Gliesch Mariana, Sanchez Leonardo Hinojosa, Boreel Kiki, Tietema Albert, de Vries Franciska T
Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Amsterdam, the Netherlands.
Glob Chang Biol. 2025 Sep;31(9):e70441. doi: 10.1111/gcb.70441.
Droughts are increasing with climate change, affecting the functioning of terrestrial ecosystems and limiting their capacity to mitigate rising atmospheric CO levels. However, there is still large uncertainty on the long-term impacts of drought on ecosystem carbon (C) cycling, and how this determines the effect of subsequent droughts. Here, we aimed to quantify how drought legacy affects the response of a heathland ecosystem to a subsequent drought for two life stages of Calluna vulgaris resulting from different mowing regimes. We imposed a subsequent drought in a long-term (20 years) drought field experiment combined with different mowing years. We hypothesised that drought legacy would reduce the impact of a subsequent drought on ecosystem respiration (ER) through shifts in microbial community composition, and we expected a stronger effect of drought legacy on building stage Calluna (mowed in 2013) than on seedlings (mowed in 2020), with knock-on effects for net ecosystem exchange (NEE) and ER. We found that drought legacy persistently shifted soil bacterial and fungal communities, but the subsequent drought had minimal effect. Drought legacy also shifted plant community composition, with the strongest effect of subsequent drought on the building stage of Calluna. Subsequent drought reduced all CO fluxes independent of drought legacy, and this effect was most pronounced in the building stage of Calluna. The observed strong and persistent shifts in soil microbial communities as a result of 20 years of summer drought did not explain ecosystem CO fluxes, which were determined by changes in plant communities. Thus, our findings show a mismatch between aboveground and belowground responses to drought, and highlight that older heathlands are more vulnerable to drought, reducing their CO uptake capacity in the crucial phase of ecosystem C stock accumulation. These findings give insight into the consequences of long-term drought for ecosystem C cycling and its response to future drought.
随着气候变化，干旱日益频繁，影响着陆地生态系统的功能，并限制了其缓解大气中二氧化碳水平上升的能力。然而，干旱对生态系统碳循环的长期影响以及这如何决定后续干旱的影响仍存在很大的不确定性。在这里，我们旨在量化干旱遗留效应如何影响石南荒地生态系统对后续干旱的响应，该响应针对不同刈割方式下普通石楠两个生命阶段而言。我们在一个长期（20年）的干旱田间试验中，结合不同的刈割年份，施加了后续干旱。我们假设干旱遗留效应会通过微生物群落组成的变化来降低后续干旱对生态系统呼吸（ER）的影响，并且我们预计干旱遗留效应在石楠生长阶段（2013年刈割）比在幼苗阶段（2020年刈割）对普通石楠的影响更强，对净生态系统交换（NEE）和ER产生连锁效应。我们发现干旱遗留效应持续改变了土壤细菌和真菌群落，但后续干旱的影响极小。干旱遗留效应还改变了植物群落组成，后续干旱对石楠生长阶段的影响最为强烈。后续干旱降低了所有碳通量，且与干旱遗留效应无关，这种影响在石楠生长阶段最为明显。20年夏季干旱导致的土壤微生物群落的强烈且持续的变化并不能解释生态系统的碳通量，碳通量是由植物群落的变化决定的。因此，我们的研究结果表明地上和地下对干旱的响应存在不匹配，并强调较老的石南荒地更容易受到干旱影响，在生态系统碳储量积累的关键阶段降低了它们的碳吸收能力。这些发现有助于深入了解长期干旱对生态系统碳循环的影响及其对未来干旱的响应。
