干热河谷稀树灌丛藤本植物叶片养分重吸收特性

Leaf nutrient resorption by savanna liana species in a dry-hot valley in Yuanjiang,southwest China

为探明我国西南干热河谷地区特殊的植被类型稀树灌丛的养分重吸收规律,选取元江干热河谷的稀树灌丛10种优势藤本植物为研究对象,测定叶片热值、灰分含量、形态性状、成熟叶和凋落叶的氮磷元素含量,计算叶片构建成本,探讨叶片构建成本、叶片性状与氮磷重吸收效率之间的相互关系。结果显示:元江干热河谷稀树灌丛藤本植物叶片的氮磷重吸收效率在不同物种之间存在较大的变异,叶片氮和磷重吸收效率平均值分别为48.0%和46.2%;叶片磷重吸收效率与氮重吸收效率呈显著正相关关系(P<0.05),而氮磷重吸收效率与叶片构建成本、比叶重呈显著负相关关系(P<0.05)。叶片构建成本较低的植物采取较快速的养分周转策略,以提高养分再利用效率;叶片构建成本较高的植物采取较保守的养分利用策略,养分回收效率较低。元江干热河谷的稀树灌丛藤本植物存在生活史策略的分化,以适应长期干热的生境。

This study was conducted to measure leaf construction cost,morphological traits,and nitrogen and phosphorus concentrations in green and senesced leaves from 10 woody liana species in a Chinese savanna in southwest China.We analyzed the relationships among leaf construction cost,morphological traits,and nutrient resorption efficiencies.Our findings revealed a large variation in nutrient resorption efficiencies among species,and respective average values of nitrogen and phosphorus resorption efficiency of 48.0%and 46.2%.Phosphorus resorption efficiency correlated positively with nitrogen resorption efficiency across species(P<0.05).Nitrogen and phosphorus resorption efficiencies were significantly negatively correlated with leaf construction cost and leaf mass per area(P<0.05).Plants with lower leaf composition cost tend to increase nutrient resorption efficiencies.In contrast,plants with higher leaf construction cost reflect more conservative nutrient utilization strategies and lower nutrient resorption efficiencies.Our results suggest a divergence in growth history strategies,reflecting a slow-fast continuum of growth among Chinese savanna liana species growing in persistently dry and hot habitats.