Primary Forest Sites Research Articles

Demographic Effects of Collecting Rattan Cane and Their Implications for Sustainable Harvesting

Abstract: Rattan, Old World climbing palm, is an extremely valuable nontimber forest product whose canes are gathered for both market and nonmarket uses. I evaluated the effects of harvesting commercial rattan, Calamus zollingeri Becc., on genet survival and ramet demography in two primary forest sites near Lore Lindu National Park in Sulawesi, Indonesia. I monitored 168 permanently marked C. zollingeri genets for 4 years and surveyed random transects for C. zollingeri genet and ramet populations and evidence of cane harvesting in 1996 and 2000. Cane harvesting had no significant effect on genet survival or mean ramet densities. However, current cane extraction rates significantly reduced mean cane lengths and total available cane throughout the area during the study period. Based on observed genet and ramet populations and average cane growth rates of 1.4 m/year, the sustained‐yield harvesting potential of C. zollingeri is approximately 101 m and 56 m/ha/year in the two study sites. Although C. zollingeri exhibits life‐history traits well suited to sustained‐yield harvesting, including production of multiple canes, cane resprouting following harvest, rapid cane growth, and widespread abundance below 1100 m, current harvest rates exceed growth and yield, and supplies of cane are being depleted. Rattan harvesting is widespread in Lore Lindu National Park. Approximately 18% of the park (42,000 ha) is likely subject to intensive and unsustainable extraction of C. zollingeri.

Litter fall, litter stocks and decomposition rates in rainforest and agroforestry sites in central Amazonia

The sustainability of agroforestry systems in Amazonia was assessed from their litter dynamics and decomposition. Litter fall and litter stocks were determined from July 1997 to March 1999 in four sites in central Amazonia: a primary rainforest, a 13-year-old secondary forest, and two sites of a polyculture forestry system which consisted of four planted tree species of commercial use amidst upcoming secondary growth. The average annual litter fall in the undisturbed primary rainforest (FLO) was 8.4 t ha−1 year−1, which is within the range of litter fall in other rainforests in the region. It was similar in one of the two polyculture sites (8.3 t ha−1 year−1), but lower in the secondary forest and in the second polyculture site. In the litter fall in secondary forest and agroforestry sites, the leaf portion was higher (76–82% of total litter fall) than in FLO, due to reduced fine matter and wood fall. Leaf litter fall variability was much lower in the plantation sites than in the forests, which is explained by the much more homogeneous stand structure of the plantations. The quality of the produced litter, measured as C/N ratio, differed significantly between the primary forest site and one polyculture and the secondary forest site. The cumulative input of nitrogen through litter fall was 144 kg ha−1 year−1 in FLO, and 91–112 kg ha−1 year−1 in the polycultures and the secondary forest. Litter fall was not correlated with soil parameters, but had a significant linear regression with canopy closure. For the primary rainforest, litter fall was also (inversely) correlated with monthly rainfall. Litter fall was higher in the first year (1997–1998; an El Nino period) than in 1998–1999. Litter stocks on the forest floor were highest in the secondary forest (24.7 t ha−1), and much lower in the polyculture sites (15.1–16.2 t ha−1) and the primary forest (12.0 t ha−1). There were no differences in the relative N content (C/N ratio) of the litter stocks between the sites, but the larger stocks led to higher absolute N contents in the litter layer in the secondary forest. From the monthly values of litter stocks (S) and litter fall (P), the decomposition coefficient k e=P/S was calculated, which was, on average, highest for the primary forest (0.059), followed by the polyculture systems (0.040–0.042), and by the secondary forest (0.024). Thus, due to low decomposition rates, the secondary forest site showed large litter accumulations in spite of a relatively low litter fall. In contrast, the primary forest showed high litter fall but low stocks, due to high decomposition rates. The decomposition coefficients of the polyculture systems ranged between the primary and the secondary forest. The reduced decomposition rates in the man-managed agroecosystems indicate quantitative and/or qualitative changes in the decomposer communities of these systems that lead to a higher build-up of litter stocks on the forest floor. However, the decomposer systems in the polyculture sites still were more functional than in the site of non-managed secondary growth. Thus, from a soil biological viewpoint, ecologically sustainable low-input agroforestry in Amazonia will benefit from the application of these polyculture systems.

