Search

Highlights • We evaluate if Eucalyptus plantations are novel or hybrid ecosystems. • We compare biotic and abiotic components among the ecosystems evaluated. • Eucalyptus plantations are hybrid ecosystems. • Proper management of this system might improve its conservation value. • Modified ecosystems present different potential for biodiversity conservation. Abstract Novel and hybrid ecosystems present different conservation values for native species. Therefore, the classification of modified ecosystems into a novel or hybrid state is an essential step to assist conservation strategies for biodiversity. During the last decades, plantations of Eucalyptus have increased in the highly threatened Atlantic Forest region, highlighting the importance of defining this ecosystem as novel or hybrid. In this study, we evaluated whether Eucalyptus plantations are novel or hybrid ecosystems by contrasting biotic components (dung beetle communities) and abiotic components (local environmental variables) within historical (Atlantic Forest remnants) and non-historical (pasture) environments in the Atlantic Forest biome, located in Bahia state, Brazil. Our results show that Eucalyptus plantations should be classified and managed as a hybrid ecosystem in this biome. Of the 21 dung beetle species found in Eucalyptus , ten were shared with historical forests (52.6% of Eucalyptus species) and 6 with pastures (31.5%). Eucalyptus plantations have environmental aspects similar to both historical forests and pastures. Despite presenting similar components to historical and non-historical ecosystems, Eucalyptus plantations are sufficiently distinct not to be classified as either one of them. Our results highlight the potential conservation value of Eucalyptus plantations in the Atlantic Forest region as complementary habitat for historical species, and we discuss how alternative management at landscape and stand (local) scales might increase this value. Although dung beetles are an excellent group to monitor biodiversity, we reinforce the necessity to perform further studies using another taxon that present different ecosystem requirements. [ABSTRACT FROM AUTHOR]

The replacement of native forests by high-density tree plantations affects the richness and composition of animal communities through the modification of the resource availability, hydrological regimes, nutrient cycles and soil structure. Previous studies have been conducted mainly on birds and mammals, whereas few have explored the response of anurans, a taxon considered at risk and in steep decline. With this study we aimed to evaluate changes in anuran diversity associated with native forest replacement by pine plantations ( Pinus taeda ) in the southern Atlantic forest of Argentina, a highly diverse and threatened ecosystem. Additionally, we intended to explore the role of the micro-habitat (terrestrial, aquatic) in the response. We characterized vegetation and habitat structure and sampled anurans in terrestrial and aquatic micro-habitats in the native forest and pine plantations monthly over two consecutive years (2012–2014), using three complementary techniques (pitfall traps, audio strip transects and larval sampling). A total of 964 individuals of 21 species were captured: Physalaemus cuvieri , Odontophrynus americanus and Elachistocleis bicolor were the most abundant species. Replacement of the structurally complex native forest by extremely simplified monoculture tree plantations influenced the patterns of anuran alpha and beta diversity. However, these changes were micro-habitat-dependent: changes in anuran diversity in the terrestrial habitat were explained by species loss, while those in the aquatic habitat were explained by both species loss and turnover. The arboreal species of the family Hylidae (eight) were found absent from tree plantations. Both the hydroperiod instability of the water bodies and the simplified vegetation structure of the tree plantations are probably limiting the suitability for both reproduction and larval development of some specialist species. The native vegetation surrounding the water bodies in the tree plantations constitutes a central element to maintain anuran diversity, through increasing the hydroperiod and providing a habitat for species reproduction in the southern Atlantic forest and to facilitate the movement of individuals among native forest remnants. [ABSTRACT FROM AUTHOR]

