Search

Based on the Web of Science Core Collection databases from 1990 to 2018, a scientometric analysis of 1,284 academic works related to forest carbon sequestration is carried out to characterize the intellectual landscape by identifying and revealing the basic characteristics, research power, intellectual base and research hotspots in this field. The results of this work show that: ① the number of publications in forest carbon sequestration research has increased rapidly and the research in this field is in its "growth stage"; Forest Ecology and Management is the most productive journal and Forestry is the most popular subject category; ② the most productive authors and institutions in this subject area are in the USA, China and Canada, with the Chinese Academy of Sciences being the key institution performing such research; ③ in the sample, 9 papers have played a key role in the evolution of the field and laid a solid foundation for future research; ④ Keyword clustering analysis showed that the main research topics in the domain of forest carbon sequestration could be summarized as: (a) temperate forest; (b) forest management; (c) uncertainty analysis; (d) forest floor; (e) REDD; (f) net primary productivity. Meanwhile, keyword bursts analysis showed that the new research hotspots or research frontiers mainly concentrated on changes in the carbon storage and carbon sequestration potential of secondary forests and tropical forests, plant litter carbon storage and contribution to total ecosystem carbon storage, and new national forest inventories (NFIs). Through in-depth analysis of forest carbon sequestration research, this paper provides a better understanding of development trends that have emerged in this field over the past 29 years, which can also offer reference for future research. [ABSTRACT FROM AUTHOR]

Clear-cutting is one of the most widespread forestry practices used in boreal forests. Clear-cutting of boreal forests in late successional stages could trigger reversion of successional trajectories back toward forests of earlier stages. Such successional setbacks could generate sustainability issues by prolonging the expected time to compositional recovery after clear-cutting. This could lead to overestimation of allowable cuts of economically important late-successional species if the occurrence of successional setbacks remains unassessed. Our objective was to assess whether clear-cutting without additional regeneration treatments has triggered successional setbacks. We studied post-clearcut successional trajectories by using forest inventory data in post-clearcut stands, in light of conceptual successional dynamics models. These data covered the actively managed boreal forest region of Quebec, eastern Canada, which is classified into two ecological regions, themselves subdivided into eastern (cool–wet) and western (warm–dry) sub regions. Clear-cutting triggered successional setbacks in half of these regions. Such setbacks could prolong, by at least an additional century, the expected time to compositional recovery after clear-cutting. To prevent the overestimation of allowable cuts of economically important late-successional species, foresters could monitor post-clear-cut successional trajectories to assess whether setbacks were triggered. Post-clear-cut successional setbacks occurred in the two western ecological regions where climatic conditions are warmer and drier than in their eastern counterpart where no setbacks occurred. Hence, sustainability issues brought on by successional setbacks may be exacerbated by climate change. Finally, furthering our understanding of the transformation of successional dynamics by anthropogenic disturbances will be essential to insure sustainable forestry practices. [ABSTRACT FROM AUTHOR]

• Multiple succession pathways possible following harvesting in Acadian Forest Region. • Early succession pathways were driven by numerous succession mechanisms. • Landscape-level climate variability had strongest influence on early stand succession. • Pre- and post-harvest overstorey composition strongly influenced stand succession. • Climate change will influence forest regeneration by inhibiting cold adapted species. • Forest managers must consider climate change in future management planning. Predicting forest succession is not a trivial pursuit and has remained a central challenge for scientists and foresters for well over a century. While thousands of papers have been published on the topic, contributing to a plethora of concepts and terminologies, there remains confusion over causal mechanisms, inhibiting our ability to adopt many lessons learned to sustainable forest management. Based on an emerging conceptual model of forest succession, presented here as the "Succession Triangle", we sought to explore the relative importance of mechanisms hypothesized to drive succession following commercial harvesting across a wide landscape in the Acadian Forest Region of eastern Canada. Using machine learning techniques and repeatedly measured forest stand inventory data, including 19,332 forest stands measured over a ≈30 year period, we uncovered dominant early succession pathways and investigated key mechanisms driving these pathways. Overall, our results show stands may follow multiple succession pathways following harvesting, including early dominance by so-called "late-succession" species (e.g., black spruce and sugar maple), depending on causal mechanisms. More specifically, mechanisms related to the state of the environment (primarily climate) and differential species availability (mainly pre- and post-harvest overstorey composition) had the strongest control over early succession. The strong influence of pre-harvest composition on early succession supports the 'direct regeneration' hypothesis; while the importance of post-harvest overstorey composition suggests the use of partial-cutting as a means of regenerating shade-tolerant species (e.g., sugar maple and red spruce). Site conditions (i.e., slope and drainage) influenced the direction of succession, but landscape-level variation in climate had the overall strongest effect, with colder, more moist climates promoting regeneration of balsam fir, while warmer, dryer climates encouraged shade-intolerant, broadleaf species (birches, red maple and poplars), especially following clear-cutting. Given the strong influence of climate, we used our fitted model to predict the impact of late 21st century climate change on early succession using the "business-as-usual" RCP 8.5 radiative forcing scenario. Our results indicate climate change is likely to increase the regeneration of shade-intolerant, broadleaf tree species (e.g., red maple and poplars) across the landscape at the loss of cold-adapted balsam fir, supporting the hypothesis that young, post-harvest stands are vulnerable to climate-driven shifts in composition as postulated by 'resilience theory', and corroborating previous simulation studies that predict rapid 21st century climate warming will lead to 'deborealization' of Canada's Acadian Forest Region. [ABSTRACT FROM AUTHOR]

