Land use legacies drive higher growth, lower wood density and enhanced climatic sensitivity in recently established forests
Land use legacies drive higher growth, lower wood density and enhanced climatic sensitivity in recently established forests
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DOI：
10.1016/j.agrformet.2019.107630
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发表时间：
2019-10-15
影响因子：
6.2
通讯作者：
Maria Espelta, Josep
中科院分区：
文献类型：
--
作者：
Alfaro-Sanchez, Raquel;Jump, Alistair S.;Maria Espelta, Josep
由于经济和人口变化导致农村地区被遗弃，欧洲正在经历大规模的森林扩张。最近建立的森林提供了关键的生态系统服务，如提供栖息地和增加碳储量。然而，与历史悠久的森林相比，过去的土地使用是否会改变它们对气候变化的适应能力，我们缺乏了解。在前农业区建立的森林可能受益于土地使用遗产，从而提高肥力，但如果涉及到功能属性的变化，降低了它们应对不利气候事件(如干旱)的能力，这种好处可能会变成劣势。在这里，我们研究了加泰罗尼亚(西班牙东北部)最近(1956年后)和长期(1956年前)的山毛榉森林在生长模式、木材密度、对气候的敏感性和对极端气候事件的反应方面的不同之处。我们的结果表明，即使在控制树龄和竞争的情况下，最近建立的森林的树木也有更高的生长量(32%)和更低的木材密度(3%)。此外，新近建立的森林对标准化降水--蒸散指数、降水和温度以及极端正负气候事件表现出更高的敏感性。在特别多雨的年份，新建立的森林显示的正指示年数是长期建立的森林的两倍。在最近建立的森林的积极年份中的补偿性增长，可能正在推动类似或甚至更高的恢复和在干旱事件后检测到的复原力。然而，最近建立的森林对气候的敏感性较高，再加上它们的生长速度更快，木材密度更低，这表明它们可能特别容易受到未来干旱的影响。这种增强的脆弱性可能会质疑它们长期促进碳固存的能力，并强调有必要考虑土地使用遗留问题，以更好地预测未来随着气候变化而发挥的森林功能。
Europe is undergoing significant forest expansion due to the abandonment of rural areas driven by economic and demographic changes. Recently established forests provide key ecosystem services such as habitat provision and increased carbon stocks. However, we lack understanding of whether past land use might alter their resilience to climate change compared with long-established forests. Forests established in former agricultural areas may benefit from land use legacies resulting in higher fertility, yet such a benefit might turn into a disadvantage if it involves changes in functional attributes that lower their ability to cope with negative climatic events (e.g. droughts). Here we examined whether recently (post 1956) and long-established (pre 1956) beech forests in Catalonia (NE Spain) differ in their growth patterns, wood density, sensitivity to climate and response to extreme climatic events. Our results indicate higher growth (32%) and lower wood density (3%) in trees from recently established forests, even when controlling for tree age and competition. In addition, recently established forests showed a higher sensitivity to Standardised Precipitation-Evapotranspiration Index (SPEI), precipitation and temperature and to extreme negative and positive climatic events. In particularly wet years, recently established forests show twice the number of positive pointer years than long-established forests. Compensatory growth during positive years in recently established forests, may be driving the similar or even higher recovery and resilience detected after drought episodes. Nevertheless, the higher climatic sensitivity of the recently established forests, together with their greater growth and lower wood density indicates that they may be particularly vulnerable to future droughts. Such enhanced vulnerability might question their ability to contribute to carbon sequestration in the long term and emphasises the need to account for land use legacies to better predict future forest function as climate changes.