Plantation Blocks Research Articles

Remnant habitat patches provide high value for a wide range of insect species in a timber plantation mosaic

Species present in transformed landscapes utilise resources from either the transformed patches, natural patches, or both. Depending on the degree to which species are specialised, species-specific responses to landscape transformation is both varied and dynamic. Understanding species-specific responses across a landscape is therefore essential to make informed conservation decisions. We investigate how spillover of stenotopic, cultural, and ubiquitous insect species respond to the different edge combinations present in a timber plantation mosaic. We use a multi-taxon approach, sampling two distinct insect assemblages (ground and foliage) across four different biotopes in a grassland-forest-plantation landscape in the Midlands of KwaZulu-Natal, South Africa, which forms part of the Maputaland-Pondoland-Albany biodiversity hotspot. We show that in this landscape, ecological networks consisting of natural grassland and forest supported high insect diversity in both ground and foliage assemblages. The foliage assemblage displayed stronger responses to the different biotope combinations than the ground assemblage. There was remarkably little spillover of habitat specialist species of either the ground or foliage assemblages from grassland or forest into the plantation stands. The few species associated with plantation stands (cultural species) had consistent levels of spillover across different types of plantation blocks, but not into the natural areas. Natural biotopes in this landscape conserved many habitat specialists, whereas plantations maintained low levels of diversity. Thus, we recommend that conservation practitioners consider the fidelity and spillover of the species present in the local landscape before designing conservation plans in these dynamic production landscapes.

Spatial patterns of the leaf crown borer Eupalamides cyparissias (Cramer, 1775) (Lepidoptera: Castiniidae) in coconut (Cocos nucifera L.) tropical region.

The leaf crown borer Eupalamides cyparissias (Cramer, 1775) is an important pest of coconut (Cocos nucifera L.) and other palms (Arecaceae) of economic importance, attacking the base of leaves, inflorescences, and infructescences, increasing fruit abortion. The objective of this study was to evaluate the spatial correlation of the infestation rate of E. cyparissias in coconut plantation blocks in the Brazilian Amazon, from January to December 2019, in the city of Santa Izabel, Pará, Brazil. The study area is a farm subdivided into 157 blocks of a commercial plantation of the green dwarf coconut. The Local Moran's Index was used to evaluate the existence of spatial autocorrelation of the E. cyparissias infestation rate in the 157 blocks with neighboring blocks. The infestation rate was calculated by the ratio between the number of plants attacked by the borer and the total number of plants in a block. There is a significant correlation of the symptomatology of the attack by E. cyparissias in the blocks of the experimental area, which indicates an aggregated pattern of distribution. There is no significant correlation between the attack by the borer and the age of the coconut tree; however there is a significant correlation between the attack by the borer and proximity to forest areas. These results indicate that forest regions are foci of infestation by the borer in coconut plantations.

Performance of Tree Species and Their Effects on Soil Properties in Chromite Mine Spoil Areas

An experiment was carried out at Kakudia dump of Sukinda chromite mines, Tata Steel Limited, Kalarangiata, Jajpur, which is located near the trijunction of Cuttack, Dhenkanal and Keonjhar districts of Odisha, where 10 tree species from plantation were selected, their growth parameters were measured, volume and biomass was estimated and soil samples were analyzed for heavy metal contents which are collected from the root zone of tree species. Around 12 mines are operating in the area without proper environmental pollution controls, which cause major health hazards. According to estimates from an Indian health group, hexavalent chromium levels in drinking water are around 60% higher than the international norms, and chromite-related illnesses are thought to be the cause of 84.75 percent of fatalities in mining regions with no controls. There has been virtually no attempt to clean up the contamination. The experiment was based on three plantation blocks which consists of ten forest species such as Melia azedarach L., Samanea saman F. Muell., Syzygium cumini L., Acacia mangium Wild., Alstonia scholaris L., Pongamia pinnata L., Casuarina equisetifolia L., Azadirachta indica A. Juss., Anacardium occidentale L., Neolamarckia cadamba Roxb. and control with a mine barren spoil and natural forest. Casuarina equisetifolia recorded significantly highest height (10.43 m), DBH (13.99 cm), crown length (8.37 m), crown spread (4.2 m), volume (0.354 m3) and biomass (115.74 kg tree-1). Acacia mangium was the next best tree species followed by Anacardium occidentale, Neolamarckia cadamba, Syzygium cumini, Pongamia pinnata, Samanea saman, Melia azedarach, Azadirachta indica and Alstonia scholaris. Also, there is significant and positive correlation found among all the tree growth parameters. Among the growth parameters of trees, positive and significantly highest correlations was observed between tree DBH and tree biomass (r = 0.997761) followed by tree volume and tree biomass (r= 0.980047).

