Non-forest Species Research Articles

Diet of the ural owl (Strix uralensis) in Slovakia

Abstract A Central European subspecies of the Ural owl Strix uralensis macroura (Wolf, 1810) is widespread in the territory of Slovakia. The work presents unpublished data on the diet of this subspecies from several territorial units of eastern and northern Slovakia, obtained from pellets and the nest linings in boxes (1 ,564 pieces). There is less data about prey brought to young in the nest but still not yet consumed (137 pieces). Published data from analysis of the stomachs of dead and shot owls come from the first six decades of the 20th century. Together with existing published data, 2,134 pieces of the diet of S. uralensis from Slovakia are evaluated. They indicate the dominance of non-forest species Microtus arvalis and a more plentiful representation of larger species of prey: Lepus europaeus, Sciurus vulgaris and Corvus sp. In upper Orava the diet of young S. uralensis also consists of frogs Rana temporaria, moles Talpa europaea and mountain species of rodents: Microtus agrestis, M. subterraneus, Sicista betulina and Arvicola amphibius. In data from the mountains of central Slovakia the Clethrionomys glareolus has high abundance, and in eastern Slovakia the Apodemus flavicollis and A. agrarius are more represented, and in the lowlands also the Cricetus cricetus. Upon evaluation ofmaterial from the entire breeding grounds of S. uralensis it can be deduced that the basic diet consist of mammals (88.6%) from the orders Soricomorpha and Rodentia. In the countries of Central Europe the species M. arvalis, M. subterraneus, A. flavicollis and Muscardinus avellanarius are more abundantly represented, and in the Baltic states the species Sorex araneus, M. agrestis, M. oeconomus and M. rossiaemeridionalis. The species S. betulina and A. agrarius occur in the diet of S. uralensis from Central Europe up through the Far East.

Forest recovery of areas deforested by fire increases with elevation in the tropical Andes

In the tropical Andes, many montane forests have been destroyed, often through human-induced fires. To facilitate the recovery of these forests, it is important to understand the processes that drive secondary succession at deforested sites, yet studies are rare. Two important filters potentially causing a delay in the recovery of tropical forests are decreasing seed rain with distance to forest edge (seed dispersal limitation) and harsher environmental conditions at deforested sites. Moreover, successional pathways along elevation gradients can differ, yet the factors driving elevation differences are poorly understood. In the Bolivian Andes, we compared soil properties, microclimate and light availability at deforested sites with conditions in the adjacent forests and sampled woody secondary vegetation near (at 20m distance) and away (at 80m) from the forest edge at eight sites that had been deforested by fires ranging from 1950m to 2500m asl. We tested the effects of distance to forest edge and elevation on environmental conditions and on basal area, density, species richness and species composition of forest and non-forest species. Environmental conditions differed between forest interiors and deforested areas in most of the measured parameters. Woody secondary vegetation comprised more non-forest (80%) than forest species (20%), indicating that montane forest recovery was strongly hampered. Unexpectedly, basal area and species richness of both forest and non-forest species were higher away than near the forest edge. Density increased with increasing elevation in both forest and non-forest species, while species richness increased with increasing elevation only in forest species. Species composition did not change with distance to forest edge, but changed significantly with elevation. Our findings reject the hypothesis of a strong effect of seed dispersal limitation on forest recovery, but provide evidence that harsh environmental conditions, i.e., hot and dry microclimates and frequent fires, inhibit forest recovery at deforested sites. With increasing elevation, forest recovery increased, probably due to milder environmental conditions at high elevations and a different species source pool. We conclude that abiotic and biotic changes with elevation are crucial for understanding capabilities of forest recovery in mountain ecosystems and highlight that forest recovery may be further reduced in the future if maximum temperatures are going to increase in the tropical Andes. From a management perspective, we propose Myrsine coriacea, the most abundant forest species at deforested sites, to be a suitable species for montane forest restoration, due to its ability for long-distance dispersal and resprouting after fire.

