Difficult climate-adaptive decisions in forests as complex social-ecological systems

Novel light regimes in European forests

Tree canopies are one of the most recognizable features of forests, providing shelter from external influences to a myriad of species that live within and below the tree foliage. Canopy disturbances are now increasing across European forests, and climate-change-induced drought is a key driver, together with pests and pathogens, storms and fire. These disturbances are opening the canopy and exposing below-canopy biodiversity and functioning to novel light regimes-spatial and temporal characteristics of light distribution at forest floors not found previously. The majority of forest biodiversity occurs in the shade within and below tree canopies, and numerous ecosystem processes are regulated at the forest floor. Altered light regimes, in interaction with other global change drivers, can thus strongly impact forest biodiversity and functioning. As recent European droughts are unprecedented in the past two millennia, and this has initiated probably the largest pulse of forest disturbances in almost two centuries, we urgently need to quantify, understand and predict the impacts of novel light regimes on below-canopy forest biodiversity and functions. This will be a crucial element in delivering much-needed information for policymakers and managers to adapt European forests to future no-analogue conditions.

Targeted rainfall enhancement as an objective of forestation

Forestation efforts are accelerating across the globe in the fight against global climate change, in order to restore biodiversity, and to improve local livelihoods. Yet, so far the non-local effects of forestation on rainfall have largely remained a blind spot. Here we build upon emerging work to propose that targeted rainfall enhancement may also be considered in the prioritization of forestation. We show that the tools to achieve this are rapidly becoming available, but we also identify drawbacks and discuss which further developments are still needed to realize robust assessments of the rainfall effects of forestation in the face of climate change. Forestation programs may then mitigate not only global climate change itself but also its adverse effects in the form of drying.

Regional proximity effects of landscape pattern evolution: Evidence from 325 county-level areas in the middle reaches of the Yangtze River, China

Unravelling the evolution of landscape patterns is essential to understand regional socio-ecological processes and to solve conflicts between environment protection and human development. However, the role of landscape transition in regional landscape pattern evolution remains unclear. Taking 325 county-level areas in the middle reaches of the Yangtze River (MRYR) as an example, this study explored the spatiotemporal associations between landscape quantity and pattern from the 1970s to 2020. Employing the methods of landscape metrics and trend and correlation analysis, associations between landscape transition and landscape pattern were found. The main results were as follows: (1) From the 1970s to 2020, urban land nearly doubled from 0.93 to 1.89 million km2. Arable land and forest showed the largest quantity reductions of 0.88 million km2 and 0.28 million km2, respectively. Other landscapes showed both decreasing and increasing trends with a spatial overlap among counties. (2) Transition in landscape quantity drives the change in landscape patches, thus affecting the landscape pattern in counties. The percentage of landscape area at the class level (CPLAND) showed relative changes in the quantities of landscape categories in each observation year, but their extreme outliers presented larger changes. (3) Diverse correlation coefficients in terms of magnitude and direction suggested that the transition from natural landscape to human-influenced landscape and the reverse processes occurred. Aggregation and diversity metrics showed spatial interaction with similar distances and the perimeter-area fractal dimension (PAFRAC) showed spatial autocorrelation at local scale. Optimal bandwidths among arable land, forest, and urban land (129.2 km) revealed direct spatial interactions and causal relationships, as did waters and unused land (66.7 km). The findings explained the evolution of landscape patterns and highlighted key areas where various landscape changes occurred, and can provide scientific support for policy-making in regional landscape transition governance.