Quality Control Analysis of Black Tea Raw Ingredients (Camellia sinensis) PT ABC

One of the companies that produce black tea in Indonesia is PT ABC. In PT ABC, the processing system Orthodox Rotorvane produces black tea powder according to market demand, which has a small particle size (broken tea) and quick brewing by applying SNI 01-1902-2016 as a reference for production activities and monitoring the production process. This study contribution to investigate the quality of tea leaf shoots used as production raw materials, especially in the flow of raw material handling, the quality control of raw materials, and the value of the proportion of damage to raw materials. The method used is an analysis based on data Tops Not Eligible/Pucuk Tidak Memenuhi Syarat (PTMS) obtained from each plantation block. The output results obtained show that the value of the proportion of damage to raw materials is still within the control limits where there are only one of the six plantation blocks, namely the Kembang plantation block, produces a value of the proportion of damage outside the control limits with the main factors causing it from human factors, equipment, raw materials and working method used. This research contributes to knowing the value of the proportion of shoot damage for each plantation block at PT ABC.

Maintaining high vegetation structural diversity in the landscape promotes arthropod diversity in dynamic production areas

Species occurrence in transformed areas (or matrix) can be enhanced by reducing the contrast in vegetation structure between the matrix and remnant natural patches. Contrast depends on both structural features of remnants and that of the matrix, which can be dynamic and determined by harvesting practices. We assess whether structurally equivalent vegetation, as determined by structural features of the matrix relative to that of remnants in the landscape, promotes species diversity and abundance in the matrix. Furthermore, we assess the relative importance of structurally equivalent vegetation compared to features of the immediate adjacent remnant patch. Arthropods were sampled from 34 sites situated in alien forestry plantation blocks of different ages, dissected by corridors of natural grassland and/or closed canopy woody habitats. We analysed how arthropod assemblages within plantations were influenced by structural features of remnant vegetation in the landscape, and that of remnant patches directly adjacent. The amount of structurally equivalent vegetation at the landscape level promoted arthropod abundance and diversity within plantations and was more important than either the structural contrast or biotope type of the immediate adjacent patch for promoting diversity in the forestry blocks. Landscapes composed of a mosaic of structurally distinct vegetation best contribute to promoting diversity within dynamic production areas. Harvesting practices that radically change the structural features of the entire plantation should be avoided. We recommend use of rotational harvesting, so creating a variety of plantation tree ages for improved arthropod spillover from both natural grassland and woody habitats.

Species diversity, abundance and damaged caused by rats in oil palm plantation in West and Central Sulawesi, Indonesia

Abstract. Ikhsan M, Priyambodo S, Nurmansyah A, Hendarjanti H, Sahari B. 2020. Species diversity, abundance and damaged caused by rats in oil palm plantation in West and Central Sulawesi, Indonesia. Biodiversitas 21: 5632-5639. Oil palm is one of the plantation commodities which has an important role in Indonesia’s economy. Indonesia is the largest producer and exporter of oil palm in the world with its export value capable of supplying 55.78% of global consumption. Rats are wild animals that are important pests for human life, both in agriculture plantations and urban areas. Rats can damage crops at various stages of plant growth. This study was aimed to determine the species abundance of rats in oil palm plantations, calculate the severity of crop damage due to rats infestation. Three blocks of mature plants were used in OC and OH plantation blocks were used to calculated, crop damage caused by rats, Identify the species of rats, and estimated rats abundance. The results of these studies showed there were four species of rats found in the oil palm plantation, namely Rattus tiomanicus, R. tanezumi, Rattus sp, and Maxomys hellwaldii. However, only R. tiomanicus and R. tanezumi were dominant species. There were significant differences in the number of, sex, and body weight between R. tiomanicus and R. tanezumi. The OC 12 block had the lowest infestation intensity than the other blocks since it was well maintained. The OH 02 block had the highest infestation intensity, infestation area, and abundance due to a lack of maintenance.