Effects of visitor pressure on understory vegetation in Warsaw forested parks (Poland)

Visitor’s access to understorey vegetation in park forest stands results in the impoverishment of plant species composition and a reduction in habitat quality. The phenomenon of biotic homogenisation is typical in urban landscapes, but it can proceed differently depending on the scale, a detail that has not been observed in previous studies. This research was carried out in seven Warsaw parks (both public and restricted access). Thirty-four forested areas were randomly selected, some subjected to strong visitors’ pressure and some within restricted access areas, free of such impacts. The latter category included woodlands growing in old forest and secondary habitats. Public access to the study areas contributed to the disappearance of some forest species and their replacement by cosmopolitan non-forest species, leading to loss of floristic biodiversity in areas of high ecological importance at the city scale. Some human-induced factors, including soil compaction and changes in soil pH, moisture and capillary volume, were found to cause habitat changes that favoured native non-forest plants. Despite changes in species composition, the taxonomic similarity of understorey vegetation in both categories—public access and restricted access—was comparable. In a distance gradient of measurements taken around selected individual trees, there was found to be significant variation (in light, soil pH and compaction) affecting the quality and quantity of understorey vegetation (including rare species). In conclusion, the protection of rare forest species could be achieved by limiting access to forested areas, particularly in old forest fragments, and we highly recommend its consideration in the proposal of future park restoration plans.

Impact des routes forestières sur la biodiversité floristique : synthèse de trois études menées en forêt de plaine

Trois etudes dans deux forets domaniales de plaine ont mis en evidence les roles multiples joues par les routes forestieres sur la biodiversite floristique : elles hebergent une flore de milieu ouvert mais sont defavorables a certaines especes forestieres. Des plantes patrimoniales et neophytes y sont rencontrees simultanement. Deux points preoccupants sont soulignes : (1) les cloisonnements d'exploitation crees a l'occasion des coupes de regeneration et la circulation des engins accentuent la portee de l'effet route jusqu'a 60 m en facilitant l'introduction d'especes non forestieres au c½ur des parcelles et en repoussant des especes forestieres loin de la route ; (2) l'apport de materiaux calcaires pour stabiliser les routes dans un environnement de sols acides augmente le pH du sol et nuit aux especes acidiphiles. Nous recommandons de raisonner la densite des routes forestieres et des cloisonnements et d'employer des materiaux de stabilisation neutres vis-a-vis du pH des sols environnants. / Three studies located in two State forests (Orleans and Montargis) have emphasized the multiple roles played by forest roads on plant biodiversity: roadsides were habitats for non-forest species but were detrimental to some forest species. Protected species and neophytes were also found on roadsides. Two areas of concern are highlighted: (1) the forest paths opened for regeneration felling and harvesting machine traffic increased the depth of road effect up to 60 m by facilitating introductions of non-forest species in the interior of forest stands and pushing away forest species far from the road; (2) the use of limestone gravel for road improvement in a native nutrient-poor environment increased soil pH and was detrimental to acidophilous species. To protect forest soil and plant biodiversity, we recommend reconsidering the density of forest roads and forest paths and using road material that do not modify the pH of the surrounding forest soils.

Impact of oil palm plantations on the structure of the agroforestry mosaic of La Gamba, southern Costa Rica: potential implications for biodiversity

Human activities often cause changes and homogenization in landscape structure. To investigate the impact of changing cultivation systems on structural and functional aspects of a tropical agroforestry system, we developed satellite based land cover maps of the La Gamba area in southwestern Costa Rica and refined them by mapping fine-scale linear landscape elements. Performing a landscape pattern analysis, we compared eight sections of the study area by landscape metrics. Furthermore we performed a Morphological spatial pattern analysis (MSPA) for hypothetical non-forest, forest generalist and forest specialist species, and compared the current situation to a possible future scenario with double the area covered by oil palm plantations after a virtual conversion of other agricultural patches. The heterogeneous rural sections clearly differed from the homogeneous forests and especially pasture-dominated rural sections included many diverse, small and elongated patches, many linear landscape elements but few big plantations. According to the scenario with double the area covered by oil palm plantations, non-forest species lost large parts of their habitat, while forest species mainly lost corridors. The protection of natural landscape elements that support wildlife movement between forest areas is of major importance, particularly as the globally increasing cultivation of oil palm is significantly altering many tropical land mosaics, including the countryside of La Gamba. We propose the establishment of eight least cost path corridor routes in the study area to make the agricultural area pervious for wildlife.

