Restoration

View brief.

In a 16-year study, Rocky Mountain Research Station Research Ecologist Sharon Hood and her colleagues assessed three types of radial thinning to determine whether they would improve the growth and survival of sugar pines, a species of white pine, in southwest Oregon on sites located in the Umpqua National Forest and Bureau of Land Management Roseburg District. In addition to evaluating a control group, the researchers examined three kinds of treatments in which trees and shrubs were removed around sugar pines to 3 m (10 ft); 7.6 m (25 ft), while retaining large trees with diameters greater than 64 cm (2 ft); or 7.6 m (25 ft). Though some of the radial thinning strategies seemed promising at the 9-year mark, the radial thinning did not improve sugar pine survival at the end of the study (year 16), as compared to the control group. The extended (7.6 m) radial thinning with complete tree removal  treatment did increase tree growth for sugar pine that survived, but the level of tree mortality was similar regardless of whether trees had radial thinning or not. Most tree mortality was due to the native mountain pine beetle.

View article.

We tested the effects of site environmental variables (elevation, mean annual precipitation, heat load, and clay content) and management choices (seed source and planting date) on germination favorability and barrier occurrence (mean) and variability (coefficient of variation). Seedling exposure to barriers was strongly linked to management decisions in addition to site mean precipitation and elevation. Later fall plantings and seed sources with slower germination (lower mean germination favorability) were less likely to encounter freezing and drought barriers. These results suggest that management actions can play a role comparable to site environmental variables in reducing exposure of vulnerable seedlings to adverse weather conditions and subsequent effects on restoration outcomes.

View article.

Tree planting has long been promoted to avert climate change and has received renewed impetus in recent years with the Bonn Challenge and related forest restoration initiatives guided by the forest and landscape restoration (FLR) framework. Much of the focus for reforestation and afforestation is on developing countries in Africa, Asia and South America, where large areas of rangelands in drylands and grassy biomes are portrayed as “degraded,” “unused,” and in need of more trees. This perception is rooted in persistent theories on forests and desertification that widely shaped colonial policy and practice and remain influential in today’s science-policy frameworks. From a rangelands perspective, the global FLR thrust raises two main concerns. First, inappropriate understandings of the ecology of drylands and grassy biomes encourage afforestation, grazing restriction and fire suppression, with negative impacts on hydrology, carbon storage, biodiversity, livestock production and pastoral livelihoods. Second, their target-driven approach requires large-scale afforestation and massive funding to achieve. Nearly half of the area pledged to the Bonn Challenge is in fact destined for forestry and other commercial plantations, which threaten pastoral livelihoods and cause ecological damage while having very limited potential to mitigate climate change. As the officially endorsed framework of the Bonn Challenge and related global restoration initiatives, FLR has become a powerful instrument for guiding global restoration efforts and funding. Its proponents have a responsibility to ensure that the framework is evidence-based and underpinned by appropriate ecological models for different ecoregions.