Tree species diversity and above-ground biomass of natural temperate forest: montane versus lowland forest

We studied the relationship between tree-species diversity and the above-ground biomass on an example of two natural Polish forest with different altitiudinal range, plant species pool, vegetation and climatic conditions. The study sought to determine whether: (1) above-ground biomass in natural forests correlates with tree-species diversity irrespective of the kind of forest (montane or lowland), and (2) the relationship in question is negative, (3) the above-ground biomass is greater in montane forests than in lowland ones. Natural forests present in 1 degrees Polish Gorce Mountains (montane forest) alongside comparable data for the 2 degrees world-renowned lowland forest that is present in the Bialowieza National Park. Data were collected within 558 sample plots (200-square-metre). The diameter at breast height of all trees with girths of or exceeding 12 cm was measured. To compute above-ground biomass we calculated dry masses for each tree on the basis of values for dbh and height, next we summed these values for all species present within each plot. The number of tree species on a plot ranged from only one (mainly in spruce stands) to six (in mixed deciduous lowland forest stands). The above-ground accumulated biomass ranged from 6 to 1155 (average 251+/-13) t ha(-1) within the lowland forest, and from 2 to 849 (average 242+/-8) t ha(-1) within the montane forest. We concluded that there was a humped-back shaped relationship between tree-species diversity and above ground biomass in both lowland and montane natural forests.