The use of bird species richness and abundance indices to assess the conservation value of exotic Eucalyptus plantations

The East Usambaras are within the Eastern Afromontane hotspot, which is known for its exceptionally rich biodiversity. The original forest of the East Usambaras has been reduced by human activities, including establishment of Eucalyptus plantations, but little is known about the value of these plantations for biodiversity. Therefore, from July 2003 to June 2004, we studied avifauna in natural forests and plantations using the timed species count (TSC) method, based on which we provide an assessment of the conservation value of Eucalyptus plantations to the local avifauna. From 240 TSCs, 100 species in 79 genera, 32 families and seven orders were recorded. A total of 63 forest species were recorded in forest and 41 forest species in the Eucalyptus plantations with four forest species exclusively in the plantations. The two habitats shared a greater percent of non-forest bird species (85%) than forest bird species (64%). There was some degree of seasonal variation in species richness and relative abundance between habitats. The study shows that ‘responsibly managed’ plantations could benefit some local avifauna. We recommend proper management of the Eucalyptus plantations, including the retention of some undergrowth and of surviving isolated forest trees, in order to provide hospitable habitats for birds.

Effects of artificial afforestation and successional stage on a lowland forest bird community in southern China

To examine the relationship between forest succession after severe logging forestry practices and the composition of avian communities, we investigated how forest bird composition and guild structure change as a function of structural properties along a successional gradient, including a climax mature forest (>400 years), a rehabilitated mixed forest (50–70 years), and a disturbed Masson pine forest (70 years) of the Dinghushan Nature Reserve, Guangdong Province, China. Of a total of 51 resident species recorded, mixed forests hosted the highest numbers of individuals and species, reflecting the high species richness of both forest and non-forest species. For forest-dependent species, however, mature stands had the highest observed and estimated species richness. Of 6 habitat-use guilds identified, vertical-profile generalists and understory-birds formed the two dominant guilds, accounting for 54.0% and 38.7% of all individuals respectively. The results of canonical correspondence analysis (CCA) clearly showed that most forest-dependent species were associated with high proportions of native canopy cover and the mean density of dead trees and large trees, which are characteristic of old-growth mature forests (horizontal heterogeneity) at stand level. Accordingly, conservation efforts should focus on the specialized requirements of the most habitat-restricted species in the future, especially for understory insectivores (Babblers) and large-tree users in mature subtropical monsoon forests of southern China. Moreover, since regenerating mixed forests are very similar to mature forests in both vegetation structure and bird community composition, we recommend that logging cycles (>50 years) be increased to a minimum of 50 years in southern China, so that a balance between economic and ecological interest can be reestablished.

Contribution of forest management artefacts to plant diversity at a forest scale

Most temperate forests are managed for wood production, and some forestry practices generate typical environmental features such as roads, paths, ditches and tractor ruts, which are likely to affect forest species distribution. We studied the influence of forestry artefacts on the overall forest-understory plant diversity in an ancient oak-dominated French forest with a long history of management. Two designs (grid design and paired design) were built in order to record the occurrence frequency of artefacts and to estimate the originality of the plant assemblage that they host. We recorded 897 plots on the grid design: 68.3% of the plots were more than 4 m away from any artefact, 23.3% were within 4 m of an artefact and 8.4% were located on an artefact. The artefact contribution to total floristic richness would lie between 8.0% and 22.6%, depending on whether the artefact surroundings were included or not in the artefact contribution. Road verges were the least frequent artefacts but provided the richest contribution to overall plant diversity (82%), whereas paths were the poorest (with only a 42% contribution). Thirteen species appeared to prefer artefacts over control plots: six forest species, five non-forest species and two generalist species. We show that forestry artefacts are key components of the floristic diversity in managed forests; therefore, forest management should take them into consideration.

Conservation Value of Cacao Agroforestry Systems for Terrestrial Herbaceous Species in Central Sulawesi, Indonesia

ABSTRACTTropical secondary forest and agroforestry systems have been identified as important refuges for the local species diversity of birds and other animal groups, but little is known about the importance of these systems for terrestrial herbs. In particular, few studies report how the conversion from tropical forest to technified cacao plantation affects the species richness and the community structure of herbs. We conducted surveys in 43 cacao plantations along the border of the Lore Lindu National Park in Central Sulawesi, ranging from agroforests to technified cacao, categorizing the plantations as rustic cacao, planted shade cacao, and technified cacao. We recorded 91 herb species. Of the 74 species determined to species level, 21 were also found in natural forests, while 53 were recorded only in agricultural habitats. Araceae was the most forest‐dependent plant family while Asteraceae included the highest number of nonforest species. Overall, the presence of forest species was confined to moderately intensively managed rustic and planted shaded plantations. Distance from the forest, which has been identified as a crucial parameter for the diversity and composition of other taxa in cacao agroforests, only played a minimal role for herbs. Our study suggests that native forest herbs maybe more vulnerable to forest conversion than animal groups. The intensification of cacao plantation management increases the presence of weedy species to the detriment of native forest species.

