Dataset on stand structure in hemiboreal forests across management histories and stand ages

This dataset compiles detailed representative forest stand structure data from a European hemiboreal forest region; it spans multiple forest types, successional stages, and forest management contexts. It integrates measurements of live trees and dead wood, including fallen trunks, snags (standing dead trees), stumps and fine woody debris (down to 3 mm diameter), together with tree species identity, dimensional attributes, and decay stages. A subset of stands has been surveyed repeatedly, capturing temporal changes in forest structure.

Estonia, hemiboreal forest zone. Field sampling was conducted between 2006 and 2024.

The dataset comprises detailed stand-structure measurements from >600 forest stands, mostly represented by 2-ha plots. It includes most common hemiboreal forest types along gradients of dominant tree species and soil moisture. These range from low-productivity, dry Scots pine-dominated forests to black alder-dominated mobile-water swamps, with particularly strong representation of productive Norway spruce-deciduous mixed forests and drained peatland forests. Stand ages range from a few years post clearcutting to old stands with the dominant tree layer >200 years old. Old stands without signs of management are well represented (98 study stands) and constitute a substantial reference set for naturally developing and old-growth forest conditions in the region. The stands encompass a broad range of silvicultural treatments, including post-clearcut and post retention-cut succession, mature forests with sanitary cutting history, stands subject to precommercial and commercial thinning, and shelterwood cutting. In addition, a subset of stands includes repeated measurements of forest structure following ditch closure (rewetting) as part of a peatland forest restoration experiment.

Live trees, standing dead trunks and stumps were recorded along strip plots (area-based sampling), while downed dead wood items were measured along transects (line-intersect method).

The dataset enables modelling above-ground tree carbon, quantitative assessment of habitat conditions for biodiversity, and analyses of their relationships with forest characteristics. It enables analyses of how specific forest management practices (clearcutting, retention forestry, shelterwood harvest, thinning) affect the stand structure, habitat quality, and carbon stocks. Because the dataset includes geopositioned measurements collected starting from the early 2000s onward, it can be combined with time-matched or contemporary remote sensing data, or with newly collected field data from stands of comparable ages, to assess structural changes in similar forest types over time. Given that hemiboreal forest types share structural features with closed-canopy boreal and northern temperate forests dominated by spruce-pine-deciduous mixtures, the dataset is applicable for regional modelling across approximately ten degrees of latitude, spanning from the Fennoscandian middle-boreal zone to the northern limit of the beech region in mid-Lithuania.