Logging Gaps Research Articles

Nitrogen aboveground turnover and soil stocks to 8 m depth in primary and selectively logged forest in southern Amazonia

AbstractExtensive areas of Amazonia undergo selective logging, modifying forest structure and nutrient cycles. Anthropogenic‐accelerated rates of nitrogen (N) turnover could increase N loss and affect regeneration, carbon sequestration and timber production. We quantified leaf area reduction, canopy opening and downed biomass and resultant N flux from reduced impact logging (RIL) activities. We compared canopy reduction, surface soil moisture and nitrate to 8 m depth between logged gaps and intact primary forest to determine if logging activities increase subsoil nitrate. To test long‐term logging effects, we evaluated surface N stocks along a 12‐year postlogging chronosequence. At the harvest rate of 2.6 trees ha−1, total N additions in logging gaps, including leaves and wood from felled crowns (24.8 kg N ha−1) and other killed trees (41.9 kg N ha−1), accounted for over 80% of the total N addition to aboveground necromass from all logging activities (81.9 kg N ha−1). Despite this N turnover by logging, belowground nitrate storage to 8 m depth did not differ between logging gaps and primary forest at the low harvest rate and disturbance intensity of this study. Soil water depletion also did not differ between gaps and primary forest over 1 year, indicating the impact on belowground inorganic N was low. Compared with primary forest, nitrate concentrations to 8 m depth in logging gaps were only significantly higher at 60–100 cm, suggesting some N redistribution beyond the bulk of the fine roots in logging gaps. Extrapolated to the Amazon Basin scale, we provide a conservative estimate that logging damage and bole export under RIL would turn over 0.14 ± 0.07 to 0.23 ± 0.12 Tg N yr−1 based on 1999–2002 selective logging rates. Greater damage during conventional selective logging would cause higher N turnover throughout the Amazon Basin than our results based on RIL.

Impacts of portable-sawmill logging on stand structure and regeneration in the lowland forests of West New Britain, Papua New Guinea

Summary Small-scale portable-sawmill logging, an option for reduced—impact logging, is promoted across Papua New Guinea by NGOs as a sustainable development mechanism for village communities. It can provide a technically feasible tool for landholders to manage their commercial forest resources rather than selling logging rights to international companies. Despite over 20 years of operational practice, however, there has been little research on the effects of portable sawmilling or its silvicultural effectiveness. This study investigated the effects of well-planned and controlled portable-sawmill logging on stand structure and regeneration in lowland hill forest at Kilu in West New Britain. Logging effects were compared with natural changes in unlogged forest. Tree diameter increment, tree health and stem mortality were assessed for a 1-ha logged stand and a 1-ha unlogged stand over 29 months. Regeneration was assessed within the logged stand and in three logging gaps over 61 months. Portable-sawmill logging, harvesting 1–2 trees ha−1, caused 1–6% of the ground area to be heavily disturbed. The logging gaps promoted abundant regeneration of primary and secondary species. Early regeneration was dominated by secondary species (61%), but after 61 months primary species became dominant and the secondary species accounted for only 9% of the juvenile population. Impacts in this study were small when compared with those found by studies of conventional industrial logging in PNG, but the differences were less marked when compared with conventional logging at similar harvest intensities elsewhere. A slightly higher harvest intensity warrants consideration to reduce the impact per stem harvested.

Disturbance, Resources, and Exotic Plant Invasion: Gap Size Effects in a Redwood Forest

Abstract Fluctuations in plant resource availability are hypothesized to promote exotic plant invasion by allowing propagules already present in an area a chance to successfully compete for unused resources. To examine the relationship between resource enrichment and exotic species invasion, we used selective logging canopy gaps over a range of sizes (56 m2 to >1500 m2) in a redwood forest (Santa Cruz County, CA) as a surrogate for disturbance intensity and level of pulsed resource enrichment. Measurements of abiotic conditions in gaps ca. 10 yr after logging suggest light is the primary difference in current resource availability, though a pulse of light and nutrients likely occurred at the time of gap formation. Exotic species richness and relative cover increased significantly as gap size increased. In a separate manipulative experiment, we compared understory plant composition between artificially shaded and unshaded plots in 2.5-year-old logging gaps. Shaded plots had a lower proportion of exotic spe...