Soil Microbial Dynamics in Costa Rica: Seasonal and Biogeochemical Constraints1

The soil microbial biomass is largely responsible for the transformation of organic matter and the associated mineralization of important nutrients that regulate plant productivity. While the controls on soil microbial biomass and activity in temperate ecosystems have been well investigated, there is a paucity of such information from tropical rain forest ecosystems. Hence, we used a natural soil gradient (nutrient-poor oxisols and nutrient-rich mollisols) to investigate seasonal changes in the size and activity of the soil microbial community in two primary tropical rain forest sites in southwestern Costa Rica. In a nutrient-poor oxisol, microbial biomass ranged from 952 μg/g in the dry season (February) to 1967 μg/g in the wet season (June). The greater microbial biomass estimates corresponded to greater rates of microbial activity in the oxisol forest; however, the active fraction of the soil microbial biomass remained consistently low, regardless of soil C availability. In addition, while there was very little seasonal variability in microbial C:N ratios, we found extreme variations in seasonal microbial C:P ratios, with the highest microbial C:P ratio occurring when microbial biomass C was at a maximum. Our results suggest the importance of P availability in regulating soil microbial processes and that decomposition during the wet season (of litter accumulated in the previous dry season) may play an important role in driving seasonal changes in microbial biomass and activity.

Effect of soil moisture on canopy conductance of Amazonian rainforest

Estimates of canopy conductance, g c, were derived from hourly eddy-covariance measurements of evaporation for a primary forest site near Manaus, Brazil, using an inverted Penman–Monteith equation. These data were used to calibrate Jarvis-type models of canopy conductance including and excluding a soil moisture dependence. A period of low canopy conductance in the observations coincided with low soil moisture and high humidity deficit. The model was able to capture this decrease in diurnal maximum g c only when a soil moisture dependence was included. The optimised value of wilting point in the soil moisture function was 465 m 3 m −3, which was comparable with estimates from soil hydraulic properties.

The peregrine earthworm Pontoscolex corethrurus in the East coast of Costa RicaThe 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Summary Sampling of earthworm communities was performed in the Caribbean coast of Costa Rica at 8 sites to assess the distribution of the peregrine pantropical species Pontoscolex corethrurus and its relationships with native species depending on the type of land use. P. corethrurus was largely dominant at each site and in almost all habitat types. Density was in the range of 143 to 182 ind.m−2. P. corethrurus was absent from only one primary forest site where only native species could be found. In banana plantations, the density reached maximum of ca. 361 ind.m−2. In all sites, an increase of this species corresponds significantly with a reduction of the rest of the earthworm fauna except for Dichogaster sp. Where P. corethrurus was absent, density of other species reached 34.4 ind.m−2. In southern Costa Rica, human immigration and sustained activities probably favoured the establishment of P. corethrurus. This species became dominant, even in remaining plots of primary forests. In contrast, the species has not yet penetrated the large primary forest of the north-east of the country.

The peregrine earthworm Pontoscolex corethrurus in the East coast of Costa Rica : The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Sampling of earthworm communities was performed in the Caribbean coast of Costa Rica at 8 sites to assess the distribution of the peregrine pantropical species Pontoscolex corethrurus and its relationships with native species depending on the type of land use. P. corethrurus was largely dominant at each site and in almost all habitat types. Density was in the range of 143 to 182 ind.m - 2 . P. corethrurus was absent from only one primary forest site where only native species could be found. In banana plantations, the density reached maximum of ca. 361 ind.m - 2 . ln all sites, an increase of this species corresponds significantly with a reduction of the rest of the earthworm fauna except for Dichogastersp. Where P. corethruruswas absent, density of other species reached 34.4 ind.m - 2 . ln southern Costa Rica, human immigration and sustained activities probably favoured the establishment of P. corethrurus. This species became dominant, even in remaining plots of primary forests. In contrast, the species has not yet penetrated the large primary forest of the north-east of the country.

