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Funder: Agua Salud Project, Funder: U.S. Department of Energy; Id: http://dx.doi.org/10.13039/100000015, Funder: CAPES; Id: http://dx.doi.org/10.13039/501100002322, Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research-from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non-forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC-BY 4.0 licence and can be access from: https://doi.org/10.5281/zenodo.6637599. To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology-from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle.

Root water uptake depth and its temporal variation are important determinants of tree mortality, resource partitioning and drought resistance; however, their effects on tropical trees remain poorly understood. In this study, we investigated interspecific differences in water uptake depth and its temporal variation using stable isotope analysis and examined the relationships between water uptake depth and aboveground traits in a humid aseasonal tropical rainforest in Borneo. Species-specific differences in water uptake depth were examined for six dominant dipterocarp species. Temporal variation in water uptake depth for various canopy trees was assessed in three periods with different soil moisture conditions. We then examined the relationships between water uptake depth and aboveground traits including wood density, maximum tree height, flowering frequency and growth rate. Dipterocarpus globosus appeared to be more reliant on deep water resources than the other dipterocarp species. Water uptake from the soil layers varied among the three sampling periods. Trees generally utilized deeper soil water during the second driest sampling period, when temperatures were lowest. During the driest and wettest sampling periods, species with higher flowering frequencies tended to preferentially uptake deep soil water. These results suggest that low temperature and soil moisture promote increased deep soil water uptake in the study region. Dynamic relationships between water uptake patterns and aboveground tree traits may be related to resource partitioning among co-existing species.

A considerable extent of interspecific hybridization among dominant canopy dipterocarp species was recently found in a tropical rain forest fragment in Singapore. However, information about the fertility of the hybrids and the growth of their successive hybrids remains limited. We studied the flowering phenology of four dipterocarp species in the genus Shorea (S. curtisii, S. leprosula, S. parvifolia, and S. macroptera) and two hybrids (S. curtisii × S. leprosula and S. leprosula × S. parvifolia) and studied the performances of seedlings reproduced from them. We observed that S. macroptera bloomed first, without overlap with congeneric species, followed by the other Shorea species and the two first filial (F1) hybrids. S. curtisii and S. leprosula, the species forming hybrids are most likely to succeed in this forest, completely overlapped with their hybrids. Fruits collected from the hybrids were viable, and these hybrid seedlings showed greater survival and a higher growth rate than those from pure species under greenhouse conditions. They included various cross types such as a backcross with each parent species. These results may imply that successive hybrids and introgression spontaneously occur among Shorea species. It may be important to consider the risk of hybridization for the management of tropical forests, particularly in degraded tropical rainforests where mechanisms of ecological isolation between closely related species might be altered. Accepted version

Heath forests which are tropical forests on sandy soils are widely distributed in Borneo and provide many ecosystem services, such as carbon storage and non-timber forest products. Over the past several decades, such forests have been disturbed by non-traditional shifting cultivation, which is usually conducted in unsuitable land with short fallow duration. Anthropogenic disturbances in forests growing on sandy soils that have low nutrient retention capacities may promote further reductions in soil fertility. Long-term monitoring of soil nutrients and biomass accumulation is rare in degraded tropical rainforests growing on sandy soils despite the known negative effects of non-traditional shifting cultivation practices on soil fertility, vegetation and biomass recovery, and the growth of trees planted to rehabilitate forests. The objective of the current study was therefore to elucidate changes in soil fertility and biomass recovery potential in degraded forests on sandy soils in Borneo. We monitored soil nutrients and chemical properties in fifty-four 12 × 12 m plots located on different topographical positions along upper and lower slopes. Samples were collected in plots aged 7 and 14 years after abandonment of shifting cultivation. The biomass of secondary forest trees in all plots 12 years after the abandonment was also measured to determine the relationship between biomass accumulation and changes in soil nutrients. We found that soil pH and cation exchange capacity, and the concentrations of most nutrients, including nitrogen, magnesium, and phosphorus, had decreased significantly 7–14 years after abandonment; biomass accumulation in the plots was also limited 12 years after abandonment (