A meta-analysis of bird and mammal response to short-rotation woody crops

Short-rotation woody cropping (SRWC) refers to silvicultural systems designed to produce woody biomass using short harvest cycles (1–15 years), intensive silvicultural techniques, high-yielding varieties, and often coppice regeneration. Recent emphasis on alternatives to fossil fuels has spurred interest in producing SRWC on privately owned and intensively managed forests of North America. We examined potential bird and small mammal response at the stand level to conversion of existing, intensively managed forests to SRWCs using meta-analysis of existing studies. We found 257 effect sizes for birds (243 effect sizes) and mammals (14 effect sizes) from 8 studies involving Populus spp. plantations. Diversity and abundance of bird guilds were lower on short-rotation plantations compared with reference woodlands, while abundance of individual bird species was more variable and not consistently higher or lower on SRWC plantations. Shrub-associated birds were more abundant on SRWC plantations, but forest-associated and cavity-nesting birds were less abundant. Effects on birds appeared to decrease with age of the SRWC plantation, but plantation age was also confounded with variation in the type of reference forest used for comparison. Both guilds and species of mammals were less abundant on SRWC plantations. These conclusions are tentative because none of these studies directly compared SRWC plantations to intensively managed forests. Plantations of SRWCs could contribute to overall landscape diversity in forest-dominated landscapes by providing shrubby habitat structure for nonforest species. However, extensive conversion of mature or intensively managed forests to SRWC would likely decrease overall diversity, especially if they replace habitat types of high conservation value.

The effects of urban or rural landscape context and distance from the edge on native woodland plant communities

The increasing rate of urban sprawl continues to fragment European landscapes threatening the persistence of native woodland plant communities. The dynamics of woodland edges depend on the characteristics of woodland patches and also on landscape context. Our aim was to assess the extent of edge influences on the understorey vegetation of small native woodlands in rural and urban landscapes. The study was carried out in two cities of north-western France. Ten comparable woodlands, each of about 1.5 ha, were surveyed; five were situated adjacent to crops and five adjacent to built-up land. Vascular plant species were recorded in 420 3 × 3 m plots placed at seven different distances from the edge (from 0 to about 45 m from the edge). Soil pH, light levels, level of disturbance and tree and shrub cover were also recorded. Plant species were first classified as non-indigenous or indigenous and then three groups of indigenous species were distinguished according to their affinity for forest habitat (forest specialists, forest generalists and non-forest species). We inferred certain ecological characteristics of understorey vegetation by using Ellenberg values. An inter-class correspondence analysis was carried out to detect patterns of variation in plant community composition. Linear mixed models were used to test the effects of adjacent land use, distance from the edge and their interactions on the species richness of the different groups and on the ecological characteristics of vegetation. Total species richness, richness of forest generalists and of non-forest species decreased from edge to interior in both urban and rural woodlands. The number of non-indigenous species depended mainly on urban–rural landscape context. Urban woodland edges were not as rich in forest specialists as rural edges. More surprisingly, the number of forest specialists was higher in rural edges than in rural interiors. Community composition was mainly affected by urban–rural context and to a lesser degree by the edge effect: the community composition of urban edges resembled that of urban interiors whereas in rural woodlands vegetation near edges (up to 10 m) strongly differed from interiors with a pool of species specific to edges. Urban woodland vegetation was more nitrophilous than rural vegetation in both edges and interiors. A major difference between urban and rural vegetation was the distribution of basiphilous species according to distance from the edge. Generally edge vegetation was more basiphilous than interior vegetation however the presence of basiphilous species fell off quickly with distance from the edge in rural woodlands (in the first 10–15 m) and more slowly (from 25 m onwards) in urban woodlands. This pattern was linked to variation in measured soil pH. As regards the conservation of flora in small native woodlands, it appeared that invasion of exotic and non-forest species was currently limited in both urban and rural landscape contexts but might pose problems in the future, especially in urban woodlands. Forest species were not negatively affected by the edge effect and indeed edges seemed to provide important habitats for this group. Hence conservationists should pay particular attention to the protection of edges in urban woodlands.

