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Populus tremuloides seedling establishment: An underexplored vector for forest type conversion after multiple disturbances

Author(s): Nathan S. Gill, Florencia Sangermano, Brian Buma, Dominik Kulakowski
Year Published: 2017

Ecosystem resilience to climate change is contingent on post-disturbance plant regeneration. Sparse gymnosperm regeneration has been documented in subalpine forests following recent wildfires and compounded disturbances, both of which are increasing. In the US Intermountain West, this may cause a shift to non-forest in some areas, but other forests may demonstrate adaptive resilience through increased quaking aspen (Populus tremuloides Michx.) dominance. However, this potential depends on ill-defined constraints of aspen sexual regeneration under current climate. We created an ensemble of species distribution models for aspen seedling distribution following severe wildfire to define constraints on establishment. We recorded P. tremuloides seedling locations across a post-fire, post-blowdown landscape. We used 3 algorithms (Mahalanobis Typicalities, Multilayer Perceptron Artificial Neural Network, and MaxEnt) to create spatial distribution models for aspen seedlings and to define constraints. Each model performed with high accuracy and was incorporated into an ensemble model, which performed with the highest overall accuracy of all the models. Populus tremuloides seedling distribution is constrained primarily by proximity to unburned aspen forest and annual temperature ranges, and secondarily by light availability, summer precipitation, and fire severity. Based on model predictions and validation data, P. tremuloides seedling regeneration is viable throughout 54% of the post-fire landscape, 97% of which was previously conifer-dominated. Aspen are less susceptible to many climatically-sensitive disturbances (e.g. fire, beetle outbreak, wind disturbance), thus, aspen expansion represents an important adaptation to climate change. Continued aspen expansion into post-disturbance landscapes through sexual reproduction at the level suggested by these results would represent an important adaptation to climate change and would confer adaptive forest resilience by maintaining forest cover, but would also alter future disturbance regimes, biodiversity, and ecosystem services. 1. Introduction Ecosystem function and resilience during a time of directional climate change are contingent on regeneration of plant communities. Plant communities are altered through disturbance and regeneration, processes that are in turn influenced by existing community structure and composition (Sousa, 1984; White and Pickett, 1985; Turner, 2010). The frequency and severity of fire, blowdown, and insect outbreaks (among other disturbances) are increasing in many temperate ecosystems due to climate change (Dale et al., 2001; Westerling et al., 2006; Allen, 2007; Evangelista et al., 2011; Siedl and Rammer, 2016), selecting for communities

Citation: Gilla NS, Sangermanoa F, Bumad B, Kulakowskia D. 2017. Populus tremuloides seedling establishment: An underexplored vector for forest type conversion after multiple disturbances. Forest Ecology and Management 404, p. 156-164. http://dx.doi.org/10.1016/j.foreco.2017.08.008
Topic(s): Fire Ecology, Resilience, Fire Effects, Ecological - Second Order, Vegetation, Recovery after fire
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
NRFSN number: 16697
Record updated: May 24, 2018