We studied seasonal changes in radiocesium (137Cs) activity and potassium concentrations in current-year leaves and branches of Pinus densiflora (naturally regenerated saplings), Cryptomeria japonica (planted saplings) and Quercus serrata (planted saplings and coppice shoots) in Fukushima, Japan. We collected current-year shoots from 10 individuals of each species over two growing seasons at intervals of 1-4 months, between June 2016 and December 2017. For the deciduous species Q. serrata, we also collected dead leaves that remained attached to branches in December to investigate reabsorption of 137Cs. All collected shoots were divided into leaves and branches, oven-dried, and ground; dry weights of each sample were recorded. 137Cs activity concentrations were measured using a germanium semiconductor detector. Potassium concentrations were quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). Increases in dry weight were observed in both leaves and branches between May/June and August; growth then slowed considerably and virtually ceased after October. Clear seasonal changes in 137Cs activity concentrations were observed in both 2016 and 2017, regardless of tree species. Concentrations were higher in young leaves and branches during May and June, then decreased and changed relatively little from August to winter. Reduced 137Cs activity concentrations in dead leaves of Q. serrata were observed only in December 2017 (approximately 15% lower than in October). This reduction may indicate reabsorption of 137Cs in leaves prior to shedding. The changes in potassium concentrations were similar to those in 137Cs in both years. Potassium concentrations were higher in young leaves than in mature leaf and branch samples collected later in the year. A reduction of about 50% in the potassium concentrations in dead leaves of Q. serrata was also observed in December. A positive relationship between 137Cs and potassium concentrations in leaves and branches was observed in all species, except for planted Q. serrata. This relationship may indicate that 137Cs moves in tree shoots with potassium. Leaf and branch weight correlated negatively with 137Cs and potassium concentrations. Reduced concentrations may indicate dilution of these elements as a result of biomass increases over the growing season. Our results imply that irrespective of species, 137Cs exhibits seasonal variations resulting from dilution; these variations correspond with trends in potassium, with higher levels in young organs and decreased levels in older organs.

To evaluate the distribution of radiocesium (137Cs) among crown positions in trees after the Fukushima Daiichi Nuclear Power Plant accident, we collected foliage and branch samples from different crown positions of four major tree species (Chamaecyparis obtusa, Cryptomeria japonica, Pinus densiflora, and Quercus serrata) from 2011 to 2019 in northeast Japan. We divided the samples into current-year and more than 1-year-old groups (called old foliage and old branches), which sometimes included directly contaminated parts. The 137Cs activity concentration in dry foliage and branches was measured using a germanium semiconductor detector. There were complex differences in the relative 137Cs activity concentration among species and organ types (i.e., foliage and branches) among crown positions. The relative 137Cs activity concentration in current-year foliage was higher in the upper crowns of C. obtusa, but higher in lower crown positions in C. japonica. No differences among crown positions were observed in P. densiflora and Q. serrata. In current-year branches, the relative 137Cs concentration in Q. serrata was similar among crown positions but higher in the upper crown in P. densiflora. The concentrations in old foliage and old branches in all species tended to be higher in the lower crown. The factors causing these interspecific and organ type differences among crown positions may be related to the organ turnover rate, dilution effect due to different growth rates, and potassium distribution within the crown. No year-to-year variation was observed in most foliage and branches in all species, except for current-year branches of Q. serrata, old foliage in C. japonica and P. densiflora, and old branches in P. densiflora. Our long-term data on the interspecific and inter-organ patterns of contamination, focusing on variation among crown positions and year-to-year trends, might help to improve the estimation of 137Cs deposition and dynamics in polluted forest ecosystems.

As climate change progresses, it is becoming more crucial to understand how timber species respond to increased drought frequency and severity. Photosynthetic traits in a 40-year-old clonal Japanese cedar (Cryptomeria japonica) plantation were assessed under artificial drought stress using a roof to exclude rainfall and a control with no exclusion. C. japonica is a commercial tree that is native to Japan and has high growth on mesic sites. The maximum carboxylation rate (Vcmax), maximum electron transfer rate (Jmax), and dark respiration rate (Rd) in current-year shoots in the upper canopy were determined from spring to autumn over two growing seasons. In addition, the photosynthetic rate at light saturation (Pmax), stomatal conductance (gs), and intrinsic water use efficiency (WUEi) were measured in the morning and afternoon during the same period. Leaf mass per unit area (LMA) and nitrogen concentration (N) were also measured. The values of Vcmax, Jmax, Rd, N, and LMA did not differ between the two plots. By contrast, significantly lower Pmax and gs and higher WUEi were found in the drought plot, and the reduction in Pmax was accompanied by low gs values. Midday depressions in Pmax and gs were more pronounced in the drought plot relative to the control and were related to higher WUEi. Under drought conditions, mature Japanese cedar experienced little change in photosynthetic capacity, foliar N, or LMA, but they did tend to close the stomata to regulate transpiration, thus avoiding drought-induced damage to the photosynthetic machinery and improving WUEi.

