Lowland Forest Types Research Articles

Composition of Paleocene forests from Antarctica based on fossil wood

A new assemblage of fossil wood of Paleocene age from Seymour Island, Antarctic Peninsula, is described. Conifer species have been identified, belonging to the fossil genera Agathoxylon, Phyllocladoxylon, Protophyllocladoxylon, and Podocarpoxylon. Angiosperm fossil wood species are assigned to Nothofagoxylon, Caldcluvioxylon, and Myrceugenellites. New wood types have been described with possible affinity to Atherospermataceae and Asteraceae (daisy family). A newly identified fossil angiosperm species, Aextoxicoxylon jacksius, has been recorded from Antarctica for the first time. It shares traits with modern Aextoxicon punctatum and other Aextoxicoxylon wood from South America but is considered a separate species due to significant differences in vessel density, ray height, and frequency. This study indicates, in accordance with previous studies that conifers were the most common elements in the Paleocene Antarctic vegetation. In particular, Agathoxylon being the most dominant wood type. Nothofagoxylon was the most common angiosperm wood type. Overall the composition of the Antarctic Paleocene vegetation deduced from the presence of fossil wood resembles that of the modern warm to cool temperate forests of Tasmania, New Zealand and southern South America. Possible upland and lowland forest types have been identified, with the lowland forests likely most similar to the modern mixed cool temperate forests on South Island, New Zealand, and Tasmania. The upland forests were similar to the modern open canopy Araucaria-Nothofagus forests on the high Andes today.

TROPICAL PALMS AND FACTORS INFLUENCING THEIR DISTRIBUTIONS AND DIVERSITY, WITH A FOCUS ON Pinanga DIVERSITY IN SOUTHEAST ASIA

ARTICLE HIGLIGHTS- The palm genus Pinanga is the most diverse in Southeast Asia. - Limited ecological studies on Pinanga show the influence of environmental factors.- High Pinanga endemism in Borneo requires conservation action.ABSTRACTPalms represent some of the keystone species in tropical forests, providing numerous ecosystem services. They are widely studied by botanists because of their iconic and majestic appearance, although ecological studies of palm abundance, distributions, and diversity have only recently begun to gain attention. The abundance and diversity of palms at different spatial scales can be influenced by various factors, such as climate, soil properties, hydrology, topography and forest structure; understanding these influences is essential for conservation. This review details four abiotic factors (climate, soil chemistry, hydrology and topography) and one biotic factor (forest structure) affecting palm distribution and diversity. The genus Pinanga, one of the most diverse genera of palms, is discussed in terms of its distribution and diversity in Southeast Asia. Ecological studies on Pinanga diversity in the region are examined, revealing the influence of micro- and macro-scale variation in environmental factors, such as litter depth and thickness, canopy openness and crown cover, elevation, slope, aspect, light intensity, humidity and air temperature. The existing knowledge gaps on Pinanga ecology in Southeast Asia are discussed, and the need for more studies on population structures, functional traits and determinants of Pinanga diversity and distributions within different lowland forest types in the region are highlighted. The high endemism shown by Pinanga necessitates a more comprehensive ecological understanding of this genus to better inform its conservation and protection.

Changes in plant diversity of European lowland forests: Increased homogenization and expansion of shade-tolerant trees