Forest loss and fragmentation effects on woody plant species richness in Great Britain

Studies on the effect of forest loss and fragmentation on plant species richness at different spatial scales have yielded contradictory results that have been attributed to different ways to measure fragmentation. The main goal of this study was to investigate the independent and combined effects of forest loss and habitat fragmentation on woody species richness. Woody species were grouped according to their habitat requirements (forest specialists, forest generalists, non-forest and total woody species). We used regression models to investigate the effect of fragmentation and human occupation on woody species richness. The underlying factors were investigated by partitioning of the variation, i.e. decomposing the variation in species richness between the pure effects of forest loss, fragmentation and human occupation. The relationship between species richness and forest loss resulted extremely non-linear. The models for forest specialist, generalist and total woody species richness accounted for 35%, 31% and 33% of the total variance respectively. Model for non-forest species richness only accounted for 7% of the total variance. The largest fraction of variability in species richness was accounted by fragmentation variables for all groups (except for non-forest species). Results emphasize the larger independent effect of fragmentation over forest loss, suggesting that species variation is mainly conditioned by the spatial configuration of the habitat.

Effect of Forest Harvest on the Vegetation of an Urban Park

Abstract Forested parks are an urban oasis, and forest management plays an important part in their maintenance. I used a systematic sampling technique to quantify the vegetation and propagule bank in a small urban park prior to and following a forest management event. The number of non-forest species and the abundance of Toxicodendron radicans (Poison Ivy) increased after forest harvest. Distance from an edge did not affect the change in vegetation. In the propagule bank, loss of basal area in a plot was positively correlated with an increase in the percent of species that were non-forest and non-native. The Sorenson coefficient of community similarity comparing the species composition of the vegetation before and after harvest was 0.769 (out of 1.0), but that for the propagule bank was 0.308. Forest management practices in small urban parks should be designed with extreme caution due to the volatile settings of these refuges.

Impact of cocoa farming on vegetation in an agricultural landscape in Ghana

AbstractCocoa production occurs almost wholly within areas identified as biodiversity hotspots in West Africa and it has been noted as a major contributor to deforestation at the forest‐agriculture interface. This study investigated the impact of cocoa farming on vegetation in relation to three land‐use types of increasing cocoa production intensity from remnant native forest through shaded to unshaded cocoa farmlands in Ghana. The study used transects and forty‐two 25 m × 25 m vegetation plots. The overall noncocoa plant species richness decreased significantly (95% CI) from the remnant native forest through shaded to the unshaded cocoa farmlands. Significant differences (P ≤ 0.05) were also found in the mean density and basal area of noncocoa plants per hectare with the remnant native forest recording the highest values and the unshaded cocoa farmlands the lowest. The relative density of about 44.7% out of the 41 most abundant plant species declined in cocoa farmlands. The results of this study showed that cocoa farming could result in a drastic forest plant species loss with subsequent recruitment of nonforest species, forest plant species population decline as well as changes in the structural characteristics of the vegetation. This impact increases with increasing cocoa production intensity.

Occupancy dynamics in a tropical bird community: unexpectedly high forest use by birds classified as non-forest species

