WILDCARD Glossary

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Alpha diversity: The diversity within a community. It describes the observed species diversity within a defined plot or within a defined ecological unit, such as a pond, a field, or a patch of forest (Andermann et al., 2022).

For plants, alpha diversity often corresponds to species richness (i.e. the count of species identified during the inventory of a vegetation plot of defined size) or abundance (Shannon’s index) or evenness (Simpson’s index) (Revermann et al., 2016).

Beta diversity: The dissimilarity among communities. It describes the amount of differentiation between species communities (Andermann et al., 2022). Beta diversity was originally defined as the ratio between gamma and alpha diversity (Whittaker, 1972).

Carbon flux: It is the amount of carbon exchanged between carbon pools within the ecosystem or between the ecosystem and the atmosphere (tC ha^-1 yr^-1).

Carbon pool: A reservoir of carbon (IPCC, 2006). The forest carbon pools are:

Aboveground biomass includes all living standing trees (at least 2.5 cm in diameter), including stems, stumps, branches, bark, seeds, and foliage. Aboveground biomass also includes living understory plants.

Belowground biomass includes all living root biomass of trees or understory plants, for roots thicker than two mm in diameter.

Deadwood includes all dead woody biomass either standing (snags, stumps) or coarse and fine woody debris lying on the ground.

Forest floor litter includes leaves, needles, twigs, and all other dead biomass with a diameter less than 2 cm, lying on the ground. This includes small-sized dead biomass that is decomposed but has not yet become part of the soil (OL horizon).

Soil carbon includes all organic and inorganic carbon in soil. In the absence of specific information upon which to select an alternative depth interval, it is good practice to compare stock change factors in the topsoil (0-30 cm, the depth used for Tier 1 calculations). It is possible to distinguish the following two horizons:
a) Soil organic horizon: horizon dominated by organic material. It is constituted by the OL (fresh litter), OF (fragmented and/or altered organic matter) and OH (dark, well-decomposed, amorphous organic matter) (ICP Forests, 2020). An O layer may be at the surface of a mineral soil or at any depth beneath the surface if it is buried (ICP Forests, 2020)
b) Soil mineral horizon: a mineral horizon formed at the surface or below an O buried horizon (ICP Forests, 2020)

The absolute quantity of carbon held within at a specified time by a carbon pool is called carbon stock. Transfer of carbon from one carbon pool to another is called carbon flux.

Carbon stock: The absolute quantity of carbon held within a pool at a specified time (tC ha^-1) (IPCC, 2000).

Chronosequence: A series of sites that differ in age or time since abandonment, but otherwise occur on similar soil types and environmental conditions within the same climatic zone (Chazdon, 2013; De Palma et al., 2018).

Chronosequences, by assuming space-for-time substitution, aim to infer temporal dynamics from measurements at sites of different ages, but similar land-use histories.

Forest reserve: Portions of a forest where harvesting is excluded. For WILDCARD purposes, a reserve can include multiple sites.

Forest stand: A community of trees, including aboveground and below-ground biomass and soils, sufficiently uniform in species composition, age, horizontal and vertical structure, and environmental conditions to be managed as a unit (IPCC, 2006, 2003).

Forest structure: Horizontal and vertical distribution of layers and attributes in a forest including the trees, shrubs, and ground cover (Gadow et al., 2012).

Forest type: A category of forest defined by its composition, and/or site factors (locality), as categorised by each country in a system suitable to its situation (EEA, 2007).

Functional diversity: Aiversity in the functional traits of the species in an assemblage (Mason and Mouillot, 2013). Functional diversity can be separated in three components:

Functional richness: the amount of functional trait space filled;

Functional evenness: the evenness of abundance distribution in filled trait space;

Functional divergence: the degree to which abundance is distributed toward the extremities of filled trait space.

Gamma diversity: The overall regional diversity. It describes the overall species diversity across communities within a larger geographic area (Andermann et al., 2022). It is often summarized across biogeographic or political units, such as ecoregions or countries (Brummitt et al., 2021).

Land abandonment: A process whereby human control over land (e.g., agriculture) is given up and the land is left to nature (FAO 2006).

Land cover: Land cover refers to the observed biotic and abiotic assemblage of the Earth’s surface and immediate subsurface (Longley, 2010).

Land use: Land use is defined as the way or manner in which the land is used (Longley, 2010).

Natural forest expansion: Expansion of forest through natural succession on land that, until then, was under a different land use (FAO, 2020).

Old-growth forest: A forest stand or area consisting of native tree species that have developed, predominantly through natural processes, structures and dynamics normally associated with late seral development phases in primary or undisturbed forests of the same type. Signs of former human activities may be visible, but they are gradually disappearing or
too limited to significantly disturb natural processes (European Commission, 2023).

This definition includes forest stands that originate not only from natural regeneration, but also from planted or sown native tree species or with visible signs of abiotic damages (e.g. storms, snow, droughts and fires) and biotic damage (e.g. from insects and diseases). Forests with visible signs of past human activity are not excluded from the definition of old-growth forests.

Phylogenetic diversity: It describes the breadth of evolutionary history that is represented among the organisms found in a particular area.

Plot: Portion of a site within which stand and/or soil data are collected and that is considered representative of that specific site.

Primary forest: Naturally regenerated forest of native tree species, where there are no clearly visible indications of human activities and the ecological processes are not significantly disturbed (European Commission, 2023).

