van Paassen José G, Britton Andrea J, Mitchell Ruth J, Street Lorna E, Johnson David, Coupar Andrew, Woodin Sarah J
School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU, UK.
The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK.
New Phytol. 2020 Oct;228(1):226-237. doi: 10.1111/nph.16671. Epub 2020 Jun 24.
Soil carbon (C) pools and plant community composition are regulated by nitrogen (N) and phosphorus (P) availability. Atmospheric N deposition impacts ecosystem C storage, but the direction of response varies between systems. Phosphorus limitation may constrain C storage response to N, hence P application to increase plant productivity and thus C sequestration has been suggested. We revisited a 23-yr-old field experiment where N and P had been applied to upland heath, a widespread habitat supporting large soil C stocks. At 10 yr after the last nutrient application we quantified long-term changes in vegetation composition and in soil and vegetation C and P stocks. Nitrogen addition, particularly when combined with P, strongly influenced vegetation composition, favouring grasses over Calluna vulgaris, and led to a reduction in vegetation C stocks. However, soil C stocks did not respond to nutrient treatments. We found 40% of the added P had accumulated in the soil. This study showed persistent effects of N and N + P on vegetation composition, whereas effects of P alone were small and showed recovery. We found no indication that P application could mitigate the effects of N on vegetation or increase C sequestration in this system.
土壤碳（C）库和植物群落组成受氮（N）和磷（P）有效性的调节。大气氮沉降影响生态系统碳储存，但不同系统的响应方向各不相同。磷限制可能会制约碳储存对氮的响应，因此有人建议施用磷肥以提高植物生产力从而增加碳固存。我们重新审视了一项有23年历史的田间试验，该试验曾在山地石南灌丛（一种广泛分布且支撑着大量土壤碳储量的栖息地）上施用氮和磷。在最后一次施肥10年后，我们量化了植被组成以及土壤和植被碳与磷储量的长期变化。添加氮，特别是与磷结合添加时，对植被组成有强烈影响，有利于禾本科植物而非普通石楠，并导致植被碳储量减少。然而，土壤碳储量对养分处理没有响应。我们发现添加的磷有40%积累在土壤中。这项研究表明氮和氮 + 磷对植被组成有持续影响，而单独施用磷的影响较小且显示出恢复。我们没有发现施用磷肥可以减轻氮对植被的影响或增加该系统碳固存的迹象。