1. Worldwide loss of biodiversity necessitates a clear understanding of the factors driving population declines as well as informed predictions about which species and populations are at greatest risk. The biggest threat to the long-term persistence of populations is the reduction and changes in configuration of their natural habitat. 2. Inconsistencies have been noted in the responses of populations to the combined effects of habitat loss and fragmentation. These have been widely attributed to the effects of the matrix habitats in which remnant focal habitats are typically embedded. 3. We quantified the potential effects of the inter-patch matrix by estimating occupancy and colonization of forest and surrounding non-forest matrix (NF). We estimated species-specific parameters using a dynamic, multi-species hierarchical model on a bird community in southwestern Costa Rica. 4. Overall, we found higher probabilities of occupancy and colonization of forest relative to the NF across bird species, including those previously categorized as open habitat generalists not needing forest to persist. Forest dependency was a poor predictor of occupancy dynamics in our study region, largely predicting occupancy and colonization of only non-forest habitats. 5. Our results indicate that the protection of remnant forest habitats is key for the long-term persistence of all members of the bird community in this fragmented landscape, including species typically associated with open, non-forest habitats. 6. Synthesis and applications. We identified 39 bird species of conservation concern defined by having high estimates of forest occupancy, and low estimates of occupancy and colonization of non-forest. These species survive in forest but are unlikely to venture out into open, non-forested habitats, therefore, they are vulnerable to the effects of habitat loss and fragmentation. Our hierarchical community-level model can be used to estimate species-specific occupancy dynamics for focal and inter-patch matrix habitats to identify which species within a community are likely to be impacted most by habitat loss and fragmentation. This model can be applied to other taxa (i.e. amphibians, mammals and insects) to estimate species and community occurrence dynamics in response to current environmental conditions and to make predictions in response to future changes in habitat configurations.

Does the effect of forest roads extend a few meters or more into the adjacent forest? A study on understory plant diversity in managed oak stands

Roads are recognised as having different ecological roles such as barrier, corridor or habitat, but the spatial extent of road effects on plant communities in forests remains unclear. We studied the effect of forest road distance on plant understory diversity at 20 sites in young and adult oak stands in a French lowland forest with a long history of management and road construction. All vascular and bryophyte species were collected at five distances ranging from the road verge to 100 m into the adjacent forest stand. We analysed species composition, individual species response, a priori life-history traits response – life form, habitat preference and dispersal mode – and environmental indicator values in relation to road distance and stand age. Plant composition strongly differed between road verge and forest interior habitats. The main road effect extended less than 5 m into the forest stand. A third habitat was detected at the forest-road edge resulting from the road effect on light and soil conditions, and from edge-specific topography. Non-forest species were almost absent from the forest interior. In contrast, many bryophytes and several vascular plants kept away from the road. We identified a posteriori six species groups that better explained the variability of plant response profiles than a priori life-history traits. Plant response to road distance was also dependent on stand age: some species colonised from the road into the forest interior in young stands following regeneration cutting, while other species displayed the reverse pattern in adult stands once canopy closed above the forest road. Even if the depth of forest road effect measured in lowland managed stands was narrow, building of a new forest road has non-negligible effects on plant population dynamics. Forest managers should take into account the impacts of roads on biodiversity, since the expected intensification of silviculture in response to global changes is set to accentuate the effect of forest roads. We recommend further study on the role of dispersal by vehicles (i.e. agestochory) in road effects.

Plant and bird diversity in natural forests and in native and exotic plantations in NW Portugal

Forest ecosystems have been subjected to continuous dynamics between deforestation and forestation. Assessing the effects of these processes on biodiversity could be essential for conservation planning. We analyzed patterns of species richness, diversity and evenness of plants and birds in patches of natural forest of Quercus spp. and in stands of native Pinus pinaster and exotic Eucalyptus globulus in NW Portugal. We analyzed data of forest and non-forest species separately, at the intra-patch, patch and inter-patch scales. Forest plant richness, diversity and evenness were higher in oak forest than in pine and eucalypt plantations. In total, 52 species of forest plants were observed in oak forest, 33 in pine plantation and 28 in eucalypt plantation. Some forest species, such as Euphorbia dulcis, Omphalodes nitida and Eryngium juresianum, were exclusively or mostly observed in oak forest. Forest bird richness and diversity were higher in both oak and pine forests than in eucalypt forest; evenness did not differ among forests. In total, 16 species of forest birds were observed in oak forest, 18 in pine forest and 11 in eucalypt forest. Species such as Certhia brachydactyla, Sitta europaea and Dendrocopos major were common in oak and/or pine patches but were absent from eucalypt stands. Species-area relationships of forest plants and forest birds in oak patches had consistently a higher slope, at both the intra and inter-patch scales, than species-area relationships of forest species in plantations and non-forest species in oak forest. These findings demonstrate the importance of oak forest for the conservation of forest species diversity, pointing the need to conserve large areas of oak forest due to the apparent vulnerability of forest species to area loss. Additionally, diversity patterns in pine forest were intermediate between oak forest and eucalypt forest, suggesting that forest species patterns may be affected by forest naturalness.

