Woodland creation and Ecological Networks (WrEN) project

Tree planting is at the forefront of the current environmental agenda to mitigate climate change and tackle the biodiversity crisis. In the United Kingdom (UK), tree planting has been a priority for more than a century and has helped increase woodland cover from a historic low of 5 per cent at the beginning of the 20th century to a current figure of 13 per cent. However, we still know relatively little about the long-term development of woodland creation sites (particularly of native woodlands) over ecologically realistic timescales. We surveyed a chronosequence of 133 temperate woodland patches encompassing 106 woodland creation sites (10–160 years old) and 27 mature ‘ancient’ woodlands (>250 years old), using a combination of field surveys and remote sensing techniques to quantify vegetation structural changes associated with woodland development. Woodland creation sites displayed similar vegetation development patterns to those described for other woodland systems, i.e. a gradual transition as woodlands undergo ‘stand initiation’, ‘stem exclusion’ and ‘understorey re-initiation’ stages, and became more similar to ‘ancient’ woodlands over time. Structural heterogeneity, average tree size and tree density were the attributes that varied the most among woodland developmental stages. In general, structural heterogeneity and average tree size increased with woodland age, whilst tree density decreased as would be expected. Younger sites in stand initiation were strongly dominated by short vegetation, stem exclusion sites by taller trees and older sites had a more even vegetation height distribution. There was a large degree of overlap between the vegetation characteristics of woodlands in understorey re-initiation stages and older ancient woodlands (partly driven by a lack of regeneration in the understorey); these results suggest that it takes between 80 and 160 years for woodland creation sites to develop certain vegetation attributes similar to those of mature ancient woodlands included in this study. Woodland management practices to create canopy gaps and reducing grazing/browsing pressure to promote natural regeneration are likely to accelerate this transition, increase the structural heterogeneity and biodiversity value of woodland creation sites and enable adaptation and resilience to climate change.

Aim Large‐scale habitat creation is crucial to mitigate the current ecological crisis, but scientific evidence on its effects on biodiversity is scarce. Here, we assess how assemblages of a biodiverse group (moths) develop over time in habitat creation sites. We use temperate woodlands as a case study, and compare species assemblages in restored and mature habitat patches. We also identify local‐ and landscape‐level attributes associated with high species richness and abundance. Location Central Scotland, United Kingdom. Methods We surveyed moths in a chronosequence of 79 temperate woodland patches encompassing woodland creation sites (20–160 years old) and mature “ancient” woodlands (250+ years old). We used structural equation models, generalized linear models and ordination techniques to quantify moth community responses to woodland creation, and degree of similarity to moth assemblages in ancient woodlands. Results Woodland creation sites harboured large numbers of moth species (212), were dominated by woodland generalists and had high species turnover. Moth abundance and diversity increased with woodland connectivity. Macromoths were more abundant and diverse in younger woodlands; micromoth specialists occurred more frequently in older woodland creation sites. Ancient woodlands had similar moth abundance/richness than woodland creation sites (except for fewer macromoth woodland specialist species), but their species composition was somewhat different. Patterns of beta diversity (low nestedness) indicated that moth species in woodland creation sites are not simply subsets of species in ancient woodlands. Main conclusions To benefit moth communities, woodland creation sites should be structurally diverse and in close proximity to other woodlands. At the landscape scale, a mosaic of woodland patches of different ages is likely to increase moth beta (and consequently gamma) diversity. Ancient woodlands and woodland creation sites each host substantial proportions of “unique” species; individual woodland patches contain distinctive moth assemblages and should be protected and valued for their contribution to regional moth diversity.

Increasing carbon (C) storage in soil is a key aspect of climate change mitigation strategies and requires an understanding of the impacts of land management on soil C cycling. The primary aim of this study is to investigate how land management impacts key soil organic matter stabilization and cycling processes affecting soil C storage. Soil sampling was un-dertaken across seven transects crossing the boundary between agriculture and forestry. The transects covered 3 pasture (AP) and 4 arable (AA) fields combined with 3 young secondary woodlands (50-60 years old-WY) and 4 mature/ancient semi-natural woodlands (110 to >400 years old-WM). Physical fractionation of soil organic matter pools was performed, together with pH, carbon and nitrogen content, as well as activity of four enzymes associated with C transformation in the soil. Woodland soils were associated with significantly higher content of light fraction C and greater enzyme activity in comparison to agricultural soils. Enzyme activity and soil organic C decreased with soil depth regardless of land-use type. We did not, however , observe any effect of the distance from the land use boundary on either enzyme activity and soil C pools. Our results indicate that analysis of soil organic matter (SOM) fractions can act as an indicator of decomposition rates of SOM in forest and agricultural ecosystems.

