Woodland Trust

Expanding forest and woodland cover is a global strategy to mitigate and adapt to the climate crisis and reverse biodiversity decline. While most woodland in temperate regions is created through tree planting, natural colonisation has been advocated for as an alternative or complementary approach. However, there is limited understanding on how the structural attributes of woodlands created through these different approaches develop through time. To address this knowledge gap, we assessed a suite of structural metrics for 28 woodland sites (aged 13-43 years) that were established along a planted to natural colonisation continuum in England. We used an Uncrewed Aerial System to collect LiDAR data alongside field surveys and calculated metrics relating to above-ground biomass accumulation (canopy height and basal area) and metrics relating to structural complexity (the horizontal and vertical arrangement of canopy) as a proxy for biodiversity potential. Canopy height and basal area were higher in woodlands with larger proportions of planting. Additionally, woodlands with higher proportions of planting displayed greater vertical complexity (canopy stratification) whereas there was weak evidence that woodlands with higher proportions of natural colonisation develop greater horizontal complexity (gap fraction). This suggests that tree planting is the better option when biomass accumulation is the primary goal, whereas natural colonisation or hybrid approaches are likely to be beneficial when the focus is biodiversity or a mix of outcomes. Woodlands created through hybrid approaches that combine planting and natural colonisation offered intermediate values of biomass accumulation and structural complexity.

1. Tree planting is a key climate mitigation strategy, but afforestation on organo-mineral soils may cause soil organic carbon (SOC) losses, limiting long-term ecosystem carbon gains over decadal timescales. New woodland creation guidance aims to avoid tree planting on high-carbon soils to protect existing SOC stocks. 2. We measured topsoil SOC stocks (0-15 cm) at a new native woodland in the Yorkshire Dales, UK, with highly variable organo-mineral soils typical of many UK uplands. The woodland design was based on peat depth, vegetation classification, archaeological features and breeding bird surveys. 3. Our study had two aims. First, to test whether the woodland design resulted in tree planting in areas with lowest SOC stocks at a site scale. Second, to assess whether low-disturbance, hand-planting techniques avoided high SOC stocks at plot scale. Five replicate 10 & times; 10 m plots were established for each of three treatments: unplanted, low-density and high-density tree planting. Each planted plot was paired with a topographically similar unplanted control. Soil cores were sampled randomly across each plot as well as close to planted trees. Fieldwork occurred 9-13 months after planting began. 4. We found SOC stocks were significantly lower in high-density plots (median = 75.60 t C ha(-1); IQR = 66.44-87.95) than in unplanted (97.70 t C ha(-1); 80.74-115.59) and low-density plots (91.47 t C ha(-1); 78.67-99.98; p < 0.05), indicating that areas selected for tree planting preferentially targeted lower carbon soils as planned. No evidence was found to suggest avoidance of higher carbon soils at the 10-m plot scale. 5. Practical implications. Our results show that careful woodland design can avoid tree-planting on high-carbon organo-mineral soils. Our work shows that new woodland creation guidelines in England are likely to reduce the potential for SOC losses by targeting high-density tree planting on soils with lower SOC stocks.

Abstract Robust data on the state of relationships between people and nature is a critical component of the evidence base for environmental governance at local, national and global scales. Social surveys are a valuable method already used by some governmental and non‐governmental organisations to gather this evidence. However, a lack of coordination hampers efforts to harness the potential of people‐and‐nature surveys to better inform policy and practice. Specifically, designers and administrators of people‐and‐nature surveys should ensure that surveys are relevant to current policy challenges, robust in their use of socially and statistically validated questions, and the data produced are accessible to diverse communities for research, practice and advocacy. Integrating the experience of a group of UK survey researchers and practitioners, this Perspective identifies six actions to enhance the value of people‐and‐nature surveys for environmental governance: strengthen access to survey data; co‐define meaningful constructs and questions; invest in continuing datasets; mix methods appropriately; track the use and impact of survey insights; and foster partnerships and capacity sharing to enable these actions. Together, these actions could enable people‐and‐nature surveys to better serve user needs, build cross‐scale usability and contribute critical insights on progress towards national and global environmental goals. Read the free Plain Language Summary for this article on the Journal blog.

