Chemical and morphological indication of the state of lodgepole pine and scots pine in restored oil shale opencast mining areas in Estonia

Abstract

Experimental comparative investigations of lodgepole pine (Pinus conforta) and Scots pine (Pinus sylvestris) plantations were carried out on exhausted oil shale opencast sites in Estonia, with the aim to assess the perspectives to avoid monocultures and to broaden the species list in the recultivation of areas destroyed by mining. The levelled detritus of the Narva opencast (59°15' N, 27°48' E) is characterized by rather extreme growth conditions for conifers: very alkaline (pH > 8.0) and stony substrate, lack of N in soil, destroyed water regime etc. The concentrations of nutrients vary in the growth substrate between plots and under different species. The needles of Scots pine contain more P, K, Ca than the needles of lodgepole pine. Comparison of the nutrient composition of two conifer species in 21-23-year-old plantations showed the deficiency of N, P and K and optimal concentrations of Ca an Mg in needles. Research indicated that lodgepole pine and Scots pine differ in their needle and shoot biomass as lodgepole pine formed longer and heavier needles and shorter and thicker shoots than Scots pine. Regardless of unfavourable soil conditions a good growth of stands have developed on levelled opencasts. From a practical point of view and taking into account the aim of the present study, besides the native Scots pine lodgepole pine from the list of introduced tree species for recultivation of oil shale opencast mining areas may be promising. © 2006 Estonian Academy Publishers.