Enrichment of logging gaps with moabi ( Baillonella toxisperma Pierre) in a Central African rain forest

Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we present the results of an experimental enrichment planting with moabi ( Baillonella toxisperma Pierre), a valuable and important timber species harvested in Central Africa. Although forest gaps are generally considered as favourable for the regeneration of this species, a survey conducted in a forest concession in south-eastern Cameroon provided an estimate of only 12.7 seedlings ha −1, suggesting that the species was, in fact, poorly represented in logging gaps within the study area. To further investigate the dynamics of the moabi in logging gaps, 795 seeds were sown in 15 logging gaps and 410 nursery-raised seedlings were planted in 15 other gaps. A biannual monitoring program over a 30-month period showed a lower survival rate for seedlings from sowing (75.9%) compared to that of nursery-raised seedlings (95.3%). Planted seedlings reached an average of 229.3 cm tall whereas seedlings from sowing were 167.5 cm tall, with the observed difference roughly corresponding to the average height of the nursery-raised seedlings at the time they were introduced to the logging gaps. After 30 months, the diameters of planted seedlings (16.8 mm) were also greater than those of the directly sown individuals (12.5 mm). Forest gap characteristics significantly influenced the growth of the plants. Factors accounting for the differences were total solar radiation, the soil content of coarse sand, the topographic position of the gap, the vegetation cover and the density of Macaranga spp. Whilst total solar radiation had a positive influence on growth, the remaining factors had impacted growth negatively. A streamlined technique was tested by planting 7 seedlings in 250 gaps. Without additional site maintenance, 29.3% of the moabi seedlings emerged naturally from the competing vegetation after 24 months. With biannual maintenance some 89.4% of seedlings became successfully established. Clearance operations had no significant influence on the height of plants whilst plant diameter was greater in cleared gaps. The total cost of the enrichment technique was 5.5 EUR per gap without maintenance and 7.5 EUR per gap with a single maintenance measure. Whilst long-term monitoring is needed, this study suggests a high survival rate of moabi introduced in logging gaps, and a growth rate 10 times higher than previously reported under canopy cover. These findings, combined with the low costs of the enrichment technique, support the use of silvicultural measures in logging gaps to restore the forest.

Bird use of logging gaps in a subtropical mountain forest: The influence of habitat structure and resource abundance in the Yungas of Argentina

Selective logging is one of the main economical activities in tropical and subtropical forests. While most of the effects of this activity on bird communities have been studied by comparing exploited vs. non-exploited areas; the use of human-created treefall gaps by birds is relatively unknown. We studied habitat structure, resource abundance (fruits, flowers and arthropods) and bird activity in logging gaps of different age (1-year-old and 10- to 20-year-old) in a mountain forest (Yungas) of northwest Argentina in both dry and wet seasons. In less than a year after creation, short herbs colonize logging gaps increasing the abundance of arthropods in the ground and the activity of understory insectivores. During dry seasons recently created gaps become an important source of resources for understory frugivores-insectivores. Later on in succession logging gaps are invaded by exotic graminoid vegetation and tall herbs (dispersed through extraction tracks) which can impede the colonization and development of pioneer trees and natural regeneration. Probably as a consequence of a high abundance of fruits and flowers in the understory and a very low abundance of these resources in the canopy, old gaps were mainly used by understory frugivores-insectivores while arboreal frugivores were rare. Because arboreal frugivores disperse most tree seeds in tropical and subtropical forests, the low activity of this guild in logging gaps contribute to the low observed regeneration. Sustainable timber harvest in tropical and subtropical forests should include gap and logging track management to minimize the invasion by exotic graminoid vegetation and facilitate natural succession.