Physical and chemical properties of aerosols in the wet and dry seasons in Rondônia, Amazonia

As part of the Large‐Scale Biosphere‐Atmosphere Experiment in Amazonia (LBA), a large study of aerosol and trace gas properties was conducted in Amazonia during the dry and wet seasons and for pasture and primary forest sites. Aerosol mass and elemental composition were measured on filters for both fine (dp < 2.0 μm) and coarse (2.0 < dp < 10 μm) modes using polycarbonate filters mounted in stacked filter units (SFU). Measurements with real‐time aerosol and trace gas monitors were made, parallel to the collection of filter samples to obtain high time resolution (1–30 min). Black carbon equivalent (BCE) was determined with a multiwavelength Aethalometer as well as by reflectance in the fine‐mode SFU samples. Elemental carbon as well as total and organic carbon was measured using an R&P 5400 real‐time carbon monitor. PM10 aerosol mass concentrations were determined with a Tapered Element Oscillating Monitor (TEOM) monitor every 5 min. CO, O3, NO, and NO2 were analyzed with Thermo Environment monitors with trace level capabilities for NOx. A TSI 3010 particle counter measured the total particle number concentration (dp > 10 nm) every minute. A 55‐m tower in a primary forest in Rondônia and a facility built on a pasture site were used to operate the instrumentation for 4 months in the wet season and 3 months in the dry season of 1999. Particle‐Induced X‐Ray Emission (PIXE) was used to measure the concentration of 22 trace elements for fine‐ and coarse‐mode aerosol. During the wet season, very clean atmospheric conditions were observed at both sites. Particle concentration averaged 900 cm−3, black carbon averaged 250 ng m−3, and mean fine‐mode mass concentration was 2.9 μg m−3. In sharp contrast, very high concentrations were observed in the dry season for all the parameters at both sampling sites. Aerosol mass concentrations up to 250 μg m−3 and particle number concentrations of more than 40,000 cm−3 were observed, while the CO peaked at 8 ppm and NO2 reached 16 ppb. High correlation was observed between BCE, NO2, CO, aerosol particle number, mass, aerosol optical thickness, and other properties linked to biomass‐burning emissions. Relatively large concentrations of phosphorus in the coarse‐mode particles were observed, especially at nighttime. The emission of biogenic particulate P could have an effect in the nutrient cycling of this essential and key nutrient, which is present almost exclusively in the form of aerosol particles. Phosphorus is exchanged in the aerosol phase and mostly for coarse‐mode particles and during nighttime.

Influence of forest type and tree species on canopy ants (Hymenoptera: Formicidae) in Budongo Forest, Uganda.

The arboreal ant fauna was investigated in Budongo Forest, a seasonal rain forest in Uganda, using the insecticidal fogging technique. Ants were collected from 61 trees, between 7 and 33m in height, belonging to four tree species. Trees were growing in adjacent plots of forests characterized by different use and structure: an old primary forest, a primary swamp forest along a small river, and a secondary forest where selective logging was carried out for 30years. A total number of 37,065 ants, belonging to 161 species in 30 genera were collected. Considering the high number of species found only once, the completeness of the canopy ant fauna was relatively high and of relatively similar magnitude as samples from the Neotropics or the Oriental region. Up to 37 ant species on a single tree, with an average of 18.2species per tree, were found. Forty-four ant species (28.1%) were found only once, less than ten individuals were found for each of 88 species (54.7%), but 64.0% of all individuals belonged to one of five species. Considering the high numerical dominance of a few ant species like a Pheidole sp., Tetramorium aculeatum (Mayr) and a Crematogaster sp., there is some evidence for an ant mosaic in the lower canopy of the Budongo Forest. Individual numbers of ants were strongly correlated with nests in the fogged tree, though the ants were not homogeneously distributed in the tree crowns. Diversity measures that strongly depend on individual numbers such as the Morisita-Horn index or rarefaction methods were calculated, but results were not concordant with those of incidence-based estimates such as jack-knife calculations. Differences in ant species richness and faunal composition between tree species were low, but more significant between forest types. The ant fauna in the secondary forest was less diverse with 12.6% fewer species compared to the primary forest sites. The average number of ant species per tree was significantly lower in the secondary forest (<20% of the species; F=8.03, df=59, P<0.01) than in the undisturbed forest types. Cataulacus, Leptothorax, Tetraponera, and Polyrhachis, which are typical canopy-dwelling ant genera, had a significantly higher diversity and frequency in the two primary forest types (F=4.17, df=53, P<0.05). Secondary forest trees are often younger, lacking dead branches and epiphytes which are important requisites for ant colonization on trees.