Dar dikim aralıklarında kurulan kavak (P.x euramericana ve P. deltoides klonları) ağaçlandırmalarının ekonomisi

At present, majority of commercial poplar plantations aimed at producing quality timbers with larger dimension are established in wider planting spacings in Turkey. The experimental poplar plantations in closer spacings were established for this study purposes in order to investigate the prospects for producing mass quantity of small dimensioned chip wood relatively in shorter period of plantation rotation rather than producing quality timber of larger dimension in longer period of rotation. Along with five various planting spacings, five different poplar clones such as “I-214”, “I-45/51”, “Samsun (I-77/51)”, “İzmit (S.307-26)” and “89.M.060” were sampled in the experimental plantation blocks which were repeated on sites of three different growth conditions. The criteria of “Net Present Value (NPV) and “Internal Rate of Return” (IRR) were used for economic analyses. The results of the analyses showed that the most suitable spacing for producing mass quantity of chip wood is “3m x 1,5m” (4,5 m2 / plant) and most promising poplar clone is “89.M.060”. The plantation rotation periods were also determined in accordance with the criteria of NPV and IRR. The period of rotation varied by the variation of the discount rate involved when the NPV criterion is used for the evaluation. The periods of rotation determined in accordance with the IRR criterion are shorter than the period determined in accordance with the NPV criterion. Therefore, the IRR criterion should be preferred for the evaluation of industrial plantation investments. According to the results of the analyses, the recommended period of plantation rotation varies between 6 to 8 years on good sites, 7 to 9 years on medium sites and 8 to 10 years on poor sites.

Effectiveness of pheromone traps for monitoring Zeuzera sp. (Lepidoptera: Cossidae) population on Eucalyptus pellita plantation

Zeuzera sp. (Lepidoptera: Cossidae) is a group of moths which the larvae is drilling holes into the stems and branches of tree. This study was conducted to record the population dynamic of Zeuzera sp. and to control the pest in Eucalyptus pellita plantation. The first damage of Zeuzera sp. was detected in 2017 at the E. pellita plantation block 4 (1 clone) owned by PT Korintiga Hutani in Central Kalimantan. It was found in 2 clones of block 5 in 2018, as well as in 3 clones of block 6 in 2019, and the tendency of the damage appeared widespread. The damage caused the broken top crown, swolen stem, and frass around the bottom part of the plant. Primary observation showed that there were several species of Zeuzera. The pest control was carried out by installing of delta trap + pheromone of Zeuzera pyrina. This pheromone trap was installed in 40 severely damaged locations. Each location had 1 trap installed. The results of monitoring with delta trap + pheromone showed that only 1 species of Zeuzera was found to be attracted by the pheromone. The density of captured adult varied depended on the clones and time of installation. The number of adult captured in May to July 2019 was 911. In conclusion, Zeuzera sp. damage in E. pellita plantation was gradually increased, and integrated pest management (silviculture, mechanical, biological, chemical) was required to prevent the damage.