Context Land-use change and habitat fragmentation are well known drivers of biodiversity declines. In forest birds, it has been proposed that landscape change can cause increased predation pressure that leads to population declines or community change. Predation can also have non-lethal effects on prey, such as creating ‘landscapes of fear’. However, few studies have simultaneously investigated the relative contribution of regional land-use and local management to creating ‘landscapes of fear’. Objectives To quantify the relative contribution of regional land-use and local management to the ‘landscape of fear’ in agricultural landscapes. Methods Bioacoustic recorders were used to quantify Eurasian Wren Troglodytes troglodytes alarm call rates in 32 naturally replicated broadleaf woodlands located in heterogeneous agricultural landscapes. Results Alarm call rates (the probability of an alarm per 10 min of audio) were positively correlated with the amount of agricultural land (arable or pasture) within 500 m of a woodland (effect size of 1) and were higher when livestock were present inside a woodland (effect size of 0.78). The amount of woodland and urban land cover in the landscape also had positive but weak effects on alarm call rates. Woodlands with gamebird management had fewer alarm calls (effect size of − 0.79). Conclusions We found that measures of both regional land-use and local management contributed to the ‘landscape of fear’ in agricultural landscapes. To reduce the impact of anthropogenic activities on ‘fear’ levels (an otherwise natural ecological process), land-managers should consider limiting livestock presence in woodlands and creating traditional ‘buffer strips’ (small areas of non-farmed land) at the interface between woodland edges and agricultural fields.

Global conservation targets to reverse biodiversity declines and halt species extinctions are not being met despite decades of conservation action. However, a lack of measurable change in biodiversity indicators towards these targets is not necessarily a sign that conservation has failed; instead, temporal lags in species’ responses to conservation action could be masking our ability to observe progress towards conservation success. Here we present our perspective on the influence of ecological time lags on the assessment of conservation success and review the principles of time lags and their ecological drivers. We illustrate how a number of conceptual species may respond to change in a theoretical landscape and evaluate how these responses might influence our interpretation of conservation success. We then investigate a time lag in a real biodiversity indicator using empirical data and explore alternative approaches to understand the mechanisms that drive time lags. Our proposal for setting and evaluating conservation targets is to use milestones, or interim targets linked to specific ecological mechanisms at key points in time, to assess whether conservation actions are likely to be working. Accounting for ecological time lags in biodiversity targets and indicators will greatly improve the way that we evaluate conservation successes. Time lags in the response of species to conservation interventions may mask success. In this Perspective, the authors explore the effects of time lags on biodiversity indicators using both theory and empirical data.

Habitat loss and fragmentation greatly affect biological diversity. Actions to counteract their negative effects include increasing the quality, amount and connectivity of semi‐natural habitats at the landscape scale. However, much of the scientific evidence underpinning landscape restoration comes from studies of habitat loss and fragmentation, and it is unclear whether the ecological principles derived from habitat removal investigations are applicable to habitat creation. In addition, the relative importance of local‐ (e.g. improving habitat quality) vs. landscape‐level (e.g. increasing habitat connectivity) actions to restore species is largely unknown, partly because studying species responses over sufficiently large spatial and temporal scales is challenging. We studied small mammal responses to large scale woodland creation spanning 150 years, and assessed the influence of local‐ and landscape‐level characteristics on three small mammal species of varying woodland affinity. Woodland specialists, generalists and grassland specialists were present in woodlands across a range of ages from 10 to 160 years, demonstrating that these species can quickly colonize newly created woodlands. However, we found evidence that woodlands become gradually better over time for some species. The responses of individual species corresponded to their habitat specificity. A grassland specialist (Microtus agrestis) was influenced only by landscape attributes; a woodland generalist (Apodemus sylvaticus) and specialist (Myodes glareolus) were primarily influenced by local habitat attributes, and partially by landscape characteristics. At the local scale, high structural heterogeneity, large amounts of deadwood and a relatively open understory positively influenced woodland species (both generalists and specialists); livestock grazing had strong negative effects on woodland species abundance. Actions to enhance habitat quality at the patch scale focusing on these attributes would benefit these species. Woodland creation in agricultural landscapes is also likely to benefit larger mammals and birds of prey feeding on small mammals and increase ecosystem processes such as seed dispersal.

