A plot-level exploratory analysis of European forest based on the results from the BioSoil Forest Biodiversity project

Abstract

The lack of multi-dimensional data is one of the major gaps which limit the knowledge and the assessment possibilities of European forests. Nowadays, the most extensive and complete data on the European forest statuses are given by National Forest Inventories (NFIs) which provide information about the extent of forest’s resources and their composition and structure. Traditionally, NFIs collect data related to trees, with a limited consideration of other habitat components, such as ground vegetation. This information which goes beyond the mere arboreal component is instead essential for a more complete forest biodiversity assessment. This paper is aimed at introducing the ICP Forests LI-BioDiv database which resulted from BioSoil Forest Biodiversity, a large collaborative European project. This database is organized as a multi-dimensional forest geodatabase that contains forest structure and vegetation records collected in 19 European countries in the period of 2005–2008. The data were acquired from 3311 geocoded plots where several different types of data were gathered: stand-level general information, tree-level data, deadwood, canopy closure and floristic composition. This paper is structured in order to: (1) give a clear overview of the raw data available in the database and to (2) present an elaboration of raw data to calculate simple plot-level forest variables (biomass, deadwood volume, alpha diversity). On the basis of the results we achieved, the LI-BioDiv database appears useful mainly for research purposes aimed at studying cross-relationships between multiple forest variables and not for an operative use for monitoring and assessing European forest. In particular, we hope that this contribution can stimulate scientists to carry out cross-analysis of the database for defining future forest biodiversity indicators that could be introduced into the field protocols of the NFIs in Europe.

Appendices

Appendix A

Information about dataset table is presented below, including detailed descriptions of all attributes within the tables. Each attribute in a table is listed with its abbreviated name followed by a description of the attribute. Attributes that are coded include a list of the codes and their meanings. The attribute called “quality” has been defined for easily filtering the necessary data for each data type.

Common attributes to all data type:

• id_unique progressive number that identified the rows;

• survey_year year when the surveys were carried out;

• code_country number that identifies the country (Table 1);

• code_plot number that identifies the plot;

• index links “code_country” and “code_plot” to the unique plot record;

• bd_subplot (only for level I): subplot number where the diameters were recorded. Code 1—subplot with a radius of 3.09 m (30 $\hbox {m}^2$). Code 2—subplot with a radius of 11.28 m (400 $\hbox {m}^2$). Code 3—subplot with a radius of 25.24 m (2000 $\hbox {m}^2$).

Specific attributes to GPL dataset:

• Latitude

• Longitude

• gps_elevation values of elevation;

• code_orientaion Code 1—North. Code 2—North-east. Code 3—East. Code 4—South-east. Code 5—South. Code 6—South-west. Code 7—West. Code 8—North-west. Code 9—Flat.

• Slope

• Code_preuse previous land use. Code 1—Forested more than 300 years. Code 2—Forested more than 100 years. Code 3—Forested for 25–100 years ago. Code 4—Forested in the past 25 years. Code 5—No information.

• Code_stand_actual Code 1—Planted. Code 2—Seeded. Code 3—Natural regeneration. Code 4—Mixed. Code 9—Unknown.

• Code_manage_intensity Code 1—Unmanaged (no evidence). Code 2—Management (evidence but for more than 10 years ago). Code 3—Managed (within the last 10 years). Code 9—Unknown.

• Code_manage_type_bd Code 1—High forest—Femelschlag. Code 2—High–Small groups. Code 3—High forest (uneven aged)—Plenterwald. Code 4—High forest (other). Code 5—Young/Medium forest (under development to high forest). Code 6—Coppice without standards. Code 7—Coppice with standards. Code 8—Other.

• Code_dw_rem Removal of coarse woody debris. Code 1—Yes, all stems and main branches have been removed. Code 2—Yes, stems and main branches have been removed. Code 3—No, stems and main branches are lying in the forest. Code 4—Partly, some stems and main branches have been removed, others still present. Code 5—Unknown. Code 6—Introduced. Code 7—Presence of accumulation (branches have been stacked in piles or in rows).

• Code_treemix Pattern of tree mixture. Code 1—Intimate (different tree species are mixed throughout the stand). Code 2—Non-intimate (different trees occur in clusters). Code 3—No mixture.

• Code_meanage_bd mean age of stand. Code 1—0–20 years. Code 2—21–40 years. Code 3—41–60 years. Code 4—61–80 years. Code 5—81–100 years. Code 6—101–120 years. Code 7—> 120 years. Code 8—Irregular stands. Code 9—Unknown.

• Code_fencing fancing of the plot. Code 1—Fenced. Code 2—Not Fenced. Code 3—Fenced in parts.

• Code_forest_type_bd code in accordance with EEA (2006).