European lowland forests have undergone significant transformations over the past century due to increased canopy closure, eutrophication and plant invasions. The new millennium has brought plant invasions, alien fungal pathogens, and extreme weather conditions, all contributing to forest diebacks. However, the response of plant diversity remains poorly understood. We examined changes in understorey vegetation following a decade (2012–2021) of severe drought in four temperate lowland forest types (dominated by oaks, hornbeams, ashes, and willows) to understand how water availability, canopy openness, and alien fungal pathogens altered diversity in interaction with climate change. Following an exceptionally warm decade, the vegetation exhibited increased homogeneity, with denser shrub and herb layers, likely resulting from diminished tree canopy, particularly in hornbeam and ash forests. Homogenization was manifested by the colonization of plants with conservative life-history strategies (higher leaf dry matter content) to cope with increased drought. Consequently, communities with fewer species increased their species richness, while species-rich communities experienced impoverishment. Conversely, herbaceous species with higher specific leaf area were declining. Compositional changes were particularly prominent in hornbeam and oakwoods at the drier end of moisture gradient where the understorey became dominated by woody plants. Ashwoods were opening up due to ash dieback by fungal pathogens, causing replacement of wetland forbs by nitrophilous forbs and woody saplings. The overall number of species decreased in oakwoods but increased in hornbeam and ashwoods due to increased cover of grasses and shade-tolerant woody species, mostly Acer campestre. Conversely, willow understorey vegetation at the wetter end of the moisture gradient remained relatively stable. Our findings suggest shifts towards more homogeneous vegetation. Conservation plans for managing the remnants of species-rich lowland forests should consider the accelerated environmental changes linked to canopy alterations, biological invasions, and extreme climate events.

Drivers of historical and projected changes in diverse boreal ecosystems: fires, thermokarst, riverine dynamics, and humans

Alaska has diverse boreal ecosystems across heterogeneous landscapes driven by a wide range of biological and geomorphic processes associated with disturbance and successional patterns under a changing climate. To assess historical patterns and rates of change, we quantified the areal extent of ecotypes and the biophysical factors driving change through photo-interpretation of 2200 points on a time-series (∼1949, ∼1978, ∼2007, ∼2017) of geo-rectified imagery for 22 grids across central Alaska. Overall, 68.6% of the area had changes in ecotypes over ∼68 years. Most of the change resulted from increases in upland and lowland forest types, with an accompanying decrease in upland and lowland scrub types, as post-fire succession led to mid- and late-successional stages. Of 17 drivers of landscape change, fire was by far the largest, affecting 46.5% of the region overall from 1949 to 2017. Fire was notably more extensive in the early 1900s. Thermokarst nearly doubled from 3.9% in 1949 to 6.3% in 2017. Riverine ecotypes covered 7.8% area and showed dynamic changes related to channel migration and succession. Using past rates of ecotype transitions, we developed four state-transition models to project future ecotype extent based on historical rates, increasing temperatures, and driver associations. Ecotype changes from 2017 to 2100, nearly tripled for the driver-adjusted RCP6.0 temperature model (30.6%) compared to the historical rate model (11.5%), and the RCP4.5 (12.4%) and RCP8.0 (14.7%) temperature models. The historical-rate model projected 38 ecotypes will gain area and 24 will lose area by 2100. Overall, disturbance and recovery associated with a wide range of drivers across the patchy mosaic of differing aged ecotypes led to a fairly stable overall composition of most ecotypes over long intervals, although fire caused large temporal fluctuations for many ecotypes. Thermokarst, however, is accelerating and projected to have increasingly transformative effects on future ecotype distributions.

Is it possible that logged-over areas can recover naturally: the case of logged-over areas in South Kalimantan

Logging causes a decline in the quality of stands in all forest types. However, these forests can recover naturally. This study aims to measure the ability to recover logged-over areas based on the species composition and above-ground biomass. This research was conducted by logged-over forest in 1987, of lowland forest type in the Kintap Research Forest, South Kalimantan. The research was carried out by making a measurement plot on three types of land with the main road’s distance as a differentiating factor. Each type of measurement plot measuring 1 hectare is divided into five replications with 20 m × 100 m. The measurement parameters are the diversity of species and above-ground biomass estimated by the allometric model. The results showed that the distance difference did not affect the species composition and the potential for above-ground ground biomass. The species composition is indicated by the diversity index, evenness index, and dominance index, including above-ground biomass. Overall, more than 100 tree species present after felling and an evenness index of higher than 0.75, indicating that the community is stable with high species diversity and low dominance. This indicates that logged-over areas can recover but that recovery requires adequate regeneration after logging. The implication is that logging must leave enough standing stands. This condition will encourage natural regeneration or succession in logged-over forests.

Fine root dynamics across pantropical rainforest ecosystems.