This definition includes forests with visible signs of abiotic damage (e.g. storms, snow, droughts and fires) and biotic damage (e.g. from insects, pests and diseases) and includes early, intermediate, seral and old-growth stages.

Proforestation: The cessation of forest management to allow spontaneous development (Kun et al., 2020; Moomaw et al., 2019).

Renaturalisation: The restoration process of ecosystems guided by human interventions (active restoration) and aimed at reinstating natural processes.

Rewilding: Testoration process aimed at reinstating natural processes by letting the nature doing the job (no human intervention; passive restoration) (Wentworth and Alison, 2016).

Sampling unit: Sampling element or point within a plot (i.e. a tree, a soil sampling point, etc.).

Secondary forest: Forest or woodland area which has regenerated through largely natural processes after human-caused disturbances or equivalently disruptive natural phenomena (Chokkalingam and De Jong, 2001).

Secondary succession: The re-establishment of an ecosystem following a disturbance or after the cessation of other land use (e.g. agriculture), triggered by remaining legacies in the site, such as plant propagules and developed soil.

Site: A homogenous area in terms of environmental conditions, land use (forest or agriculture) and time since abandonment. For the purposes of the WILDCARD project, it includes one or more plots.

Time since abandonment: Time in years after the abandonment of forest management or agricultural use.

References

Andermann, T., Antonelli, A., Barrett, R.L., Silvestro, D., 2022. Estimating Alpha, Beta, and Gamma Diversity Through Deep Learning. Front. Plant Sci. 13, 839407. https://doi.org/10.3389/FPLS.2022.839407/BIBTEX

Brummitt, N., Araújo, A.C., Harris, T., 2021. Areas of plant diversity—What do we know? Plants, People, Planet 3, 33–44. https://doi.org/10.1002/PPP3.10110

Chazdon, R.L., 2013. Tropical Forest Regeneration. Encycl. Biodivers. Second Ed. 277–286. https://doi.org/10.1016/B978-0-12-384719-5.00377-4

Chokkalingam, U., De Jong, W., 2001. Secondary forest: a working definition and typology. Int. For. Rev. 3, 19–26.

De Palma, A., Sanchez-Ortiz, K., Martin, P.A., Chadwick, A., Gilbert, G., Bates, A.E., Börger, L., Contu, S., Hill, S.L.L., Purvis, A., 2018. Challenges With Inferring How Land-Use Affects Terrestrial Biodiversity: Study Design, Time, Space and Synthesis. Adv. Ecol. Res. 58, 163–199. https://doi.org/10.1016/BS.AECR.2017.12.004

EEA, 2007. European Forest Types. Categories and types for sustainable forest management, reporting and policy. Technical Report 09/2006. Copenhagen.

European Commission, 2023. Commission guidelines for Defining, Mapping, Monitoring and Strictly Protecting EU Primary and Old-Growth Forests, Commission Staff Working Document. https://doi.org/10.2779/205712

FAO, 2020. Global Forest Resources Assessment. Rome.

Gadow, K. v., Zhang, C.Y., Wehenkel, C., Pommerening, A., Corral-Rivas, J., Korol, M., Myklush, S., Hui, G.Y., Kiviste, A., Zhao, X.H., 2012. Forest Structure and Diversity 29–83. https://doi.org/10.1007/978-94-007-2202-6_2

ICP Forests, 2020. Sampling and analysis of soil.

IPCC, 2006. Guidelines for National Greenhouse Gas Inventories – Agriculture, Forestry and Other Land Use (volume 4).

IPCC, 2003. Good Practice Guidance for Land Use, Land-Use Change and Forestry.

IPCC, 2000. Land use, land use change and forestry. Cambridge University Press.

Kun, Z., DellaSala, D., Keith, H., Kormos, C., Mercer, B., Moomaw, W.R., Wiezik, M., 2020. Recognizing the importance of unmanaged forests to mitigate climate change. GCB Bioenergy 12, 1034–1035. https://doi.org/10.1111/gcbb.12714

Longley, P., 2010. Global Mapping Of Human Settlement: Experiences, Datasets, and Prospects. Photogramm. Rec. 25, 205–207. https://doi.org/10.1111/J.1477- 9730.2010.00574_3.X

Mason, N.W.H., Mouillot, D., 2013. Functional Diversity Measures. Encycl. Biodivers. Second Ed. 597–608. https://doi.org/10.1016/B978-0-12-384719-5.00356-7

Moomaw, W.R., Masino, S.A., Faison, E.K., 2019. Intact Forests in the United States: Proforestation Mitigates Climate Change and Serves the Greatest Good. Front. For. Glob. Chang. 2, 1–10. https://doi.org/10.3389/ffgc.2019.00027

Revermann, R., Finckh, M., Stellmes, M., Strohbach, B.J., Frantz, D., Oldeland, J., 2016. Linking Land Surface Phenology and Vegetation-Plot Databases to Model Terrestrial Plant α- Diversity of the Okavango Basin. Remote Sens. 2016, Vol. 8, Page 370 8, 370. https://doi.org/10.3390/RS8050370

Wentworth, J., Alison, J., 2016. Rewilding and Ecosystem Services. Parliamentary Office of Science and Technology, London.

Whittaker, R.H., 1972. Evolution and Measurement of Species Diversity. Taxon 21, 213–251. https://doi.org/10.2307/1218190