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Dive into the research topics where Iskandar Z. Siregar is active.

Publication


Featured researches published by Iskandar Z. Siregar.


Philosophical Transactions of the Royal Society B | 2016

Ecological and socio-economic functions across tropical land use systems after rainforest conversion

Jochen Drescher; Katja Rembold; Kara Allen; Philip Beckschäfer; Damayanti Buchori; Yann Clough; Heiko Faust; Anas Miftah Fauzi; Dodo Gunawan; Dietrich Hertel; Bambang Irawan; I Nengah Surati Jaya; Bernhard Klarner; Christoph Kleinn; Alexander Knohl; Martyna M. Kotowska; Valentyna Krashevska; Vijesh V. Krishna; Christoph Leuschner; Wolfram Lorenz; Ana Meijide; Dian Melati; Miki Nomura; César Pérez-Cruzado; Matin Qaim; Iskandar Z. Siregar; Stefanie Steinebach; Aiyen Tjoa; Teja Tscharntke; Barbara Wick

Tropical lowland rainforests are increasingly threatened by the expansion of agriculture and the extraction of natural resources. In Jambi Province, Indonesia, the interdisciplinary EFForTS project focuses on the ecological and socio-economic dimensions of rainforest conversion to jungle rubber agroforests and monoculture plantations of rubber and oil palm. Our data confirm that rainforest transformation and land use intensification lead to substantial losses in biodiversity and related ecosystem functions, such as decreased above- and below-ground carbon stocks. Owing to rapid step-wise transformation from forests to agroforests to monoculture plantations and renewal of each plantation type every few decades, the converted land use systems are continuously dynamic, thus hampering the adaptation of animal and plant communities. On the other hand, agricultural rainforest transformation systems provide increased income and access to education, especially for migrant smallholders. Jungle rubber and rubber monocultures are associated with higher financial land productivity but lower financial labour productivity compared to oil palm, which influences crop choice: smallholders that are labour-scarce would prefer oil palm while land-scarce smallholders would prefer rubber. Collecting long-term data in an interdisciplinary context enables us to provide decision-makers and stakeholders with scientific insights to facilitate the reconciliation between economic interests and ecological sustainability in tropical agricultural landscapes.


Tree Genetics & Genomes | 2006

Genetic diversity within and among populations of Shorea leprosula Miq. and Shorea parvifolia Dyer (Dipterocarpaceae) in Indonesia detected by AFLPs

Cui-Ping Cao; Reiner Finkeldey; Iskandar Z. Siregar; Ulfah J. Siregar; Oliver Gailing

The genetic diversity within and among populations of Shorea leprosula and Shorea parvifolia from Indonesia was investigated using amplified fragment length polymorphisms (AFLPs). The results indicated that S. leprosula is genetically more variable than S. parvifolia. At the population level, a higher level of genetic diversity was revealed for S. leprosula with a percentage of polymorphic loci (PPLp) of 53.32% and an expected heterozygosity (Hep) of 0.16 in comparison with S. parvifolia showing PPLp of 51.79% and Hep of 0.14. At the species level, S. leprosula showed PPLs of 92.86% and Hes of 0.21, while S. parvifolia showed PPLs of 85.71% and Hes of 0.21. Genetic differentiation (Gst) indicated that 25 and 31% of total genetic diversity in S. leprosula and S. parvifolia, respectively, were attributed to the differences among populations. An analysis of molecular variance (AMOVA) at two hierarchical levels exhibited that most genetic variation resided within populations with proportion of 70.2% for S. leprosula and 66.2% for S. parvifolia. The AMOVA at three hierarchical levels performed for S. leprosula and S. parvifolia together revealed that the genetic difference between the two species was remarkably higher with a proportion of 44.1% than the differences within and among populations (38.1 and 17.8%, respectively). The genetic differentiation between islands was significant for S. leprosula but not for S. parvifolia. The observed genetic diversity agreed with the life history traits of Shorea species. Highly differentiating individual AFLP markers were found for each species, which will serve as diagnostic markers for the identification of wood of different species, from different islands and regions.