A post-logging assessment of some soil physical properties in a Ghanaian moist semi-deciduous forest

We assessed the impact of logging operations on some soil physical properties: penetration resistance, bulk density and matric potential in four logging gaps; loading bays, tree-fall gaps, primary skid trails, secondary skid trails and undisturbed site as control in a moist semi-deciduous forest in Ghana. Penetration resistance was significantly higher in loading bays and primary skid trails than in the other logging gaps with penetration resistance values of 64.84N/cm2, 116.56N/cm2 and 155.2N/cm2 for 0-2cm, 2-5cm and 5-7cm depths in the loading bays. Tree-fall gaps were the least compacted with corresponding penetration resistance values of 19.16N/cm2, 64.28.52N/cm2 and 91.38 N/cm2 for the various soil depths. Bulk density and soil matric potential however, did not significantly differ between gaps suggesting the impact of logging on soil compaction was quite low and could only be captured by penetration resistance. The low level of logging impacts on the forest soil may be accounted for by the time of logging which was the dry season and the small number of trees extracted (0.6 tree/ha) during logging. Keywords: Logging, moist semi-deciduous forest, soil physical properties, Ghana Ghana Journal of Forestry Vol. 19 & 20 2006: pp. 54-62

Treefall gaps of certified, conventionally managed and natural forests as regeneration sites for Neotropical timber trees in northern Honduras

Forest certification programmes promote sustainable management of the world's forests. Certification can be given to a forest management system that fulfils certain environmental, social and economic criteria. The ecological criteria for certified forestry include limiting harvest intensity and minimizing the mechanical damage of logging. Based on these requirements, we hypothesized that in comparison to conventionally managed forests, the logging gaps of certified forests would (1) host more established saplings of timber trees, due to a higher abundance of seed trees left in the forest, and (2) provide more favourable environments for the establishment and growth of timber seedlings, due to the control of negative logging impacts. We tested these hypotheses, using regeneration data on 10 shade-tolerant Neotropical timber species in a total of 46 treefall gaps in certified, conventionally managed and natural broad-leaved forests in northern Honduras. We analysed 12 environmental gap characteristics as determinants of sapling abundance, using a statistical approach that emphasizes their sensitivity to the forest management system as well as their ecological role. We found that gaps in certified forests were characterized by lower levels of logging-related disturbance than gaps in conventionally managed forests. The differences were however relatively small, since loggings are done at low intensity and without heavy machinery in the area. Despite the more favourable gap environment, regeneration success was poorer in certified forests than in conventionally logged forests. As expected, highest regeneration was found in natural forests. The good regeneration success in conventionally logged forests was largely due to the high abundance of a single species, Mortoniodendron vestitum. To explain the remaining differences in regeneration between management types, we suggest that loggings in certified forests have been more intensive in the past, leading to a scarcity of timber seed trees. We further propose two alternative explanations related to treefall gap frequency: (a) low logging intensity after certification may have led to low frequency of treefall gaps, limiting the recruitment of timber species; or (b) intensive loggings currently maintain an environment with too much disturbance for the success of timber regeneration.

Technical and financial analysis of enrichment planting in logging gaps as a potential component of forest management in the eastern Amazon

Studies of natural regeneration in logged forests indicate that without silvicultural intervention, succession in logging gaps may not result in establishment and recruitment rates adequate for sustained timber production from many tree species. I investigated the potential for management of timber tree species regeneration in disturbed areas within logged forest at a moist forest site in the eastern Amazon, through experimental introduction of seeds and seedlings of six timber species to logging gaps ranging in size from 165 to 455 m 2. I tested the effect of tending (removing competing vegetation) established seedlings in logging gaps at year 1 on seedling growth and survival over a 4-year period, and examined the influence of gap size on seedling development for each of the species. Seedling performance varied dramatically among logging gaps, related primarily to light conditions and competition. Tending was as important as gap size in determining sapling sizes at year 4 after planting. Projections based on species growth rates in logging gaps observed in this study suggest that individuals of all six species could recruit from seedling to minimum commercial size (50 cm dbh) within 60 years or less in logging gaps subjected to a regular thinning regime. Enrichment planting and tending of plants in logging gaps created in the first harvest could provide a substantial percentage of the timber volume in the third harvest, as well as serving to maintain viable populations of high-value timber species that appear unlikely to regenerate adequately in logged stands without direct interventions. However, low net present value of timber harvests projected for enrichment areas in year 60 relative to the upfront costs of this silvicultural treatment mean that widespread adoption of gap enrichment planting will likely only occur if financial incentives or new forest regulations are implemented.

