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The effects of commercial logging on tree diversity in tropical rainforest are largely unknown. In this study, selectively logged tropical rainforest in Indonesian Borneo is shown to contain high tree species richness, despite severe structural damage. Plots logged 8 years before sampling contained fewer species of trees greater than 20 centimeters in diameter than did similar-sized unlogged plots. However, in samples of the same numbers of trees (requiring a 50 percent larger area), logged forest contained as many tree species as unlogged forest. These findings warrant reassessment of the conservation potential of large tracts of commercially logged tropical rainforest

Many studies of post-dispersal seed predation have focused on density and distance dependent mortality, while relatively few have examined the fates of isolated seeds. Yet, scatter-dispersed seeds (sensu Howe) are commonly deposited singly or in small groups. Furthermore, even in species with highly aggregated seed distributions, the fates of the most widely dispersed individuals may be critical for recruitment. We compared predation rates on single, isolated seeds, among 40 species of trees in lowland tropical rain forest at Gunung Palung, West Kalimantan, Indonesia. Seeds were placed along four replicate transects and monitored for damage by predators, removal and germination in four trials, each lasting at least 30 days. Tethering of seeds did not affect removal rates, indicating that removals were attributable to seed predators and not merely to physical disturbance by animals or abiotic factors. After 30 days, mortality due to seed predation, averaged over species, was more than 50%; among species, predation losses ranged from 0 to 100%. Over the range of seed sizes we examined (0.1 g to 11.6 g fresh weight) predation rates were negatively associated with seed size and with the thickness and hardness of the seed coat. Lower predation on larger seeds is contrary to theoretical predictions and some prior empirical findings, and may be partially explained by the scarcity of predators capable of penetrating the physical defenses of large seeds with hard seed coats. Large, soft seeds with low predation rates may have poor nutrition or may be protected by chemical defenses. Species differed greatly in 30-day germination rates, ranging from 0 to 47%. Some species with low predation rates also had low germination rates; the implications for the overall risk of predation during the seed stage are discussed. Predation rates were not associated with species' natural dispersal mode (clumped vs scatter-dispersed), contrary to theoretical predictions. Spiny rats (Maxomys spp.) were the most abundant seed eating rodent. Caged spiny rats avoided large, hard seeds and preferred soft, medium sized seeds. The substantial rates of post dispersal predation on isolated seeds that we measured may be sufficient to influence strongly the population dynamics and life history evolution of trees in this rain forest community.

Ecological and economic data are essential to the identification of tropical nontimber forest products with the potential for sustainable and profitable extraction in a managed system. We studied the demographic effect and economic returns of harvesting aromatic gaharu wood from fungus-infected trees of Aquilaria malaccensis Lam. at Gunung Palung National Park, Indonesia, to evaluate the management potential of gaharu wood. Aquilaria malaccensis trees of >20 cm in diameter occurred at low preharvest densities (0.16- 0.32 ha) but were distributed across five of six forest types surveyed. During a recent harvest, 75% of trees were felled, with harvest intensities ranging from 50% to 100% among forest types. Overall, 50% of trees contained gaharu wood, but trees at higher elevations contained gaharu wood more frequently (73%) than trees at lower elevation (27%). The mean density of regeneration (juveniles >15 cm in height) near adult trees (3-7 m away) was 0.2/m2, 200 times greater than at random in the forest (10/ha), but long-term data on growth and survivorship are needed to determine whether regeneration is sufficient for population recovery. Gaharu wood extraction from Gunung Palung was very profitable for collectors, generating an estimated gross financial return per day of US $8.80, triple the mean village wage. Yet, the estimated sustainable harvest of gaharu wood at natural tree densities generates a mean net present value of only $10.83/ha, much lower than that of commercial timber harvesting, the dominant forest use in Kalimantan. Returns per unit area could be improved substantially, however, by implementing known silvicultural methods to increase tree densities, increase the proportion of trees that produce gaharu wood, and shorten the time interval between successive harvests. The economic potential of gaharu wood is unusual among nontimber forest products and justifies experimental trials to develop small-scale cultivation methods.

Many rain-forest trees in South-East Asia, including the dominant canopy family Dipterocarpaceae, reproduce in gregarious mast-fruiting events once every 2–11 y (Ashton et al. 1988). The dominant hypothesis for the evolution of masting is that predators are incapable of consuming mast seed crops, so that natural selection has favoured parent trees that fruit in synchrony (Janzen 1974, 1976). Mast flowering and fruiting are visually spectacular and quantified in harvest records for dipterocarp species producing large, oil-rich tengkawang seeds (Curran et al. 1999). Seedling recruitment following a mast is less obvious and has no immediate commercial value. However, a number of pulses of recruitment have been documented (Ashton et al. 1988, Chan 1980, Fox 1972, Liew & Wong 1973). These, together with general acceptance of the satiation hypothesis, have led to the widespread assumption that masts reliably increase seedling density and generate distinct seedling cohorts (Whitmore 1998). Indeed, foresters in Malaysia and Indonesia often recommend harvesting only after a mast, to ensure high densities of seedling regeneration.

