Forest habitat types in the State Forests and their age structure in the years 2009-2012

The dataset contains data illustrating the area occupied by various types in the State Forests and their age structure over the years 2009-2012. It should be noted that this only concerns forests managed by the State Forests National Forest Holding. The average age is determined as a weighted average, with the area in individual age classes and subclasses taken as the weight. The term forest area refers to the area of forests excluding land related to forest management. The main source of information for the study is the Forest Data Bank (www.bdl.lasy.gov.pl).
Data Structure
Each row contains the following columns:

Year - Data year
Typ_siedliskowy_lasu - Forest site type (code)
Powierzchnia_ha - Area in hectares
Powierzchnia_procent - Area as percentage of total area
Niezalesione_procent - Percentage of unforested forest land
Klasa_I_procent to Klasa_VII_procent - Percentage share of individual age classes
KO_KDO_BP_procent - Percentage for KO, KDO, BP categories
Zalesionych_razem_procent - Total forested percentage
Razem_procent - Total percentage (sum)

Legend of Forest Site Types:

Bs - Dry Pine Forest (Bór suchy)
Bśw - Fresh Pine Forest (Bór świeży)
Bw - Moist Pine Forest (Bór wilgotny)
Bb - Bog Pine Forest (Bór bagienny)
Lśw - Fresh Deciduous Forest (Las świeży)
Lw - Moist Deciduous Forest (Las wilgotny)
Ol - Alder Forest (Ols)
Lt - Riparian Forest (Las łęgowy)
Lwyż - Upland Forest (Las wyżynny)
Ltwyż - Upland Riparian Forest (Las łęgowy wyżynny)

Legend of Age Classes:

I-VII - Forest age classes (I = youngest stands, VII+ = oldest)
KO, KDO, BP - Shrub stands, bushy stands and pioneer birch

Summary:
Total number of records: 36 rowsPeriod: 2009-2012Number of site types: 10 different types
Largest areas according to 2012:

Fresh Pine Forest (Bśw): 1,433,387 ha (20.7%)
Alder Forest (Ol): 1,180,863 ha (17.1%)
Riparian Forest (Lt): 1,116,636 ha (16.1%)
Fresh Deciduous Forest (Lśw): 677,556 ha (9.8%)
Moist Deciduous Forest (Lw): 330,240 ha (4.8%)

Time trends:

Most forest site types show stable areas over time
Small fluctuations in age class structure indicate natural forest stand dynamics
Percentage of unforested areas remains at low levels (0.2-8.9%)