Regeneration of timber species following selective logging in a moist semi-deciduous forest in Ghana

The natural regeneration and growth of timber tree species were studied in four logging gaps; loading bays, tree-fall gaps, primary skid trails and secondary skid trails with forest shade as control in a moist semi-deciduous forest in Ghana. There was prolific tree seedling emergence in all the sites in the first few months following logging but declined after 8 months. Species diversity as well as seedling numbers increased with reducing gap size from the loading bays to secondary skid trails. Weed biomass, however, increased with increasing gap size. Pioneer species were relatively abundant in loading bays than all the ecological species guilds while the non-pioneers showed preference for smaller gaps. Ceiba pentandra (pioneer), for example, was the only species that survived in the loading bays for the 27-month period of the study but could not survive in the forest shade. The limited regeneration of commercial tree species and increased colonization by competing weeds in larger gaps indicate the need for better control over harvest operations through gap size reduction and post-harvest competition control treatments to ensure sustainable production of economic tree species. Keywords: Ghana, moist semi-deciduous forest, logging, regeneration Ghana Journal of Forestry Vol. 17 & 18 2005: pp. 20-35

Natural regeneration and environmental relationships of tree species in logging gaps in a Bolivian tropical forest

Successional dynamics and environmental associations of 18 pioneer and 24 commercial tree species were studied in a 4-year chronosequence of logging gaps in a Bolivian tropical forest. Logging gap area ranged from 108 to 1246 m 2. Pioneer regeneration was 71–387 more abundant than that of commercial species in all harvest years. Pioneer saplings (>1.5 m tall and <10 cm dbh) were more abundant in 2- and 4-year-old gaps than in 1-year-old gaps, but pioneer seedlings (≤1.5 m tall) were more abundant in 1-year-old openings. By contrast, there were no significant differences among harvest years in size class distributions of commercial seedlings or saplings. Some pioneers ( Acacia polyphylla, Urera baccifera, Heliocarpus americana, Cecropia concolor, and Inga edulis) were associated with large gaps or coarse soils with high herbaceous cover. Among commercial trees, Ampelocera ruizii, Hura crepitans, and Pseudolmedia laevis were associated with fine textured soils, while Pouteria nemorosa was associated with high fern cover and rock outcrops. Although most logging gaps were dominated by a few pioneer species, the commercial species A. ruizii, H. crepitans, P. nemorosa, and Terminalia oblonga may eventually dominate many gaps. Notably absent among gap regeneration were some of the most commercially valuable tree species, such as Swietenia macrophylla, Cedrela fissilis, Cariniana ianeirensis, and Ficus boliviana. Outplanting programs may be needed to ensure successful regeneration of these rare but valuable species.

An impacts of logging operations on understory plants for the broadleaved/Korean pine mixed forest on Changbai Mountain, China

Natural regeneration of tree species is important to the sustainability of native forest ecosystems in the temperate zone of north- east China. This study compared the densities and heights of seedlings and the diversities of shrubs and herbs on three sites of logging op- erations: log-skidding trails (LST), logging gaps (LG) and log landing sites (LLS). Sites undisturbed by logging gaps operations were sam- pled as control. The species, counts and height of tree seedlings and the species, counts, height and percentage coverage of shrubs and herbs were recorded in the field. The highest density and greatest height of regeneration trees were observed at LG and LST. The effects of LST on the densities of broadleaved trees were greater than those of coniferous trees. The difference in seedling density between LLS and control was significant (p=0.05). There was no significant difference in average seedling height for all the tree species between the disturbed sites and control. There were more shrub and herb species at the disturbed sites than at control. The diversity of understory plants at LG was the highest among all the sites. LST and LLS were different in shrub diversity, so were LLS and control. Both LG and LLS were different from control in herb diversity. Active measures need to be taken on the operation sites to protect the coniferous trees and the diversities of under- story plants for sustaining the structure and composition of the broadleaved-Korean pine mixed forest on Changbai Mountain of China. Since different operation sites have different effects on different tree species, site-dependent actions must be taken to assure the regeneration of ecologically important tree species.

Arrested succession in logging gaps: is tree seedling growth and survival limiting?