Forest plantations of fast-growing exotic species constitute an important economic activity in tropical and temperate regions of developing countries. Large areas of native forests and grasslands are being turned into tree plantations without assessing their impacts on natural communities. We evaluated the effects of replacing native forests by non-native pine ( Pinus taeda ) plantations on the diversity and composition of assemblages of terrestrial mammals and ground-dwelling and understory birds, in a forest productive landscape of the Upper Paraná Atlantic Forest of Misiones, Argentina. Camera-trap stations were deployed in three different “environments”: 53 in a continuous forest, 69 in forest fragments, and 62 in tree plantations. The evaluation focused on the effect of the environment, the structural complexity of the vegetation, the cost-distance (distance weighted by connectivity) to the continuous forest, the percentage of native forest within different radii, and the cost of human access (as a proxy for hunting pressure) on both mean species richness per station and species composition. Alpha diversity of the assemblages of each environment was estimated using Hill numbers (effective number of species): q 0 = richness, q 1 = number of common species and q 2 = number of dominant species. Changes in community composition were evaluated by comparing the assemblages of the three environments using three similarity indices: Sorensen (q0 = similarity in species identity), Horn (q1 = similarity in common species), and Morisita-Horn (q2 = similarity in dominant species). For mammals and birds, richness was significantly higher in forest stations (both continuous and fragmented) than in those located in plantations. For both taxa, it also decreased with the distance to the continuous forest (but with a negative quadratic term in birds). Tree plantation stands contained biased and impoverished subsets of the original assemblages. Mammal composition was affected by the environment, the distance to the continuous forest, the proportion of native forest in the landscape, and human access. The bird assemblages of plantations were seriously affected, and their composition was also influenced by changes in vegetation structure. Alternative management practices (e.g. pruning, thinning) and landscape features can partially mitigate the negative effect of tree plantations on mammal and bird assemblages. Large areas of forest that function as population sources and forest fragments immersed in the matrix of plantations are strictly necessary to preserve the original native mammal and bird assemblages in the productive landscape. Promoting connectivity and improving hunting controls will also support their conservation. [ABSTRACT FROM AUTHOR]

Recent studies have advanced our understanding of the mechanisms behind population and community responses to edge effects. However, functional responses remain poorly explored. Seed dispersal is a key process in ecosystem functioning, and edge effects may alter patterns of seed dispersal through changes in dispersers' behavior and environmental conditions. Here, we test predictive models of edge effects and habitat suitability on seed dispersal by considering different scenarios given by differences in the dispersal agent (wind and vertebrate dispersal), and the contrast between habitats of native southern Atlantic forest and tree plantations that occur across the entire area of influence of the edge. We fit our data to non-linear theoretical models to explore the response of seed rain to three general patterns of response to edge effects and differences on habitat suitability: (1) monotonic (sigmoid or exponential) (seed rain is higher in one of the habitats), (2) unimodal (seed rain shows either a maximum or a minimum near the edge, with or without differences on habitat suitability between adjacent habitats) and (3) neutral response (seed rain is constant across the ecotone). We estimated abundance and richness of wind- and vertebrate-dispersed seeds using seed traps, and measured vegetation structure in four different edges between native forest and tree plantations (from recent to mature plantations). Edge effects affected seed rain patterns depending on both the degree of vegetation contrast between habitats and the dispersal agent. Wind-dispersed seeds showed a monotonic response to most edges, whereas responses of vertebrate-dispersed seeds varied among edges (monotonic, unimodal and neutral), consistent with the dispersers' behavior. High contrast edges (forest-recent plantation) showed unimodal edge response, while those created by low contrast edges (forest-mature plantation) exhibited monotonic responses (sigmoid). Differences on habitat suitability on vertebrate-dispersed seeds increased with edge contrast, while richness and abundance of vertebrate-dispersed seeds in the habitat interior showed the opposite pattern. The abundance of wind-dispersed seeds inside the studied habitats increased with edge contrast. The current analytical framework developed to explore responses of populations and communities to edge effects successfully described the response of seed dispersal. Furthermore, edge effects affected seed dispersal patterns differently depending on the dispersal agent and the contrast between habitats. Our findings contribute to the understanding of forest regeneration processes and may help increase the effectiveness of restoration efforts. [ABSTRACT FROM AUTHOR]

Abstract: Efforts are needed in order to increase confidence for carbon accounts in the land use sector, especially in tropical forest ecosystems that often need to turn to default values given the lack of precise and reliable site specific data to quantify their carbon sequestration and storage capacity. The aim of this study was then to estimate biomass and carbon accumulation in young secondary forests, from 4 and up to 20years of age, as well as its distribution among the different pools (tree including roots, herbaceous understory, dead wood, litter and soil), in humid tropical forests of Costa Rica. Carbon fraction for the different pools and tree components (stem, branches, leaves and roots) was estimated and varies between 37.3% (±3.3) and 50.3% (±2.9). Average carbon content in the soil was 4.1% (±2.1). Average forest plant biomass was 82.2 (±47.9) Mgha−1 and the mean annual increment for carbon in the biomass was 4.2Mgha−1 yr−1. Approximately 65.2% of total biomass was found in the aboveground tree components, while 14.2% was found in structural roots and the rest in the herbaceous vegetation and necromass. Carbon in the soil increased by 1.1Mgha−1 yr−1. Total stored carbon in the forest was 180.4Mgha−1 at the age of 20years. In these forests, most of the carbon (51–83%) was stored in the soil. Models selected to estimate biomass and carbon in trees as predicted by basal area had R 2 adjustments above 95%. Results from this study were then compared with those obtained for a variety of secondary and primary forests in different Latin-American tropical ecosystems and in tree plantations in the same study area. [Copyright &y& Elsevier]

