Centre for Ecology and Hydrology, Wallingford, Oxon OX10 8BB, UK.
Philos Trans R Soc Lond B Biol Sci. 2011 Nov 27;366(1582):3316-29. doi: 10.1098/rstb.2011.0045.
The rate of above-ground woody biomass production, W(P), in some western Amazon forests exceeds those in the east by a factor of 2 or more. Underlying causes may include climate, soil nutrient limitations and species composition. In this modelling paper, we explore the implications of allowing key nutrients such as N and P to constrain the photosynthesis of Amazon forests, and also we examine the relationship between modelled rates of photosynthesis and the observed gradients in W(P). We use a model with current understanding of the underpinning biochemical processes as affected by nutrient availability to assess: (i) the degree to which observed spatial variations in foliar [N] and [P] across Amazonia affect stand-level photosynthesis; and (ii) how these variations in forest photosynthetic carbon acquisition relate to the observed geographical patterns of stem growth across the Amazon Basin. We find nutrient availability to exert a strong effect on photosynthetic carbon gain across the Basin and to be a likely important contributor to the observed gradient in W(P). Phosphorus emerges as more important than nitrogen in accounting for the observed variations in productivity. Implications of these findings are discussed in the context of future tropical forests under a changing climate.
在某些亚马逊西部地区，地上木质生物质的生产速率（W(P)）比东部高出 2 倍以上。其潜在原因可能包括气候、土壤养分限制和物种组成。在本文的建模研究中，我们探讨了允许关键养分（如氮和磷）限制亚马逊森林光合作用的影响，还检验了模型化光合作用速率与观测到的 W(P)梯度之间的关系。我们利用一个模型，该模型考虑了养分供应对潜在生化过程的影响，以评估：(i) 亚马逊地区观测到的叶片[N]和[P]的空间变化对林分水平光合作用的影响程度；以及 (ii) 森林光合碳获取的这些变化与亚马逊流域观测到的茎生长地理模式有何关系。我们发现，养分供应对整个流域的光合作用碳增益有很强的影响，并且可能是导致 W(P) 观测梯度的重要因素。磷在解释生产力的观测变化方面比氮更为重要。在气候变化背景下，这些发现的影响在未来热带森林中进行了讨论。