AbstractThirty years after selective timber harvest in the Kibale National Park, Uganda, many abandoned logging gaps are dominated by Acanthus pubescens, and show little forest recovery. To examine if this arrested successional state was caused by limited tree seedling growth and survival, we planted seedlings of four forest tree species (Albizia grandibracteata, Mimusops bagshawei, Prunus africana and Uvariopsis congensis) in A. pubescens‐dominated logging gaps and in control areas of adjacent forest. To assess if clearing A. pubescens facilitates forest regeneration, we planted seedlings of two species (A. grandibracteata and U. congensis) in small clearings cut within the logging gaps. We examined mortality, growth, herbivory and site characteristics among the treatments. Finally, we described the physical attributes of the A. pubescens‐dominated gaps. Seedlings of all the four species survived and grew equally well in A. pubescens and forest treatments, and most site characteristics were also similar. Seedlings planted in clearings grew more than in either forest or A. pubescens sites. Very few established trees were found in A. pubescens sites, and most of these were near the forest edges. We also discussed the role of elephants (Loxodonta africana) and collapsing A. pubescens canopies in the maintenance of an arrested successional state in these logging gaps.

Growth response by big-leaf mahogany ( Swietenia macrophylla) advance seedling regeneration to overhead canopy release in southeast Pará, Brazil

Big-leaf mahogany ( Swietenia macrophylla) is a valuable neotropical timber species whose seedling survival and growth dynamics in natural forests are poorly understood. To document regeneration dynamics of mahogany in seasonal transitional evergreen forests of southeast Pará, Brazil, we followed naturally established seedlings in the forest understory and in experimental canopy gaps. We found that only 1–2% of seedlings in the forest understory survived 8 years after germination; mean height growth was approximately 4 cm year −1 of height over this period, confirming mahogany's classification as a light demanding species. To test whether seedlings could survive and respond to canopy release after a period of suppression beneath competing secondary vegetation, we opened experimental canopy gaps above naturally established seedling regeneration in 2–3-year old logging gaps; seedlings were monitored at intervals through 80 months. Seedling survival probability and seedling growth rates demonstrated significant positive correlation with initial seeding height, canopy opening size, and seedling distance to gap edge. Of these factors, initial seedling height (indicating performance in logging gaps prior to experimental release) was the most important predictor of survival and growth response. More seedlings died during the first dry season beginning 6 months after canopy release than during any other census interval. Mean height growth rate of seedlings in gaps peaked at 126.1 ± 23.9 cm year −1 during the third-year census interval, declining afterwards as secondary vegetation overtook seedling crowns. Attack rates by the mahogany shootborer ( Hypsipyla grandella) were low amidst dense secondary vegetation that grew up after canopy opening. These results indicate that (1) advance regeneration experiencing early vigorous growth beneath disturbed canopies in logging gaps may respond to subsequent overhead canopy release, and (2) response vigor may depend on vigor of initial seedling growth.

The effect of seed mass and gap size on seed fate of tropical rain forest tree species in guyana.

For eleven tree species, differing in seed mass, germination success (emergence success for two small-seeded species) and the causes of failure to germinate were studied in the forest understorey and in logging gaps in the tropical rain forests of Guyana. In the forest understorey, germination success increased with seed mass. However, as gap size increased the difference between smaller and larger seeded species diminished because germination success of smaller-seeded species increased slightly, while that of larger-seeded species decreased dramatically. The negative effect of gap size on germination success of larger-seeded species was caused by an increased risk of desiccation with gap size, which was a far more important seed mortality agent for larger than for smaller-seeded species. Generally, seeds of smaller-seeded species suffered more from insect predation and were removed at higher rates than larger-seeded species. On the other hand, larger-seeded species were eaten more by mammals than smaller-seeded species. It is concluded that logging can result in shifts in the species composition in the tropical rain forests of Guyana which are dominated by species with large seeds, since germination success of larger-seeded species is dramatically reduced in large logging gaps.