Specific attributes to DBH dataset:

• tree_number number that identified the tree inside each plots;

• dw_dbh values of diameters (cm);

• code_tree_status Code 1—standing living tree. Code 2—standing dead tree. Code 3—lying dead tree;

• code_tree_species number that identifies the tree species;

• quality attribute to filter data availability. Code 1—Fields holding "diameter”, "code_tree_status” and "code_tree_species” (D > 10 cm). Code 2—Fields holding "diameter” , "code_tree_species” and does not contain "code_tree_status”(D > 10 cm). Code 3—Fields holding "diameter”, "code_tree_status” and does not contain "code_tree_species” (D > 10 cm). Code 4—Fields holding "diameter”, "code_tree_status” and "code_tree_species” (3 $\le$ D $\le$ 10 cm). Code 5—Fields holding "diameter”, "code_tree_species” and does not contain "code_tree_status” (3 $\le$ D $\le$ 10 cm). Code 6—Fields holding "diameter”, "code_tree_status” and does not contain "code_tree_species” (3 $\le$ D $\le$ 10 cm). Code 999—Unclassified or incorrect data;

• code_decay deadwood decomposition is assigned in 5 decay classes according to Hunter (1990). Code 1—No evidence of decay. Code 2—Solid wood. Less than 10 % changed structure due to decomposition. The wood is solid at its surface. The wood is attacked only to a very mall degree by wood decomposing organisms. Code 3—Slightly decayed. 10–25% of the wood has a changed structure due to decomposition. This can be assessed by sticking the wood with a harp object. Code 4—Decomposed wood 26–75% of the wood is soft to very soft. Code 5—Very decomposed wood. 76%–100% of the wood is soft.

Specific attributes to deadwood (DWD) dataset:

• deadwood_id number that identified the wood inside each plots;

• dw_type existing classification based on type of deadwood detected. Code 1—Coarse woody debris (D > 10 cm). Includes stems, limbs, branches lying on the ground. Code 2—Fine woody debris (5 cm < D < 10 cm). Includes small wood pieces. Code 3—Snag (height > 1.3 m and DBH > 10 cm). Standing deadwood without branches. Code 4—Stump (height <1.3 m and  D  at cut > 10 cm). Stump is a snag below breast height. Code 5—Other. All cases with values falling outside the above mentioned definitions or undefined. (e.g.: values < 5 cm for diameter with code = 2 or unsolvable code or definition conflicts). Code 9—Special cases. Threshold values, erroneously not defined in the old manual (i.e.: D = 10 cm, D = 5 cm, DBH = 10 cm, height = 1.3 m);

• code_dw_species number that identifies the group of tree species. Code 1—deciduous, code 2—conifer, code 3—unknown;

• diameter values of diameters (cm);

• dw_length values of length of woody debris (m);

• code_decay deadwood decomposition is assigned in 5 decay classes according to Hunter (1990), see DBH dataset code decay;

• quality attribute to filter data availability. Code 1—Fields holding “diameter”, ““dw_length”, “code_dw_species” and “code_decay” (CWD). Code 2—Fields holding “diameter”, “dw_length”, “code_dw_species” and does not contain “code_decay” (CWD). Code 3—Fields holding “diameter”, “code_dw_species”, “code_decay” and does not contain “dw_length” (CWD). Code 4—Fields holding “diameter”, “dw_length”, “code_decay” and does not contain “code_dw_species” (CWD). Code 5—Fields holding “diameter”, “dw_length”, “code_dw_species” and “code_decay” (FWD). Code 6—Fields holding “diameter”, “dw_length”, “code_decay” and does not contain “code_dw_species” (FWD). Code 7—Fields holding “diameter”, “dw_length”, “code_dw_species” and does not contain “code_decay” (FWD). Code 8—Fields holding “diameter”, “code_dw_species”, “code_decay” and does not contain “dw_length” (FWD). Code 999—Unclassified or incorrect data.

Specific attributes to canopy (CAN) dataset:

• code_canopy code that identified the average percentage of canopy cover. Code 1—open sky. Code 2—1–25%. Code 3—25–50%. Code 4—50–75%. Code 5—> 75%;

• n_tree_layer number of distinct tree layer. Code 1—one layer (one dominant tree layer). Code 2—two layers (dominant tree layer plus 1 sublayer). Code 3—three layers (dominant plus two sublayers). Code 4—more than three layers. Code 5—no tree layer;

• n_trees number of trees in the plot;

• quality attribute to filter data availability. Code 1—Fields holding “code_canopy”, “n_tree_layer” and “n_trees”. Code 2—Fields holding “code_canopy”, “n_tree_layer” and does not contain the “n_trees”. Code 3—Fields holding “code_canopy” and does not contain the “n_tree_layer” and “n_trees”. Code 4—Fields holding “code_canopy”, “n_trees” and does not contain the “n_tree_layer”. Code 999—Unclassified or incorrect data.

Specific attributes to ground vegetation (GVG) dataset:

• code_species number that identifies the species;

• code_layer_surface code of layers where vegetation was evaluated. Code 1—tree layer (only ligneous and all climbers) > 5 m height, code 2—shrub layer (only ligneous an all climbers) > 0.5 m height, code 3—herb layer (all non-ligneous and ligneous < 0.5m height), code 4—moss layer (i.e. terricolous bryophytes and lichens), code 5—lower Shrubs, code 6—upper Shrubs;

• cover percentage of coverage of the species;

• quality attribute to filter data availability. Code 1—Fields holding “code_species” and “cover”. Code 2—Fields holding “code_species” and does not contain “cover” and “code_layer_surface”. Code 3—Fields holding “code_species”, “cover” and “code_layer_surface”. Code 4—Fields holding “code_species”, “code_layer_surface” and does not contain “cover”;

• class Field refers to “code_species”. Code S, “code_species” identified the species. Code G, “code_species” identified the genus.

Appendix B

See Figs. 9, 10 and 11).

Fig. 9

Basal area ($\hbox {m}^2$$\hbox {ha}^{-1}$) from the ICP Forests LI-BioDiv dataset

Fig. 10

CAN data available from the ICP Forests LI-BioDiv dataset and canopy cover variation

Fig. 11

Type of GVG data available from the ICP Forests LI-BioDiv dataset