Implementasi Algoritma K-Means Clustering dalam Menentukan Blok Tanaman Sawit Paling Produktif

PTP.Nusantara-IV (Persero) especially in the Marjandi Gardens located in Panombean Panei, Simalungun Regency is an Indonesian state-owned enterprise engaged in the plantation sector, one of which is Oil Palm. Among the many oil palm plantation blocks, there are productive and unproductive oil palm plant blocks. Unproductive blocks affect the profits of Marjandi Gardens in the production of Palm Oil. Therefore, it is necessary to conduct research to find out the most productive and unproductive blocks of Oil Palm Plants. This study was conducted in Afdeling III Marjandi Gardens with oil palm planting years 2005 and 2006. The method used was the K-Means Clustering method, the blocks were divided into 2 Clusters namely High Clusters for the most productive blocks and Low Clusters for unproductive blocks. Based on the research that has been done, the results obtained are the number of 14 blocks of the most productive oil palm plants, namely (BM, BN, BO, BP, BR, BY, CE, CF, CK, CY, DE, DF, DG) and 26 blocks of plants Oil palm is unproductive, namely (BL, BQ, BS, BW, BX, BZ, CA, CB, CD, CG, CL, CM, CN, CO, CP, CQ, CR, CS, CW, CX, DA, DB, DC, DD). It is expected that the company can develop the most productive oil palm block so that the quality of the oil palm plant blocks is always maintained. As for the unproductive oil palm plant blocks, the company can make repairs to produce a productive block of oil palm in the future.

Effects of Understory Vegetation Management on Plant Communities in Oil Palm Plantations in Sumatra, Indonesia

Oil palm plantations have expanded rapidly in recent decades, and are causing substantial impacts on tropical habitats and biodiversity. However, owing to its long lifespan (25-30 years), oil palm forms a much more varied and structurally-complex habitat than many other crops. This can include abundant understory vegetation and also epiphytes on palm trunks. However, the diversity of this plantation vegetation has been poorly studied, and there has been little consideration of the impacts of common plantation vegetation management practices on plant communities. We conducted a long-term vegetation management experiment that forms part of the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme in Riau, Indonesia. We manipulated herbicide and manual cutting regimes within mature oil palm plantations to create three different understory complexity treatments (Reduced, Normal, and Enhanced vegetation) across replicated sets of plots. Plant communities were surveyed before and after experimental understory vegetation treatments began in three different microhabitats: within the middle of the plantation block (core), on the road edge (edge) and on oil palm trunks (trunk). Part of the sampling was also conducted during a drought event. We recorded 120 plant species, which comprised a mixture of native, non-native, ‘beneficial’, and ‘problem’ species. We found substantial variation in plant communities between edge, core, and trunk microhabitats, indicating high levels of heterogeneity within the plantation. There were significant effects of varying understory treatment within both core and edge microhabitats, but no spillover of impacts into the trunk microhabitat. We also observed substantial impacts of drought on plant communities, with declines in either biomass, percentage cover, or richness seen across core, edge, and trunk microhabitats during low-rainfall periods. Our findings highlight the diversity of plant communities that can be supported within oil palm plantations, and the substantial impacts that management decisions, and also drought, can have on them. Given the role that diverse plant communities can have in supporting species in other groups, this is likely to have a significant impact on the wider plantation biodiversity. We suggest that plantation management strategies give greater consideration to within-plantation understory plant communities and choose more wildlife-friendly options where possible.

Dynamic Programming to Solve Picking Schedule at the Tea Plantation

The tea picking schedule at PT Perkebunan Ciater is set to be the same for all plantation blocks. In fact, the altitude from sea level and the pruning age of each plantation block is different, this results in the difference of buds’ growth. The implementation of the same picking schedule causes the quality and quantity of tea buds often could not be fulfilled. This research is to determine the precise picking schedule by considering the buds’ growth of each plantation block. Two steps are implemented to solve the problem. The first step is to look for picking period and the pattern of buds’ quality for each plantation block, which corresponds to the altitude of the location and the pruning age. The regression method is applied in this first step. The buds’ quality pattern is then used to determine the cost of decreasing buds’ quality and the costs of the buds that left in the plantation. The second step is to develop the picking schedule using dynamic programming, which minimizes the total cost of picking. In addition to this, we also develop a rolling schedule, which schedule time interval is three days. The model results show that the proposed schedule gives a better total cost than the current schedule and the buds’ quality target is easier to achieve.

