by Claire Morin | 10 April 2020
Published in Front. Biogeogr. 9(4): e33282. https://doi.org/10.21425/F59433282
Climate change already affects species in many ecosystems worldwide. Since climate is an important component of a species’ ecological niche, up-to-date information about climatic niches is needed to model future species distributions in a context of climate change. The eastern red-backed salamander (Plethodon cinereus) is a wide-ranging woodland species and one of the most abundant verte-brates in northeastern North America. Though salamanders contrib-ute to several forest ecosystem functions, little is known about their climatic niche and future distribution. Using a dataset of 400,090 observations from 8302 localities in 5 Canadian provinces and 22 American states, we determined the current climatic niche of P. cinereus and predicted how the species’ distribution could shift in a context of climate change, especially in the northern part of its range. We also aimed to document factors that could affect the species’ distribution. We show that P. cinereus can live in various geographic and climatic conditions and tolerate a wide range of seasonal temperatures. The species’ current potential and future (until 2061–2080) distributions show a gap of up to 400 km with the northern limit of its current observed distribution. Assuming a mean colonization rate of approximately 100 m per year, we calculated that P. cinereus would need about 4000 years to reach the northern limit of the future distribution range modeled for the 2061–2080 period. The climate-modeled future distribution suggests that the presence of P. cinereus could decrease in the south and increase in the north. This, combined with the potential presence of habitats that are unsuitable for the species’ colonization in the north and with interspecific inter-actions in the south, could induce a contraction of the species’ range. Regardless of climate warming, the physical environment and natural and anthropic disturbances could also limit the species’ northern post-glaciation migration.
by Marie-Claude Boileau | 10 April 2020
Published in Physiologia Plantarum 165(1): 29-38. https://doi.org/doi:10.1111/ppl.12735
Black spruce (Picea mariana [Mill.] BSP) is a boreal tree species characterized by the formation of an adventitious root system. Unlike initial roots from seed germination, adventitious roots gradually appear above the root collar, until they constitute most of mature black spruce root system. Little is known about the physiological role they play and their influence on tree growth relative to initial roots. We hypothesized that adventitious roots present an advantage over initial roots in acquiring water and nutrients. To test this hypothesis, the absorptive capacities of the two root systems were explored in a controlled environment during one growing season. Black spruce seedlings were placed in a double-pot system allowing irrigation (25 and 100% water container capacity) and fertilization (with or without fertilizer) inputs independent to initial and adventitious roots. After 14 weeks, growth parameters (height, diameter, biomass), physiology (net photosynthetic rate, stomatal conductance, shoot water potential) and nutrient content (N, P, K, Ca and Mg foliar content) were compared. Most measured parameters showed no difference for the same treatment on adventitious or initial roots, except for root biomass. Indeed, fertilized black spruce seedlings invested heavily in adventitious root production, twice as much as initial roots. This was also the case when adventitious roots alone were irrigated, while seedlings with adventitious roots subjected to low irrigation produced initial root biomass equivalent to that of adventitious roots. We conclude that black spruce seedlings perform equally well through adventitious and initial roots, but if resources are abundant, they strongly promote development of adventitious roots.
by Claire Morin | 10 April 2020
Published in Forest ecology and management 442: 96-104. doi: 10.1016/j.foreco.2019.03.040
From a forest management stand point, it is crucial to know which ecological processes are most likely to drive changes in tree species distributions and abundance under warming climate conditions. In this study, we simulated forest dynamics in a 703,580 km2 territory that straddles the boreal and temperate broadleaved forest biomes in the province of Québec (Canada), under a RCP 8.5 climate change scenario. The objective was to evaluate how future forest composition is sensitive to variation in four potential drivers: fire regimes, harvesting regimes, the capacity of tree species to persist under warmer climate conditions, and species capabilities for long-distance colonization. The results indicate that forest composition in 2100 is most sensitive to variation in the parameters controlling species persistence when conditions become warmer or dryer than the conditions found in their current range. Concretely, this points to avenues of research to improve the accuracy of our predictions regarding the impacts of climate change on forest composition. For instance, we should further investigate the underlying ecological (competition) or physiological (drought stresses) processes that influence tree species persistence at the receding edge of their current distributions.
by Audrey Verreault | 10 April 2020
Published in Landscape Ecology 34: 159-174
Context: Forest landscapes at the boreal–temperate ecotone have been extensively altered. Reducing the gap between current and presettlement forest conditions through ecosystem-based forest management (EBFM) is thought to enhance ecological integrity. However, climate change may interfere with this goal and make these targets unrealistic.
Objectives: We evaluated the impacts of climate change on the ability of EBFM to reduce discrepancies between current and presettlement forest conditions in southeastern Canada.
Methods: We used early-land-survey data as well as projections from a forest landscape model (LANDISII) under four climate change scenarios and four management scenarios to evaluate future discrepancies between presettlement forest conditions and future forest landscapes.
Results: By triggering swift declines in most latesuccession boreal conifer species biomass, climate change would greatly reduce the ability of forest management to reduce the gap with presettlement forest composition, especially under severe anthropogenic climate forcing. Scenarios assuming extensive clearcutting also favor aggressive competitor species that have already increased with high historical harvest levels (e.g., poplars, maples).
Conclusions: EBFM would still be the ‘‘less bad’’ forest harvesting strategy in order to mitigate composition discrepancies with the presettlement forests, though it is likely to fail under severe climate forcing. In this latter case, one might thus question the relevancy of using presettlement forest composition as a target for restoring degraded forest landscapes. As such, we advocate that managers should relax the centrality of the reference condition and focus on functional restoration rather than aiming at reducing the gaps with presettlement forest composition per se.
by Audrey Verreault | 10 April 2020
Published in Nature Communications 10: 1265. doi:10.1038/s41467-019-09265-z
Predicting future ecosystem dynamics depends critically on an improved understanding of how disturbances and climate change have driven long-term ecological changes in the past. Here we assembled a dataset of >100,000 tree species lists from the 19th century across a broad region (>130,000km2) in temperate eastern Canada, as well as recent forest inventories, to test the effects of changes in anthropogenic disturbance, temperature and moisture on forest dynamics. We evaluate changes in forest composition using four indices quantifying the affinities of co-occurring tree species with temperature, drought, light and disturbance. Land-use driven shifts favouring more disturbance-adapted tree species are far stronger than any effects ascribable to climate change, although the responses of species to disturbance are correlated with their expected responses to climate change. As such, anthropogenic and natural disturbances are expected to have large direct effects on forests and also indirect effects via altered responses to future climate change.
