Assessing Pathways of Climate Change Effects in SpaDES: An Application to Boreal Landbirds of Northwest Territories Canada

Abstract

Distributions of landbirds in Canadian northern forests are expected to be affected by climate change, but it remains unclear which pathways are responsible for projected climate effects. Determining whether climate change acts indirectly through changing fire regimes and/or vegetation dynamics, or directly through changes in climatic suitability may allow land managers to address negative trajectories via forest management. We used SpaDES, a novel toolkit built in R that facilitates the implementation of simulation models from different areas of knowledge to develop a simulation experiment for a study area comprising 50 million ha in the Northwest Territories, Canada. Our factorial experiment was designed to contrast climate effects pathways on 64 landbird species using climate-sensitive and non-climate sensitive models for tree growth and mortality, wildfire, and landbirds. Climate-change effects were predicted to increase suitable habitat for 73% of species, resulting in average net gain of 7.49 million ha across species. We observed higher species turnover in the northeastern, south-central (species loss), and western regions (species gain). Importantly, we found that most of the predicted differences in net area of occupancy across models were attributed to direct climate effects rather than simulated vegetation change, despite a similar relative importance of vegetation and climate variables in landbird models. Even with close to a doubling of annual area burned by 2100, and a 600 kg/ha increase in aboveground tree biomass predicted in this region, differences in landbird net occupancy across models attributed to climate-driven forest growth were very small, likely resulting from differences in the pace of vegetation and climate changes, or vegetation lags. The effect of vegetation lags (i.e., differences from climatic equilibrium) varied across species, resulting in a wide range of changes in landbird distribution, and consequently predicted occupancy, due to climate effects. These findings suggest that hybrid approaches using statistical models and landscape simulation tools could improve wildlife forecasts when future uncoupling of vegetation and climate is anticipated. This study lays some of the methodological groundwork for ecological adaptive management using the new platform SpaDES, which allows for iterative forecasting, mixing of modeling paradigms, and tightening connections between data, parameterization, and simulation.

Effects of global change on animal biodiversity in boreal forest landscape: an assemblage dissimilarity analysis

“…Immediate effects that were expressed through the change in climate conditions apparently strongly modified the assemblage composition more than did the lagged effects. In fact, the difference in magnitude between the two effects was due to the mismatch that was generated by rapid climate variation compared to slower vegetation change (Wu et al, 2015; Stralberg et al, 2015; Micheletti et al, 2021). Regionally, both climate effects acted on the decrease in number of winner species and on the increase in assemblage dissimilarity by ordered comparison of RCP 4.5 through RCP 8.5 to the baseline scenario.…”

“…In addition, we found that indirect effects, through climate-induced changes in habitat only, were smaller in magnitude compared to the combined indirect and direct effects for both taxa. This conclusion can be explained by the mismatch between the climate and the biota (Stralberg et al, 2015; Wu et al, 2015; Micheletti et al, 2021). For example, Brice et al (2020) noted that under climate change the variation in climate conditions would be faster than the capacity of tree species to migrate, which creates a gap between the climatic niche and the observed distribution of species.…”

“…We analyze the effects of climate change in two ways: (1) indirectly, i.e., habitat-based climate change (Wisz et al, 2013;Boulanger and Puigdevall, 2021;Micheletti et al, 2021) and ( 2) by combining indirect and direct effects, i.e., those stemming from climate variables per se (Thuiller et al, 2018). This distinction is made to quantify the effects of those pathways on biodiversity, which requires different conservation actions (Micheletti et al, 2021). We aimed to project how species community composition would change following anthropogenic and natural disturbances that are based upon two climate-induced pathways: immediate and lagged.…”

“…The indirect climate effects alter the vegetation and wildfire, which cause changes in habitat. Impacts could be also direct characterized by immediate effects that are exerted by climate and meteorological conditions that are not related to vegetation (Micheletti et al, 2021). The two climate-induced effects must be seen as complementary when studying their implications on ecosystem functionality.…”

“…Climate change might act on biodiversity in different ways ((Wisz et al, 2013; Boulanger and Puigdevall,2021; Micheletti et al, 2021)). The indirect climate effects alter the vegetation and wildfire, which cause changes in habitat.…”