(1) In a perennial grassland undergoing succession after the removal of domestic grazers, three natural processes could disrupt the canopy, and thus affect colonization. These are: canopy gap formation due to the death of individual bunchgrasses; soil disturbance by gophers; and grazing by native animals. (2) Species' abilities to colonize canopy gaps and gopher mounds were assessed in the field, with seed introduction experiments, for the five most cover-dominant grass species: Anthoxanthum odoratum, Holcus lanatus, Deschampsia holciformis, Rytidosperma pilosum (all perennial bunchgrasses) and Vulpia bromoides (an annual grass). (3) The effects of native grazers on colonization by the most abundant species, Anthoxanthum, were assessed, using grazer exclosures and seed introductions in annual-dominated vegetation, where grazing activity was highest. (4) Colonization success was quantified as total leaf area, number of survivors and seed production, in sites where seeds of the colonist either fell naturally, or were introduced at natural densities. (5) The formation of canopy gaps by the death of individual bunchgrasses and soil disturbances by gophers strongly affected colonization success. The best colonizers were Anthoxanthum and Holcus, whose colonization success was increased 6-2500-fold by canopy gap formation, and 10-200-fold by the formation of gopher mounds. Few, small seedlings of Deschampsia and Rytidosperma survived in canopy gaps or on gopher mounds. Unlike Anthoxanthum and Holcus, Deschampsia and Rytidosperma did not reproduce in gaps or on mounds over a two-year period. (6) Vulpia colonists had higher seed production on mounds than the four perennials. Vulpia also colonized canopy gaps, but was excluded by perennial vegetation in the second year of growth in the gaps. (7) In annual-dominated vegetation, neither aboveground biomass nor colonization by Anthoxanthum was affected by excluding grazers. However, exclusion of grazers led to an increase in the cover of forbs after two years. Clipping aboveground vegetation allowed Rytidosperma to achieve dominance in sites where, under undisturbed conditions, it existed only as a suppressed understorey. All other perennials were negatively affected by clipping. (8) The species with the highest natural densities of seed rain also had the greatest perseed colonization success, even though negative density-dependent effects must have been strongest for those species. (9) Seed size was positively correlated with survivorship on mounds, but was unrelated to the sizes of individual colonists in gaps or on mounds. (10) Overall, canopy gaps and gopher mounds favoured the same species that colonized well in undisturbed sites. Both types of disturbance increased colonization by perennials in annual-dominated vegetation, and canopy gaps were required for changes in species dominance in perennial vegetation.*

1. Growth responses to hurricane disturbance were assessed for the dominant species in two sites in a northern-hardwood forest at Hubbard Brook, New Hampshire, USA. The species comprised two shade-tolerant trees, Acer saccharum (sugar maple) and Fagus grandifolia (American beech), one relatively shade-intolerant tree, Fraxinus americana (white ash) and one tree of intermediate tolerance, Betula alleghaniensis (yellow birch). The two sites, 0.6 km apart, were similar except for contrasting disturbance histories. The hurricane-damaged site was devastated by a hurricane in 1938, whilst the control site was only lightly damaged by the hurricane. Radial growth was compared between species, size classes, time periods and sites. 2. Radial growth of all species increased dramatically immediately following the hurricane in the damaged site; proportional growth increased more than sevenfold, on average. Radial growth remained high in the hurricane-damaged stand 49 years later. There was no change in radial growth in the control stand following the hurricane. 3. F. americana (the least shade-tolerant species) showed the greatest proportional increase in growth after the hurricane and maintained the highest growth rates several decades after disturbance. B. alleghaniensis, A. saccharum and F. grandifolia had very similar growth responses. Smaller trees had a greater proportional increase in growth than larger trees following the hurricane, especially for F. americana. 4. Stem density remained higher and mean tree basal area remained lower in the hurricane-damaged site than in the control site 49 years after the hurricane. 5. The pioneer species Prunus pensylvanica (pin cherry) invaded after the hurricane in the damaged site, but 49 years later was present only as dead stems, having been replaced by the later successional species B. alleghaniensis, A. saccharum, F. grandifolia and F. americana. This is the same successional sequence that follows clearcutting in northern-hardwood forests.

We examined the spatial structure and regeneration of Tetramerista glabra, a dominant canopy tree in peat swamp rain forest in Borneo (West Kalimantan, Indonesia). T. glabra has strong spatial structure that changes dramatically during the life cycle; seedlings were highly aggregated, saplings were random and trees were evenly distributed. Germination and seedling relative growth were highest within canopy gaps, but seedling densities were highest at gap edges. Concentration of seedlings in gap edges, rather than localized seed dispersal, was responsible for seedling patchiness. The slope of the relationship between relative growth rate and seedling height decreased from gap, to gap edge to understory habitats, suggesting that competition within the seedling layer is more important in gaps than in the understory. The processes that break down seedling aggregation, leading to over-dispersion of trees, must be density dependent, but remain unknown.

(1) The colonization and inhibition abilities of species were identified as two essential and distinct components of competitive ability. These components can be quantified to evaluate species interactions and predict population and community change in a community where changes in abundance depend on colonization processes. (2) Colonization and inhibition abilities were quantified and compared in a patchy Californian grassland community. This was accomplished with an experimental study of the colonization of vegetated sites, using natural seed-rain densities. (3) The four most abundant perennial species, Anthoxanthum odoratum, Holcus lanatus, Deschampsia holciformis and Rytidosperma pilosum, differed greatly in colonizing ability, as measured by survival, growth and reproduction. All perennial species effectively inhibited colonization of their stands, but annual vegetation could be colonized by Anthoxanthum, and to a lesser degree by Holcus. (4) Species differences in colonizing ability depended in part on their different densities of seed rain, but there were major differences in intrinsic, per-seed colonizing ability as well. (5) In contrast, species differences in inhibition ability could be explained by above-ground biomass alone; intrinsic differences among species in their per-unit biomass inhibition effects were not important. (6) The findings led to definite predictions about successional change in undisturbed sites. These methods and results may have some quite general application to the analysis of population and community dynamics