Differentiation in physiological activity is a critical component of resource partitioning in resource-limited environments. For example, it is crucial to understand how plant physiological performance varies through time for different functional groups to forecast how terrestrial ecosystems will respond to change. Here, we tracked the seasonal progress of 13 plant species representing C₃ shrub, perennial C₃ and C₄ grass, and annual forb functional groups of the Colorado Plateau, USA. We tested for differences in carbon assimilation strategies and how photosynthetic rates related to recent, seasonal, and annual precipitation and temperature variables. Despite seasonal shifts in species presence and activity, we found small differences in seasonally weighted annual photosynthetic rates among groups. However, differences in the timing of maximum assimilation (A_net) were strongly functional group-dependent. C₃ shrubs employed a relatively consistent, low carbon capture strategy and maintained activity year-round but switched to a rapid growth strategy in response to recent climate conditions. In contrast, grasses maintained higher carbon capture during spring months when all perennials had maximum photosynthetic rates, but grasses were dormant during months when shrubs remained active. Perennial grass A_net rates were explained in part by precipitation accumulated during the preceding year and average maximum temperatures during the past 48 h, a result opposite to shrubs. These results lend insight into diverse physiological strategies and their connections to climate, and also point to the potential for shrubs to increase in abundance in response to increased climatic variability in drylands, given shrubs’ ability to respond rapidly to changing conditions.

在资源受限的环境中，生理活动的差异是资源分配的关键组成部分。例如，至关重要的是要了解不同功能组的植物生理性能如何随时间变化，以预测陆地生态系统将如何响应变化。在这里，我们追踪了代表C ₃灌木，多年生C ₃和C ₄的13种植物的季节性进展草和美国科罗拉多高原的年度Forb功能组。我们测试了碳同化策略的差异以及光合速率与近期，季节性和年度降水量和温度变量之间的关系。尽管物种存在和活动的季节性变化，我们发现各组之间季节性加权的年度光合速率的细微差异。但是，最大同化时间（A _net）的差异强烈依赖于官能团。C ₃灌木采用相对一致的低碳捕获策略，并全年保持活动，但为了适应近期的气候条件，改用快速增长策略。相反，在所有多年生植物都具有最大光合速率的春季月份中，草保持较高的碳捕获，而在灌木保持活跃的月份中，草处于休眠状态。多年生草本植物一个_网发生率的部分原因是前一年积累的降水和过去48小时的平均最高气温，与灌木相反。这些结果使人们对各种生理策略及其与气候的联系有了更深入的了解，并指出了灌木对干旱环境的快速响应能力，以应对干旱地区干旱气候变化而增加其丰度的潜力。