Woodland restoration is underway globally, to counter the negative soil quality and ecological impacts of agricultural expansion and woodland fragmentation, and restore or enhance biodiversity, ecosystem functions and services. However, we lack information about the long‐term effects of woodland restoration on agricultural soils, particularly at temporal scales meaningful to woodland and soil development. This study utilised soil and earthworm sampling across a chronosequence of sites transitioning from ‘agricultural land’ to ‘secondary woodland’ (50‐110 years) and ‘ancient woodland’ (>400 years), with the goal of quantifying the effects of woodland restoration on agricultural land, on key soil quality parameters (soil bulk density, pH, carbon and nitrogen stocks, and earthworm abundance, biomass, species richness and diversity). Broad‐leaved woodland restoration led to significantly greater soil organic carbon (SOC) stocks compared to arable land, and young (50‐60 years) secondary woodland increased earthworm species and functional diversity compared to both arable and pasture agricultural land. SOC stocks in secondary broad‐leaved woodlands (50‐110 years) were comparable to those found in long‐term ancient woodlands (>400 years). Our findings show that broad‐leaved woodland restoration of agricultural land can lead to meaningful soil ecological improvement and gains in SOC within 50 to 110 years, and provide intel on how restoration activities may be best targeted to maximise soil quality and functions. This article is protected by copyright. All rights reserved.

Landscape context can affect how individuals perceive patch quality during colonization. However, although context-dependent colonization has been observed in aquatic environments, it has rarely been studied in terrestrial environments or at large spatial scales. In this paper, we assessed how landscape context influenced colonization rates in a large-scale (ca 7000 km2) terrestrial system where colonizers (Willow Warbler Phylloscopus trochilus) are capable of rapid, long-distance movements. Bioacoustic recorders were used to detect first song dates (an indicator of colonization or re-colonization) and settlement in 23 naturally replicated habitat patches. We compared support for three competing hypotheses describing colonization patterns that depend on landscape context ('redirection', 'landscape-selection' and 'relative patch size') with two patch-level hypotheses (patch 'quality' and 'heterospecific attraction'). First song was earlier when habitat availability in the landscape was low, supporting the 'redirection' hypothesis. Settlement probability was best predicted by patch 'quality' and was lower in woodlands with a dense understorey. Results suggest that colonization of habitat patches by male P. trochilus after spring migration is spatially hierarchical. First, initial colonization depends on landscape context, and settlement is then determined by fine-scale vegetation characteristics. More broadly, we suggest that patterns observed in fragmented aquatic environments (e.g. 'redirection') can, in some circumstances, be extended to large-scale terrestrial environments.

New native woodlands are typically created in a small and isolated configuration, potentially reducing their value as a resource for biodiversity. The use of ecological networks for habitat restoration and creation could be beneficial for woodland biodiversity. This approach is conceptualised as local and landscape-scale conservation actions designed to increase the area, quality, amount and connectivity of habitat types. However, there is limited evidence about the value of secondary woodlands and the relative or combined effects of network variables for woodland insects. 2.Seventy-eight woodland sites created in the last 160 years across England and Scotland were sampled for hoverflies (Diptera: Syrphidae) and craneflies (Diptera: Tipuloidea), using two Malaise net traps placed in the centre of each woodland. The diversity of insects supported by created woodland patches was analysed using measures of dissimilarity, and the relative direct and indirect effects of ecological network variables on their abundance and species richness were assessed using structural equation models. 3.We found 27% of British woodland hoverfly species and 43% of British woodland cranefly species in the study sites, indicating that woodland insects are colonising created native woodlands, despite their fragmented nature. However, these species communities were highly variable across woodland patches. 4.Landscape-scale variables had no effect on woodland-associated hoverflies or craneflies relative to local-scale variables. Local-scale variables relating to habitat quality (i.e. structural heterogeneity of trees and understory cover) had the strongest influence on abundance and species richness. 5.Synthesis and applications. To benefit woodland-associated Diptera, woodland creation and restoration should maintain a focus on habitat quality. This should include active management to facilitate a diverse tree and understorey vegetation structure. Many woodlands in the UK are privately owned and landowners should be encouraged to plant and actively manage their woodlands to increase structural heterogeneity and resources for woodland insects. This article is protected by copyright. All rights reserved.

