Because fire regimes (i.e., the size, frequency, and severity of fires) impact tree species with varied life-history attributes differently, post-fire forest dynamics also depend on tree distributions and abundances. Fire is the major disturbance agent in many forest ecosystems. For example, fires can remove resident trees that could otherwise persist in novel climate conditions no longer suitable for seedling establishment, and thus increase the replacement of resident tree species by providing establishment opportunities for migrating tree species (Turner, 2010, Boulanger et al., 2019, Brice et al., 2020). Thus, colonization and extinction events in response to environmental changes are often delayed (Loehle, 2000, Boulangeat et al., 2012, Bertrand et al., 2016), especially when facing competition from the persistent resident tree species (Davis and Shaw, 2001, Mcgill, 2012, Zhu et al., 2012, Bouchard et al., 2019).ĭisturbances can catalyze climate-induced shifts in species composition and distribution. Indeed, trees are long-lived species, have limited dispersal capacity, and need time (10–40 years) to reach reproductive maturity. Increasing evidence suggests that tree species may fail to keep pace with the rate of climate change due to demographic constraints, resulting in migration lags (Woodall et al., 2013, Sittaro et al., 2017, Wang et al., 2018, Liang et al., 2018, Román-Palacios and Wiens, 2020). Global warming has led to tree species migrating toward higher latitudes and elevations (Parmesan and Yohe, 2003, Chen et al., 2011), resulting in shifts in species composition and distribution in local systems. The results can help policymakers and forest managers determine tradeoffs among strategies to mitigate or adapt to climate change under altered fire regimes. Therefore, species composition shifts were faster following frequent, small fires than infrequent, large fires. Frequent, small fires resulted in 13% and 23% higher increases in pioneer and temperate species respectively, relative to infrequent, large fires. Results showed fire-catalyzed, climate-induced transitions from boreal to pioneer and temperate forest communities. We designed two fire scenarios (frequent, small fires and infrequent, large fires) to represent different fire regimes in terms of fire size. We simulated fire regimes using the LANDIS PRO fire module. Here we investigated the effects of future fire-regime variability on the boreal-temperate ecotone of northeastern China under climate change using a coupled forest dynamic model (LANDIS PRO) and ecosystem process model (LINKAGES). Large and small fires create and regulate distinct burn patterns, which may influence tree-species responses and post-fire successional trajectories. Future fire regimes could be characterized by many small fires or a few large fires. However, the role of fire size and its interactions with tree species with varied life-history attributes in driving climate-induced shifts is not understood. Wildfire can kill resident trees, and thus provide establishment opportunities for migrating tree species. Climate change is expected to increase fire activity, which has the potential to accelerate climate-induced shifts in species composition and distribution in the boreal-temperate ecotone.
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