Theoretical and methodological developments in the field of fragmentation-biodiversity research continue to rely on the central concept of the habitat patch where patch size and number are considered particularly relevant to spatially structured ecological communities. However, although great interest has been shown in the effects of habitat fragmentation, appropriate methods for the spatial delineation of habitat have not received equal attention. In this paper, we argue that existing methods are not consistent with a functional definition of habitat as they fail to address key methodological challenges. These relate to the need to acknowledge a) the contribution of multiple resource types to habitat, b) the influence of neighbouring land cover types and c) the continuity-contiguity problem (the tendency of habitat to exhibit properties of gradation and aggregation). In this second of two papers on this topic, we present an application of a new methodological framework outlined by Dennis et al. (this issue) that offers a route to a more functional definition and delineation of habitat through the use of spatial kernels and the generation of Type 1 and 2 fuzzy sets from landscape classification algorithms. We present a demonstration of the framework applied to a real-world landscape, in which we illustrate the impact of adopting alternative perspectives with respect to habitat delineation on the ecological process of habitat connectivity. We demonstrate the functional delineation of habitat for a focal generic woodland species (FGWS) in a real-world landscape classified through the application of a fuzzy Random Forest classifier. We employ nesting, foraging and dispersal parameters relevant to the FGWS to achieve a functional estimate of habitat. We test the influence of habitat fragmentation (number of patches controlling for total habitat amount) on potential functional connectivity for the FGWS based on contiguous (emphasising aggregation and homogeneity), continuous (emphasizing gradation) and functional (integrating multiple resource types and neighbourhood effects) habitat perspectives. Our results indicate large discrepancies between the three perspectives on habitat delineation across key fragmentation-relevant metrics (total area, number of patches and potential functional connectivity). Importantly, a functional habitat perspective supports markedly different conclusions (compared to contiguous and continuous perspectives) with respect to the relationship between fragmentation (number of patches) and connectivity, and estimates of the contribution of individual habitat patches to landscape-scale connectivity. The functional habitat perspective, operationalized by harnessing uncertainty in landscape classification and employing spatial kernels to parameterise neighbourhood effects based on species-specific parameters, achieves a functional delineation of habitat. Our study suggests that such a view has major implications for our understanding of habitat fragmentation because it requires that the latter also be assigned a functional definition. The framework centred on functional habitat delineation is generalizable to a wide range of landscape contexts and advances current methods in spatial ecology. This opens up opportunities for inquiry and the development of new theoretical positions within the fragmentation-biodiversity debate.

There is growing recognition of agroforestry’s potential to help mitigate and provide resilience to the climate and biodiversity crises. Beyond its environmental benefits, agroforestry can also enhance production and profits, making it a sustainable farming solution that is scalable. Despite this, uptake within Europe is low, and many knowledge gaps remain that need to be addressed to promote adoption and optimize the management and implementation of agroforestry systems. We co-developed a research agenda for agroforestry using a multi-actor approach and a modified Delphi method in 2023. 156 UK-based stakeholders contributed to this process, including farmers, advisors, policy makers, NGOs, and researchers. An initial list of 238 research priorities (high-priority research questions) was submitted via a survey and a workshop. This was shortened during a second workshop with 48 participants. The final list included 40 research priorities across the themes “environment and production,” “human livelihoods, knowledge, and perceptions,” and “policy, financing, and markets.” There was high agreement about which priorities to include, with questions on policy incentives, knowledge-exchange, agroforestry design (e.g., tree/crop selection), biodiversity, ecosystem functioning, well-being, markets, and food security. We identified a need for landscape-scale and longer-term research. Our agenda is a rare example of a research-prioritization process that includes farmers and other agricultural stakeholders throughout the research process. The value of this approach can be seen in the inclusion of research priorities that are grounded in the real world and relevant to different actors. Our agenda goes beyond existing evidence syntheses in scope, and should be used alongside them to identify stakeholder-relevant gaps for future primary research and evidence synthesis. By guiding researchers and funding bodies to impactful areas of enquiry, it can promote evidence-based agroforestry practice and policy. Addressing this research agenda requires better support for long-term, transdisciplinary, multi-stakeholder research, and funded demonstration sites or living labs.