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We evaluated the effects of hydrologic setting on the growth sensitivity of two conifer species to recent atmospheric climatic variability and change in a region experiencing a warming (annual Tmin: 0.07 °C/decade) and wetting trend (total annual PPT 9.8 mm/decade; 1911–2012). Tree-ring chronologies were constructed for the boreal disjunct balsam fir ( Abies balsamea ; n = 72; 1916–2012) and range-centered eastern white pine ( Pinus strobus ; n = 84; 1707–2012) at three forested, groundwater-fed wetlands (fens) and their neighboring uplands in New York State, USA. Soil temperature monitoring in 2010 confirmed that upland soils were significantly warmer than fen soils during the spring and summer months (11.5–13.9 °C; p < 0.05). Climate-growth relationships for Abies balsamea varied substantially based on hydrologic setting and season. Compared with a remnant upland population that showed an increasingly negative sensitivity to warm summer temperatures over time A. balsamea positioned in fens were less sensitive to recent warming. While atmospheric climate-growth relationships were more consistent across hydrologic settings for Pinus strobus , we still observed qualitatively different responses to atmospheric climate variables between fen and upland populations. Overall, the climate-growth relationships identified in this study suggest that relative to trees growing in mesic upland soils, growth sensitivity to warm ambient climate in summer is ameliorated by groundwater inputs. The climate modulating effects of groundwater on tree-growth observed in our study suggests that for temperate and boreal regions where fens are abundant further consideration of groundwater influences on climate-growth relationships is warranted. [ABSTRACT FROM AUTHOR]

Sugar maple ( Acer saccharum ) is among the most ecologically and economically important tree species in North America, and its growth and regeneration is often the focus of silvicultural practices in northern hardwood forests. A key stressor for sugar maple (SM) is acid rain, which depletes base cations from poorly-buffered forest soils and has been associated with much lower SM vigor, growth, and recruitment. However, the potential interactions between forest management and soil acidification – and their implications for the sustainability of SM and its economic and cultural benefits – have not been investigated. In this study, we simulated the development of 50 extant SM stands in the western Adirondack region of NY (USA) for 100 years under different soil chemical conditions and silvicultural prescriptions. We found that interactions between management prescription and soil base saturation will strongly shape the ability to maintain SM in managed forests. Below 12% base saturation, SM did not regenerate sufficiently after harvest and was replaced mainly by red maple ( Acer rubrum ) and American beech ( Fagus grandifolia ). Loss of SM on acid-impaired sites was predicted regardless of whether the shelterwood or diameter-limit prescriptions were used. On soils with sufficient base saturation, models predicted that SM will regenerate after harvest and be sustained for future rotations. We then estimated how these different post-harvest outcomes, mediated by acid impairment of forest soils, would affect the potential monetary value of ecosystem services provided by SM forests. Model simulations indicated that a management strategy focused on syrup production – although not feasible across the vast areas where acid impairment has occurred – may generate the greatest economic return. Although pollution from acid rain is declining, its long-term legacy in forest soils will shape future options for sustainable forestry and ecosystem stewardship in the northern hardwood forests of North America. [ABSTRACT FROM AUTHOR]

In this study, we combined policy analysis with landscape change modeling to simulate outcomes of alternative forest conservation instruments proposed by opposing policy coalitions. In 1992, concern over rapid land conversion to timber plantations ( Pinus radiata and Eucalyptus spp.) in Chile gave rise to a protracted policy process resulting in the 2008 Native Forest Law (NFL), which subsidizes reforestation and management with native forest. To date, however, NFL has had little impact on native forest conservation. To understand how the policy process that created the NFL shaped its outcomes, we employed the Dyna-CLUE modeling approach to simulate land use changes in south-central Chile from 1993 to 2007, based on 3 scenarios: (1) enactment of NFL in 1993 when the law was originally debated, and the different configurations of subsidies and regulations proposed in the NFL policy debate by (2) the industrial forestry coalition and (3) the forest conservation coalition. We observed no major difference in native forest loss between simulated outcomes of the industry-advocated policy and the actual NFL legislation. The conservation coalition’s policy scenario increased native forest area, primarily in shrub steppe areas, but also via conversion of pine plantations if incentive payments were large enough. However, NFL payments are inadequate to make native forest management a viable economic land use alternative to industrial pine plantations, which are also subsidized in Chile. Gains in native forest cover occurred mostly on lands under ancestral indigenous claims (unrelated to the discussion of the NFL). We conclude that the NFL, even if enacted in 1993, would have been ineffective in preventing native forest loss, because tree plantations are more profitable and NFL regulations were weakened by the industrial coalition that opposed—and strongly shaped—the final legislation. Effective incentives for protecting early-successional forests and shrublands are needed to mitigate further losses and foster recovery of Chile’s native forests. [ABSTRACT FROM AUTHOR]