Changes in fire regime break the legacy lock on successional trajectories in Alaskan boreal forest
Changes in fire regime break the legacy lock on successional trajectories in Alaskan boreal forest
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DOI：
10.1111/j.1365-2486.2009.02051.x
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发表时间：
2010-04-01
影响因子：
11.6
通讯作者：
Mack, Michelle C.
中科院分区：
文献类型：
--
作者：
Johnstone, Jill F.;Hollingsworth, Teresa N.;Mack, Michelle C.
预测植物群落对不断变化的环境条件的反应是预测和减轻全球变化影响的一个关键因素。干扰可以在这些动态中发挥重要作用，通过启动次级演替的周期，并为长寿生物体的社区创造机会，以替代配置进行重组。本研究使用的环境条件，林分结构，并在阿拉斯加的一个极端火灾年的干扰，以研究这些因素如何影响的演替轨迹在北方森林为主的黑云杉的规模变化。由于阿拉斯加内陆的火灾间隔通常太短，不允许接力继承，火灾后招募的幼苗的初始队列在很大程度上决定了未来的冠层组成。因此，在一个动态稳定的景观，火灾后的树苗组成应该类似于火灾前的森林站，火灾后的树木组成的净变化不大。从90个被烧毁的立场幼苗招聘数据表明，火灾后建立的黑云杉与环境条件密切相关，是最高的网站是潮湿的，有高密度的火灾前云杉。虽然落叶阔叶树没有从大多数火灾前的立场，落叶树木从种子在许多网站和最丰富的网站，火灾燃烧严重，消耗大部分的表面有机层。火灾前和火灾后的树木组成的比较表明，预期的轨迹黑云杉自我更换是典型的，只有在潮湿的网站，燃烧低火灾的严重程度。在严重烧毁的网站，落叶树木占主导地位的火灾后树苗社区，这表明这些网站将遵循替代，落叶为主的轨迹的继承。随着气候变暖，北方森林火灾的严重程度增加，可能会催化向越来越多的落叶主导景观的转变，大大改变北方森林这一部分的景观动态和生态系统服务。
Predicting plant community responses to changing environmental conditions is a key element of forecasting and mitigating the effects of global change. Disturbance can play an important role in these dynamics, by initiating cycles of secondary succession and generating opportunities for communities of long-lived organisms to reorganize in alternative configurations. This study used landscape-scale variations in environmental conditions, stand structure, and disturbance from an extreme fire year in Alaska to examine how these factors affected successional trajectories in boreal forests dominated by black spruce. Because fire intervals in interior Alaska are typically too short to allow relay succession, the initial cohorts of seedlings that recruit after fire largely determine future canopy composition. Consequently, in a dynamically stable landscape, postfire tree seedling composition should resemble that of the prefire forest stands, with little net change in tree composition after fire. Seedling recruitment data from 90 burned stands indicated that postfire establishment of black spruce was strongly linked to environmental conditions and was highest at sites that were moist and had high densities of prefire spruce. Although deciduous broadleaf trees were absent from most prefire stands, deciduous trees recruited from seed at many sites and were most abundant at sites where the fires burned severely, consuming much of the surface organic layer. Comparison of pre- and postfire tree composition in the burned stands indicated that the expected trajectory of black spruce self-replacement was typical only at moist sites that burned with low fire severity. At severely burned sites, deciduous trees dominated the postfire tree seedling community, suggesting these sites will follow alternative, deciduous-dominated trajectories of succession. Increases in the severity of boreal fires with climate warming may catalyze shifts to an increasingly deciduous-dominated landscape, substantially altering landscape dynamics and ecosystem services in this part of the boreal forest.