Matyssek R, Kozovits A R, Wieser G, King J, Rennenberg H
Technische Universität München, TUM School of Life Sciences Weihenstephan, Chair of Ecophysiology of Plants, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, Germany.
Universidade Federal de Ouro Preto, Department of Biodiversity, Evolution and Environment, Campus Morro do Cruzeiro, Bauxita, 35.400-000 Ouro Preto, MG, Brazil.
Tree Physiol. 2017 Jun 1;37(6):706-732. doi: 10.1093/treephys/tpx009.
Forests store the largest terrestrial pools of carbon (C), helping to stabilize the global climate system, yet are threatened by climate change (CC) and associated air pollution (AP, highlighting ozone (O3) and nitrogen oxides (NOx)). We adopt the perspective that CC-AP drivers and physiological impacts are universal, resulting in consistent stress responses of forest ecosystems across zonobiomes. Evidence supporting this viewpoint is presented from the literature on ecosystem gross/net primary productivity and water cycling. Responses to CC-AP are compared across evergreen/deciduous foliage types, discussing implications of nutrition and resource turnover at tree and ecosystem scales. The availability of data is extremely uneven across zonobiomes, yet unifying patterns of ecosystem response are discernable. Ecosystem warming results in trade-offs between respiration and biomass production, affecting high elevation forests more than in the lowland tropics and low-elevation temperate zone. Resilience to drought is modulated by tree size and species richness. Elevated O3 tends to counteract stimulation by elevated carbon dioxide (CO2). Biotic stress and genomic structure ultimately determine ecosystem responsiveness. Aggrading early- rather than mature late-successional communities respond to CO2 enhancement, whereas O3 affects North American and Eurasian tree species consistently under free-air fumigation. Insect herbivory is exacerbated by CC-AP in biome-specific ways. Rhizosphere responses reflect similar stand-level nutritional dynamics across zonobiomes, but are modulated by differences in tree-soil nutrient cycling between deciduous and evergreen systems, and natural versus anthropogenic nitrogen (N) oversupply. The hypothesis of consistency of forest responses to interacting CC-AP is supported by currently available data, establishing the precedent for a global network of long-term coordinated research sites across zonobiomes to simultaneously advance both bottom-up (e.g., mechanistic) and top-down (systems-level) understanding. This global, synthetic approach is needed because high biological plasticity and physiographic variation across individual ecosystems currently limit development of predictive models of forest responses to CC-AP. Integrated research on C and nutrient cycling, O3-vegetation interactions and water relations must target mechanisms' ecosystem responsiveness. Worldwide case studies must be subject to biostatistical exploration to elucidate overarching response patterns and synthesize the resulting empirical data through advanced modelling, in order to provide regionally coherent, yet globally integrated information in support of internationally coordinated decision-making and policy development.
森林储存着陆地最大的碳库，有助于稳定全球气候系统，但却受到气候变化（CC）及相关空气污染（AP，突出表现为臭氧（O₃）和氮氧化物（NOₓ））的威胁。我们认为，CC - AP驱动因素和生理影响具有普遍性，导致不同生物带的森林生态系统产生一致的应激反应。本文从有关生态系统总初级生产力/净初级生产力和水循环的文献中列举了支持这一观点的证据。比较了常绿/落叶叶片类型对CC - AP的反应，讨论了树木和生态系统尺度上营养和资源周转的影响。不同生物带的数据可用性极不均衡，但生态系统反应的统一模式是可辨别的。生态系统变暖导致呼吸作用和生物量生产之间的权衡，对高海拔森林的影响大于低地热带和低海拔温带地区。对干旱的恢复力受树木大小和物种丰富度的调节。O₃浓度升高往往会抵消二氧化碳（CO₂）浓度升高带来的刺激作用。生物胁迫和基因组结构最终决定生态系统的反应能力。早期演替而非成熟晚期演替群落对CO₂浓度升高有反应，而在自由空气熏蒸条件下，O₃对北美和欧亚树种的影响较为一致。CC - AP以生物群落特定的方式加剧了昆虫食草作用。根际反应反映了不同生物带类似的林分水平营养动态，但受落叶和常绿系统之间树木 - 土壤养分循环差异以及自然与人为氮（N）供应过剩的调节。目前可得的数据支持森林对相互作用的CC - AP反应具有一致性这一假设，为建立一个跨越生物带的全球长期协调研究站点网络奠定了先例，以便同时推进自下而上（如机理方面）和自上而下（系统层面）的理解。之所以需要这种全球综合方法，是因为目前各个生态系统的高生物可塑性和地貌变化限制了森林对CC - AP反应预测模型的发展。对碳和养分循环、O₃ - 植被相互作用以及水分关系的综合研究必须针对生态系统反应的机制。全球范围的案例研究必须接受生物统计学探索，以阐明总体反应模式，并通过先进建模对所得实证数据进行综合，以便提供区域连贯但全球整合的信息，支持国际协调的决策和政策制定。