Fine roots constitute a significant component of the net primary productivity (NPP) of forest ecosystems but are much less studied than aboveground NPP. Comparisons across sites and regions are also hampered by inconsistent methodologies, especially in tropical areas. Here, we present a novel dataset of fine root biomass, productivity, residence time, and allocation in tropical old-growth rainforest sites worldwide, measured using consistent methods, and examine how these variables are related to consistently determined soil and climatic characteristics. Our pantropical dataset spans intensive monitoring plots in lowland (wet, semi-deciduous, and deciduous) and montane tropical forests in South America, Africa, and Southeast Asia (n=47). Large spatial variation in fine root dynamics was observed across montane and lowland forest types. In lowland forests, we found a strong positive linear relationship between fine root productivity and sand content, this relationship was even stronger when we considered the fractional allocation of total NPP to fine roots, demonstrating that understanding allocation adds explanatory power to understanding fine root productivity and total NPP. Fine root residence time was a function of multiple factors: soil sand content, soil pH, and maximum water deficit, with longest residence times in acidic, sandy, and water-stressed soils. In tropical montane forests, on the other hand, a different set of relationships prevailed, highlighting the very different nature of montane and lowland forest biomes. Root productivity was a strong positive linear function of mean annual temperature, root residence time was a strong positive function of soil nitrogen content in montane forests, and lastly decreasing soil P content increased allocation of productivity to fine roots. In contrast to the lowlands, environmental conditions were a better predictor for fine root productivity than for fractional allocation of total NPP to fine roots, suggesting that root productivity is a particularly strong driver of NPP allocation in tropical mountain regions.

Estimation of Carbon Stock in Sungai Merah Protection Forest, Musi Banyuasin Regency of South Sumatra Province

Calculation and estimation of carbon stocks in various types of forests and ecosystems in Indonesia has been widely practiced. However, the availability of carbon stock information for some locations in the remaining forest area in South Sumatra Province is still very limited. This study aim to measuring the carbon storage potential and the ratio between the carbon storage value derived from the interpretation of satellite imagery and the storage of carbon stock from the field calculation. The method used is to calculate the estimation of carbon stock through satellite imagery interpretation and field measurement. The largest estimation of carbon stock through satellite image interpretation was found in secondary forest cover type with yield 896,234 ton/c/ha, followed by plantation land type with a yield of 147.104 ton/c/Ha and the smallest is open land cover with value yield of 2.883 tons/c/ha. While carbon stocks through field measurement yield 429,181 ton/c/ha of secondary forest cover type, followed by plantation land type with 41,169 ton/c/ha and 4,283 ton/c/ha for open land type. A comparison of carbon stock estimates of the two approaches used, yielding a reference value of 220%. These comparative values can be used to assist in carrying out initial estimates of carbon stocks in some types of land cover, especially for lowland forest types.

Fruit Bat Assemblage in Different Lowland Forest Types in the Northern Sierra Madre Mountains, Philippines

Prior studies of species assemblages of fruit bats in the Philippines have focused on primary and disturbed habitats as the point of comparison. No studies to date have been conducted on assemblages of fruit bats within primary lowland forest vegetation types. This study aimed to determine the fruit bat assemblage in dipterocarp, mangrove and lowland ultramafic forest and their association with these vegetation types. We hypothesize that difference in the diversity and abundance of fruit-producing plants in these habitat types would influence the abundance and diversity of bats. The study was conducted in the Northern Sierra Madre Natural Park, Philippines from April to October 2017. Eleven species of fruit bats were captured during the study, in order of decreasing abundance: Rousettus amplexicaudatus, Ptenochirus jagori, Cynopterus brachyotis, Macroglossus minimus, Haplonycteris fischeri, Eonycteris robusta, Desmalopex leucopterus, Eonycteris spelaea, Pteropus vampyrus, Acerodon jubatus and Pteropus hypomelanus. Species richness was highest in dipterocarp forest (11 species), and lowest in the mangrove area (seven species), but species diversity was highest in the lowland ultramafic forest. The study suggests that species diversity and abundance of fruit bats in the different lowland vegetation habitats can be linked to their diet and morphology. Frugivores were strongly associated with dipterocarp forest and lowland ultramafic forest where fruit-producing plant diversity is high. Haplonycteris fischeri, C. brachyotis and P. jagori were more abundant in the dipterocarp than in the ultramafic forest. The abundance of nectarivores varied between vegetation types. Macroglossus minimus was more abundant in the mangrove while E. robusta and R. amplexicaudatus were more abundant in the dipterocarp and ultramafic forest. The difference in plant species composition and abundance may explain the variation in frugivore and nectarivore abundance between vegetation types. No pattern could be discerned for the large flying foxes (A. jubatus, P. hypomelanus, and P. vampyrus) because of few captures in each habitat, except for D. leucopterus, which was frequently captured in lowland ultramafic forest. The low captures of flying foxes may be attributed to the difficulty of capturing high-flying bats. Further research on foraging behavior, fruit selection by bats and the role of forest structure in determining the abundance and distribution of fruit bats is needed.

