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Explaining patterns of primary production from individual level traits

机译：从个人水平特征解释初级生产的模式

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QuestionDo species traits explain differences in productivity in grazed and ungrazed plots?LocationRio de la Plata grasslands, Uruguay (31 degrees 54'S, 58 degrees 15'W).MethodsIn a greenhouse experiment, we measured the relative growth rate (RGR) of grasses with contrasting responses to grazing (increasers and decreasers). We performed six harvests at weekly intervals in order to calculate the RGR and assess 12 plant traits. We compared the RGR between increaser and decreaser species after 2 and 5 weeks using t-tests. Linear and potential regression models were fitted to time versus natural logarithm of total dry biomass relationships. The RGR temporal trajectories of increaser and decreaser species were obtained from the derivatives of the best-fit functions. Principal component analysis (PCA) was used to sort species according to their traits.ResultsThe RGR of decreaser grasses was higher than that of increasers at the second week, while at the fifth week the opposite was observed. The RGR of decreasers dropped through time, while the RGR of increaser species was constant. The PCA separated increaser from decreaser species. The attributes related to increaser species were: high specific leaf area, tillering rate, green leaf rate, total leaf number, root weight ratio and leaf weight ratio; while those associated with decreaser species were: high dead biomass, senescence rate, reproductive biomass, leaf elongation rate and total biomass.ConclusionsTraits possessed by decreasers reduce light availability and increase the reproductive investment, explaining the drop in RGR. Specific differences in RGR seem to scale up to the ecosystem level and would explain the pattern in aboveground net primary production observed in the field under contrasting grazing regimes.
机译：物种特征是否解释了放牧和未沼泽土地上生产力的差异？位置乌拉圭里约热内卢普拉塔草原（31°54'S，58°15'W）方法在温室试验中，我们通过对比测量了草的相对生长率（RGR）对放牧的反应（增加和减少）。为了计算RGR并评估12种植物性状，我们每周进行六次收获。我们使用t检验比较了2和5周后增加和减少种类之间的RGR。将线性和潜在回归模型拟合为总干生物量关系的时间对自然对数。从最佳拟合函数的导数中获得了增加和减少种类的RGR时间轨迹。结果采用主成分分析法（PCA）对物种进行分类。结果：第二周，矮化草的RGR高于增高草的RGR，而在第五周则相反。减速器的RGR随时间下降，而上升器的RGR不变。 PCA将还原剂与还原剂种类分开。与增加剂种类有关的属性是：高比叶面积，分till率，绿叶率，总叶数，根重比和叶重比;结论：减少剂具有的特性降低了光的利用率并增加了繁殖投资，这说明了RGR的下降。这是与减少种相关的：死生物量高，衰老率，生殖生物量，叶片伸长率和总生物量。 RGR的具体差异似乎可以扩大到生态系统水平，并且可以解释在不同放牧制度下在田间观察到的地上净初级生产模式。

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