In response to irradiance seasonality, saplings under brighter conditions increased leaf biomass with high photosynthesis to realize high growth, whereas understory saplings depend on photosynthesis during canopy leaf fall, and larger root biomass contributed to storage. We studied the changes in photosynthesis, biomass partitioning, and starch content in Abies firma saplings in a mixed deciduous forest in southwest Japan. Saplings were examined under high, intermediate, and low irradiance levels. The relative irradiance at intermediate and low irradiance levels increased significantly during winter and spring due to leaf fall in the deciduous canopy trees. The maximum photosynthetic rates (P max) under low irradiance were lower than those under high irradiance throughout the year. The needle daily carbon balance in summer was negative under low irradiance, whereas the balance became positive in winter and spring due to increases in irradiance. The needle daily carbon balance in intermediate- and high-irradiance saplings remained positive year-round, although the midday photosynthetic depression suppressed the daily needle carbon gain under high irradiance. The starch content in needles, branches, and roots was higher in spring due to high photosynthetic production, and then decreased in summer under all irradiance levels. Root starch under low irradiance levels may be used to maintain carbon balance during summer, thereby contributing to survival. High needle biomass coupled with a high P max facilitated carbon gain under high and intermediate irradiance, whereas high relative root biomass under low irradiance may enhance storage ability. Overall, A. firma saplings seemed to acclimate to different irradiance levels with seasonal changes through changes in photosynthetic traits, starch storage, and biomass partitioning.

The morphological and physicochemical traits of leaves are important in terms of plant adaptation to various growth environments, because such traits play central roles in various functions including photosynthesis. We measured the toughness, mass per unit area (LMA), nitrogen content, and δ15N levels of the leaves of different life-forms of 39 broadleaf woody plants in interior Alaska. The plants were divided into three life-forms based on the maximum height of adult plants: understory (15N values reflected the presence of root symbionts such as ericoid mycorrhiza or Frankia sp. Our results suggest that leaf traits may affect both the life-form of the host plants and leaf longevity in both evergreen and deciduous species.

Black spruce (Picea mariana (Mill.) B.S.P.) is a dominant species on north-facing slopes located on the permafrost in the Alaskan Interior, where tree growth rates vary significantly across slope gradients. To better understand the effects of nitrogen (N) and mycorrhizal associations on plant growth, we investigated the relationships between tree growth and isotope ratios of nitrogen (δ15N) in foliage and roots, because plant δ15N values reflect tree dependencies on N uptake by mycorrhizae. We established two transects (one along a slope gradient, and a second on a north-to-east axis at a fixed elevation) and four plots on the slope gradient transect. We measured current shoot growth of saplings on transects and aboveground biomass (AGB) in the plots. We collected foliage and fine root samples and measured their δ15N signatures and N concentrations. The AGB and shoot growth varied widely across the gradient: values were higher at high elevations and at the east–northeast aspect. Foliage δ15N values and N concentrations were positively correlated with tree growth, but growth rate was negatively correlated with the dependency on mycorrhizae for N uptake. Thus, black spruce had a reduced dependency on mycorrhizae for N uptake on the upper slope, where conditions were N-rich. On the lower slope, where the soil active layer was shallow, black spruce growth was limited and had an elevated dependency on mycorrhizae for N uptake.

