Productivity of Short-Rotation Poplar Crops: A Case Study in the NE of Romania

Abstract

In Romania, the productivity of the new clones of hybrid poplar has not been tested in recent years. This case study aims to fill a gap on the productivity map of the new poplar clones, estimating, by biomass measurements, the productivity of two clones (AF2 and AF8) with different planting densities (from 1333 trees·ha−1 to 2667 trees·ha−1). The short-rotation woody crops (SRWCs) were established in homogeneous conditions, in North-East (NE) Romania and the northern part of Suceava County. Using a specifically developed method, biomass production was estimated using destructive methods, with 190 poplar trees being harvested, measured, and weighed to compute the accumulated biomass for each growing season The biomass production of the crops with 1667 trees·ha−1 planting density highlighted significant differences in productivity in favour of the AF2 clone after five growing seasons. The crops shared similar annual growth patterns, and the stem biomass represents approximately 73–80% of the total biomass of the trees. The second research question concerning planting density influence on productivity showed fluctuations of biomass accumulations at different planting densities (1333 trees ha−1, 1667 trees ha−1 and 2667 trees ha−1) for a 5-year rotation. The outcomes emphasized the influence of the annual weather conditions—primarily the rainfall in May–June—on poplar growth, showing that productivity also depends on the genotype, density and biotic disturbances.