Abstract: The extensive removal of competing broadleaved shrubs in forest plantations typically results in structural and compositional simplification of early seral habitat. However, information on the tradeoffs between such intensive forestry practices and biodiversity is scant. Here we assess the magnitude and direction of potential impacts of intensive forest management on populations of early seral-associated breeding birds. Observed population declines of several Neotropical migrant bird species are hypothesized to be linked to the loss of early seral habitat on the breeding grounds. We investigated the association between broadleaved hardwood cover and avian abundance and diversity in intensively managed early seral Douglas-fir (Pseudotsuga menziesii) stands of the Pacific Northwest. Bird species richness decreased across an elevational gradient, but did not vary as a function of either local vegetation composition or structure. In contrast, bird abundance was strongly associated with hardwood cover at local and landscape scales, especially for foliage-gleaning species. We found strong support for the existence of a threshold in relative bird abundance as a function of hardwood at the stand scale; abundance doubled with an increase from 1% to ∼6% hardwood and then reached a plateau. Though abundance of leaf-gleaners increased even more strongly across a gradient in hardwood cover, evidence for a distinct threshold was less clear. We conclude that when early seral hardwood forest is scarce, even small increases in hardwood may provide substantial conservation benefits. However, for some species (i.e., foliage gleaners), there may be more direct trade-offs in abundance and juvenile recruitment with hardwood management intensity. [Copyright &y& Elsevier]

Abstract: Land-use and land cover strongly influence carbon (C) storage and distribution within ecosystems. We studied the effects of land-use on: (i) above- and belowground biomass C, (ii) soil organic C (SOC) in bulk soil, coarse- (250–2000μm), medium- (53–250μm) and fine-size fractions (<53μm), and (iii) 13C and 15N abundance in plant litter, bulk soil, coarse-, and medium- and fine-size fractions in the 0–50cm soil layer in Linaria AB, Canada between May and October of 2006. Five adjacent land-uses were sampled: (i) agriculture since 1930s, (ii) 2-year-old hybrid poplar (Populus deltoides × Populus × petrowskyana var. Walker) plantation, (iii) 9-year-old Walker hybrid poplar plantation, (iv) grassland since 1997, and (v) an 80-year-old native aspen (Populus tremuloides Michx.) stand. Total ecosystem C stock in the native aspen stand (223MgCha−1) was similar to that of the 9-year-old hybrid poplar plantation (174MgCha−1) but was significantly greater than in the agriculture (132MgCha−1), 2-year-old hybrid poplar plantation (110MgCha−1), and grassland (121MgCha−1). Differences in ecosystem C stocks between the land-uses were primarily the result of different plant biomass as SOC in the 0–50cm soil layer was unaffected by land-use change. The general trend for C stocks in soil particle-size fractions decreased in the order of: fine>medium>coarse for all land-uses, except in the native aspen stand where C was uniformly distributed among soil particle-size fractions. The C stock in the coarse-size fraction was most affected by land-use change whilst the fine fractions the least. Enrichment of the natural abundances of 13C and 15N across the land-uses since time of disturbance, i.e., from agriculture to 2- and then 9-year-old hybrid poplar plantations or to grassland, suggests shifts from more labile forms of C to more humified forms of C following those land-use changes. [Copyright &y& Elsevier]

Abstract: In the current scenario of a fragmented Atlantic Forest, with less than 7% of the original cover remaining, the dominant agricultural and agroforestal matrices should be incorporated into conservation planning. However, little information is available on the conservation value of different land uses, especially those of commercial tree plantations. We studied bird communities in native forests and in commercial plantations of an exotic (Pinus spp.) and a native (Araucaria angustifolia) tree species, through local and regional surveys in the Upper Paraná Atlantic Forest, Argentina. Bird species richness was 50% lower in plantations than in native forests, showing the negative impact of replacing the natural forest with tree plantations. Both species richness and composition were similar between Pine and Araucaria plantations (independently of the extent of the surveyed area); yet, there is a threatened species only found in Araucaria forests. Estimated bird richness in native forests was higher in the regional than in the local survey, likely reflecting habitat heterogeneity. Forest-dependent and threatened species were especially affected by the replacement of native forest; bird communities in commercial plantations were mainly composed of forest-generalist and edge species rather than forest-dependent species. Our study demonstrates that major changes in bird species richness and composition are associated with forest replacement by commercial tree plantations under the current management conditions. Many silvicultural measures could favor bird communities, such as the protection of forest remnants inside plantations and the improvement of forest belts between stands. [Copyright &y& Elsevier]