Recruitment of lianas into logging gaps and the effects of pre-harvest climber cutting in a lowland forest in Cameroon

The abundance of lianas (woody vines) and the detrimental impact that they have on tropical rain forest trees is widely recognized. Lianas are particularly abundant in disturbed areas of the forest, such as logging gaps, and pre-harvest liana cutting has been widely recommended throughout the tropics to reduce the impact of lianas during and following tree harvest. The effectiveness of forest-wide liana cutting, however, is currently unresolved, particularly for reducing liana abundance in logging gaps. Furthermore, our understanding of the dynamics and rate of liana colonization in gaps is limited. We tested: (1) the speed at which lianas recruit into logging gaps and their dynamics afterwards; and (2) whether pre-harvest liana cutting actually reduces the abundance of lianas in post-harvest logging gaps. To test hypothesis 1, we compared liana recruitment in new, 1 and 6-year-old logging gaps. For hypothesis 2, we compared liana abundance and tree infestation by lianas in 1-year-old logging gaps in which all lianas had been cut 9 months prior to tree felling vs. 1-year old logging gaps in which lianas were not cut. Lianas recruited heavily into logging gaps within 1 year, mostly by means of stem sprouts, and many of these new stems were apparently able to persist for longer than 6 years. Lianas were significantly more abundant in the root/bole zone of gaps than in the canopy zone, mostly due to the vigorous regeneration of stem sprouts. Canopy openness was highest in gaps one year after logging, possibly due to the smothering effect of the lianas on developing trees. Although liana abundance increased significantly over the 6-year gap chronosequence, direct liana infestation of trees remained the same. Pre-logging liana cutting, however, significantly reduced the number of lianas and also the number of liana-infested trees in logging gaps. Consequently, liana cutting appears to be an effective method to reduce the abundance of lianas and thus minimize their detrimental effects on regenerating trees in logging gaps.

Effects of seed availability, site conditions, and herbivory on pioneer recruitment after logging in Sabah, Malaysia

Woody pioneers invade disturbed tropical forests but can be patchily distributed. We investigated causes of this patchiness in selectively logged forests near the Danum Valley Field Centre (DVFC) in Sabah, Malaysia. In a recently logged forest, we compared seed sources and seedling establishment between two logging systems (conventional practices [CL] and reduced impact logging [RIL]) and between two soil disturbance classes (topsoil or subsoil exposed). Tree seeds were less abundant than shrub and treelet seeds, and seed banks contributed many more viable seeds than did seed rain. Topsoil removal reduced seed and seedling counts and growth rates of planted seedlings. More pioneer seedlings established on RIL than on CL plots, but survival of planted seedlings was lower under RIL, perhaps due to denser canopy cover. Broadcasting seeds increased seedling recruitment for five animal-dispersed pioneer trees but not for two wind-dispersed trees. Longer term survival and growth of pioneer seedlings were compared between logging gaps (canopy but not soil disturbed) and skid tracks (canopy and soil disturbed) at a second site. Relative numbers in gaps vs. skid tracks varied by species, but across species, seedlings grew 40% more rapidly in gaps than in skid tracks. Survivorship differed among species but not between habitats. The three most common species experienced >95% mortality within 42 months. At a third site, we compared effects of mammalian herbivores on pioneer seedling performances in exclosures and open (control) plots centered at the edge of recently abandoned skid tracks. Fewer pioneer seedlings established in skid tracks than in less-disturbed edges, but abundances did not differ between exclosure and control plots. Over 18 months, pioneers survived better and grew on average 44% taller with mammalian herbivores excluded. Pioneer colonization can be seed limited, but high seedling mortality, exacerbated by herbivore damage, can limit recruitment even when seeds are available.

Spatial Analyses of Logging Impacts in Amazonia Using Remotely Sensed Data

(see, e.g., Sist (2000) for details on RIL operations), which Performances of selected spatial methods are investigated for include a range of impacts from road openings to treefall gap characterizing canopy disturbance in a reduced-impact log- openings of various sizes, present a good opportunity to examging operation in central Amazonia using Landsat-7 ETM and ine the performances of spatial methods in detecting canopy Ikonos visible, near-infrared, and normalized difference vege- disturbances at the low end of logging impacts. tation index data. Texture, fractal dimension (D), and Moran’s This paper describes the potential of spatial methods for I index of spatial autocorrelation were calculated for (1) 10- characterizing managed tropical forests using satellite data. ha plots representing logged (LF), logged excluding major roads The objectives of this study were to (1) investigate the sensitivand patios (L), and old-growth (OG) forest; and (2) 335-ha plots ity of Ikonos and Landsat 7 ETM data to selective logging representing LF and OG. impacts in a central Amazonian forest, (2) investigate the perIkonos data were sensitive to roads, patios, and some formance of selected spatial methods for characterizing logging gaps, whereas ETM data were only sensitive to major reduced-impact logging activities along a simple disturbance logging features. The spatial methods were effective at charac- gradient, and (3) examine the effects of measurement and geoterizing the different logging feature treatments at both plot graphic scales on the outcomes of these methods. This was sizes; DTPSA and Moran’s I were most sensitive to fine-scale achieved through comparing the behavior of selected spatial surface details. The spatial methods show potential for moni- methods at different measurement and geographic scales using toring and management of logging activities over landscape Ikonos and ETM data over two plot sizes. The methods evaluscales. The importance of scale, given the ever-increasing ated were texture, spatial autocorrelation, and fractal dimenchoice of remotely sensed data, is emphasized. sion. The research was carried out in a moist tropical forest reduced-impact logging operation near Manaus, Brazil, where

