A simulation of the importance of length of growing season and canopy functional properties on the seasonal gross primary production of temperate alpine meadows
A simulation of the importance of length of growing season and canopy functional properties on the seasonal gross primary production of temperate alpine meadows
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DOI：
10.1093/aob/mcm318
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发表时间：
2008-03-01
期刊：
影响因子：
4.2
通讯作者：
Choler, Philippe
中科院分区：
文献类型：
--
作者：
Baptist, Florence;Choler, Philippe
研究背景与目的：沿着融雪梯度，温带高山草甸的冠层在结构和生物化学性质上存在很大差异。方法对沿着明显融雪梯度分布的7种高山植物冠层的叶面积指数（LAI）、叶角和叶氮含量的群落聚集值进行了估算，并对不同的冠层类型和不同的生长季长度对植物季节性初级生产力（GPP）的影响进行了研究。并将其作为遮阳冠层整体光合作用模型的输入变量。该模型进行了验证的早期和后期融雪网站的植物群落通过测量瞬时CO2通量与冠层封闭室技术。进行敏感性分析，以估计冠层特性和环境因素对每日和季节GPP.Key结果的相对影响碳吸收主要与叶面积指数和冠层总氮含量，但不叶角。对于一个给定的光合有效辐射水平，CO2同化量较高的阴天条件下。敏感性分析表明，生长季节长度的增加对季节性GPP的影响大于任何其他因素的类似增加。它还发现，所观察到的氮含量和较大的叶面积指数的冠层在融雪后期的网站在很大程度上弥补了负面影响的减少growing season.Conclusions的结果强调的首要重要性，雪引起的变化，在高山温带草甸的碳吸收的生长季节的长度。它还表明，如何使用叶性状值的优势是一个有用的方法，模拟生态系统的碳循环相关的过程，特别是当连续测量二氧化碳通量在技术上是困难的。因此，这项研究代表了一个重要的一步，在解决的挑战，使用植物功能性状的方法为地球化学建模。
Background and Aims Along snowmelt gradients, the canopies of temperate alpine meadows differ strongly in their structural and biochemical properties. Here, a study is made of the effects of these canopy dissimilarities combined with the snow-induced changes in length of growing season on seasonal gross primary production (GPP).Methods Leaf area index (LAI) and community-aggregated values of leaf angle and leaf nitrogen content were estimated for seven alpine plant canopies distributed along a marked snowmelt gradient, and these were used as input variables in a sun-shade canopy bulk-photosynthesis model. The model was validated for plant communities of early and late snowmelt sites by measuring the instantaneous CO2 fluxes with a canopy closed-chamber technique. A sensitivity analysis was conducted to estimate the relative impact of canopy properties and environmental factors on the daily and seasonal GPP.Key Results Carbon uptake was primarily related to the LAI and total canopy nitrogen content, but not to the leaf angle. For a given level of photosynthetically active radiation, CO2 assimilation was higher under overcast conditions. Sensitivity analysis revealed that increase of the length of the growing season had a higher effect on the seasonal GPP than a similar increase of any other factor. It was also found that the observed greater nitrogen content and larger LAI of canopies in late-snowmelt sites largely compensated for the negative impact of the reduced growing season.Conclusions The results emphasize the primary importance of snow-induced changes in length of growing season on carbon uptake in alpine temperate meadows. It was also demonstrated how using leaf-trait values of the dominants is a useful approach for modelling ecosystem carbon-cycle-related processes, particularly when continuous measurements of CO2 fluxes are technically difficult. The study thus represents an important step in addressing the challenge of using a plant functional-trait approach for biogeochemical modelling.