Multi-scale variation in fine-root biomass in a tropical rain forest: A seven-year study
Multi-scale variation in fine-root biomass in a tropical rain forest: A seven-year study
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DOI：
10.1890/06-1257.1
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发表时间：
2007-08-01
影响因子：
6.1
通讯作者：
Clark, D. A.
中科院分区：
文献类型：
--
作者：
Espeleta, J. F.;Clark, D. A.
了解生态系统过程在空间和时间尺度上的依赖性，对于目前模拟生态系统对全球变化的响应至关重要。在这里，我们提出了一个案件的时间和空间尺度之间的非线性相互作用的细根生物量响应的高空间和时间分辨率的研究土壤和气候变化在低地热带雨林（拉塞尔瓦，哥斯达黎加）。细根的时空变化明显大于地上生物量和凋落物量。活的和死的细根常备股票变化强烈，在7年期间（高达10倍），并在两个土壤梯度不同的土壤养分和水分变化（高达4倍）。细根生物量下降，土壤肥力和土壤体积含水量，但整个景观梯度的反应（减少与土壤总P和K，增加与N：P之间的两个Oxisols具有不同的风化比）不同的地形梯度在老Oxisols（增加与总铁和铝和减少与钙，镁，和C：N比下降的斜坡）。景观梯度的空间对比度（但不是在地形梯度）随着时间的推移发生了很大的变化，他们，事实上，完全消失的研究间隔的中间。因此，短期监测地下生物量可能会导致重要的偏差时，量化根的反应。正的时间X梯度的相互作用，在细根生物量在不同的土壤类型（但不是下坡）也表明非线性变化的空间格局在时间尺度上，所以时间响应的研究也需要在空间上明确在狭窄的尺度。这种相互作用似乎也比以前认识到的更复杂：学期平均细根生物量与土壤含水量呈负相关，在前一个学期，但这种关系仅限于残留Oxisols。为了提高未来全球碳循环模型的准确性，对区域和全球尺度生态系统过程观测的一个重要补充将是量化这些过程，这些过程将持续多年，并跨越景观中通常存在的大量土壤梯度。
Understanding the dependency of ecosystem processes on spatial and temporal scales is crucial in current efforts to model ecosystem responses to global change. Here we present a case of nonlinear interactions between temporal and spatial scales in a high spatial- and temporal-resolution study of fine-root biomass responses to edaphic and climatic variation in a lowland tropical rain forest (La Selva, Costa Rica). The spatiotemporal variation in fine roots in this forest was considerably greater than that for aboveground live biomass and litterfall. Standing stocks of both live and dead fine roots varied strongly during a seven-year period (up to 10-fold) and across two edaphic gradients with different soil nutrient and water variation (up to four-fold). Fine-root biomass decreased with soil fertility and volumetric soil water content, but responses across a landscape gradient (decreasing with total soil P and K and increasing with N:P ratio between two Oxisols with different weathering) differed from those across a topographic gradient in older Oxisols (increasing with total Fe and Al and decreasing with Ca, Mg, and C:N ratio down the slopes). The spatial contrasts across the landscape gradient (but not in the topographic gradient) changed substantially through time, and they, in fact, disappeared entirely by the middle of the study interval. Shortterm monitoring of belowground standing biomass could thus lead to important biases when quantifying root responses. The positive time X gradient interaction in fine-root biomass across soil types (but not downslope) also indicates nonlinear changes in spatial patterns across temporal scales, so studies on temporal responses also need to be spatially explicit at narrow scales. This interaction also appears to be more complex than previously recognized: semester-averaged fine-root biomass was negatively correlated with soil water content in the preceding semester, but the relationship was restricted to residual Oxisols. To increase the accuracy of global carbon cycle models in the future, a critical complement to observations of ecosystem processes at regional and global scales will be quantifying these processes through multiple years and across the substantial edaphic gradients that typically exist within landscapes.