Evolution of endemismon a young tropical mountain

Tropical mountains are hot spots of biodiversity and endemism1–3, but the evolutionary origins of their unique biotas are poorly understood4. In varying degrees, local and regional extinction, long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities5. Also, it is debated whether mountain endemics mostly originate from local lowland taxa, or from lineages that reach the mountain by longrange dispersal from cool localities elsewhere6. Here we investigate the evolutionary routes to endemism by sampling an entire tropical mountain biota on the 4,095-metre-high Mount Kinabalu in Sabah, East Malaysia. We discover that most of its unique biodiversity is younger than the mountain itself (6 million years), and comprises a mix of immigrant pre-adapted lineages and descendants from local lowland ancestors, although substantial shifts from lower to higher vegetation zones in this latter group were rare. These insights could improve forecasts of the likelihood of extinction and ‘evolutionary rescue’7 in montane biodiversity hot spots under climate change scenarios

Komposisi Famili Tingkat Semai dan Sapihan pada Hutan Sekunder Berbeda Umur di Sarawak Malaysia

Kehadiran tingkat semai dan sapihan sebagai sumber regenerasi pertumbuhan dan perkembangan hutan merupakan hal yang sangat penting. Informasi tentang kehadiran dan komposisi berdasarkan famili pada tumbuhan tingkat semai dan sapihan pada hutan sekunder berbeda umur di Sarawak masih terbatas. Penelitian ini bertujuan untuk mengetahui kehadiran dan komposisi tumbuhan tingkat semai dan sapihan (DBH<5 cm) pada hutan sekunder umur 10 dan 20 tahun di Sarawak, Malaysia. Seluruh semai dan sapihan dengan DBH<5 cm pada plot-plot penelitian berukuran 1 hektar masing-masing pada hutan sekunder umur 10 dan  20 tahun disurvei dan dicatat. Pada hutan sekunder umur 10 tahun, tercatat 3.092 individu semai dan sapihan yang termasuk dalam 55 famili. Terdapat 2.352 semai dan sapihan yang termasuk dalam 46 famili di hutan sekunder umur 20 tahun. Kehadiran dan komposisi semai dan sapihan berdasarkan famili merupakan informasi penting untuk memprediksi potensi permudaan alami yang terdapat di hutan sekunder

The diameter increment of selected tree species in a secondary tropical forest in Sarawak, malaysia

The diameter at breast height (DBH) increments of dominant tree species in a secondary forest can determine forest growth in the area. This study was conducted to investigate the DBH increments of the nine dominant tree species in a secondary tropical forest. A total number of 180 trees representing nine species, seven genera, and six families were selected for the assessment of DBH increments during two years of study. Those nine species, namely: Acacia mangium Willd. (2.33 cm year-1), Endospermum diadenum (Miq.) Airy Shaw (1.05 cm year-1), Cratoxylum arborescens Blume. (0.96 cm year-1), Vernonia arborea Buch. Ham. (0.96 cm year-1), and Cratoxylum glaucum Korth. (0.80 cm year-1) had shown a high growth rate during the assessment, while the other four species such as Macaranga gigantea Mull. Arg., Macaranga triloba Mull. Arg., Euodia glabra (Bl.) Bl., and Vitex pubescens Vahl. had 0.53, 0.48, 0.37, and 0.30 cm year-1 in DBH increments, respectively. The average DBH increments for the entire selected species was 0.86 cm year-1 for periodic measurement and 0.75 cm year-1 for monthly measurement. This information is needed in order to understand the succession process in the secondary forests. It is important for the selection of the suitable species in a reforestation and a rehabilitation projects