Measurement data from sample plots characterizing three development stages of a subalpine spruce forest and describing the bird assemblages associated with them.

The paper presents data on tree stands located in a subalpine spruce forest in the Gorce National Park (Western Carpathians, Poland) as well as on the birds inhabiting them in the breeding and nonbreeding seasons. The authors conducted stand measurements on a total of twenty-four sample plots, with eight plots established in each of the three studied forest development stages (mature, break-up, and growing-up) representing successive phases of subalpine forest development. The study area designated for each stage was 30 ha. The development properties of each study area resulted from both biotic and abiotic factors. Tree stands were characterized in terms of the tree layer, saplings, and deadwood. The types of deadwood measured were: standing entire dead trees, snags, stumps, and downed deadwood. In the case of birds, the presented data include species composition and pair density in the breeding season and individual bird density in the nonbreeding season. The authors used these data in a paper [1] examining the relationship between forest structural indicators and bird diversity in the three forest development stages. Other researchers can also utilize these data for the purpose of comparison with other areas representing similar forest communities or for studies on stand dynamics, especially in the face of climate change which may substantially affect those phenomena. Furthermore, the presented data may be useful in studies concerning the abundance and dynamics of bird assemblages and other organisms associated with the subalpine zone as well as in research devoted to the diversity of ecological niches. Such investigations may lay foundations for developing conservation guidelines for the ecosystems in question.