Ecosystem function and resilience are compromised when habitats become fragmented due to land-use change. This has led to national and international conservation strategies aimed at restoring habitat extent and improving functional connectivity (i.e. maintaining dispersal processes). However, biodiversity responses to landscape-scale habitat creation and the relative importance of spatial and temporal scales is poorly understood, and there is disagreement over which conservation strategies should be prioritised. Addressing these knowledge gaps has been challenging because (1) there can be a significant time lag between habitat creation and biodiversity responses, and (2) many taxa respond to landscape characteristics over large spatial scales. These conditions can be difficult to replicate in a controlled setting but can be simulated using 'natural' experiments. Here, we used 160 years of historic post-agricultural woodland creation as a natural experiment to evaluate biodiversity responses to landscape-scale habitat creation. Specifically, we disentangle the direct and indirect relationships between bird abundance and diversity, ecological continuity, patch characteristics and landscape structure, and quantify the relative importance of local and landscape scales. Results suggest that ecological continuity has an indirect effect on total bird species richness through its direct effects on stand structure. However, for functional groups most closely associated with woodland habitats, ecological continuity had little influence. This was probably because woodlands were rapidly colonised by woodland generalists in < 10 years (the minimum patch age), but were on average too young (median 50 years) to be colonised by woodland specialists. Local, patch characteristics were relatively more important than landscape characteristics. We conclude that biodiversity responses to habitat creation are dependent on local and landscape-scale factors that interact across time and space. We also suggest that knowledge gained from studies of habitat fragmentation/loss should be used to inform habitat creation with caution, since the two are not necessarily reciprocal. This article is protected by copyright. All rights reserved.

Title Landscape-scale conservation: the role of space and time in the realisation of biodiversity benefits Authors Nick Synes1, Kevin Watts2, Kamil Barton3, Stephen Palmer3, Justin Travis3 Affiliations 1 Institute of Complex Systems Simulation, University of Southampton, University Road, SO30 3HF, UK. 2 Forest Research, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK 3 Institute of Biological and Environmental Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK. Contact Nick Synes: n.synes@soton.ac.uk Abstract Using RangeShifter, a novel modelling platform which combines population dynamics with individual-based dispersal behaviour, this study tests a number of landscape-scale conservation actions, and their impact on biodiversity. Species in the model are parameterised with trait-space data broadly representative of real dispersal and life-history attributes. Future landscapes have been created to represent the spatial application of management actions such as habitat improvement, restoration, creation and landscape matrix modifications. Previous studies on landscape management have often simulated instantaneous impacts on biodiversity when management decisions are made. Empirical data on the time-lag between the action and the realisation of biodiversity benefits are used to generate more realistic representations of landscape transitions through time. The implications of the spatial location of these actions will be tested, i.e. the biodiversity benefits of creating new habitat adjacent to existing habitat, or creating it randomly within the landscape. Model results should provide guidance on the best management practices for landscape-scale conservation; for example, testing the relative biodiversity benefits of habitat creation versus improvement of existing habitat. This study will provide useful information to underpin the current shift towards landscape-scale conservation and climate change adaptation.