The importance of gallery forests in the tropical lowlands of Costa Rica for understorey forest birds

Rivers and streams lined by narrow forest strips are common in the lowland countryside of south-western Costa Rica. We studied the importance of these gallery forests for understorey birds, especially forest species. Using mist-nets, we captured 1110 birds belonging to 90 species between June and September 2007 at 16 sites spread equally over four habitat types: forest interior, forest margin, gallery forest connected to closed forest, and isolated gallery forest. Though isolated gallery forests had the greatest number of expected species in total, they supported the lowest number of forest-specialist species, lower even than connected gallery forests. Granivorous birds showed an increase from forest to isolated gallery forest, all other feeding guilds however showed no change. The studied habitats differed from each other in their faunal composition. Assemblages of three species groups categorised by their habitat preferences (forest specialists, forest generalists, non-forest species) showed nested distribution patterns across the four habitats. There was no significant difference in the proportion of birds with brood patches or of recaptures across the studied habitat types, leading to the assumption that birds not only use gallery forests for movement and foraging but also for reproduction. Though of limited conservation value for most forest understorey birds, at least for a small fraction of forest species gallery forests constitute an important secondary habitat. More significantly, they can form corridors or stepping stones that allow movements within the matrix of human-dominated habitats, and represent an important landscape component benefiting total bird species richness in the Costa Rican countryside.

Fuelling the biodiversity crisis: species loss of ground-dwelling forest ants in oil palm plantations in Sabah, Malaysia (Borneo)

Oil palm plantations today cover large areas of former tropical lowland rain forest in Southeast Asia and are rapidly expanding on the island of Borneo. Study of the community of ground-dwelling ants in different plantations in Sabah, Malaysia, over 2 years using tuna baiting, revealed that the oil palm plantation ground ant community was severely reduced in species richness in comparison to the forest interior, regardless of age, undergrowth cover, or proximity to neighbouring forest. The results indicate that oil palm plantation habitats, now covering more than 15% of Sabah’s land area, can sustain only about 5% of the ground-dwelling ant species of the forest interior. Nine of the 23 ant species baited in the plantations were never recorded inside forest. All numerically dominant ants were non-forest species. The most common species was Anoplolepis gracilipes, an invasive species present at 70% of all bait sites and known to cause ‘ecological meltdowns’ in other situations. The low frequency and species number of forest ground ants indicates that oil palm plantations act as effective dispersal barriers leading to community isolation in rain forest remnants. The replacement of natural forests with oil palm plantations poses a serious threat to the conservation of biodiversity on Borneo if similar results are confirmed in other taxa.

Edge effects on soil seed banks and understory vegetation in subtropical and tropical forests in Yunnan, SW China

Human-induced forest edges are common in many forest landscapes throughout the world. Forest management requires an understanding of their ecological consequences. This study addressed the responses of three ecological groups (non-forest species, secondary forest species and primary forest species) in edge soil seed banks and edge understory vegetation, and explored the relationship between the invasion of non-forest species in edge understory vegetation and the accumulation of their seeds in edge soil seed banks. The soil seed banks and understory vegetation were sampled along transects established at the edges of a continuous subtropical evergreen broad-leaved forest tract ( Lithocarpus xylocarpus forest) bordering anthropogenic grasslands and three tropical seasonal rain forest fragments ( Shorea wantianshuea forest) bordering fallows. Species composition in both soil seed banks and understory vegetation showed great difference among edge sites. In soil seed banks, the dominance (relative abundance and relative richness) of each ecological group did not change significantly along the edge to interior gradient. In understory vegetation, the invasion of non-forest species concentrated on the first several meters along the edge to interior gradient. The dominance of secondary forest species decreased with distance from the edge, while the dominance of primary forest species increased with distance from the edge. In forest edge zones, the invasion of a majority of non-forest species in understory vegetation lags behind the accumulation of their seeds in soil seed banks. Forest edges do not act as a good barrier for the penetration of non-forest species seeds. The lack of non-forest species in understory vegetation must then be due to conditions that are not appropriate for their establishment. Therefore, to prevent germination and survival of non-forest species further into the forest, management should focus on maintaining interior forest conditions.