Data from: Quercus suber dieback alters soil respiration and nutrient availability in Mediterranean forests

An increase in tree mortality rates has been recently detected in forests world-wide. However, few works have focused on the potential consequences of forest dieback for ecosystem functioning.
Here we assessed the effect of Quercus suber dieback on carbon, nitrogen and phosphorus cycles in two types of Mediterranean forests (woodlands and closed forests) affected by the aggressive pathogen Phytophthora cinnamomi. We used a spatially explicit neighbourhood approach to analyse the direct effects of Q. suber dieback on soil variables, comparing the impact of Q. suber trees with different health status, as well as its potential long-term indirect effects, comparing the impact of non-declining coexistent species.
Quercus suber dieback translated into lower soil respiration rates and phosphorus availability, whereas its effects on nitrogen varied depending on forest type. Coexistent species differed strongly from Q. suber in their effects on nutrient availability, but not on soil respiration rates. Our models showed low interannual but high intra-annual variation in the ecosystem impacts of tree dieback.
Synthesis. Our results support that tree dieback might have important short- and long-term impacts on ecosystem processes in Mediterranean forests. With this work, we provide valuable insights to fill the existent gap in knowledge on the ecosystem-level impacts of forest dieback in general and P. cinnamomi-driven mortality in particular. Because the activity and range of this pathogen is predicted to increase due to climate warming, these impacts could also increase in the near future altering ecosystem functioning world-wide.

近期全球范围内的森林均被监测到树木死亡率上升的现象。然而，针对森林衰退对生态系统功能的潜在影响，相关研究仍较为匮乏。
本研究针对受侵袭性病原菌樟疫霉（Phytophthora cinnamomi）侵染的两类地中海森林（疏林与密闭林），评估了栓皮栎（Quercus suber）衰退对碳、氮、磷循环的影响。我们采用空间显式邻域分析法，通过对比不同健康状态栓皮栎植株的影响，分析栓皮栎衰退对土壤变量的直接效应；同时通过对比未衰退伴生树种的影响，探究其潜在的长期间接效应。
栓皮栎衰退会导致土壤呼吸速率与磷有效性降低，但其对氮循环的影响则因森林类型而异。伴生树种对养分有效性的影响与栓皮栎存在显著差异，但对土壤呼吸速率的影响并无显著不同。本研究的模型结果显示，树木衰退对生态系统的影响存在较低的年际间变异性，但具有较高的年内变异性。
研究总结。本研究结果表明，树木衰退可能对地中海森林的生态系统过程产生重要的短期与长期影响。本研究填补了当前在森林衰退（尤其是樟疫霉介导的树木死亡）的生态系统级影响方面的认知空白，并为此提供了极具价值的研究见解。鉴于气候变暖将导致该病原菌的活动范围与侵染能力进一步扩张，此类生态影响在未来可能进一步加剧，进而改变全球范围内的森林生态系统功能。