Untersuchungen zur genetischen Variation von Teak (Tectona grandis Linn. f.) in Myanmar als Grundlage für die Erhaltung und nachhaltige Nutzung genetischer Ressourcen

Teak (Tectona grandis) ist eine hochwertige tropische Baumart und natürlich in Indien, Laos, Myanmar und Thailand verbreitet. Mithilfe von 10 polymorphen nukleären Mikrosatelliten- (SSRs) and 71 AFLP-Markern (Amplified Fragment Length Polymorphisms) wurde die genetische Variation in natürlichen Teakpopulationen in Myanmar untersucht. In bewirtschafteten und unbewirtschafteten Populationen in jeweils vier Regionen im Norden und Süden Myanmars wurden adulte Bäume und ihre Verjüngung sowie in zwei Plantagen in Benin adulte Bäume beprobt. Insgesamt wurden 1667 Proben mit SSRs und 1573 Proben mit AFLPs untersucht. Die genetische Diversität in den Teakpopulationen ist generell hoch und es gibt keine signifikanten Unterschiede zwischen den Bewirtschaftungsformen sowie zwischen den Adulten und der Verjüngung. Die Populationen Myanmars weisen mit den SSR-Markern eine niedrigere Diversität auf als die Populationen in Benin und di

Recovery Process of Fallow Vegetation in the Traditional Karen Swidden Cultivation System in the Bago Mountain Range, Myanmar (<Special Issue>Ecological Resource Use and Social Change in the Minority Regions of Myanmar)

Forests in Myanmar have a long history of teak (Tectona grandis Linn.) production, which can be traced back to the age of the English rule in the 19th century, when forests in Myanmar were categorized into those for timber production and those for other uses. Many farmers such as the Karen people, who were swidden cultivators, inhabited the forests. Therefore, the government established the "Karen Area" in the late 19th century, permitting swidden cultivation (shifting cultivation) for their self consumption. Short cultivation, long fallow swidden cultivation has been continued for over 100 years in the areas. We surveyed fallow vegetation and total carbon and nitrogen after swidden cultivation by Karen people in the Bago mountain range and compared with those in natural teak forests under selective logging systems. We set 9 circular plots 20 m in radius at fallow stands of various ages. Trees were identified and measured by diameter at breast height (DBH). Surface soil was sampled at 0–5 cm.The amounts of total carbon and nitrogen in soils varied among the plots, but no stand age dependency was observed. Grass and herb species such as Chromolaena odoratum and Thysanolaena maxima were dominant and comprised the maximum biomass in 1- and 2-year fallows. Bamboo species such as Bambusa polymorpha and Bambusa tulda rapidly recovered after grass and herb species, and the bamboo biomass in the 5-year fallow was nearly equivalent to that in over-40-years fallows. Tree species recovered to nearly the same biomass level as that of bamboos in the 10-year fallow, and further facilitated the increase in the above-ground biomass. Xylia xylocarpa was the most common tree species while species such as T. grandis might be excluded from the fallow vegetation cycle. On the whole, swidden cultivation with a short cultivation period of 1 year and over 12-year fallows maintained sufficient fallow vegetation recovery to sustain continuous swidden cultivation in the Bago mountain range

Structure and Composition of a Teak-bearing Forest under the Myanmar Selection System (<Special Issue>Ecological Resource Use and Social Change in the Minority Regions of Myanmar)