Our goal was to assess the potential of two exotic and five native tree species in reestablishing trees to degraded land in the humid tropics of southern Costa Rica. Our study site was deforested in the 1950s. Steep topography and high rainfall led subsequently to severe erosion, which exposed nutrient-poor, acid, unproductive subsoil. Our site is typical of many tropical overgrazed pastures that have been established in high rainfall areas on ultisols worldwide. Restoration of useful trees to such lands is difficult when erosion is severe.We established 30 experimental blocks in 1994 across our study site that varied in topography and degree of erosion. We analyzed survival over 7 years and height after 3 and 7 years. Pinus tecunumanii, non-native to Costa Rica but native to Central America, was the outstanding performer with best growth and survival among all blocks. Several of the Costa Rican natives, all considered valuable for timber, survived and grew moderately well (Vochysia guatemalensis, Terminalia amazonia, Calophyllum brasiliense).We assessed the effect of erosion on survival and growth. Survival and/or growth negatively correlated with degree of erosion in five of the seven species. P. tecunumanii, an ectomycorrhizal species, survived and grew uniformly well and independently of erosion. T. amazonia survived better but grew worse on more eroded sites.These results suggest the following recommendations for projects that attempt to restore trees to tropical degraded cattle pastures similar to our site: [Copyright &y& Elsevier]

Tree plantations are increasingly common in tropical landscapes due to their multiple uses. Plantations vary in structure and composition, and these variations may alter soil fauna communities. Recent studies have demonstrated the important role of soil fauna in the regulation of plant litter decomposition in the tropics. However, little is known about how plantation species affect soil fauna populations, which may in turn affect the biogeochemistry of the plantation system. We measured soil macroinvertebrate abundance and biomass in 9-year-old N2-fixing Leucaena leucocephala, Casuarina equisetifolia, and non-N2-fixing Eucalyptus robusta plantations on a degraded site in Puerto Rico. Nutrient concentrations and standing stocks of forest floor litter were also determined to examine the relationship between litter chemistry and soil macroinvertebrates. Leucaena plantations had significantly higher abundances and biomass of millipede species than Casuarina and Eucalyptus. Earthworm biomass did not differ among plantation treatments. Nitrogen, P, and K concentrations were generally higher in Leucaena litter, which resulted in higher standing stocks of these nutrients in fragmented, moderately decomposed litter (Oe horizon). Millipede biomass was highly correlated to N concentration and C/N ratio in the Oi litter horizon. These results suggest that plantation species differ in their influence on soil fauna, and the biomass and abundance of soil fauna can be regulated through careful selection of plantation species in degraded tropical lands. [Copyright &y& Elsevier]

• The understory plant diversity of mixed-species plantations was significantly higher than that of monocultures in China. • Tree-shrub mixtures were more beneficial to increase understory plant diversity. • The improvement of understory plant diversity enhanced with the increasing stand age. • The response ratio of understory plant diversity did not change significantly with the mean annual temperature and precipitation. Understory plants are one of the important components of forest biological diversity and play important roles in forest function. Although convincing evidence exists that mixed-species plantations are more conducive to increase the productivity and stability of forest ecosystems than monocultures, the effect of mixed-species plantations on the understory plant diversity (UPD) remains uncertain. This study conducted a meta -analysis based on 205 paired observations of plant species mixtures and corresponding monocultures from 76 peer-reviewed studies to assess the impact of tree mixtures on the UPD in China. The results showed that the UPD was on average 18.2 % higher in mixed-species plantations than in monocultures. This positive mixture effect increased over time, but it would take at least ten years for the effect size of UPD to change from negative to positive. In terms of different mixed forest types, tree-shrub mixtures were more beneficial to maintain the UPD than tree-tree mixtures, and this positive effect was more significant over time. In addition, the response ratio of UPD decreased with mean annual temperature (MAT) and precipitation (MAP), but this relationship was not significant. Therefore, our results suggested that planting mixed-species plantations was a more effective approach to enhance the UPD than monocultures in China. This study revealed the characteristics of UPD under different afforestation modes and could provide a scientific basis for forest management. [ABSTRACT FROM AUTHOR]