Conservation strategies to tackle habitat loss and fragmentation require actions at local (e.g. improving/expanding existing habitat patches) and landscape level (e.g. creating new habitat in the matrix). However, the relative importance of these actions for biodiversity is still poorly understood, leading to debate on how to prioritise conservation activities. Here, we assess the relative importance of local vs. landscape-level attributes in determining the use of woodlands by bats in fragmented landscapes; we also compare the role of habitat amount in the surrounding landscape per se vs. a combination of both habitat amount and configuration and explore whether the relative importance of these attributes varies with species mobility and landscape context. We conducted acoustic surveys in 102 woodland patches in the UK which form part of the WrEN project (www.wren-project.com), a large-scale natural experiment designed to study the effects of 160 years of woodland creation on biodiversity and inform landscape-scale conservation. We used multivariate analysis and a model-selection approach to assess the relative importance of local (e.g. vegetation structure) and landscape-level (e.g. amount/configuration of surrounding land types) attributes on bat occurrence and activity levels. Species mobility was an important trait determining the relative importance of local vs. landscape-level attributes for different bat species. Lower mobility species were most strongly influenced by local habitat quality; the landscape became increasingly important for higher mobility species. At the landscape-scale, a combination of habitat amount and configuration appeared more important than habitat amount alone for lower mobility species, whilst the opposite was observed for higher mobility species. Regardless of species mobility, landscape-level attributes appeared more important for bats in a more homogeneous and intensively farmed landscape. Conservation strategies involving habitat creation and restoration should take into account the mobility of target species and prioritise landscape-level actions in more homogeneous and intensively farmed landscapes where habitat loss and fragmentation have been more severe. This article is protected by copyright. All rights reserved.

The development of ecological networks could help reverse the effects of habitat fragmentation on woodland biodiversity in temperate agricultural landscapes. However, efforts to create networks need to be underpinned by clear evidence of the relative efficacy of local (e.g. improving or expanding existing habitat patches) versus landscape-scale actions (e.g. creating new habitat or corridors in the landscape matrix). Using cluster analyses we synthesised the findings of 104 studies, published between 1990 and 2013 focusing on the responses of woodland vascular plant, vertebrate, cryptogam and invertebrate species to local and landscape variables. Species responses (richness, diversity, occurrence) were strongly influenced by patch area, patch characteristics (e.g. stand structure) and isolation (e.g. distance between habitat patches). Patch characteristics were of overriding importance for all species groups, especially cryptogams. Many studies recording significant species responses to patch characteristics did not record significant responses to patch area and vice versa, suggesting that patch area may sometimes act as a surrogate for patch characteristics (i.e. larger patches being of ‘better quality’). Ecological continuity was important for vascular plants, but assessed in only a few vertebrate and invertebrate studies. Matrix structure (e.g. presence of corridors) was important for vertebrates, but rarely assessed for other species groups. Actions to develop ecological networks should focus on enhancing the quality and/or size of existing habitat patches and reducing isolation between patches. However, given that very few studies have assessed all local and landscape variables together, further information on the relative impacts of different attributes of ecological networks in temperate agricultural landscapes is urgently needed.

Natural experiments have been proposed as a way of complementing manipulative experiments to improve ecological understanding and guide management. There is a pressing need for evidence from such studies to inform a shift to landscape-scale conservation, including the design of ecological networks. Although this shift has been widely embraced by conservation communities worldwide, the empirical evidence is limited and equivocal, and may be limiting effective conservation. We present principles for well-designed natural experiments to inform landscape-scale conservation and outline how they are being applied in the WrEN project, which is studying the effects of 160 years of woodland creation on biodiversity in UK landscapes. We describe the study areas and outline the systematic process used to select suitable historical woodland creation sites based on key site- and landscape-scale variables – including size, age, and proximity to other woodland. We present the results of an analysis to explore variation in these variables across sites to test their suitability as a basis for a natural experiment. Our results confirm that this landscape satisfies the principles we have identified and provides an ideal study system for a long-term, large-scale natural experiment to explore how woodland biodiversity is affected by different site and landscape attributes. The WrEN sites are now being surveyed for a wide selection of species that are likely to respond differently to site- and landscape-scale attributes and at different spatial and temporal scales. The results from WrEN will help develop detailed recommendations to guide landscape-scale conservation, including the design of ecological networks. We also believe that the approach presented demonstrates the wider utility of well-designed natural experiments to improve our understanding of ecological systems and inform policy and practice.