Ecology and Evolution | 2012

Population structure and demographic history of a tropical lowland rainforest tree species Shorea parvifolia (Dipterocarpaceae) from Southeastern Asia

Hiroko Iwanaga; Kosuke M. Teshima; Ismael A. Khatab; Nobuyuki Inomata; Reiner Finkeldey; Iskandar Z. Siregar; Ulfah J. Siregar; Alfred E. Szmidt

Distribution of tropical rainforests in Southeastern Asia has changed over geo-logical time scale, due to movement of tectonic plates and/or global climatic changes. Shorea parvifolia is one of the most common tropical lowland rainforest tree species in Southeastern Asia. To infer population structure and demographic history of S. parvifolia, as indicators of temporal changes in the distribution and extent of tropical rainforest in this region, we studied levels and patterns of nucleotide polymorphism in the following five nuclear gene regions: GapC, GBSSI, PgiC, SBE2, and SODH. Seven populations from peninsular Malaysia, Sumatra, and eastern Borneo were included in the analyses. STRUCTURE analysis revealed that the investigated populations are divided into two groups: Sumatra-Malay and Borneo. Furthermore, each group contained one admixed population. Under isolation with migration model, divergence of the two groups was estimated to occur between late Pliocene (2.6 MYA) and middle Pleistocene (0.7 MYA). The log-likelihood ratio tests of several demographic models strongly supported model with population expansion and low level of migration after divergence of the Sumatra-Malay and Borneo groups. The inferred demographic history of S. parvifolia suggested the presence of a scarcely forested land bridge on the Sunda Shelf during glacial periods in the Pleistocene and predominance of tropical lowland rainforest at least in Sumatra and eastern Borneo.


Tree Genetics & Genomes | 2009

Genetic variation in nine Shorea species (Dipterocarpaceae) in Indonesia revealed by AFLPs

Cui-Ping Cao; Oliver Gailing; Iskandar Z. Siregar; Ulfah J. Siregar; Reiner Finkeldey

Shorea is the largest and most important genus of the Dipterocarpaceae. The genetic diversity and structure of nine Shorea species from two different locations, namely Nanjak Makmur in Sumatra and Sumalindo in Borneo, were evaluated using amplified fragment length polymorphism (AFLP) markers. A total of 274 trees were investigated at 85 polymorphic AFLP loci. Levels of genetic diversity of these species ranged from


Journal of Plant Research | 2006

Genetic variation at AFLPs for the Dipterocarpaceae and its relation to molecular phylogenies and taxonomic subdivisions

Cui-Ping Cao; Oliver Gailing; Iskandar Z. Siregar; Sapto Indrioko; Æ Reiner Finkeldey


Archive | 2012

Incorporating Social and Natural Science in the Restoration of an Indonesian Conservation Forest: A Case Study from Jambi

Ulfah J. Siregar; Iskandar Z. Siregar; S. Wilarso Budi; Yulius Hero; Didik Suharjito; Hardjanto

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Journal of Forestry Research | 2018

Tree growth performance and estimation of wood quality in plantation trials for Maesopsis eminii and Shorea spp.

Lina Karlinasari; Suhada Andini; Descarlo Worabai; Prijanto Pamungkas; Sri Wilarso Budi; Iskandar Z. Siregar


Jurnal Perbenihan Tanaman Hutan | 2017

Morphological Diversity of Fruits, Seeds and Seedlings of Pongamia (Pongamia pinnata (L.) Pierre) in Java Island

Nfn Supriyanto; Iskandar Z. Siregar; Ani Suryani; Aam Aminah; Dede J. Sudrajat

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Jurnal Perbenihan Tanaman Hutan | 2016

MORFOLOGI , ANATOMI DAN KANDUNGAN KIMIA BENIH MINDI DARI BERBAGAI ASAL BENIH

Yulianti Bramasto; Nurheni Wijayanto; Iskandar Z. Siregar


Journal of the Korean wood science and technology | 2016

Morphological and Anatomical Evaluation of Grafted Pinus merkusii

Arida Susilowati; Apri Heri Iswanto; Imam Wahyudi; Supriyanto Supriyanto; Iskandar Z. Siregar

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Collaboration


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Ulfah J. Siregar

Bogor Agricultural University

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Dede J. Sudrajat

Bogor Agricultural University

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R Sri Wilarso Budi

Bogor Agricultural University

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Imam Wahyudi

Bogor Agricultural University

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Irdika Mansur

Bogor Agricultural University

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Supriyanto Supriyanto

Bogor Agricultural University

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Tedi Yunanto

Bogor Agricultural University

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Endah Retno Palupi

Bogor Agricultural University

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Nurul Khumaida

Bogor Agricultural University

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Anas Miftah Fauzi

Bogor Agricultural University

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