Regeneration of the forest after logging at Kintap, South Kalimantan, Indonesia.

Abstract

A study on tlie regeneration of the forest after logging was conducted in tlie Hutan Kintap concession. South Kalimantan. Indonesia. The study began in 1991, and nineteen 0.2S lia plots were set up in a total of six blocks Block A was a newly logged forest and had five plots, and Blocks B - D were in forest which had been logged in 1979. Block B (five plots) had received no silvicultural treatment. Block C (fi\e plots) and D (one plot) had been lightly tliiimed after felling and Block C received a further thinning treatment. Block E (one plot) had been heavily tliimted. and Block F (2 plots) was an unlogged control. The study included observations on the condition of tlie forest in the plots, the growth rate of the remaining trees, seedlings and saplings, and the size of the soil seed banks and seed rain. It was completed in 1996. Tlie average aimual precipitation in tlie study area was about 3000 mm, the average temperature recorded in Pelaihari (60 km from tlie study site) ranged between 26.4° C and 27.6° C, humidity between 76 % and 87 and irradiation between 35 % and 77 % sunsliinc hours (between 0800 and 1600), Tlie topograph> was undulating with an altitude of 10 - 200 m above sea level. A soil survey revealed mainly ultisols but there were gleyed areas and some lithosols. Soil particles were dominated by clay with pH’s ranging between 4.8 and 6 I. available-P between 0.1 and 5.9 pg g ' , total P between 92 and 503 pg g ', and organic C. CEC and the sum of e.xchangeablc cations all relatively high. In all 19 plots the Dipterocarpaceae were the leading family in terms of number of indi\ iduals and basiil area There were at least 305 species of tree (> 10 cm dbh) included in 49 families. Growth rates in the plots \ aricd among Blocks and among plots of tl\e same Block, ranging from 0.31 to 0.57 nr ha 'year ' depending among other factors on tlie site condition and species composition. Liberation treatment in Block C resulted in a liigher increment rate than in Blocks A and B, the difference however was not significant. Dipterocarps had the highest increment in the study area. Mortality within tlie study sites ranged from 1.15 to 2.70 % year ' The density of seedlings varied within the study sites, and averaged 47000 ha"' to 121000 ha''. Tlie mean height growth per Block was from 2.9 cm year ' to 10.5 cm year '. Seedling mortality ranged from 16 to 37 % year"', and declined with height class. Tlie density of saplings ranged from 68(K) ha ' to 7700 ha ' and the\ had a diameter growth of 0.8 nun year ' to 2.2 nun year ', and a height growth of 12.6 cm year ' to 21.8 cm year"' Tlte size of seed banks varied greatly among plots, ranging from 73 m'* to 1084 m'-. and the number of identified species varied from 10 to 29 per plot. Pioneers contributed most to the seed banks both in numbers of species and individuals. Seed fall was 4534 (collected in traps with a total area of 57 nr), with the pc;ik occurring in Febniao' - March 1992 (45 Vo). Tlte heavy seed rain in Febnmry - March 1992 followed a mast flowering and fruiting in November - December 1991. Dipterocarp seeds contributed 847 seeds (15 m') from 12 species and 3 genera. Given llic condition of the logged-over forest of the study sites, the forest rccot ery will take up to 50 t ears. Sufficient seedlings and saplings and the productivity of the remaining stands as indicated by the seed fall dunng a mast fniiting ensure the regeneration of tlie forest after logging. Unfortunately the condition of the logged-over forests were very much worse outside the study area, and no predictions can be made of the rccovert time or even if recovery w ill ever occur over most of the concessionary area.