Rooting depth as a key woody functional trait in savannas.
Rooting depth as a key woody functional trait in savannas.
复制标题
根系深度是稀树草原中关键的木质功能性状。
作者：
Yong Zhou;B. Wigley;M. F. Case;C. Coetsee;A. Staver
在稀树草原的树木根系的尺寸知之甚少，尽管是必不可少的资源收购和干扰后恢复。我们研究了在南部非洲热带稀树草原的树木生根模式问：如何影响树木生根策略的物种对严重干旱的反应;以及潜在的生根深度如何在土壤质地和降雨量的梯度变化。首先，在克鲁格国家公园的8个物种的详细挖掘表明，深，浅主根直径的比例提供了一个合理的代理潜在的生根深度，促进广泛的种间比较。详细的挖掘还表明，分配到深根交易浅侧根投资，干旱敏感的物种比抗旱的根更浅。更广泛地说，在南部非洲的57个物种中，潜在的生根深度受到遗传学的限制，在miombo Detarioids中，对深根的投资是明显的，这与表明它们在季节性降雨来临之前变绿色的结果一致。土壤基质解释了变异，相对于粘土、营养丰富的土壤，桑迪、营养贫乏的土壤上的根更深。虽然潜在的生根深度随着雨季长度的增加而减少，但年平均降雨量对生根深度没有系统的影响。总的来说，我们的研究结果表明，生根深度系统结构的热带稀树草原树木的生态。进一步研究其他解剖和生理根系特征应该是了解稀树草原对气候变化和干扰的反应的优先事项。
Dimensions of tree root systems in savannas are poorly understood, despite being essential in resource acquisition and post-disturbance recovery. We studied tree rooting patterns in Southern African savannas to ask: how tree rooting strategies affected species responses to severe drought; and how potential rooting depths varied across gradients in soil texture and rainfall. Firstly, detailed excavations of 8 species in Kruger National Park suggest that the ratio of deep to shallow taproot diameters provides a reasonable proxy for potential rooting depth, facilitating extensive inter-specific comparison. Detailed excavations also suggest that allocation to deep roots traded off with shallow lateral root investment, and that drought-sensitive species rooted more shallowly than drought-resistant ones. More broadly across 57 species in Southern Africa, potential rooting depths were phylogenetically constrained, with investment to deep roots evident among miombo Detarioids, consistent with results suggesting they green up before onset of seasonal rains. Soil substrate explained variation, with deeper roots on sandy, nutrient-poor soils relative to clayey, nutrient-rich ones. Although potential rooting depth decreased with increasing wet season length, mean annual rainfall had no systematic effect on rooting depth. Overall, our results suggest that rooting depth systematically structures the ecology of savanna trees. Further work examining other anatomical and physiological root traits should be a priority for understanding savanna responses to changing climate and disturbances.