Preliminary studies of micropropagation of Hopea odorata,a dipterocarp tree

Plantlet development from in vitro cultures of Hopea odorato Roxb. is described. Embryos excised from seeds and cultured on Gamborg's B5 or modified Murashige and Skoog (MS) medium with benzyladenine (BA, 2.2–22.2 M) produced axillary shoots at cotyledonary and/or stem nodes. Shoot production was greatest in germinated embryos on modified MS medium with 8.9 M BA. Excised axillary shoots formed few buds when cultured on medium with BA and limited root development occurred on Woody Plant Medium with naphthaleneacetic acid. Nodal explants from aseptically grown plantlets sprouted axillary shoots in modified MS medium with BA.Abbreviations BA 6-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IBA indolebutyric acid - NAA naphthaleneacetic acid - PVPP polyvinylpolypyrrolidone     

Soil Nutrients Limit Fine Litter Production and Tree Growth in Mature Lowland Forest of Southwestern Borneo

Efforts to improve models of terrestrial productivity and to understand the function of tropical forests in global carbon cycles require a mechanistic understanding of spatial variation in aboveground net primary productivity (ANPP) across tropical landscapes. To help derive such an understanding for Borneo, we monitored aboveground fine litterfall, woody biomass increment and ANPP (their sum) in mature forest over 29 months across a soil nutrient gradient in southwestern Kalimantan. In 30 (0.07 ha) plots stratified throughout the watershed (∼340 ha, 8–190 m a.s.l.), we measured productivity and tested its relationship with 27 soil parameters. ANPP across the study area was among the highest reported for mature lowland tropical forests. Aboveground fine litterfall ranged from 5.1 to 11.0 Mg ha⁻¹ year⁻¹ and averaged 7.7 ± 0.4 (mean ± 95 C.I.). Woody biomass increment ranged from 5.8 to 23.6 Mg ha⁻¹ year⁻¹ and averaged 12.0 ± 2.0. Growth of large trees (≥60 cm dbh) contributed 38–82% of plot-wide biomass increment and explained 92% of variation among plots. ANPP, the sum of these parameters, ranged from 11.1 to 32.3 Mg ha⁻¹ year⁻¹ and averaged 19.7 ± 2.2. ANPP was weakly related to fine litterfall (r ² = 0.176), but strongly related to growth of large trees at least 60 cm dbh (r ² = 0.848). Adjusted ANPP after accounting for apparent “mature forest bias” in our sampling method was 17.5 ± 1.2 Mg ha⁻¹ year⁻¹.Relating productivity measures to soil parameters showed that spatial patterning in productivity was significantly related to soil nutrients, especially phosphorus (P). Fine litterfall increased strongly with extractable P (r ² = 0.646), but reached an asymptote at moderate P levels, whereas biomass increment (r ² = 0.473) and ANPP (r ² = 0.603) increased linearly across the gradient. Biomass increment of large trees was more frequently and strongly related to nutrients than small trees, suggesting size dependency of tree growth on nutrients. Multiple linear regression confirmed the leading importance of soil P, and identified Ca as a potential co-limiting factor. Our findings strongly suggest that (1) soil nutrients, especially P, limit aboveground productivity in lowland Bornean forests, and (2) these forests play an important, but changing role in carbon cycles, as canopy tree logging alters these terrestrial carbon sinks. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Differential Responses of Dipterocarp Seedlings to Soil Moisture and Microtopography

Niche diversification is prominent among the mechanisms proposed to explain tropical rain forest tree diversity, with many studies focusing on trade‐offs among shade tolerance and growth. Less obvious is the impact of occasional, ephemeral and often minor disturbances on tree seedling survival. We propose that differential tolerances to soil waterlogging can contribute to the distribution of tree seedling communities along microtopographical gradients. We test this hypothesis experimentally by evaluating survival and performance of planted seedlings across microtopographical gradients in a periodically inundated tropical rain forest environment. Survival and relative growth rates were assessed for six Shorea (Dipterocarpaceae) species in Sepilok Forest Reserve (Sabah, Malaysia) over a 2‐yr period, during which seedlings were subjected to two brief flooding events. The species were selected on the basis of soil habitat affinities, with two species being primarily associated with low‐lying alluvial flats subject to inundation, two being associated with non‐flooded mudstone hills, and two species occurring in both habitats. Seedling performance was related to microtopographic elevation within and among plots and to soil moisture among plots. The faster growing species, Shorea argentifolia, Shorea leprosula and Shorea parvifolia, tended to be more vulnerable to high soil moisture in terms of mortality than the three species with lower growth rates. Within plots, soil moisture was inversely correlated with microelevation, and seedlings located at higher microelevations had an increased probability of survival. Microtopographical differences in seedling position could therefore contribute to species assembly processes through differential mortality, particularly in areas subject to minor and ephemeral flooding events.     

龙脑香科植物对丛枝菌根真菌的影响

在天然林地和温室盆栽条件下,比较研究了龙脑香科植物对丛枝菌根(Arbuscular mycorrhizas,AM)真菌孢子密度、相对多度、频度、属的组成、丰度和侵染状况等方面的影响.结果表明,用坡垒作盆栽寄主加富培养后,菌根侵染率、泡囊、丛枝和侵入点都低于原采样植物,以原坡垒土壤中栽植苗木的侵染率为最高,可达20.3%;而以望天树根围土壤栽植的苗木为最低,仅为10.6%;坡垒还不同程度地改变了原采样植物根围土壤中AM真菌孢子的密度、相对多度、频度、属的组成、丰度等.在4种土壤中,栽植坡垒苗木后,AM真菌的孢子密度都有不同程度的增长.采用与原采样相同种类的植物作为AM真菌加富培养的寄主更有利于促进AM真菌的生长发育、保持AM的多样性.     