Arthropod assemblages deep in natural forests show different responses to surrounding land use

Many contemporary landscapes have vast areas of production land-uses within landscape mosaics, which may impact species dispersal and occurrence. Here, we determined the extent to which commercial exotic plantation forests affect arthropod diversity associated with natural Afrotemperate forests in the southern Cape Afrotemperate landscape mosaic, South Africa. Natural forests and fynbos vegetation naturally coexist here, with the addition of exotic plantation forests to form a heterogeneous landscape. Epigaeic arthropods were collected by means of pitfall trapping at stations along transects from inside natural Afrotemperate forest, across the edge and into the surrounding land use, which included natural fynbos vegetation, mature forestry plantation blocks (Pinus radiata) and areas where plantations have been clear-felled. Stations were set at 5, 10, 20, 30 and 50 m to both sides of the forest edge with the addition of 100 m stations situated in the natural forest. Arthropod assemblages were distinct in all land-use types. Natural edge effect between forest and fynbos, as measured by arthropod compositional changes, was 20 m into natural forests, yet when bordered by plantations this edge increased up to 30 m into the forest. Once plantations were clear-felled, edge effects increased up to 50 m into natural forests. Responses in terms of assemblage composition and species richness were however taxon specific. Results show that (1) pine plantations are not alternative habitat for native Afrotemperate forest arthropods, (2) there were stark changes in arthropod assemblage composition at edges between these land-use types and (3) that the effects of timber plantation practices (re: clear-felling) also penetrate deep into surrounding natural forests and need to be considered in regional landscape planning. The need for an effective rehabilitation strategy of clear-felled areas is identified as key priority for bordering natural forests. Ongoing monitoring in both the disturbed area and the adjoining natural forest should be undertaken to ensure sufficient recovery.

HUBUNGAN ANTARA DIAMETER BATANG DENGAN UMUR TANAMAN TERHADAP PERTUMBUHAN DAN HASIL TANAMAN KELAPA SAWIT

Oil palm is a plant which is quite important commodities in Indonesia and still have a fairly bright development prospects Production of fresh fruit bunches (FFB) is the result of work activities in the field of plant maintenance. The success of FFB production depends by several factors, including environmental factors, the crop factor and factor cultivation purpose of this study was to determine and learn the age and size of the trunk palm trees both in achieving production, and Knowing how the relationship between stem diameter and plant age with results production of fresh fruit bunches (FFB). This study used 75 samples are grouped according to the age of the plant that is 2 years, 4 years, 6 years, 8 years and 10 years. Each sample was observed with 7 parameter pengamatanDari results of this study can be concluded that the larger the diameter of the stem of the plant oil palm as well as the age tanama or rather would affect positively correlated or significantly affected the production of oil palm plantation itself. All variables observation showed positive correlation with stem diameter relationship of age with less plant oil palm plantations. But there was one that did not happen correlation / negative correlations were age first fruit the size of a small diameter This is due to many factors such as rainfall is high enough to some areas or plantations are often flooded by rainwater, farming areas mostly are the tidal rivers, especially in 8 years old plantation blocks and handling of the plantation itself is still lacking.

Conserving natural heterogeneity is crucial for designing effective ecological networks

Large-scale ecological networks (ENs) are an important mitigation measure in agriculturally transformed landscapes. However, understanding the multitude of pressures influencing the presence/absence of species, and subsequent degree of species spatial heterogeneity, is important when planning effective ENs. We aim here to measure these pressures and determine species heterogeneity in ENs against natural reference sites. We use arthropods, as they are effective bioindicators for measuring these pressures and heterogeneity, as many are habitat sensitive. Here we use many arthropod taxa to determine how a suite of variables influences the spatially sensitive grassland interior species of both EN corridors and protected areas (PAs). At each of 48 selected sites, nine stations were sampled for arthropods, with six stations in plantation block (i.e. transformed grassland) or natural indigenous forest, as well as associated edge zone and three stations in EN corridor or PA interior. Eleven variables were measured and classed into environmental, design, and current and historical management variables. Data were split into: overall data, recording all species found in interior zones, and datasets containing only species that had >50 or >75 % of their abundance sampled in the interior zone. These datasets were split into total species and singleton-removed datasets. Overall, the richness of non-singleton species, i.e. those frequently sampled in grassland interiors, were most responsive to natural background environmental variables, while design and management variables were most important for datasets with singletons retained. This means that when planning ENs, we first need to conserve the natural range of environmental heterogeneity to conserve a range of interior specialists. This natural spatial heterogeneity then needs to be incorporated into design and management planning to conserve the full range of biodiversity in ENs, as if in PAs.

