Fine root decay rates vary widely among lowland tropical tree species
Fine root decay rates vary widely among lowland tropical tree species
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DOI：
10.1007/s00442-009-1379-9
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发表时间：
2009-05
期刊：
影响因子：
2.7
通讯作者：
J. Raich;A. Russell;O. Valverde‐Barrantes
中科院分区：
文献类型：
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作者：
J. Raich;A. Russell;O. Valverde‐Barrantes
在哥斯达黎加低地的幼树种植园中，多产的细根生长加上少量的死亡细根堆积表明细根的产生、死亡和腐烂的速度很快。然而，已发表的研究表明，热带森林中细根的腐烂相对较慢。为了解决这一差异，我们使用完整核心技术量化了四个本地树种的单一树种人工林中细根的第一年腐烂率。我们检验了三个假设：第一，不同树种的细根会以不同的速度腐烂；第二，细根生长速度快的树种也会有快速的细根腐烂速度；第三，物种之间细根腐烂的差异可以用以前被认为影响衰变速度的细根化学变量来解释。细根腐烂速度较慢(k=0.29±0.15/年−1)，细根腐烂速度较快7倍(k=2.00±0.13/年−1)。其余两个种的衰减率分别为1.36和1.28，−1。细根腐烂率与活细根相对生长率呈极显著正相关(R=0.93，n=0.43，P=0.072)。细根腐烂与细根木质素N呈极显著负相关(R=0.99，P=0.0 1)，支持在陆地生态系统模型中使用木质素：N作为腐烂控制因子。我们在这个单一研究地点观察到的腐烂速率涵盖了以前在潮湿的热带森林中观察到的整个细根腐烂速率范围，因此表明单个树种在生物丰富的热带雨林环境中改变地下有机质和养分动态的巨大潜力。
Prolific fine root growth coupled with small accumulations of dead fine roots indicate rapid rates of fine root production, mortality and decay in young tree plantations in lowland Costa Rica. However, published studies indicate that fine roots decay relatively slowly in tropical forests. To resolve this discrepancy, we used the intact-core technique to quantify first-year decay rates of fine roots in four single-species plantations of native tree species. We tested three hypotheses: first, that fine roots from different tree species would decay at different rates; second, that species having rapid fine root growth rates would also have rapid rates of fine root decay; and third, that differences in fine root decay among species could be explained by fine root chemistry variables previously identified as influencing decay rates. Fine roots inVirolakoschnyiplantations decayed very slowly (k= 0.29 ± 0.15 year−1); those ofVochysiaguatemalensisdecayed seven times faster (k= 2.00 ± 0.13 year−1). Decay rates of the remaining two species,Hieronyma alchorneoidesandPentaclethra macroloba, were 1.36 and 1.28 year−1, respectively. We found a positive, marginally significant correlation between fine root decay rates and the relative growth rates of live fine roots (R= 0.93,n= 4,P= 0.072). There was a highly significant negative correlation between fine root decay and fine root lignin:N (R= 0.99,P= 0.01), which supports the use of lignin:N as a decay-controlling factor within terrestrial ecosystem models. The decay rates that we observed in this single study location encompassed the entire range of fine root decay rates previously observed in moist tropical forests, and thus suggest great potential for individual tree species to alter belowground organic matter and nutrient dynamics within a biotically rich rainforest environment.