Reviewing the use of resilience concepts in forest sciences

Purpose of the review Resilience is a key concept to deal with an uncertain future in forestry. In recent years, it has received increasing attention from both research and practice. However, a common understanding of what resilience means in a forestry context, and how to operationalise it is lacking. Here, we conducted a systematic review of the recent forest science literature on resilience in the forestry context, synthesising how resilience is defined and assessed. Recent findings Based on a detailed review of 255 studies, we analysed how the concepts of engineering resilience, ecological resilience, and social-ecological resilience are used in forest sciences. A clear majority of the studies applied the concept of engineering resilience, quantifying resilience as the recovery time after a disturbance. The two most used indicators for engineering resilience were basal area increment and vegetation cover, whereas ecological resilience studies frequently focus on vegetation cover and tree density. In contrast, important social-ecological resilience indicators used in the literature are socio-economic diversity and stock of natural resources. In the context of global change, we expected an increase in studies adopting the more holistic social-ecological resilience concept, but this was not the observed trend. Summary Our analysis points to the nestedness of these three resilience concepts, suggesting that they are complementary rather than contradictory. It also means that the variety of resilience approaches does not need to be an obstacle for operationalisation of the concept. We provide guidance for choosing the most suitable resilience concept and indicators based on the management, disturbance and application context

Ice age effects on the satellite-derived J˙<inf>2</inf> datum: Mapping the sensitivity to 3D variations in mantle viscosity

Studies of glacial isostatic adjustment (GIA) based on spherically symmetric viscoelastic Earth models have argued that the rate of change of the degree 2 zonal harmonic of the Earth’s geopotential, or J˙2, provides an important constraint on mean viscosity in the deep mantle (Mitrovica and Peltier, 1993; Nakada et al., 2015; Lau et al., 2016). To refine this constraint, we compute Fr´echet kernels using an adjoint methodology that reveal the sensitivity of the datum to 3D variations in mantle viscosity. We demonstrate that the mantle sensitivity of the datum is largely limited to the region below the ancient Laurentide ice sheet that covered Canada and significant portions of the northeastern United States at Last Glacial Maximum (LGM). In the bottom half of the lower mantle, this region of maximum sensitivity lies outside the location of Large Low Shear Velocity Provinces (LLSVPs) imaged from seismic tomographic studies. Thus, if the low shear velocity of these provinces originates from thermal effects, previous inferences of viscosity based upon the J˙ 2 datum are likely higher than the actual mean viscosity of the lower mantle