Isoprene and monoterpene emissions of Amazônian tree species during the wet season: Direct and indirect investigations on controlling environmental functions

As part of the project LBA‐EUSTACH (European Studies on Trace gases and Atmosphere Chemistry as a contribution to the Large‐Scale Biosphere‐Atmosphere experiment in Amazonia), we examined the diel pattern of isoprenoid exchange in the wet season of 1999 at a remote field site in Rondônia, Brazil. The emission pattern of two tree species in a secondary forest was investigated by means of a dynamic branch enclosure system and was compared on the basis of climatological variables like temperature and light and physiological parameters such as assimilation, transpiration, and stomatal conductance. While the species Hymenaea courbaril was found to be a strong isoprene emitter, Apeiba tibourbou was found to exclusively emit monoterpenes and no isoprene. Species‐related standard emission factors calculated on a carbon basis were 45.4 μg g−1 h−1 (24.9 nmol m−2 s−1) for isoprene and 3.6 μg g−1 h−1 (0.75 nmol m−2 s−1) for monoterpene emission, representing a nontrivial carbon loss by the plants of 1.8% and 0.1% C relative to the net carbon assimilation on a daily basis. About 90% of the total monoterpene emission from A. tibourbou was comprised of sabinene, α‐pinene, β‐pinene, myrcene, and limonene, in decreasing quantity. Despite the difference in isoprenoid emission composition, the diel emission pattern of both tree species reacted similarly toward the environmental conditions, fluctuating light and temperature, indicating that closely related metabolic controls were involved in the actual emission. Both isoprene emission and monoterpene emission exhibited a light saturation curve similar to CO2 assimilation. No isoprenoid emission was found during nighttime. The strong light dependence of the monoterpene emission by A. tibourbou suggests that this tree species does not store monoterpenes but emits them immediately upon production. The diel pattern of both the isoprene and the monoterpene emission could be adequately simulated by current isoprene algorithms. The ambient air mixing ratios of isoprenoids were clearly dominated by isoprene, with peak values of 8 ppb inside the main canopy. Vertical gradients of ambient air mixing ratios in and above a primary rain forest site illustrated the emission of isoprene by the main canopy dependent upon light and temperature but were also indicative of a potential sink at the forest floor. For monoterpenes, corresponding gradients could hardly be resolved, reflecting observed ambient air mixing ratios more than an order of magnitude lower than for isoprene. Nevertheless, a strong diel cycle of short‐lived monoterpene compounds like α‐pinene was found in the primary as well as in the secondary forest site, which further strengthens our finding of a strong light dependence of biogenic monoterpene emission even on a larger scale. Our findings to some extent question the applicability of the commonly used monoterpene emission algorithm to the tropics. A strong light dependence of biogenic monoterpene emissions may, if generalized for tropical tree species in common, have a strong impact on estimated global flux rates for tropical regions.

Dynamics of Aboveground and Soil Carbon and Nitrogen Stocks and Cycling of Available Nitrogen along a Land-use Gradient in Rondônia, Brazil

High rates of deforestation in the Brazilian Amazon have the potential to alter the storage and cycling of carbon (C) and nitrogen (N) across this region. To investigate the impacts of deforestation, we quantified total aboveground biomass (TAGB), aboveground and soil pools of C and N, and soil N availability along a land-use gradient in Rondonia, Brazil, that included standing primary forest, slashed primary and secondary forest, shifting cultivation, and pasture sites. TAGB decreased substantially with increasing land use, ranging from 311 and 399 Mg ha–1 (primary forests) to 63 Mg ha–1 (pasture). Aboveground C and N pools declined in patterns and magnitudes similar to those of TAGB. Unlike aboveground pools, soil C and N concentrations and pools did not show consistent declines in response to land use. Instead, C and N concentrations were strongly related to percent clay content of soils. Concentrations of NO3-N and NH4-N generally increased in soils following slash-and-burn events along the land-use gradient and decreased with increasing land use. Increasing land use resulted in marked declines in NO3-N pools relative to NH4-N pools. Rates of net nitrification and N-mineralization were also generally higher in postfire treatments relative to prefire treatments along the land-use gradient and declined with increasing land use. Results demonstrate the linked responses of aboveground C and N pools and soil N availability to land use in the Brazilian Amazon; steady reductions in aboveground pools along the land-use gradient were accompanied by declines in inorganic soil N pools and transformation rates.