Plants Flowering and Fruiting Behaviour in Alas Purwo National Park, Banyuwangi, East Java

Alas Purwo National Park (APNP) is a conservation area with lowland forest type. The adaptation of plants conserved is strongly influenced by environmental factors and the behaviour of flowering and fruiting. The aims of this research were to find the number, species, dominance, and abundance of flowering and fruiting plants, comparison of flowering and fruiting species, and environmental factors affecting the flowering and fruiting time in APNP observation tracks. This study used purposive random sampling in each observation track where flowering and fruiting plants were found. Environmental factors (temperature, humidity, light intensity, soil pH, elevation, and coordinates) in each observation track were measured. Data analysis was conducted using Microsoft Excel and PAST 4.0. statistic program. The behaviour of flowering and fruiting plants species in APNP was unique. There were 90 species of flowering and fruiting plants in APNP from 45 families. Most species often found flowering and fruiting were Orophea enneandra, Polyalthia littoralis and Leea angulata which were scattered in Moto Lele, Patirtan Mas, and Sadengan Savanna. Fruiting plants species were more often found than flowering ones. Temperature and light intensity became the two most affecting environmental factors on flowering and fruiting plants behaviour. The study of flowering and fruiting behaviour is very important for genetic resources conservation and conservation areas management.

Contrasting nitrogen fluxes in African tropical forests of the Congo Basin

AbstractThe observation of high losses of bioavailable nitrogen (N) and N richness in tropical forests is paradoxical with an apparent lack of N input. Hence, the current concept asserts that biological nitrogen fixation (BNF) must be a major N input for tropical forests. However, well‐characterized N cycles are rare and geographically biased; organic N compounds are often neglected and soil gross N cycling is not well quantified. We conducted comprehensive N input and output measurements in four tropical forest types of the Congo Basin with contrasting biotic (mycorrhizal association) and abiotic (lowland–highland) environments. In 12 standardized setups, we monitored N deposition, throughfall, litterfall, leaching, and export during one hydrological year and completed this empirical N budget with nitrous oxide (N2O) flux measurement campaigns in both wet and dry season and in situ gross soil N transformations using15N‐tracing and numerical modeling. We found that all forests showed a very tight soil N cycle, with gross mineralization to immobilization ratios (M/I) close to 1 and relatively low gross nitrification to mineralization ratios (N/M). This was in line with the observation of dissolved organic nitrogen (DON) dominating N losses for the most abundant, arbuscular mycorrhizal associated, lowland forest type, but in contrast with high losses of dissolved inorganic nitrogen (DIN) in all other forest types. Altogether, our observations show that different forest types in central Africa exhibit N fluxes of contrasting magnitudes and N‐species composition. In contrast to many Neotropical forests, our estimated N budgets of central African forests are imbalanced by a higher N input than output, with organic N contributing significantly to the input‐output balance. This suggests that important other losses that are unaccounted for (e.g.,NOxand N2as well as particulate N) might play a major role in the N cycle of mature African tropical forests.

