Post-logging silvicultural treatments are generally performed to improve yields of the remaining tree species by increasing their growth rate. In this study the effects of silvicultural treatment on the growth rates of commercial (dipterocarps and non-dipterocarps) as well as noncommercial tree species in a tropical forest in West Kalimantan were examined and were compared to a control treatment. Silvicultural treatment applied was liberation of future crop trees from lianas and neighbouring competing trees. Treatments were applied to six plots of 80 m x 80 m each. The plots comprised 64 quadrats of 10 m x 10 m to allow better control of measurements. The treatment and control plots were established 6 years after logging. Effects were measured 2, 4 and 7 years after treatment application. In all observation periods, the growth rates increased with silvicultural treatment. Overall, commercial dipterocarps, commercial non-dipterocarps and non-commercial tree species groups differed in response to silvicultural treatment. The growth rates of commercial tree species in plots that received silvicultural treatment were 62-97% higher than in the control plots. For non-commercial tree species, the increase of growth rates was 20-58%, compared to the control plots. These results indicate that the application of silvicultural treatments after logging could help improve the growth of the residual stands. These provide quantitative information that silvicultural treatments in logged-over forest should be considered as a viable management option and may guide the choice of cutting cycle.

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The dynamics of species composition, stand structure and aboveground biomass were studied over a 4.3-yr period (December 2004-April 2009) in a lowland dipterocarp forest of Samboja, East Kalimantan. This study was conducted in six permanent sample plots (100 m x 100 m each) distributed over an area of 26.5 ha of Samboja Research Forest. All woody plants ≥ 10 cm dbh (diameter at 1.3 m aboveground) were identified. In December 2004, 2.143 trees were measured in the six plots, consisting of 39 families, 82 genera and 111 species. The condition in April 2009 (after 4.3 yr) was: 2,466 trees, 40 families, 86 genera and 123 species. Most species were found in both occasions. Fourteen new species were registered, which contributed to 9.8% of a net addition of the total number of species found in the six plots. Over the 4.3-yr period, there was also an increase of 15.1% in density, 12.9% in basal area, and 11.6% in aboveground biomass, respectively. The density increased from 357 to 411 trees per ha; the basal area increased from 20.09 to 22.67 m 2 ha-1 ; and the aboveground biomass increased from 286.3 to 319.4 ton ha-1. The family Dipterocarpaceae was the richest in species (more than 20 species found in both occasions), followed by Euphorbiaceae, Burseraceae, Fabaceae, and Anacardiaceae (more than five species). Most genera (80%) contained just one species, but Shorea with 13 species was the richest. Four families (Dipterocarpaceae, Fabaceae, Myrtaceae and Lauraceae) contained more than 80% of the aboveground biomass in both occasions (75% of them from Dipterocarpaceae family). The increases in species richness and density did not cause any significant differences in the diversity index and diameter distribution. This condition suggested that forest vegetation of the study site maintains its diversity composition and structural features over the period of study.

The study was aimed to obtain stand structure dynamic model that can be used to estimate yield production in logged-over area. The model can help to develop forest management planning especially for yield regulation. For this purpose, time series data from re-measured permanent sample plots (PSP) in the concession area of PT. Intracawood Manufacturing, East Kalimantan, were used. The PSP have been remeasured 7 times since 10 years ago. The stand represented the distribution of trees by diameter class and species group covering commercial, non-commercial, and all species. In general, the constructed stand structure dynamic models were based on correlation between diameter class and number of trees per hectare. In this study, the models were modified by adding some parameters i.e. the number of trees in diameter class i at the initial measurement, number of trees in diameter class i at time t-1, and time (the measurement year). The resulted models of each species group were: -commercial:where, Ndi t is the number of trees in diameter class i at time t, Ndi t-1 is number of trees in diameter class i at time t-1, Di is the diameter class i, N 0 di is the number of trees in diameter class i at the initial measurement, t is the measurement year since the first measurement. The models have high accuracy level with its coefficient determination more than 0.998 for each models. Stand volume projection showed that the mean annual increment of stand volume for 50 cm up of trees i.e. 2.080 m 3 /ha/year for commercial species; 0.308 m 3 /ha/year for non-commercial species; and 2.372 m 3 /ha/year for all species. ABSTRAKPenelitian ini bertujuan untuk mendapatkan model dinamika struktur tegakan yang dapat digunakan dalam memproyeksi pendugaan hasil di hutan alam bekas tebangan, sehingga diharapkan dapat membantu perencanaan produksi terutama dalam pengaturan hasil. Bahan yang digunakan dalam penelitian ini adalah data pengukuran ulang petak-petak ukur permanen (PUP) yang terdapat di kawasan konsesi HPH PT. Intracawood Manufacturing (Unit Sesayap), Kalimantan Timur. PUP tersebut sudah diukur ulang sebanyak tujuh kali pengukuran dalam waktu 10 tahun. Tegakan yang dijadikan obyek penelitian menggambarkan sebaran pohon berdasarkan kelas diameter dan kelompok jenis, meliputi komersial, non komersial, dan semua jenis. Dalam penelitian ini, dicoba untuk mendapatkan model dinamika struktur tegakan dengan memodifikasi persamaan eksponensial hubungan N dan D dengan menambahkan parameter jumlah pohon pada pengukuran awal, jumlah pohon tahun sebelumnya serta waktu. Model dinamika struktur tegakan yang dihasilkan, antara lain : -Komersial: Ndi dimana, Ndi t adalah jumlah pohon pada kelas diameter i pada waktu t; Ndi t-1 adalah jumlah pohon pada kelas diameter i pada waktu t-1; Di adalah kelas diameter ke i; N 0 di adalah jumlah pohon pada kelas diameter i pada awal pengukuran; t adalah tahun pengukuran. Model dinamika struktur tegakan tersebut mempunyai tingkat ketelitian yang tinggi dengan nilai koefisien determinasi (R 2 ) lebih dari 0,99...