Climate and interrelated tree regeneration drivers in mixed temperate–boreal forests

• Published in: Landscape ecology Vol. 28; no. 1; pp. 149 - 159
• Main Authors: Fisichelli, Nicholas A., Frelich, Lee E., Reich, Peter B.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.01.2013; Springer; Springer Nature B.V
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Biomedical and Life Sciences; Biota; Boreal forests; Climate change; Ecology; Environmental Management; Forestry; Forests; Fundamental and applied biological sciences. Psychology; General aspects; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Landscape Ecology; Landscape/Regional and Urban Planning; Life Sciences; Nature Conservation; Observational studies; Plant species; Research Article; Sustainable Development; Trends; Understory; Variables; United States > US; Great Lakes area; North America; USA; North America, Great Lakes; Ecotone; Mixed temperate–boreal forest; Overstory neighborhood effects; Tree regeneration; Variation partitioning; Boreal forest; Regeneration; Climate; Mixed temperate-boreal forest; Environmental factor; Tree; Temperate forests
• ISSN: 0921-2973; 1572-9761
• DOI: 10.1007/s10980-012-9827-z

Forest compositional shifts in response to climate change are likely to be initially detectable in the understory tree regeneration layer near species range limits. Because many factors in addition to climate, such as seedbed and soil characteristics, overstory composition, and interactions with other understory biota, drive tree regeneration trends, a thorough understanding of the relative importance of all variables as well as their interrelationships is needed. The range limits of several widespread temperate and boreal tree species overlap in the upper Great Lakes region, USA, thus facilitating an observational study over relatively short regional climate gradients. We used redundancy analysis and variation partitioning to quantify the unique, shared, and total explanatory power of four sets of explanatory variables. The results showed that all four variable sets (climate 9.5 %, understory environment 13.7 %, overstory composition 26.3 %, and understory biota 13.8 %) were significantly associated with tree regeneration compositional variation in mixed temperate–boreal forests. Partitioning also revealed high confounded or shared explanatory power, but also that each set contributed significant unique explanatory power not shared with other sets. Spatial patterning in regeneration composition was strongly related to broad scale environmental patterns, while the large majority of unexplained variation did not have a detectable spatial structure, suggesting factors with local scale variability. Future forest shifts across the landscape will depend not only on the rate and direction of climate change but also on how the strengths and interrelationships among other explanatory variables, such as overstory composition and understory biota, shift with a changing climate.