• Poplar plantations host significantly less woodpeckers than semi-natural woodlands. • Amount and size of standing dead wood affect woodpeckers' use of plantations. • Scarce breeding activity and low densities indicate that plantations are suboptimal habitats. • A woodpecker oriented management of plantations can benefit also other species. A growing portion of woodlands worldwide is allocated to tree plantations. These are intensively managed and support significantly lower biodiversity than natural forests. However, given their rising extension and importance, understanding how to enhance the role of plantations in aiding biodiversity is crucial. In the present study, we assessed the suitability of traditional poplar plantations for two woodpecker species (Great Spotted Woodpecker Dendrocopos major and Lesser Spotted Woodpecker Dryobates minor), in the western Po Plain (Northern Italy). During Spring 2019, we counted woodpeckers in 29 plots located in plantations. As a comparison, 30 plots placed in semi-natural woodlands nearby were also surveyed. Moreover, within plantations, we monitored the breeding activity of woodpeckers by camera inspection, and we recorded micro-habitat, stand, and landscape variables for every plot. Densities of both species were significantly lower in plantations than in woodlands. In plantations, the occurrence of Lesser Spotted Woodpecker and abundances of Great Spotted Woodpecker were positively related to the amount and size of standing dead trees, respectively. No relationship with the landscape composition were detected. Only 11 woodpecker nests were found in a surveyed area of 274 ha, indicating scarce breeding activity. In stands with breeding woodpeckers, the loss of revenue due to the presence of dead trees ranged from 0.15% to 1.81%. We conclude that poplar plantations are marginal habitats for woodpeckers. To improve the suitability of plantations for these species, a management strategy should pursue the retention of standing dead wood, the increment of natural elements within and close by the plantation and the establishment of multi-age stands. Simultaneous implementation of these measures would buffer the detrimental effects of intensive management, thus acting as a step forward towards the achievement of a multipurpose forest. [ABSTRACT FROM AUTHOR]

• Tree plantations in the Pacific Northwest (PNW), USA, underpin the global economy. • Early successional forests vary based on productivity, ownership, and disturbance. • Collaborative frameworks can address conservation challenges in young forests stands. The ecological value of unmanaged early successional habitat created by disturbances has received considerable research attention. Less well studied is the capacity of tree plantations to contribute to local and regional biological diversity while subsidizing conservation strategies. We present a conceptual framework for describing variability in early successional forests and illustrate how the spatial pattern of this habitat may vary as a function of productivity, land ownership, and disturbance in the Pacific Northwest, USA. We posit that plantations will only increase in ecological and economic importance as the world addresses conservation and resource production challenges associated with climate change, altered disturbance regimes, increasing rates of global wood consumption, and evolving social, legal, and economic expectations. Researchers and managers can foster collaborative frameworks to encourage provisioning of non-timber services on private land, while prioritizing non-timber benefits of early successional habitat on public land to optimize biodiversity conservation and ecosystem services provided in managed forest landscapes. [ABSTRACT FROM AUTHOR]

• The effect of a woodland habitat can be influenced by another woodland habitat. • Nonnative woodlands are not detrimental when combined with native forests. • Nonnative woodlands are not a surrogate of natural forests. • Management plans should account for the entire woodland mosaic. In Europe land use change has produced loss and fragmentation of the original forest habitat. On the other hand, the area covered by tree plantations and altered stands dominated by exotic tree species is increasing. Forest specialist birds are considered to be among the best candidates to assess the consequences of this transformation on wildlife. Here we investigate the link between the abundances of three forest specialist bird species (the Eurasian Nuthatch Sitta europaea , the Marsh Tit Poecile palustris and the Lesser Spotted Woodpecker Dryobates minor) and the woodland habitats of a highly modified landscape located in north-western Italy. In the area, the cover of anthropogenic woodland habitats, such as poplar plantations and Black Locust (Robinia pseudoacia) stands, exceeds that of native oak and riparian forests. During breeding season, birds were counted for three times along 105 transects of 300 m each, scattered in all the wooded contexts of the study area. Using n-mixture models, we investigated the effect of the amount and configuration of woodland habitats on the abundances of each species. First we selected for each variable the strongest scale of effect, ranging from 0.1 to 4 km. Then we built a full model including all variables at selected scales, accounting for correlation among variables and possible interactions. Forest specialists' abundances were affected by the composition of the entire woodland mosaic, not of native forests only. A high cover of nonnative woodlands in the landscape showed a null or positive effect on the species, if combined with a high cover of native forests. However, at a local scale and when dominating in the landscape, nonnative woodlands had mostly a detrimental effect. Alongside with the protection of remnant native forests, it should be contemplated the retention of nonnative woodland habitats when these contribute to enhance the heterogeneity of the landscape. [ABSTRACT FROM AUTHOR]