Occurrence of non-heterocyclic resveratrol tetramer in Vatica chinensis

A resveratrol (Res) tetramer, vaticanol L (1), was isolated from the stem of Vatica chinensis (Dipterocarpaceae). The structure was identified on the basis of spectroscopic evidence and absolute configuration elucidated from circular dichroism data. This is the first report on oligostilbenoids that shows the occurrence of a Res tetramer without a heterocyclic ring. A biogenetic pathway to 1 is proposed.     

Pakaraimaea dipterocarpacea is ectomycorrhizal, indicating an ancient Gondwanaland origin for the ectomycorrhizal habit in Dipterocarpaceae

The consistent association of Paleotropical Dipterocarpaceae with ectomycorrhizal (ECM) fungi suggests that ECM status is an ancestral character in the family. Despite its distinctive morphology, Pakaraimaea dipterocarpacea, a Neotropical Dipterocarpaceae endemic to the Guayana Region, is phylogenetically related to the Paleotropical Dipterocarpaceae. The confirmation of P. dipterocarpacea ECM status would indicate that Paleotropical Dipterocarpaceae and P. dipterocarpacea probably had a common ECM ancestor. Mycorrhizal colonization of P. dipterocarpacea was assessed, and ECMs were recorded using histological and molecular methods. P. dipterocarpacea was highly colonized by typical ECMs, and several ECM fungal taxa belonging to Clavulinaceae, Sebacinaceae, Cortinariaceae and Amanitaceae were identified. This paper provides the first documented evidence of ECM in a neotropical genus of Dipterocarpaceae and indicates that ECMs possibly evolved in Gondwana in ancestors of Dipterocarpaceae before the separation of South America from Africa by the Atlantic, c. 135 million years ago. The observation of Sebacinaceae and Clavulinaceae suggests that broad host range fungi are important components of P. dipterocarpacea ECM communities.     

Wood and bark anatomy of Muntingiaceae: A phylogenetic comparison within Malvales s. l.

Quantitative and qualitative data on wood and bark anatomy are given for Muntingia calabura L. and Dicraspidia donnell-smithii Standley. These data are compared with phylogenetic schemes, based on DNA analysis, in which Muntingiaceae belong to the “dipterocarp clade” within Malvales. The data are consistent with this hypothesis, although Muntingiaceae lack pit vestures in vessels, which are seen in the other malvalean families (Cistaceae, Dipterocarpaceae, Neuradaceae, Sarcolaenaceae, Thymeleaceae), and this may represent a loss of pit vestures. All families of the dipterocarp clade agree with both genera of Muntingiaceae in having tracheids as the imperforate tracheary element type (at least ancestrally), although fiber-tracheids also occur in some Dipterocarpaceae and Thymeleaceae. The large size of some malvalean families (with attendant greater diversity in character states) and a paucity of wood studies in those families make for difficulty in comparison of features such as axial parenchyma and ray types with those of Muntingiaceae; character states of these features are consistent with placement of Muntingiaceae in the dipterocarp clade of Malvales. Banded phloem fibers in bark of Muntingiaceae are much like those of other Malvales. Wood of Muntingiaceae is highly mesomorphic according to quantitative vessel features.     

Microsatellite loci for a tropical emergent tree,Dipterocarpus tempehes V. Sl. (Dipterocarpaceae)

Polymerase chain reaction primers amplifying 10 microsatellite loci for a tropical emergent tree, Dipterocarpus tempehes (Dipterocarpaceae) were developed. The polymorphism was estimated by screening 34 adult trees. The numbers of alleles per locus were from seven to 14 with the average of 10.3. Expected heterozygosity ranged from 0.57 to 0.88 with the average of 0.78. Total exclusion probabilities with the present 10 loci for the first and second parents of seedlings were 0.9962 and 0.9999, respectively. The high level of polymorphism indicates that the present loci are useful for the analysis of pollen movement, seed dispersal and inbreeding depression.     

版纳植物园龙脑香科植物迁地保护成效与应用探讨

龙脑香科植物广泛分布于热带亚洲,被认为是亚洲热带雨林的标志性物种。中国科学院西双版纳热带植物园从建园开始就注重龙脑香科植物的研究、收集与保护,并建立了龙脑香科植物专类园。经过几十年收集,现已成为我国龙脑香科植物重要的保育基地。该文结合历年的引种保育、物候及生长量观测等资料,系统整理了版纳植物园在龙脑香科植物引种保育和研究利用的工作。结果表明:自建园以来,版纳植物园共收集了7属34种龙脑香科植物,国内的有11种,国外的有28种。国内引种种类长势良好,除广西青梅外均能开花结果。国外种类开花结果的有13种。此外,版纳植物园部分龙脑香科植物种子生物学特性、植株抗寒及抗病虫能力的分析,也说明版纳植物园的龙脑香科植物的迁地保护是成功的。该文还结合新的研究成果,对龙脑香科植物在造林、生态恢复等方面的应用进行了探讨,以期为进一步加强该科植物的引种、保育及研发等工作提供参考。