可能会引起人们极大的兴趣，因为它们在全球变化的背景下对森林管理产生了影响，该区域预测温度会升高，降水量减少和不规则以及火灾风险会更高。

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