Carbon Per cent in Different Components of Tree Species and Soil Organic Carbon Pool Under these Tree Species in Kashmir Valley

Carbon is a critical element that trees accumulate and use to support their structure and sustain physiological processes. Besides being a key element in forest ecosystems, carbon is also essential for sustaining life on a global scale. The study attempted to quantify carbon per cent in different tree components of Cedrus deodara, Fraxinus floribunda and Ulmus wallichiana,an important tree species of Kashmir valley were planted in plantation block of Faculty of Forestry at Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar way back in 1992. The soil organic carbon pool under these tree species was also estimated. This information however is poor and fragmented as no published literature is available in this region. Statistical analysis of the data reveals that carbon per cent was significantly higher in Cedrus deodara (45.41%) followed by Fraxinus floribunda (41.36%) and Ulmus wallichiana (40.78%) respectively. Besides the soil attributes like organic carbon and bulk density were also determined and the same were used for preparing the carbon pool inventory. The pooled results revealed that organic carbon was significantly higher in Ulmus wallichiana (2.08%) as compared to Cedrus deodara (1.86%) and Fraxinus floribunda (1.53%). However the bulk density was significantly higher in Fraxinus floribunda (1.26 gcm-3) as compared to Cedrus deodara (1.24 gcm-3) and Ulmus wallichiana (1.20 gcm

Importance of habitat heterogeneity in remnant patches for conserving dung beetles

Landscape heterogeneity affects the spatial distribution of species. This makes it an important consideration for conservation planning, particularly when designing sustainable production landscapes. We determine whether conserving landscape elements within a transformed landscape is adequate for conserving dung beetle biodiversity. Dung beetles are excellent indicators for landscape biodiversity studies as they are ecologically sensitive. Here we measure dung beetle alpha-diversity, as well as beta-diversity within landscape elements and across different landscape elements. In doing so, we assess the value of landscape elements, as well as variation within landscape elements, in determining the spatial distribution of dung beetles across a production landscape. The study was conducted in the commercial timber production area of the KwaZulu-Natal Midlands, South Africa. In this system, the different landscape elements are a mosaic of natural indigenous forests, grasslands and alien pine plantation blocks. Our results show that the only response for dung beetle alpha-diversity was higher species richness in grasslands and pine blocks compared to natural forests. The highest beta-diversity for a landscape element was the grassland, for elevational category was low elevational areas and grassland type was the Midlands Mistbelt Grassland. The compositional diversity (beta-diversity between elements) was significantly different for all pairwise variations between landscape elements, the elevational categories and grassland types. Natural forests embedded in the two different grassland types had greater differences in compositional diversity than those embedded in natural (grassland) or transformed (pine blocks) matrices. This highlights the need to conserve a range of similar remnant patches of natural vegetation regionally, in addition to conserving broad landscape elements (i.e. grasslands or natural forests) as conservation targets. Furthermore, our results are encouraging for the potential benefits from the ecosystem service provided by dung beetles across the whole landscape, even in the transformed elements.

