Climate warming is expected to stimulate plant growth in high‐elevation and high‐latitude ecosystems, significantly increasing aboveground net primary production (ANPP). However, the effects of simultaneous changes in temperature, snowmelt timing, and summer water availability on total net primary production (NPP)—and elucidation of both above‐ and belowground responses—remain an important area in need of further study. In particular, measures of belowground net primary productivity (BNPP) are required to understand whether ANPP changes reflect changes in allocation or are indicative of a whole plant NPP response. Further, plant functional traits provide a key way to scale from the individual plant to the community level and provide insight into drivers of NPP responses to environmental change. We used infrared heaters to warm an alpine plant community at Niwot Ridge, Colorado, and applied supplemental water to compensate for soil water loss induced by warming. We measured ANPP, BNPP, and leaf and root functional traits across treatments after 5 yr of continuous warming. Community‐level ANPP and total NPP (ANPP + BNPP) did not respond to heating or watering, but BNPP increased in response to heating. Heating decreased community‐level leaf dry matter content and increased total root length, indicating a shift in strategy from resource conservation to acquisition in response to warming. Water use efficiency (WUE) decreased with heating, suggesting alleviation of moisture constraints that may have enabled the plant community to increase productivity. Heating may have decreased WUE by melting snow earlier and creating more days early in the growing season with adequate soil moisture, but stimulated dry mass investment in roots as soils dried down later in the growing season. Overall, this study highlights how ANPP and BNPP responses to climate change can diverge, and encourages a closer examination of belowground processes, especially in alpine systems, where the majority of NPP occurs belowground.

中文翻译：

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高山冻原的变暖提高了地下产量，并使社区向资源获取特性转变

预计气候变暖将刺激高海拔和高纬度生态系统中的植物生长，从而显着增加地上净初级生产力（ANPP）。但是，温度，融雪时间和夏季可用水量的同时变化对总净初级生产（NPP）的影响以及对地下和地下响应的阐明仍然是需要进一步研究的重要领域。特别是，需要采取地下净初级生产力（BNPP）的措施，以了解ANPP的变化是反映分配的变化还是表明整个工厂的NPP响应。此外，植物功能性状提供了从单个植物扩展到社区水平的关键途径，并提供了对NPP对环境变化的响应驱动力的见解。我们使用红外加热器加热了科罗拉多州Niwot Ridge的一个高山植物群落，并补充了水以补偿由于变暖引起的土壤水分流失。在连续变暖5年后的整个处理过程中，我们测量了ANPP，BNPP以及叶和根的功能性状。社区一级的ANPP和总NPP（ANPP + BNPP）对取暖或浇水没有反应，但是BNPP随着加热而增加。加热降低了社区水平的叶片干物质含量，增加了总根长，表明应对气候变化的策略从资源保护转向获取。水分利用效率（WUE）随着加热而降低，表明缓解了水分约束，这可能使植物群落提高了生产力。加热可能会通过使雪更早融化并在生长季初期增加水分含量而减少WUE，并在生长季初期创造更多的日子，但由于土壤在生长季后期变干，因此刺激了根部的干物质投资。总的来说，这项研究强调了ANPP和BNPP对气候变化的反应如何不同，并鼓励更深入地研究地下过程，特别是在大多数NPP发生在地下的高山系统中。