Demography of the Brazil nut tree (Bertholletia excelsa) in the Bolivian Amazon: impact of seed extraction on recruitment and population dynamics

A demographic study was carried out on Bertholletia excelsa, the Brazil nut tree, in two primary forest sites in Northern Bolivia where Brazil nuts have been harvested for several decades. In spite of the large proportion (93%) of seeds that are harvested, reasonable densities of recently emerged seedlings were found. Seeds of Bertholletia are contained in woody fruits that are primarily opened by agoutis. Most fruits are left untouched on the forest floor for 1–2 y before they are opened, possibly due to high energetic costs of fruit opening just after fruit fall. However, the proportion of viable seeds is strongly reduced in older fruits.Growth in diameter at breast height (dbh) was low for pole-sized trees (&lt; 15 cm dbh) and adult trees (&gt; 100 cm dbh) and peaked for intermediate-sized trees (30–60 cm). These trees often attained a growth rate of &gt; 1.5 cm y−1, which is high compared with other non-pioneer tropical trees. This, and the strong growth response to increased light availability found for seedlings and saplings, suggest that Bertholletia excelsa can be classified as a gap-dependent species. Matrix population models were constructed for both study populations. Population growth rates (λ) were close to one, and were most sensitive to persistence in one size category. Age estimates revealed that age at first reproduction (at dbh &gt; 60 cm) amounts to over 120 y, and age in the last category (dbh &gt; 160 cm) to almost 300 y. Given the continuous rejuvenation of the population, the stable population size, the high age at maturity and the long reproductive period, it is concluded that current levels of Brazil nut extraction may be sustained at least for several decades and perhaps for even longer periods.

Improved method for quantifying levoglucosan and related monosaccharide anhydrides in atmospheric aerosols and application to samples from urban and tropical locations.

An improved analytical method was developed and validated for the determination of the monosaccharide anhydrides levoglucosan, mannosan, and galactosan in atmospheric aerosol samples. The method uses an external recovery standard, extraction in dichloromethane, trimethylsilylation, addition of an internal standard (1-phenyl dodecane), and analysis by gas chromatography with flame ionization detection (GC-FID) and gas chromatography/mass spectrometry (GC/MS). As external recovery standard, we selected 1,2,3-trihydroxyhexane, which has a similar polarity as the monosaccharide anhydrides; furthermore, it was ensured that the trimethylsilylation step leads to complete derivatization into trimethylsilyl ethers. The reproducibility of the combined trimethylsilylation and analysis of levoglucosan was about 2% for standard solutions, whereas the precision of the entire method for the sum of all three monosaccharide anhydrides (MAs) in real aerosol filter samples was about 5%. The method was applied to aerosol samples from urban and tropical locations. The atmospheric concentration of the MAs in fine (<2.5 microm) aerosols at a primary forest site in Rondĵnia, Brazil, was on average 2.15 microg m(-3) during the dry season when intensive biomass burning occurs, which was almost 400 times higher than during the wet (nonburning) season. Urban total aerosols collected in Gent, Belgium, showed an average atmospheric concentration of MAs of 0.56 microg m(-3) for the winter season, which was a factor of 20 higher than for the summer season. The carbon in the MAs accounted on average for about 5.1% and 1.8% of the organic carbon in the Brazilian dry season and Gent winter aerosols, respectively. Levoglucosan was the major MA, with a relative abundance in the range of 76-93%.

Diversity and abundance of vascular epiphytes: a comparison of secondary vegetation and primary montane rain forest in the Venezuelan Andes

Species diversity of vascular epiphyte plant communities was studied in La Carbonera, a montane rain forest dominated by Podocarpaceae in the Venezuelan Andes. We compared the epiphyte communities of the primary, disturbed, and secondary forest areas of La Carbonera in order to augment the scarce knowledge on the effects of anthropogenic disturbance on these important elements of tropical vegetation. Diversity of vascular epiphytes (191 species in the whole forest area) was low in the disturbed and secondary areas (81 spp.) compared to adjacent primary forest (178 spp.). Four types of disturbed forest and secondary vegetation supported different numbers of epiphyte species, showing a decline with increasing degrees of disturbance (65 spp. along a road transect, 42 spp. on relict trees in disturbed forest, 13 spp. in a tree plantation and 7 spp. in a former clearing, both secondary vegetation units). Epiphytic species composition in primary and disturbed or secondary forest areas differed markedly: disturbed habitats harboured fewer fern and orchid species but more bromeliad species than the primary forest. Probably the families occurring only in primary forest sites of our study may be useful as bioindicators to determine the degree of disturbance in other habitats of mountain rain forests as well. Epiphyte abundance was also lower in disturbed habitats: a remnant emergent tree supported only about half as many epiphyte individuals as a member of the same species of similar size in the primary forest. The decrease in species numbers and abundance as well as the differences in species composition are mainly due to the less diverse phorophyte structure and less differentiated microclimate in the disturbed and secondary vegetation compared to the primary forest.