Aim: To evaluate current and future dynamics of 25 tree species spanning United States and Canada. Location: United States and Canada. Methods: We combine, for the first time, the species compositions from relative importance derived from the USA's Forest Inventory Analysis (FIA) with gridded estimates based on Canada's National Forest Inventory (NFI‐kNN))‐based photo plot data to evaluate future habitats and colonization potentials for 25 tree species. Using 21 climatic variables under RCP 4.5 and RCP 8.5, we model climatic habitat suitability (HQ) within a consensus‐based multimodel ensemble regression approach. A migration model is used to assess colonization likelihoods (CL) for ~100 years and combined with HQ to evaluate the various combinations of HQ + CL outcomes for the 25 species. Results: At a continental scale, many species in the conterminous United States lose suitable climatic habitat (especially under RCP 8.5) while Canada and USA's Alaska gain climate habitat. For most species, even under optimistic migration rates, only a small portion of overall future suitable habitat is projected to be naturally colonized in ~100 years, although considerable variation exists among species. Main conclusions: For the species examined here, habitat losses were primarily experienced along southern range limits, while habitat gains were associated with northern range limits (especially under RCP 8.5). However, for many species, southern range limits are projected to remain relatively intact, albeit with reduced habitat quality. Our models predict that only a small portion of the climatic habitat generated by climate change will be colonized naturally by the end of the current century—even with optimistic tree migration rates. However, considerable variation among species points to the need for significant management efforts, including assisted migration, for economic or ecological reasons. Our work highlights the need to employ range‐wide data, evaluate colonization potentials and enhance cross‐border collaborations. [ABSTRACT FROM AUTHOR]

Currently, there is no consensus regarding the way that changes in climate will affect boreal forest growth, where warming is occurring faster than in other biomes. Some studies suggest negative effects due to drought‐induced stresses, while others provide evidence of increased growth rates due to a longer growing season. Studies focusing on the effects of environmental conditions on growth–climate relationships are usually limited to small sampling areas that do not encompass the full range of environmental conditions; therefore, they only provide a limited understanding of the processes at play. Here, we studied how environmental conditions and ontogeny modulated growth trends and growth–climate relationships of black spruce (Picea mariana) and jack pine (Pinus banksiana) using an extensive dataset from a forest inventory network. We quantified the long‐term growth trends at the stand scale, based on analysis of the absolutely dated ring‐width measurements of 2,266 trees. We assessed the relationship between annual growth rates and seasonal climate variables and evaluated the effects of various explanatory variables on long‐term growth trends and growth–climate relationships. Both growth trends and growth–climate relationships were species‐specific and spatially heterogeneous. While the growth of jack pine barely increased during the study period, we observed a growth decline for black spruce which was more pronounced for older stands. This decline was likely due to a negative balance between direct growth gains induced by improved photosynthesis during hotter‐than‐average growing conditions in early summers and the loss of growth occurring the following year due to the indirect effects of late‐summer heat waves on accumulation of carbon reserves. For stands at the high end of our elevational gradient, frost damage during milder‐than‐average springs could act as an additional growth stressor. Competition and soil conditions also modified climate sensitivity, which suggests that effects of climate change will be highly heterogeneous across the boreal biome. [ABSTRACT FROM AUTHOR]