Although cutting is a useful method for vegetative propagation and tree breeding, there is a difference in rooting ability between tree species and even between node positions within a species. A large number of F1 hybrids of Shorea (Shorea curtisii × S. leprosula) (Dipterocarpaceae) have recently been found in Singapore. Given that some of the hybrid traits appear to have higher physiological performances than those of their parent species, understanding the rooting ability of the leafy-stem cuttings of F1 hybrids may contribute to performance improvement in dipterocarp trees. In this study, we compared the rooting abilities of cuttings taken from seedlings of F1 hybrids and their parent species at different node positions. The cuttings of F1 hybrids showed rooting ability with small internode differences, and the rooting rate (32.2%) was almost intermediate between those of S. curtisii (42.0%) and S. leprosula (21.0%). The rooting rates of hybrids and parents fell into the middle range of previously reported values for 21 closely related Shorea species. Overall, the rooting ability of F1 hybrids is comparable with that of their parent species and/or other Shorea species in the red meranti group. Thus, F1 hybrids could be mass propagated through cuttings. Published version

Background: Dry deciduous forest (DDF) is distributed throughout the monsoon area of South-east Asia. Leaf morphological and photosynthetic traits are essential for adaptation to the environmental variability and usually change with tree height and season.Aims: To clarify the differences in leaf traits as influenced by tree height, light conditions and season for two dominant dipterocarps of DDF: Dipterocarpus tuberculatus and Shorea obtusa.Methods: We measured changes in leaf traits with tree height, namely leaf mass per area (LMA), maximum photosynthetic rate (Amax), stomatal conductance (gs) and nitrogen concentration (N), in the rainy and early and mid-dry seasons. To identify the effects of height and light intensity on leaf traits, we conducted multiple regression analyses using leaf traits as the dependent variables and the height, light and season as independent variables.Results: Tree height was more important for gradients in most leaf traits, especially in LMA in both species, than light intens...

Background: Although natural hybridisation between dipterocarp trees is considered rare, putative dipterocarp hybrids (Shorea spp.) are found in a forest fragment in Singapore. Understanding the performance of hybrids is critical to inform conservation efforts and has implications for the demographic and genetic viability of these small populations.Aims: First, is there a difference in the frequency of hybrids between the mature and seedling stages, and second, do parent and hybrid seedlings have different ecological traits?Methods: We analysed seedling survival and growth rates in relation to environmental variables for Shorea curtisii, S. leprosula and hybrids of the two species. We monitored the height and diameter of seedlings for 4 years, as well as light conditions and soil moisture.Results: The proportion of hybrids at the seedling stage was 41% for S. leprosula and 17% for S. curtisii, respectively. Hybrids were more frequent at the seedling stage than at the mature stage. Hybrid individuals had g...

Nitrogen is one of most limiting nutrients of plants' growth. Lowland tropical rainforests in Southeast Asia are characterized by high species diversity despite limited soil nitrogen conditions. We analyzed δ(15)N values and nitrogen content (N %) in leaves and roots of 108 woody species with different types of symbiotic microorganisms, of different life forms (emergent, canopy, subcanopy, understory, and canopy gap species), and from different families in a Bornean lowland dipterocarp forest to gain more insight into the diversity of nitrogen uptake strategies in the rhizosphere. The plant nitrogen isotope ratio (δ(15)N) changes depending on soil nitrogen source or root symbiotic fungi. Leaf δ(15)N values in the species studied varied widely, from -7.2 to 5.0 ‰, which is comparable to the values of known Asian trees, including those from temperate, subtropical, and tropical mountain forests. Leaf δ(15)N also varied significantly among both life forms and families, though the phylogenetically independent contrast (PIC) relationships were not statistically significant among life form, family, and symbiotic types. Some families showed specific leaf δ(15)N values; Dipterocarpaceae, the dominant family in the canopy layer with symbiotic ectomycorrhiza in Southeast Asia, had small intraspecific variation and higher leaf δ(15)N values (0.03 ‰) compared with species exhibiting arbuscular mycorrhiza, whereas several families such as Burseraceae, Euphorbiaceae, and Phyllanthaceae showed large interspecific variation in leaf δ(15)N (e.g., from -7.2 to 5.0 ‰ in Euphorbiaceae). These variations suggest that tropical species may have family- or species-specific strategies, such as root symbiotic microorganisms, for nitrogen uptake under low-nutrient conditions in tropical rainforests in Southeast Asia., This proceeding is a compilation of findings and progress activities of research collaboration between the Forest Department Sarawak (FDS) and the Japan Research Consortium for Tropical Forests in Sarawak (JRCTS). To highlight the research findings, An International Symposium entitled "Frontier in Tropical Forest Research: Progress in Joint Projects between the Forest Department Sarawak and the Japan Research Consortium for Tropical Forests in Sarawak" was ii held in Kuching, Sarawak on 21-22 September 2015.

