Fig. 4
From: Low-level retention forestry, certification, and biodiversity: case Finland
Numbers of living large-diameter (DBH > 20 cm, solid line) and small-diameter (10–20 cm, dotted line) retention trees and dead trees (DBH > 10 cm or DBH > 20 cm from 2005 onwards, dashed line) (no. of trees per hectare) in 1998–2017 in clearcutting areas of private forests (data: Forestry Centre Tapio 2013, Finnish Forest Centre 2019). The numbers of living large-diameter retention trees have decreased during the monitoring years from the level of the early years of PEFC certification (early 2000s) (Kendall’s rank correlation coefficient rK = − 0.37, p = 0.026), and the numbers of living small-diameter retention trees (rK = 0.52, p = 0.002) and dead retention trees (rK = 0.51, p = 0.002) have increased during the monitoring years. The pooled numbers of all living retention trees (rK = − 0.01, p = 1.0) have remained the same during the monitoring years