Abstract

The integration of trees within agricultural systems delivers the opportunity to provide multiple benefits over those afforded by agriculture without trees. The use of windbreaks as a form of agroforestry, in water scarce environments, is primarily used to reduce windspeeds in order to decrease evapotranspiration. Quick growing poplar species such as Populus simonii ((Carrière) Wesm.) are frequently utilised within windbreak structures, but to date, few allometric equations are available to quantify biomass production and to make inferences about carbon storage potential of this species, and none outside the forest. To fill this knowledge gap, we destructively sampled 17 P. simonii growing within a windbreak on a wine estate in the Western Cape Provence, South Africa. Power functions were constructed to explain tree height, whole tree aboveground woody biomass, stem and branch biomass as a function of stem diameter at 1.3 m. Additional functions were developed to predict individual branch length and biomass based on branch stub diameter. The presented models explained each variable with high significance. The models could be used to estimate carbon stock per km of windbreak for the given example. Furthermore, bark percentage predicted by stem sectional diameter was modelled to provide a function that can separate wood and bark fractions as a further outlook for the species’ utilisation.

中文翻译：

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南非西开普省小叶杨防风林的生物量和碳储存评估

摘要

将树木融入农业系统提供了比没有树木的农业提供多种效益的机会。在缺水环境中，使用防风林作为农林业的一种形式，主要用于降低风速，以减少蒸散量。快速生长的杨树物种，如小叶杨((Carrière) Wesm.) 经常在防风结构中使用，但迄今为止，很少有异速生长方程可用于量化生物量生产并推断该物种的碳储存潜力，而且除此之外还没有任何异速生长方程。森林。为了填补这一知识空白，我们对南非普罗旺斯西开普省的一个葡萄酒庄园的防风林内生长的17株西莫尼进行了破坏性采样。构建幂函数来解释树高、整树地上木质生物量、茎和枝生物量与 1.3 m 茎直径的函数关系。开发了额外的函数来根据分支残端直径预测单个分支长度和生物量。所提出的模型解释了具有高度意义的每个变量。该模型可用于估计给定示例中每公里防风林的碳储量。此外，对通过茎截面直径预测的树皮百分比进行了建模，以提供可以分离木材和树皮部分的函数，作为该物种利用的进一步展望。