Climate change exposes vegetation to unusual drought, causing risk of a decline in productivity and increased mortality. It still remains unclear how trees and forests respond to such unusual drought, particularly in tropical rain forests. For a detailed study of tropical tree responses to soil drying, a through-fall exclusion experiment was conducted on three target trees of Dryobalanops aromatica, which is one of the dominant canopy tree species, for three months at Lambir Hills National Park. We compared the control and treatment trees regarding leaf water use at the top of the crown, including transpiration, stomatal conductance, photosynthesis, leaf water potential (predawn: Ψpre, midday: Ψmid and at turgor loss point: πtlp), osmotic potential at full turgor (π100), and a bulk modulus of elasticity (ε), by use of tree-tower and canopy-crane systems. During the experiment, there was no evidence of canopy dieback. However, the treatment trees showed higher water stress than the control trees, because predawn and midday leaf water potential decreased with soil drying. Additionally, the drought treatment led to a reduction in stomatal conductance (gs), and the treatment trees showed about half the value of gs compared with the control trees. Consequently, transpiration and photosynthetic rates clearly decreased compared with those in the control trees. Minimum values of midday leaf water potential in the treatment trees decreased during the drought, and were lower than πtlp in the control trees. However, the treatment trees also decreased their πtlp by osmotic adjustment, and their πtlp values were lower than the minimum values of their midday leaf water potential. These results suggest that this species may have plasticity in drought tolerance by maintaining turgor pressure to improve its leaf water relations and regulating water consumption during severe drought., This proceeding is a compilation of findings and progress activities of research collaboration between the Forest Department Sarawak (FDS) and the Japan Research Consortium for Tropical Forests in Sarawak (JRCTS). To highlight the research findings, An International Symposium entitled "Frontier in Tropical Forest Research: Progress in Joint Projects between the Forest Department Sarawak and the Japan Research Consortium for Tropical Forests in Sarawak" was ii held in Kuching, Sarawak on 21-22 September 2015.

The vertical structure of a tropical rain forest is complex and multilayered, with strong variation of micro-environment with height up to the canopy. We investigated the relation between morphological traits of leaf surfaces and tree ecological characteristics in a Malaysian tropical rain forest. The shapes and densities of stomata and trichomes on the abaxial leaf surfaces and their relation with leaf characteristics such as leaf area and leaf mass per area (LMA) were studied in 136 tree species in 35 families with different growth forms in the tropical moist forest. Leaf physiological properties were also measured in 50 canopy and emergent species. Most tree species had flat type (40.4 %) or mound type (39.7 %) stomata. In addition, 84 species (61.76 %) in 22 families had trichomes, including those with glandular (17.65 %) and non-glandular trichomes (44.11 %). Most leaf characteristics significantly varied among the growth form types: species in canopy and emergent layers and canopy gap conditions had higher stomatal density, stomatal pore index (SPI), trichome density and LMA than species in understory and subcanopy layers, though the relation of phylogenetically independent contrasts to each characteristic was not statistically significant, except for leaf stomatal density, SPI and LMA. Intrinsic water use efficiency in canopy and emergent tree species with higher trichome densities was greater than in species with lower trichome densities. These results suggest that tree species in tropical rain forests adapt to a spatial difference in their growth forms, which are considerably affected by phylogenetic context, by having different stomatal and trichome shapes and/or densities.

