Arid
DOI10.1111/1365-2745.12010
Tree effects on grass growth in savannas: competition, facilitation and the stress-gradient hypothesis
Dohn, Justin1; Dembele, Fadiala2; Karembe, Moussa3; Moustakas, Aristides4,5; Amevor, Kosiwa A.3; Hanan, Niall P.6
通讯作者Dohn, Justin
来源期刊JOURNAL OF ECOLOGY
ISSN0022-0477
EISSN1365-2745
出版年2013
卷号101期号:1页码:202-209
英文摘要

1. The stress-gradient hypothesis (SGH) predicts an increasing importance of facilitative mechanisms relative to competition along gradients of increasing environmental stress. Although developed across a variety of ecosystems, the SGH’s relevance to the dynamic tree-grass systems of global savannas remains unclear. Here, we present a meta-analysis of empirical studies to explore emergent patterns of tree-grass relationships in global savannas in the context of the SGH.


2. We quantified the net effect of trees on understorey grass production relative to production away from tree canopies along a rainfall gradient in tropical and temperate savannas and compared these findings to the predictions of the SGH. We also analysed soil and plant nutrient concentrations in subcanopy and open-grassland areas to investigate the potential role of nutrients in determining grass production in the presence and absence of trees.


3. Our meta-analysis revealed a shift from net competitive to net facilitative effects of trees on subcanopy grass production with decreasing annual precipitation, consistent with the SGH. We also found a significant difference between sites from Africa and North America, suggesting differences in tree-grass interactions in the savannas of tropical and temperate regions.


4. Nutrient analyses indicate no change in nutrient ratios along the rainfall gradient, but consistent nutrient enrichment under tree canopies.


5. Synthesis. Our results help to resolve questions about the SGH in semi-arid systems, demonstrating that in mixed tree-grass systems, trees facilitate grass growth in drier regions and suppress grass growth in wetter regions. Relationships differ, however, between African and North American sites representing tropical and temperate bioclimates, respectively. The results of this meta-analysis advance our understanding of tree-grass interactions in savannas and contribute a valuable data set to the developing theory behind the SGH.


英文关键词Africa competition facilitation North America plant-plant interactions rainfall gradient savanna stress-gradient hypothesis tree-grass interactions hypothesis
类型Article
语种英语
国家USA ; Mali ; England
收录类别SCI-E
WOS记录号WOS:000317922200022
WOS关键词PLANT-PLANT INTERACTIONS ; RELATIVE IMPORTANCE ; ABIOTIC STRESS ; ENVIRONMENTS ; PRODUCTIVITY ; VEGETATION ; QUALITY ; AVAILABILITY ; METAANALYSIS ; COMMUNITIES
WOS类目Plant Sciences ; Ecology
WOS研究方向Plant Sciences ; Environmental Sciences & Ecology
来源机构University of London ; Colorado State University
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/178249
作者单位1.Colorado State Univ, Nat Resource Ecol Lab, Dept 1499, Ft Collins, CO 80523 USA;
2.Inst Polytechn Rurale Format & Rech Appl IPR IFRA, Koulikouro, Mali;
3.Univ Bamako, Fac Sci & Tech, Bamako, Mali;
4.Univ London, Sch Biol & Chem Sci, London E1 4NS, England;
5.Univ Leeds, Inst Integrat & Comparat Biol, Fac Biol Sci, Leeds LS2 9JT, W Yorkshire, England;
6.S Dakota State Univ, Geog Informat Sci Ctr Excellence, Brookings, SD 57007 USA
推荐引用方式
GB/T 7714
Dohn, Justin,Dembele, Fadiala,Karembe, Moussa,et al. Tree effects on grass growth in savannas: competition, facilitation and the stress-gradient hypothesis[J]. University of London, Colorado State University,2013,101(1):202-209.
APA Dohn, Justin,Dembele, Fadiala,Karembe, Moussa,Moustakas, Aristides,Amevor, Kosiwa A.,&Hanan, Niall P..(2013).Tree effects on grass growth in savannas: competition, facilitation and the stress-gradient hypothesis.JOURNAL OF ECOLOGY,101(1),202-209.
MLA Dohn, Justin,et al."Tree effects on grass growth in savannas: competition, facilitation and the stress-gradient hypothesis".JOURNAL OF ECOLOGY 101.1(2013):202-209.
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