AN INVESTIGATION OF SOIL PHYSICO-CHEMICAL VARIABLES ACROSS DIFFERENT LOWLAND FOREST ECOSYSTEMS OF BRUNEI DARUSSALAM

Tropical forests undisputedly harbor the largest share of global plant diversity, but the mechanisms of maintenance for this diversity cannot be well understood without good data on environmental variables, primarily soil characteristics. This study investigates differences in soil physico-chemical properties in various tropical lowland forest types in Brunei Darussalam, in the Northwest Borneo plant diversity hotspot. Nine different vegetation types were investigated: intact primary mixed-dipterocarp forest, old disturbed secondary forest, young disturbed secondary forest (partly invaded by alien Acacias), heath (Kerangas) forest, peat swamp forest, swampy heath (Kerapah) forest, core mangrove, fringe mangrove and island mangrove forests. Nine 60 x 20 m plots were set up, and sampled for soils at topsoil (0-15 cm depth) and subsoil (15-30 cm depth) layers. Soil gravimetric water and organic matter content, texture, nutrient concentrations, pH, and salinity were determined. The peat swamp and core mangrove forests recorded highest soil nutrient concentrations. Peat swamp forest had the highest GWC, OM content, total N, and total Ca recorded, whereas the soil in core mangrove forest had higher total P, total Mg, total K, exchangeable Mg, exchangeable Ca, exchangeable K and salinity compared to the other habitat types. These results were also highlighted by the principal component analysis for the soil parameters measured. The most nutrient-poor soils were found in the Kerapah and heath forest sites. The difference between topsoil and subsoil for soil variables were generally not significantly different from each other. The present study has shown that soil physico-chemical properties differ significantly between the nine vegetation types studied, and this may have important implications upon differences seen in plant community compositions in these vegetation types.Keywords: Heath forest, Mangrove forest, Mixed Dipterocarp forest, Peat swamps, Edaphic

Responses of Primates and Other Frugivorous Vertebrates to Plant Resource Variability over Space and Time at Gunung Palung National Park

Identifying patterns of primate diversity and abundance over space and time provides a window into the ecological processes that influence species distributions and community composition. Long-term studies of primate communities across multiple habitat types at small spatial scales are rare, yet can improve our understanding of habitat and resource use. Within primate community ecology, there has been recent interest in studying primate species in the context of the broader faunal communities of which they are a part because interactions with ecologically similar but distantly related species may influence habitat use. We present the results of a 64-mo study of 10 vertebrate frugivore species with highly overlapping diets inhabiting seven distinct forest types at the Cabang Panti Research Station, West Kalimantan, Indonesia. We used survey transects and phenology plots to measure variation in vertebrate population densities (four primate, three hornbill, two squirrel, and one pig species) and fruit resources over space and time. We found little evidence of habitat partitioning or specialization. Densities of all 10 frugivore species, however, varied spatially, due largely to elevation and forest structure. Ordination analyses demonstrated that forest types differed in their structure, floristic composition, plant phenology, and frugivore communities. We also documented substantial temporal variation in orangutan densities, reflecting movements over large spatial scales. The densities of other mammalian and avian frugivores, particularly other primates, varied comparatively little over time. Our results demonstrate the importance of forest structure for determining frugivore community structure and highlight the importance of lowland forest types for the conservation of tropical frugivores.