To estimate above- and below-ground biomass in teak (Tectona grandis) plantations throughout Thailand, we developed general allometric relationships between tree size parameters (stem diameter and height) and tree biomass (of leaves, stems, and roots). Trees were harvested from 18 plantations within the native range of teak in Thailand and across the area covered by these plantations. Allometric equations for total above- and below-ground biomass showed no significant inter-site differences and high correlation coefficients (0.90–0.99). This similarity across sites may be due to similarities in wood density among different age and/or size of teak trees. The majority of previous biomass estimation models for teak trees gave higher estimated values for both above- and below-ground biomass, suggesting that they should not be applied within Thailand. To estimate belowground biomass using root: shoot ratio (RSR), we evaluated RSR among stands of various ages and sizes. We further identified differences in RSR between Thailand and other regions. Estimated RSR varied among stands and decreased significantly with stand age and average tree size. This relationship suggests that belowground biomass can be estimated from aboveground biomass using RSR. However, RSR values differed among countries and regions. In summary, general allometric equations and RSR value can be used to accurately estimate above- and below-ground biomass in teak plantations across Thailand.

Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (δ 15 N) from more than 43,000 samples acquired over 37 years, here we show that foliar N concentration declined by 9% and foliar δ 15 N declined by 0.6–1.6‰. Examining patterns across different climate spaces, foliar δ 15 N declined across the entire range of mean annual temperature and mean annual precipitation tested. These results suggest declines in N supply relative to plant demand at the global scale. In all, there are now multiple lines of evidence of declining N availability in many unfertilized terrestrial ecosystems, including declines in δ 15 N of tree rings and leaves from herbarium samples over the past 75–150 years. These patterns are consistent with the proposed consequences of elevated atmospheric carbon dioxide and longer growing seasons. These declines will limit future terrestrial carbon uptake and increase nutritional stress for herbivores. Fil: Craine, Joseph M.. Jonah Ventures; Estados Unidos Fil: Elmore, Andrew J.. University of Maryland; Estados Unidos Fil: Wang, Lixin. Indiana University; Estados Unidos. Purdue University; Estados Unidos Fil: Aranibar, Julieta Nelida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Bauters, Marijn. University of Ghent; Bélgica Fil: Boeckx, Pascal. University of Ghent; Bélgica Fil: Crowley, Brooke E.. University of Cincinnati; Estados Unidos Fil: Dawes, Melissa A.. Swiss Federal Institute for Forest, Snow and Landscape Research; Suiza Fil: Delzon, Sylvain. Universite de Bordeaux; Francia. Institut National de la Recherche Agronomique; Francia Fil: Fajardo, Alex. Centro de Investigación en Ecosistemas de la Patagonia; Chile Fil: Fang, Yunting. Chinese Academy of Sciences; República de China Fil: Fujiyoshi, Lei. Research Institute for Humanity and Nature; Japón Fil: Gray, Alan. North American Electric Reliability Corporation. Centre for Ecology and Hydrology; Estados Unidos Fil: Guerrieri, Rossella. Consejo Superior de Investigaciones Científicas. Centre de Recerca Ecológica I Aplicacions Forestals; España Fil: Gundale, Michael J.. Swedish University of Agricultural Sciences; Suecia Fil: Hawke, David J.. Ara Institute of Canterbury. Department of Science and Primary Industries; Nueva Zelanda Fil: Hietz, Peter. University of Natural Resources and Life Sciences. Institute of Botany; Austria Fil: Jonard, Mathieu. Université Catholique de Louvain; Bélgica Fil: Kearsley, Elizabeth. University of Ghent; Bélgica Fil: Kenzo, Tanaka. Forestry and Forest Products Research Institute. Department of Plant Ecology; Japón Fil: Makarov, Mikhail. Moscow M.V. Lomonosov State University; Rusia Fil: Marañón Jiménez, Sara. Universidad de Granada; España. Consejo Superior de Investigaciones Científicas. Centre de Recerca Ecológica I Aplicacions Forestals; España Fil: McGlynn, Terrence P.. University of California; Estados Unidos. Natural History Museum of Los Angeles County. Department of Entomology; Estados Unidos Fil: McNeil, Brenden E.. West Virginia University. Department of Geology and Geography; Estados Unidos Fil: Mosher, Stella G.. University of Cincinnati; Estados Unidos Fil: Nelson, David M.. University of Maryland; Estados Unidos Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Roggy, Jean Christophe. Institut National de la Recherche Agronomique; Francia. Ecologie des Forêts de Guyane; Francia Fil: Sanders Demott, Rebecca. Boston University; Estados Unidos Fil: Song, Minghua. Chinese Academy of Sciences; República de China Fil: Szpak, Paul. Trent University. Department of Anthropology; Canadá Fil: Templer, Pamela H.. Boston University; Estados Unidos Fil: Van der Colff, Dewidine. South African National Biodiversity Institute; Sudáfrica Fil: Werner, Christiane. Albert Ludwigs University of Freiburg; Alemania Fil: Xu, Xingliang. Chinese Academy of Sciences; República de China Fil: Yang, Yang. Chinese Academy of Sciences; República de China Fil: Yu, Guirui. Chinese Academy of Sciences; República de China. University of Chinese Academy of Sciences. College of Resources and Environment; República de China Fil: Zmudczyńska Skarbek, Katarzyna. University of Gdańsk; Polonia