Gap formation and forest regeneration in a Micronesian mangrove forest

Gaps created by the death of one or more contiguous trees are common in mangrove forests but are poorly understood. In Kosrae, Federated States of Micronesia, where mangrove wood is harvested for local use, most natural gaps were &lt; 50 m2, whereas most logging gaps were &gt; 100 m2. Interior zones, where access is facilitated by roads, were the most heavily exploited. Although the forests contained 11 species, two species were primarily responsible for gap formation. Natural gaps were caused mainly by broken stems and large branches of Sonneratia alba trees, whereas logging gaps were created primarily by harvesting Rhizophora apiculata trees. Most natural gaps were formed by the fall of more than one tree or branch. Seedling densities were higher in logging gaps than in natural gaps and higher in gaps than under intact canopy. Bruguiera gymnorrhiza was the most common seedling species in gaps and under intact canopy. Relative rates of growth in height were faster in gaps than under intact canopy for R. apiculata and B. gymnorrhiza seedlings. Current harvesting practices on the island do not seem to be altering species richness, although R. apiculata may become less common as gaps are increasingly captured by B. gymnorrhiza.

Recovery of conservation values in Central African rain forest after logging and shifting cultivation

Secondary forests in Central Africa are increasing in importance for biodiversity conservation as old growth forests outside the few protected areas are disappearing rapidly. We examined vegetation recovery in a lowland rain forest area in Cameroon based on a detailed botanical survey of old growth forest and different-aged logging gaps (5-27 years) and shifting cultivation fields (10-60 years). Our analysis focuses on the long-term recovery of botanical conservation values by analysing trends in vegetation structure, species composition, species diversity and levels of endemism and rarity. In the total survey (4.25 ha), we recorded 834 species of which 23% were endemic to the Lower Guinea forest region. The proportion of endemic species was high in shrubs and low in herbs. Geographic range and (local) rarity were not significantly associated. The proportion of rare species (relative frequency ,10%) was high in woody climbers and low in trees. In logging gaps, recovery of all vegetation characteristics was relatively quick (5-14 years). Recovery in shifting cultivation sites took longer (30-60 years). Endemic species were found to be highly sensitive to shifting cultivation practices and even after 50-60 years the level of endemism was still significantly lower compared to old growth forest. The proportion of rare species was not significantly different between disturbed sites and old growth forest. We conclude that secondary forests can contribute to biodiversity conservation, e.g. as buffer zones around protected areas. However, this contribution should be assessed differently between land use types and widespread versus endemic species.

PRE-LOGGING LIANA CUTTING REDUCES LIANA REGENERATION IN LOGGING GAPS IN THE EASTERN BRAZILIAN AMAZON

The cutting of all lianas prior to logging is a reduced-impact logging technique that is predicted to reduce liana proliferation in logging gaps. This study compares liana abundance and species composition in gaps created during conventional and reduced-impact logging in a forest of the eastern Brazilian Amazon. Logging treatments were conducted in side-by-side plots. Shortly following logging, 50-m2 plots were located in the approximate centers of four single treefall and four multiple treefall gaps in each logging area. Six years following logging, there were ∼40% fewer climbing lianas in reduced-impact gaps than in conventional logging gaps. In both logging areas multiple-tree gaps had higher liana densities and a higher proportion of lianas recruiting from seed than single tree gaps, where sprouts from cut or fallen lianas were more common. The mean number of liana species encountered per plot did not differ among treatments nor was there any significant difference in species diversity (Fisher's α) be...