Black bear use of seismic lines in Northern Canada

ABSTRACTThe development of hydrocarbon resources in northwestern Canada has resulted in a vast network of seismic lines. Seismic lines are a conservation concern because they are believed to alter the use of space by predators and ultimately change predator‐prey relationships. Such changes are believed to be a key factor influencing declines in boreal woodland caribou (Rangifer tarandus caribou). Using remote wildlife cameras, we measured the behavioral response of a known caribou predator, the black bear (Ursus americanus), to seismic lines at 2 spatial scales. At the line scale, we compared black bear use of lines that varied in width and vegetation recovery state to undisturbed forest interior locations. At a 5‐km2 scale, we compared the probability of bear use across a continuum of seismic line density. At both spatial scales, we also tested for an interaction between bear use of seismic lines and use of upland and lowland forest types. Black bears used most types of seismic lines more frequently than undisturbed forest interior and upland forest more than lowland forest. We found no evidence of an interaction between lines and forest type, as the relative difference in seismic line versus forest interior use was the same in lowland and upland forest. At the 5‐km2 scale, we found no evidence of increased use of lowland forest in areas with greater seismic line density. Thus, seismic lines did not appear to increase black bear use of lowland forest types per se. However, bears used seismic lines more than forest interiors, which might alter their ability to locate and capture caribou and other ungulate prey, thereby creating the potential for altered predator‐prey dynamics in landscapes with seismic lines. Bears do not appear to use seismic lines ≤2 m wide more often than the forest interior. We suggest that where new seismic lines are constructed, those seismic lines should be a maximum width of 2 m to reduce the potential for altered predator‐prey dynamics in areas being developed for oil and gas extraction. © 2014 The Wildlife Society.

Hyperdominance in the Amazonian Tree Flora

The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species--less diverse than the North American tree flora--accounts for half of the world's most diverse tree community.

Threatened predator on the equator: multi-point abundance estimates of the tiger Panthera tigris in central Sumatra

AbstractInformation on spatial and temporal variation in abundance is crucial for effective management of wildlife. Yet abundance estimates for the Critically Endangered Sumatran tiger Panthera tigris sumatrae are lacking from Riau, the province historically believed to hold the largest percentage of this subspecies. Recently, this area has had one of the highest global rates of deforestation. Using camera traps we investigated tiger abundance across peatland, flat lowland, and hilly lowland forest types in the province, and over time, in the newly established Tesso Nilo National Park, central Sumatra. We estimated densities using spatially explicit capture–recapture, calculated with DENSITY, and traditional capture–recapture models, calculated with CAPTURE. With spatially explicit capture–recapture the lowest tiger density (0.34 ± SE 0.24 per 100 km2) was estimated in the hilly lowland forest of Rimbang Baling and the highest (0.87 ± SE 0.33 per 100 km2) in the flat lowland forest of the Park. Repeated surveys in the Park documented densities of 0.63 ± SE 0.28 in 2005 to 0.87 ± SE 0.33 per 100 km2 in 2008. Compared to traditional capture–recapture the spatially explicit capture–recapture approach resulted in estimates 50% lower. Estimates of tiger density from this study were lower than most previous estimates in other parts of Sumatra. High levels of human activity in the area appear to limit tigers. The results of this study, which covered areas and habitat types not previously surveyed, are important for overall population estimates across the island, provide insight into the response of carnivores to habitat loss, and are relevant to the interventions needed to save the tiger.

Functional diversity of epiphytes in two tropical lowland rainforests, French Guiana: using bryophyte life-forms to detect areas of high biodiversity

Recent studies have described a new tropical lowland forest type in the Guianas, the tropical lowland cloud forest. It is characterized by an enriched epiphytic species diversity particularly for bryophytes compared to common lowland rainforest, and is facilitated by frequent early morning fog events in valley locations. While the increase in epiphytic species diversity in lowland cloud forests has been documented, uncertainties remain as to (1) how this small scale variation in water supply is shaping the functional diversity of epiphytic components in lowland forests, and (2) whether information on functional group composition of epiphytes might aid in discerning these cloud forests from the common lowland rainforest. We compare the distribution of functional groups of epiphytes across height zones in lowland cloud forest and lowland rain forest of French Guiana in terms of biomass, cover as well as the composition of bryophyte life-forms. Both forests differed in functional composition of epiphytes in the canopy, in particular in the mid and outer canopy, with the cloud forest having a higher biomass and cover of bryophytes and vascular epiphytes as well as a richer bryophyte life-form composition. Bryophyte life-forms characteristic for cloud forests such as tail, weft and pendants were almost lacking in the canopies of common rain forest whereas they were frequent in lowland cloud forests. We suggest that ground-based evaluation of bryophyte life-form composition is a straightforward approach for identifying lowland cloud forest areas for conservation, which represent biodiversity hotspots in tropical lowland forests.