Large variations in leaf δ 15 N in Bornean tropical rainforest trees may indicate that various tropical species have species-specific strategy for nitrogen uptake under low soil nutrient conditions, including root symbiotic microorganisms such as ectomycorrhiza. Lowland tropical rainforests in Southeast Asia are characterized by high species diversity despite limited soil nutrient conditions. The plant nitrogen isotope ratio (δ15N) reflects plant uptake of soil nitrogen. We analyzed δ15N values and nitrogen content (N %) in leaves and roots of 108 woody species with different types of symbiotic microorganisms, of different life forms (emergent, canopy, sub-canopy, understory, and canopy gap species), and from different families in a Bornean lowland dipterocarp forest to gain more insight into the diversity of nitrogen uptake strategy in the rhizosphere. Leaf δ15N values in the species studied varied largely from −7.2 to 5.0 ‰, which is comparable to the values of known Asian trees including temperate, sub-tropical, and tropical mountain forests. Leaf δ15N also varied significantly among both life forms and families, though the phylogenetically independent contrast (PIC) relationships were not statistically significant among life form, family, and symbiotic types. Some families showed specific leaf δ15N values; Dipterocarpaceae, the dominant family in the canopy layer with symbiotic ectomycorrhiza in Southeast Asia, had small intraspecific variation and higher leaf δ15N values (0.03 ‰) compared with species exhibiting arbuscular mycorrhiza, whereas several families such as Burseraceae, Euphorbiaceae, and Myrtaceae showed large interspecific variation in leaf δ15N (e.g., from −7.2 to 5.0 ‰ in Euphorbiaceae). These variations suggest that tropical species may have family- or species-specific strategy, such as root symbiotic microorganisms, for nitrogen uptake under low-nutrient conditions in tropical rainforests in Southeast Asia.

Tropical canopy tree species can be classified into two types by their heterobaric and homobaric leaves. We studied the relation between both leaf types and their water use, together with the morphological characteristics of leaves and xylem, in 23 canopy species in a tropical rain forest. The maximum rates of photosynthesis and transpiration were significantly higher in heterobaric leaf species, which also underwent larger diurnal variations of leaf water potential compared to homobaric leaf species. The vessel diameter was significantly larger and the stomatal pore index (SPI) was significantly higher in heterobaric than that in homobaric leaf species. There was a significant positive correlation between the vessel diameter, SPI, and maximum transpiration rates in all the studied species of both leaf types. However, there was no significant difference in other properties, such as leaf water-use efficiency, leaf mass per area, leaf nitrogen content, and leaf δ13C between heterobaric and homobaric leaf species. Our results indicate that leaf and xylem morphological differences between heterobaric and homobaric leaf species are closely related to leaf water-use characteristics, even in the same habitat: heterobaric leaf species achieved a high carbon gain with large water use under strong light conditions, whereas homobaric leaf species can maintain a high leaf water potential even at midday as a result of low water use in the canopy environment.

Although an estimation of forest biomass is essential for the development of a carbon storage baseline in the ''Reducing Emissions from Deforestation and Deg- radation in Developing Countries'' scheme, few have been conducted in logged-over rain forests of Southeast Asia. We measured the aboveground and belowground biomass in logged-over mixed dipterocarp forests growing on an infertile soil with bleached white sand (Sabal) and on a clay and nutrient-rich soil (Balai Ringin) in Sarawak, Malaysia. We established four 0.5-ha plots on each site and calcu- lated the biomass. Basal area and stand density of large trees (diameter at breast height, DBH C 10 cm) were