Context European forests are expanding and becoming denser following the widespread abandonment of farmland and rural areas. Yet, little is known about the goods and services that spontaneous forest regrowth provide to people.

Aims We assessed the changes in nature’s contributions to people (NCP) from spontaneous forest regrowth, i.e. forest expansion and densification, in South-West Europe.

Methods We investigated 65 forest plots in four different landscapes with contrasting ecological and societal contexts. Two landscapes are located in rural areas undergoing human exodus and forest expansion and densification; the other two, in peri-urban areas with intense land use and forest densification but negligible expansion. For each forest plot, we estimated variables related to ten out of the 18 main NCP defined by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). Regulating and material NCP were addressed using variables measured in the field as proxies. Non-material NCP were studied through stakeholder interviews.

Results Our results show across the cases that forest expansion and densification is generally associated with greater climate regulation and energy provision. Changes in other NCP, especially in non-material ones, were strongly context-dependent. The social perception of spontaneous forest regrowth was primarily negative in rural areas and more positive in peri-urban landscapes.

Conclusion Passive restoration through spontaneous forest expansion and densification can enhance regulating and material NCP, especially when adaptive management is applied. To optimise NCP and to increase the societal awareness of and interest in spontaneous forest regrowth, the effects of this process should be analysed in close coordination with local stakeholders to unveil and quantify the many and complex trade-offs involved in rural or peri-urban social perceptions.

The dataset was collected by four different teams who took part in the project. It consisted on four case studies of forest regrowth (including expansion and densification) after rural abandonment with contrasting ecological and societal contexts. The study took place in Spain and France. Two landscapes are located in rural areas undergoing human exodus and forest expansion and densification; the other two, in peri-urban areas with intense land use and forest densification but negligible expansion. For each forest plot, we estimated variables related to ten out of the 18 main Nature's contributions to people (NCP) defined by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Regulating and material NCP were addressed using variables measured in the field as proxies. Non-material NCP were studied through stakeholder interviews.

Thus, this dataset contains data on NCP associated with forest regrowth of Juniperus thurifera L., Fagus sylvatica L., Quercus ilex L., and Quercus robur L stands. It includes a total of 65 study plots and 2,837 individual trees. The considered NCP included four regulating, three material, and three non-material NCP as well as one NCP common to all categories. The four regulating NCP were habitat creation and maintenance; pollination and dispersal of seeds and other propagules; regulation of climate through biological carbon (C) sequestration and storage; and regulation of detrimental organisms and biological processes. The two material NCP were energy; and medicinal, biochemical and genetic resources. The three non-material NCP were learning and inspiration; physical and psychological experience; and supporting identities. The NCP common to all categories was the maintenance of options, reflected in maintaining biodiversity (estimated in this case with the Shannon diversity index). The dataset contains information at both individual and plot level.

Habitat creation and maintenance (NCP1) was calculated by computing the spatial connectivity of the plots in Q. ilex and Q. robur stands. It was inferred by calculating the percentage cover of broadleaved forest in a circular buffer (radius = 500 m) around each plot.

Pollination and the dispersal of seeds and other propagules (NCP2) was estimated by counting all seedlings and saplings in each plot and divided them by the plot area to obtain the density of saplings per hectare. 

Climate regulation in terms of biological carbon (C) storage and sequestration (NCP4) was estimated by the overall C stock contained in the trees of the study plots. We calculated the total biomass per tree using species-specific allometric equations that combine the dbh and the height of the sampled trees. We also calculated the C stock per tree multiplying the obtained biomass by the percentage of C in each species. 

The regulation of detrimental organisms and biological processes (NCP10) was assessed using the percentage of invertebrate herbivory. For all except the J. thurifera case study, we determined herbivore damages by visually estimating the percentage of leaf area removed by invertebrates.

Energy provision (NCP11) was understood as the production of biomass-based fuels such as fuelwood. We estimated biomass input from thick and medium branches (i.e. the tree parts normally employed as fuelwood) for each tree within plots. Biomass input from thick and medium branches was calculated from allometric equations specific for each species.

The provision of medicinal, biochemical and genetic resources (NCP14) includes the production of plant genes and genetic information. In each plot we quantified gene diversity corrected for sample size as proxy for NCP14.

The maintenance of options (NCP18) includes the benefits associated with species diversity. We scored woody species richness and abundance and computed the Shannon diversity index as proxy. 

Additionally, interviews regarding social perceptions related to learning and inspiration (NCP15), physical and psychological experiences (NCP16) and supporting identities (NCP17) were conducted at the case study level. Please notice that the social perception dataset is not uploaded to ensure data privacy policy. 

More information and detailed Methodology can be found in Martín-Forés et al. (2020) People and Nature, in both the main text and the Supplementary Material S1.

Some values are missing because the methodology was adjusted according to each case study. For more information please read the detailed information provided by Martín-Forés et al. (2020) People and Nature, in both the main text and the Supplementary Material S1.