A comparison of two common flight interception traps to survey tropical arthropods

Tropical forests are predicted to harbor most of the insect diversity on earth, but few studies have been conducted to characterize insect communities in tropical forests. One major limitation is the lack of consensus on methods for insect collection. Deciding which insect trap to use is an important consideration for ecologists and entomologists, yet to date few study has presented a quantitative comparison of the results generated by standardized methods in tropical insect communities. Here, we investigate the relative performance of two flight interception traps, the windowpane trap, and the more widely used malaise trap, across a broad gradient of lowland forest types in French Guiana. The windowpane trap consistently collected significantly more Coleoptera and Blattaria than the malaise trap, which proved most effective for Diptera, Hymenoptera, and Hemiptera. Orthoptera and Lepidoptera were not well represented using either trap, suggesting the need for additional methods such as bait traps and light traps. Our results of contrasting trap performance among insect orders underscore the need for complementary trapping strategies using multiple methods for community surveys in tropical forests.

Facultative nitrogen fixation by canopy legumes in a lowland tropical forest

Symbiotic dinitrogen (N(2)) fixation is often invoked to explain the N richness of tropical forests as ostensibly N(2)-fixing trees can be a major component of the community. Such arguments assume N(2) fixers are fixing N when present. However, in laboratory experiments, legumes consistently reduce N(2) fixation in response to increased soil N availability. These contrasting views of N(2) fixation as either obligate or facultative have drastically different implications for the N cycle of tropical forests. We tested these models by directly measuring N(2)-fixing root nodules and nitrogenase activity of individual canopy-dominant legume trees (Inga sp.) across several lowland forest types. Fixation was substantial in disturbed forests and some gaps but near zero in the high N soils of mature forest. Our findings suggest that canopy legumes closely regulate N(2) fixation, leading to large variations in N inputs across the landscape, and low symbiotic fixation in mature forests despite abundant legumes.

Coppice-with-standards in floodplain forests - a new subject for nature protection

: At present, the coppice-with-standards system has become so rare in floodplain forests that it is considered a natural monument. In 1990, the coppice-with-standards system was not recorded in the territory of the Czech Republic. This state contradicts the increasing interest of nature protection organizations in the relict remainders of the coppice-with-standards system, which is to be considered the closest to naturally preserved lowland forest type, and is, therefore, recommended as the final state of the biocentres and biocorridors in today’s floodplain forests. The aim of this paper is to present the results of the inventory dealing with the present occurrence of the coppice-with-standards system in the floodplain forest of the Litovelské Pomoraví Protected Landscape Area (PLA) in a historical context.

Are Montane Forests Demographic Sinks for Bornean White‐bearded GibbonsHylobates albibarbis?

ABSTRACTI estimated habitat‐specific population densities for a population of Bornean white‐bearded gibbonsHylobates albibarbisinhabiting seven distinct forest types at Gunung Palung National Park, West Kalimantan, Indonesia. Population densities in montane forests (0.44 individuals/km2) were almost ten times lower than those in the next best habitat (upland granite forest; 4.2 individuals/km2) and far lower than those in lowland forest types. Demographic data on 33 gibbon groups living across the seven forest types showed that reproduction was substantially depressed in montane forests compared to high‐quality lowland habitats. A simple model suggests that montane forests are demographic sinks for gibbons at Gunung Palung. Follow‐up data from observations of montane groups 5 yr after the initial observation period support this result. As high‐quality lowland forests (source habitat for gibbons) are being disproportionately lost in and around Gunung Palung National Park due to illegal logging and conversion to oil palm plantations, an increasing percentage of the remaining forest in the park comprises sink habitat for gibbons. This result has disquieting implications for the long‐term viability of gibbon populations at Gunung Palung. In addition, as montane forests are generally low‐quality habitat for most rainforest vertebrates, and since lowland forests are being lost at alarming rates across the tropics, source‐sink population dynamics similar to those I describe here may characterize populations of other tropical vertebrate species.