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Understanding the interaction between land ownership, climate conditions, and harvesting strategies is essential for promoting long-term tree species diversity and ensuring sustainable forest ecosystems. This study uses forest inventory, climate, soil and socio-economic data to examine how land ownership types, climate gradients, and soil characteristics influence tree species diversity in Maine, USA. Our results suggest that southern Maine, characterized by milder climate conditions, supports greater tree species diversity compared to colder, boreal-dominated northern regions. Family forest owners, predominantly situated in southern Maine, consistently exhibited the highest diversity, reflecting less intensive management practices. Conversely, industrial and institutional forests concentrated in northern Maine demonstrated lower species diversity, likely driven by uniform, economically driven management practices. Incorporating soil attributes significantly improved the explanatory power of our diversity models. Harvesting activities showed varied impacts on biodiversity. Harvesting effects varied among ownership types: while overall biodiversity changes were minor post-harvest, industrial forests in northern Maine experienced a sustained 7 % decline in species diversity approximately ten years after harvesting, suggesting the need for continued long-term monitoring. Consequently, it is essential to develop management strategies at both the stand- and landscape-levels that effectively balance economic objectives while mitigating long-term biodiversity losses. 

This is an updated version of the original TREEMAP 2016 raster and the associated files for CONUS. Additions to the TREEMAP 2016 raster attribute table are the SDI, SDImax and RD estimates. 

Tree taper has been of interest for over a century, yet questions remain regarding the effects of silvicultural treatments and forest health on recoverable volume. This work utilizes data from Douglas-fir ( Pseudotsuga menziesii (Mirb.)) ( n = 608) and red alder ( Alnus rubra (Bong.)) ( n = 495) trees to assess the influences of fertilization, pruning, thinning, regeneration origin, and defoliation caused by Swiss Needle Cast (SNC; Nothophaeocryptopus gaeumannii), on stem taper in the Pacific Northwest. The Kozak (2004; For. Chor. 80: 507–515) variable-exponent equation was used to test the addition of treatment and crown variables as the model is widely regarded for its flexibility in application. Using a mixed effects framework, results reveal that thinning of Douglas-fir can result in a 3.5% increase in upper stem diameter inside bark, while pruning may lead to a 4.1% decrease. SNC-induced defoliation of Douglas-fir reduced mean diameter above-breast height by 11.5%. Total volume of artificially regenerated red alder was 16% greater than naturally regenerated stems. Overall, thinning of healthy Douglas-fir and planting red alder may increase recoverable volume and C captured in long-term timber products in the region, and the inclusion of crown variables can increase the predictive power of taper estimates for some species. 

Climate zones play a significant role in shaping the forest ecosystems located within them by influencing multiple ecological processes, including growth, disturbances, and species interactions. Therefore, delineation of current and future climate zones is essential to establish a framework for understanding and predicting shifts in forest ecosystems. In this study, we developed and applied an efficient approach to delineate regional climate zones in the northeastern United States and maritime Canada, aiming to characterize potential shifts in climate zones and discuss associated changes in forest ecosystems. The approach comprised five steps: climate data dimensionality reduction, sampling scenario design, cluster generation, climate zone delineation, and zone shift prediction. The climate zones in the study area were delineated into four different orders, with increasing subzone resolutions of 3, 9, 15, and 21. Furthermore, projected climate normals under Shared Socioeconomic Pathways 4.5 and 8.5 scenarios were used to predict the shifts in climate zones until 2100. Our findings indicate that climate zones characterized by higher temperatures and lower precipitation are expected to become more prevalent, potentially becoming the dominant climate condition across the entire region. These changes are likely to alter regional forest composition, structure, and productivity. In short, such shifts in climate underscore the significant impact of environmental change on forest ecosystem dynamics and carbon sequestration potential. 

Eastern spruce budworm (Choristoneura fumiferana Clem; SBW) is a native forest pest that can severely damage spruce-fir forests in Maine. Monitoring SBW defoliation and populations is important to ensure forest managers make timely decisions regarding forest management. This research brief presents the results of a survey of Maine’s large forest owners and managers. Our findings indicate a need for clear policies and collaborations between forest organizations to prepare for a SBW outbreak. While many forest organizations use satellite imagery, personnel capacity and lack of knowledge are barriers to using remote sensing. We recommend strengthening forest health programs by hiring a remote sensing specialist and increasing knowledge and skills around remote sensing in Maine’s forest sector.