Mechanisms of interaction between a leguminous shrub and its understorey in a semi-arid environment
Mechanisms of interaction between a leguminous shrub and its understorey in a semi-arid environment
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DOI：
10.1111/j.1600-0587.1997.tb00360.x
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发表时间：
1997-04-01
期刊：
影响因子：
5.9
通讯作者：
Puigdefabregas, J
中科院分区：
文献类型：
--
作者：
Moro, MJ;Pugnaire, FI;Puigdefabregas, J
在半干旱环境下的云杉灌木通常有茂密的一年生和多年生草本植物下层，形成所谓的“丰饶岛”。在西班牙东南部半干旱环境下，研究了冠层对土壤肥力和小气候的影响，以及冠层和凋落物对物种多样性和生产力的综合影响。土壤化学性质在冠层下3个位置之间存在显著差异，其中内外位置差异最大。冠层中间位置土壤有机质的潜在矿化率显著高于冠层中心和冠层边缘土壤。土壤化学肥力和估算土壤种子库在中间位置土壤中最高，在边缘位置土壤中最低。较低的温度和照射有利于灌木冠层下植物区系的生长和土壤肥力的提高。从土壤种子库中出现的物种明显分为冠层内和冠层外两类。不同水平凋落物添加量显著降低了物种丰富度和出苗数量。在田间，近中心位置、中间位置和冠层边缘放置的盆栽在物种丰富度和生物量产量方面存在显著差异。总体而言，微气候条件与土壤化学肥力的增加和凋落物的抑制作用相结合，在冠层中心和边缘之间的中间位置产生了大量草本植物。该位置一年生物种凋落物的高比例增加了矿化率，从而增加了养分动态，这一过程也有利于灌木。
Retama sphaerocarpa shrubs in semi-arid environments often have a dense understorey of annual and perennial herbs forming so-called ''islands of fertility.'' The effect of the canopy on soil fertility and microclimate and the combined effect of canopy and litter on species diversity and productivity were assessed under Retama sphaerocarpa shrubs in a semi-arid environment in southeast Spain. Soil chemical properties differed significantly among three positions under the canopy, particularly between inner and outer positions. The potential mineralization rate of organic matter was significantly higher in soils from an intermediate position under the canopy than in soils from either the centre and the edge. Soil chemical fertility and estimated soil seed bank were highest also in soil at an intermediate position and lowest in soil from the edge. The understorey flora was favoured by the lower temperature and irradiation and increased soil fertility under the shrubs canopies. Species emerging from the soil seed bank separated clearly into two groups which occupied inner and outer positions under the canopy. Different levels of addition of Retaina litter significantly decreased species richness and the number of emerged seedlings. In the field, pots placed near the centre, at an intermediate position and at the edge of the canopy of Retama shrubs differed significantly in species richness and biomass production. Overall, micro-climatic conditions combined with increased chemical fertility of the soil and inhibitory effects of litter to produce a large biomass of herbs at intermediate positions between the centre and the edge of the canopy. The high proportion of litter from annual species in that position increases the mineralization rate and hence nutrient dynamics in a process which also could benefit the shrub.