Ecological networks act as extensions of protected areas for arthropod biodiversity conservation

Summary1. Landscape‐scale ecological networks (ENs) are composed of linear corridors and are widely used to mitigate the adverse effects of intensive land use. One drawback with ENs used for conservation is that being small or linear they result in more edge relative to interior than would be the case naturally. Furthermore, there is little evidence to date that ENs do conserve indigenous biodiversity.2. Here, we use five arthropod taxa at many sites over two geographical areas within South Africa with different elevations and grassland types to test the conservation value of remnant grassland ENs in a plantation forestry context. In particular, the relative value of arthropod biodiversity in exotic plantation blocks, their edges and the interiors of ENs among the plantations were compared with those in neighbouring protected areas (PAs). We use the effects that the plantation blocks have on the adjacent PAs as a reference for comparing the ENs among the plantations. Arthropods were selected to represent biodiversity, as they are small, diverse, habitat sensitive, resource dependent, ecologically important and can be sampled in large numbers.3. In total, 10 422 individuals from 244 species were sampled. Importantly, there were no significant differences in species richness, abundance or assemblage composition between EN interior zones and PA interior zones in both geographical areas.4. Using earlier established edge zones of 32 m, we found that plantation blocks had the lowest species richness and abundance compared with either grassland edge zones (<32 m from the edge) or grassland interior zones (≥ 32 m from the edge).5. Synthesis and applications. Ecological networks are established to conserve biodiversity in areas of intensive land use. Provided that ecological networks are wide enough (i.e. >64 m) to overcome edge effects, they can support similar levels and quality of arthropod biodiversity as protected areas. Remnant grassland ecological networks in agroforestry can provide natural finger‐like extensions from neighbouring protected areas and therefore have conservation value.

Conservation management of complex natural forest and plantation edge effects

Timber plantation forestry is a major threat to indigenous grassland biodiversity, with ecological networks (ENs) currently being used to mitigate this threat. Being composed mostly of linear corridors, ENs create more edge than would occur naturally. To determine the minimum width of corridors for maximising biodiversity conservation, we need first to establish the extent of edge effects from plantation blocks into corridors. We compared arthropod diversity along transects that ran from within plantation blocks into grassland corridors. We also studied the edge effects of natural forest adjacent to natural grasslands within ENs. Sites in grasslands of neighbouring protected areas acted as natural reference sites against which the biodiversity of the EN transects were compared. Two types of exotic plantation trees and various tree age classes were studied. We found a 32 m edge zone from plantation blocks into grassland corridors. Few significant edge effects from plantation blocks occurred at greater distances than this, which suggested that grassland corridors with a width <64 m are essentially all edge. However, and importantly, this situation was complex, as different arthropod taxonomic groups responded differently to edges of plantation blocks and natural forest patches. Natural forest supported many additional species, not just within the forest, but also in associated grassland corridors. This means that maintaining natural forest imbedded within the ENs will protect both indigenous grassland and indigenous forest species as well as help maintain biodiversity across this timber production landscape.

The origins of bark-stripping by blue monkeys (Cercopithecus mitis): implications for management

Blue monkeys (Cercopithecus mitis Wolf) on the Zomba Plateau, Malawi, damage exotic softwood plantations by bark-stripping. An ecological study was carried out to investigate the causes of this. The history of forestry practice on the Plateau reveals that, though bark-stripping did not start until 1976, plantation of exotic softwoods goes back to the beginning of the century. In the last 20 years the area of plantations close to the core of blue monkey habitat has increased substantially and some significant clearance of natural habitat has occurred. Bark-stripping is practised only by the groups which are in closest contact with the plantations. Its seasonality may be related to rainfall through sap quantity. There is no indication that the persistence of bark-stripping is the result of food shortage or agonistic encounters due to overcrowding. The most likely explanation for the genesis of bark-stripping is the encroachment of large blocks of plantations, combined with some clearance of natural habitat in 1973–74. The mechanism proposed for the initiation and maintenance of bark-stripping is a combination of temporary food shortage caused by travel through young plantations and a resultant acquired taste for sweet-tasting sap. Leaving areas of indigenous scrub adjacent to the core areas used by these primates and possibly the non-destruction of indigenous food trees within exotic plantations are suggested as ways of alleviating the problem in the future.