Protected forest areas contain many different habitats in Estonia, including old–growth remnant structures and various features originating from semi-natural woodlands (e.g. former pastures). Dynamics of habitats changes with the change of management regime of these ecosystems. EU Natura 2000 network of protected sites was formed in Estonia in 2004 resulting drastic change of the management of selected new protected areas. Species composition and structural and functional qualities of two forest habitat types – Fennoskandian herb-rich forests with Picea abies and Western taiga (Habitats Directive habitat types 9050 and 9010 respectively) – are analyzed in this study. The study is based on sample plots from the Estonian Network of Forest Research Plots measured in 2015-2016 and located in protected areas. Oxalis, Vaccinium-myrtillus, Vaccinium vitis-idaea forest site types are included for assessment of species diversity, tree structure and coarse wood debris (CWD).
Results/Conclusions
The results reflect the changes in habitat type and habitat quality in the Natura 2000 network. Forest ecosystem composition and quality assessment divided 100 measured plots in four habitat representativeness classes: A-old-growth, B- good, C-average and D-potential stand. Species inventory results in these classes showed the highest average Shannon index (H) was in A class (vascular plants H=2.32, mosses H=1.75, lichens H=3.56), but polypore fungi showed opposite trend and the highest index scores were in C class (H=1.58). According to Multi-response permutation procedure (MRPP) analysis most of the species didn`t have any difference between representativeness classes (vascular plants p=0.09; T=-1.42; lichens p=0.51, T=0.18; polypore fungi p=0.44, T=0.19). The only difference occurred with mosses where the A and B classes highlighted from others (p=0.04).
For CDW assessment we divided laying down trees to five decomposable stages: from 1 being the hardest and 5 most decomposed from 1.3 meters from the stump side. The bigger amount of CDW 210-294 m3 occurred in first (1-2 stages) and smaller amount CDW 57-65 m3 in the following stages. The most common CDW species were Norway spruce 49% and Scots pine 18% along with aspen (Populus tremula) 3,4%, birch (Betula pendula and B.bubesens) 7,5%, black alder (Alnus glutinosa) 0,3% and unidentified species 22,5%.The highest amount (m3/ha) of CWD was as expected in A class and dropped along with habitat representativeness.
We conclude that unmanaged areas that develop differently from previously assumed trajectories should apply habitat management and restoration treatments to meet conservation objectives.