Organic matter stabilization in a Xanthic Ferralsol of the central Amazon as affected by single trees: chemical characterization of density, aggregate, and particle size fractions

Not only the amount of organic carbon in soil is important for soil organic matter (SOM) stability, but also its physical and chemical properties. The appropriate technique for the assessment of SOM dynamics can vary between soil types, and information about this is lacking for Ferralsols of the central Amazon basin. First, this work identified SOM pools which are sensitive to land-use changes on the terra firme in the central Amazon. In a second step, the effects of single trees on SOM properties were evaluated in a mixed tree crop plantation in comparison to secondary and primary forest sites. Thus, the processes of organic matter stabilization could be studied in the highly aggregated soils. A combination of aggregate and density fractionation was found to be most suitable for physical SOM characterization. The particulate organic matter (POM, density less than 1.6 Mg m −3) varied by one order of magnitude between sites and could be used as a sensitive indicator of land-use changes. Aggregate stability was not related to SOM contents or bulk SOM properties. The incorporation of plant material into stable SOM, however, was enhanced by aggregation. Among aggregate separates, the fraction, 0.25–0.5 mm, showed single-tree effects the most. SOM replenishment was higher under tree species with low quality litter, i.e. high C-to-N and polyphenol-to-N ratios. High quality litter from a leguminous ground cover, however, showed low soil nitrogen and carbon replenishment but increased nitrogen concentrations in light fractions. Litter with a high quality may improve soil nitrogen availability but not amounts of total SOM, which could only be shown for low quality litter. The results indicate the importance of aggregation and POM dynamics for SOM stabilization in the studied Xanthic Ferralsols of the central Amazon basin.

Survival and growth of rattan intercropped with coffee and cacao in the agroforests of Indonesia.

This study investigated the intercropping of rattan, an important non-timber forest product, in coffee and cacao agroforests in Sulawesi, Indonesia. The viability of producing seedlings from seeds and vegetative cuttings with the large-diameter rattan, Calamus zollingeri Beccari, and initial seedling survival, growth and response to light and soil drainage were investigated in village nurseries and perennial farms. Over 96% of seeds and 61% of vegetative cuttings were raised to transplanting size (25 cm with two to three leaves) over 20 months. One hundred C. zollingeri seedlings produced from cuttings were transplanted into each of three coffee or cacao farms and one primary forest site and exhibited an overall survival rate of 96%, 12.7 cm of height growth and the production of 0.8 new leaves per plant after eight months. No significant differences were observed between the four sites with respect to seedling survival, growth, or leaf production and no significant differences were found between seedling survival, growth or leaf production and light intensity (based on multiple PAR measurements). However, poorly drained sites exhibited significantly reduced C. zollingeri seedling survival and growth. The cultivation of C. zollingeri rattan in coffee and cacao agroforests represents a potential means of intensifying and diversifying perennial cash crop farming systems.

The effect of termite biomass and anthropogenic disturbance on the CH4 budgets of tropical forests in Cameroon and Borneo

SummaryThe exchange of CH4 between tropical forests and the atmosphere was determined by simultaneously measuring the net CH4 flux at the soil surface and assessing the flux contribution from soil‐feeding termite biomass, both within the soil profile and in mounds. In Cameroon the flux of CH4 ranged from a net emission of 40.7 ng m–2 s–1 to a net CH4 oxidation of –53.0 ng m–2 s–1. Soil‐inhabiting termite biomass was significantly correlated with CH4 flux. Termite mounds emitted up to 2000 ng s–1 mound–1. Termite‐derived CH4 emission reduced the soil sink strength by up to 28%. Disturbance also had a strong effect on the soil sink strength, with the average rate of CH4 oxidation, at – 17.5 ng m–2 s–1, being significantly smaller (≈ 36%) at the secondary forest site than the –27.2 ng m–2 s–1, observed at the primary forest site. CH4 budgets calculated for each site indicated that both forests were net sinks for CH4 at – 6.1 kg ha–1 y–1 in the near‐primary forest and – 3.1 kg ha–1 y–1 in the secondary forest.In Borneo, three forest sites representing a disturbance gradient were examined. CH4 oxidation rates ranged from 0 to – 32.1 ng m–2s–1 and a significant correlation between the net flux and termite biomass was observed only in an undisturbed primary forest, although the biomass was insufficient to cause net emission of CH4. Rates of CH4 oxidation were not significantly different across the disturbance gradient but were, however, larger in the primary forest (averaging – 15.4 ng m–2 s–1) than in an old‐growth secondary forest (–13.9 ng m–2s–1) and a young secondary re‐growth (– 10.8 ng m–2s–1). CH4 flux from termite mounds ranged from net oxidation in an abandoned mound to a maximum emission of 468 ng s–1 mound–1. CH4 budgets calculated for each site indicated that CH4 flux from termite mounds had an insignificant effect on the budget of CH4 at the regional scale at all three forest sites. Annual oxidation rates were – 4.8, – 4.2 and – 3.4 kg ha–1 y–1 in the primary, secondary and young secondary forests, respectively.