The impact of selective logging on a natural teak-bearing forest was examined in the Kabaung Reserve Forest, Bago Division, Myanmar. The examined forest was under selective logging from 2001 to 2002. In the area, a bamboo, Cephalostachyum pergracile, flowered in 2002 and then died back in 2003. Thirty-seven circular plots of 20 m radius (4.65 ha in total) were set in the forest and 837 tree stems (DBH ≥ 10 cm) and 1809 bamboo clumps were enumerated in the plots. The average basal area density was 30.2 m2 ha–1, and bamboo accounted for 33% of the basal area. Trees with a DBH ≥ 10 cm and 60 cm were 180 ha–1 and 10.1 ha–1, respectively. The 37 plots were classified into four stand types, Tectona grandis type, Xylia xylocarpa type, Bambusa polymorpha type, and Dipterocarpus alatus type. The felling operation was conducted only in 10 of the 37 plots sampled and 11.7% of the basal area of trees over 10 cm DBH was removed during the logging. The percentage of extracted basal area (%-extracted) varied from 6.9 to 51.0% among the 10 plots. The highest %-extracted was recorded in D. alatus stands (38.7–51.0%), while the %-extracted in the other stand types was rather smaller (6.9–36.5%). As a result, the impact of harvesting was minimal except in the case of D. alatus stands. Teak was most abundant in the sapling layer (427 ha–1). The combination of the logging operation and bamboo dieback enabled the sapling bank to accelerate height growth and to enter the pole size class, while logging or bamboo dieback alone had no significant effect. In the bamboo dieback sites with the logging operation, 84–96% of tree saplings overtopped bamboo seedlings, but the value decreased to between 53 and 56% in non-logged stands. The combination of logging operations and bamboo flowering thus had remarkable effects on the sapling banks of tree species and enhanced recruitment of pole-size trees

Genetic diversity and structure of teak (Tectona grandis L. f.) and dahat (Tectona hamiltoniana Wall.) based on chloroplast microsatellites and Amplified Fragment Length Polymorphism markers

© 2015, Springer Science+Business Media Dordrecht. Teak (Tectona grandis L. f.) is a tropical forest tree species naturally occurring in India, Laos, Myanmar and Thailand. The closely related dahat (Tectona hamiltoniana Wall.) is an endemic tree species confined to Myanmar. Two chloroplast Simple Sequence Repeat (cpSSR) and sixty-nine Amplified Fragment Length Polymorphism (AFLP) markers were applied to assess patterns of genetic variation in four T. grandis and three T. hamiltoniana populations in Myanmar. The cpSSR analysis confirmed a clear genetic differentiation between species, revealing a single haplotype (H1) in T. grandis, while the three T. hamiltoniana populations were fixed on different haplotypes (H2 or H3). AFLP analysis revealed that genetic diversity varied between species, showing a slightly higher variation in T. grandis than in T. hamiltoniana. The T. hamiltoniana populations showed similar levels of genetic variation, while parameters varied considerably in T. grandis populations. Analyses of Molecular Variance revealed significant genetic differentiation between the two species (38.4 %, p \u3c 0.05) and among populations within species. Genetic variation mainly resided within populations. Significant pairwise genetic differentiation (pairwise FST) was detected between most populations (p \u3c 0.05). An Unweighted Pair Group Method with Arithmetic Mean dendrogram based on Nei’s genetic distances revealed a clear genetic differentiation between species. Diagnostic AFLP markers with complete or nearly complete differentiation between species and complete differentiation at cpDNA markers indicated strong phylogenetic divergence between teak and dahat

Data from: Genetic resources of teak (Tectona grandis Linn. f.) – strong genetic structure among natural populations

Twenty-nine provenances of teak (Tectona grandis Linn. f.) representing the full natural distribution range of the species were genotyped with microsatellite DNA markers to analyse genetic diversity and population genetic structure. Provenances originating from the semi-moist east coast of India had the highest genetic diversity while provenances from Laos showed the lowest. In the eastern part of the natural distribution area, comprising Myanmar, Thailand and Laos, there was a strong clinal decrease in genetic diversity the further east the provenance was located. Overall, the pattern of genetic diversity supports the hypothesis that teak has its centre of origin in India, from where it spread eastwards. The analysis of molecular variance (AMOVA) gave an overall highly significant F st value of 0.227—population pairwise F st values were in the range 0.01–0.48. Applying the G″st differentiation parameter, the estimated overall differentiation was 0.632, implying a strong genetic structure among populations. A neighbour-joining (NJ) tree, using the pairwise population matrix of G″st values as input, contained three distinct groups: (1) the eight provenances from Thailand and Laos, (2) the Indian provenances from the dry interior and the moist west coast and (3) the provenances from northern Myanmar. The provenances from southern Myanmar were placed close to the root of the tree together with the three provenances from the semi-moist east coast of India. A Bayesian cluster analysis using the STRUCTURE software gave very similar results, with three main clusters, each containing two sub-clusters, while Bayesian cluster analysis in the Geneland software, exploiting the spatial coordinates of the provenances, resulted in five clusters in accordance with the former results. The implications of the findings for conservation and use of genetic resources of the species are discussed