Factors affecting changes in landscape diversity in rural areas of the Fagus crenata forest region of central Japan

We compared landscape diversity in a primary forest site and a coppice forest site in rural area of the Fagus crenata forest region of central Japan. We focused on the factors affecting landscape diversity, with special reference to land ownership, and the relationship between changes in landscape diversity and the spatial distribution of landscape elements. We were able to identify two patterns that led to increased landscape diversity in the study sites. In the first, which was most apparent in the primary forest site, increased diversity resulted primarily from an increase in the number of landscape elements. In the other, which was seen in the coppice forest site, increased diversity resulted from a decrease in the difference between the numbers of grid squares dominated by each landscape element while the number of landscape elements remained unchanged. Land ownership also had different implications for the increase of landscape diversity. The changes in the Contagion Index, which decreased in private land and increased in the national forest, showed that private land contains many small patches while the landscape of the national forest consists of a few large, contiguous patches. Thus, an evaluation of changes in landscape structure requires measuring a variety of indexes in addition to the diversity.

Litter and fine-root production in three types of tropical premontane rain forest in SE Venezuela

We investigated the productivity of three premontane primary forest sites in an extremely nutrient-poor environment on the Guyana shield in SE Venezuela. Aboveground litter production (total 5.58; leaves 4.30 Mg ha−1 year−1) was low, but comparable to other tropical forests. Due to the low nutrient status, net production of fine roots was among the highest ever reported (11.14 Mg ha−1 year−1). Only 20% of fine root stock was alive, 80% consisted of necromass. Similar values were obtained for dead and living root tips. Element concentrations in fine roots (including bio- and necromass), especially Ca, were low, whereas Al concentrations were relatively high. The upper limit of average fine root lifetime was 253 days. We conclude that the high proportion of necromass was mainly caused by slow mineralisation of nutrient-poor fine roots.

Identifying spatial patterns in the tropical rain forest structure using hemispherical photographs

This work emphasises the usefulness of hemispherical photography for identifying spatial patterns in the tropical rain forest structure. Structural variability was investigated at a local (intra-site) scale, in relation to the forest mosaic, and at a regional (inter-sites) scale, for its implication in forest typology. Four primary forest sites, from 0.6 to 1 ha, were investigated in Central Sumatra, Indonesia.

Shifting cultivation along the Trans-African Highway and its impact on the understorey bird community in the Ituri Forest, Zaire

summarySince the 1940s, horticulturalists (the Lese) have been settled along the sides of the roads that traverse a large part of the forest in eastern Zaire. These people have maintained their lifestyle of shifting cultivation and trade with the Mbuti pygmies. This has resulted in corridors of heavily disturbed and regenerating forest. The results of a study of the understorey bird community at three sites in the Okapi Reserve in the Ituri forest in Zaire are reported here. Two primary forest sites (one monodominant Gilbertiodendron forest) in the Reserve were compared with an area of forest disturbed by shifting cultivation. The two primary forest sites were more similar in species composition than they were to secondary forest created by shifting cultivation. Shifting cultivation had a more severe impact on the bird community than selective logging does in forests in Uganda and Malaysia. There was a shift following disturbance from a bird community dominated by insectivores to one with more frugivore-insectivores and nectarivores. Ground thrushes Zoothera spp. and flycatchers were abundant in the monodominant Gilbertiodendron forest and appear to suffer from the change in forest structure following disturbance. The Okapi Reserve currently conserves some important bird species and at least 333 birds have been reported to occur there.