Mixed Native Species Research Articles

Sparse large trees in secondary and planted forests highlight the need to improve forest conservation and management

Large trees are essential for carbon storage and biodiversity conservation. While an increasing number of studies have focused on large trees in primary forests, little is known about them in secondary and planted forests. We surveyed 86,936 trees in secondary forests and 91,294 trees in planted forests in Zhejiang, China, to investigate the distribution patterns and determinants of large trees in these forests. We found a mean density of large trees (DBH ≥ 30 cm) of 15 ± 13 stems ha−1 in secondary forests and 11 ± 9 stems ha−1 in planted forests. Moreover, the mean density of trees with DBH ≥ 60 cm was 0.36 stems ha−1, indicating that large trees are particularly rare in secondary and planted forests. These large trees were primarily occurred in secondary forests that living in high-elevation area with less human exploitation and colder and wetter climates, and in planted forests with higher species richness and lower tree density. In addition, the density of large trees in these forests significantly increased with tree species richness and decreased with increasing tree density. These results indicate that the sparse large trees were the legacy of historical human activities in the studied area, but currently, the development of large trees is still limited by the improper forest structure characterized by low species diversity and high tree density. To better conserve large trees, there is an urgent need for enhanced conservation policies for secondary forests, such as establishing forest parks for forests with large trees, and implementing near-natural forest management practices for planted forests, which include planting mixed native tree species and maintaining moderate tree density.

Assessment of carbon sequestration potential of tropical tree species for urban forestry in India

Urban, peri urban and patch forests play a critical role in climate change mitigation through increased carbon storage and for that, it is imperative to assess the species response in an eco-region to recommend a potentially higher carbon sequestering species. In urban settings, green spaces, in particular, trees play a vital role in preserving biodiversity, reducing the impact of urban heat islands, enhancing the hydrological cycle, as well as sequestering carbon. When introduced in urban greening projects, native species provide better ecosystem services, conserve and maintain biodiversity more sustainably than exotic species. However, fewer efforts are being made to evaluate the carbon sequestration potential of native tropical tree species in urban greening initiatives. The present study aims to assess the biomass production and carboxylation efficiency of three native tropical tree species to identify the high carbon sequestering species, which will enhance the carbon stocks under urban green spaces. Above ground biomass, carbon stock and physiological performance of three native tropical tree species (Tectona grandis, Mallotus nudiflorus and Syzygium cumini) were measured in Botanical Garden of CSIR-National Botanical Research Institute, Lucknow for eight years old tree stands. Above ground biomass (AGB, Mg/ha) was measured using a non-destructive method by applying allometric equations. Tree height, diameter at breast height (DBH) and leaf area index (LAI) was maximum in T. grandis stand (10.43 m, 29.21 cm, 1.95, respectively). Maximum AGB (71.94 Mg/ha) and carbon stock (25.54 Mg/ha) was observed in T. grandis plantations among the three tree stands. T. grandis stand also had maximum litter fall (5.82 Mg/ha). Highest diurnal photosynthesis rate, water use efficiency and stomatal conductance were also observed in T. grandis stand. However, maximum photosynthetic rate was observed in Mallotus nudiflorus. One way ANOVA revealed significant differences (p < 0.001) in AGB, carbon stock and physiological parameters among the three species. Pearson's Correlation matrix established the positive relationship between growth performance and physiological traits of species with their capacity to sequester carbon. T. grandis can be promoted for urban greening projects for achieving carbon sequestration targets with short time span, however plantation of mixed native species will provide better delivery of all ecosystem services in sustainable mode. Results from the present study shed light on the patterns of carbon sequestration by these species, which in turn will help in the decision-making process for sustainable urban greening. Further, more tropical species can be assessed for their biomass and carbon capture capacities to determine the best species matrix for plantations to enhance carbon storage and develop climate resilient greenbelt under urban landscape forestry programs.

A global meta‐analysis of the impacts of tree plantations on biodiversity

AbstractAimPlanted forests are becoming increasingly common world‐wide for a variety of reasons, including water conservation and carbon sequestration, although the effects of tree plantations on biodiversity are unclear with respect to whether planted ecosystems are “green deserts” or valuable habitats for biodiversity.LocationGlobal.Time period1980–2020.Taxa studiedFlora, fauna and microorganisms.MethodsBy conducting a meta‐analysis of 361 observations from 138 sites world‐wide, we explored the global patterns and associated drivers of biodiversity responding to tree plantations by comparing biodiversity levels in plantations and adjacent habitats (primary or secondary forests).ResultsOverall, the biodiversity (species richness) and abundance across multitrophic levels in tree plantations were lower than those in primary forests, reached similar values to secondary succession, but varied with plantation and management regimes. Specifically, the biodiversity across multitrophic levels in reforestation was higher than that in afforestation; the biodiversity in mixed, native species and unmanaged plantations was higher than that in monoculture, exotic species and managed plantations. The diversity of vertebrates, invertebrates and plants in reforestation was lower than that in primary forests, whereas belowground biodiversity in reforestation showed no difference from primary forests. Invertebrate diversity in reforestation was lower than that in secondary succession, whereas plant diversity was higher than that in secondary succession. Moreover, the biodiversity in reforestation increased with reforestation age. Furthermore, structural equation models showed that aboveground faunal diversity in reforestation was driven by canopy coverage and plant diversity and that reforestation affected belowground biodiversity mainly by changing soil organic carbon.Main conclusionsOur findings suggest that reforestation by planting mixed native species will be more beneficial to biodiversity. We reveal that biodiversity in intensively managed plantations is significantly lower than that in restoration‐oriented plantations. We highlight that primary forests are not replaceable, but that planted forests might be a reliable way to restore biodiversity rapidly.

Estimationof Biomass and Carbon Sequestration by Non-Destructive Method in Dry Deciduous Forest of Shivpuri, Madhya Pradesh, India

The study aims to assess the plant biomass and carbon storage potential of the forests of Shivpuri, Madhya Pradesh, India. The study was carried out in Satanwada Range in Shivpuri Forest Division. A total of 96 quadrats of 10×10 m2 were laid. The non-destructive algometric method was used to estimate carbon sequestration. The results show that Acacia catechu (202 individuals/ha) dominated the forest, followed by Anogeissus pendula (90 individuals/ha). The total biomass of the forest was estimated to be 34.72±0.41t/ha, with Boswellia serrata (7.943t) recording the highest. The minimum biomass was recorded for Grewia sp (0.06t). The highest carbon content was found in B. serrata (3.97t; 25 individuals) followed by A. Catechu (2.92t; 195 individuals). Although A. catechu was dominant in the area, due to its lower girth class and young age, the net carbon storage was less than that of B. serrata. It was found that plots with higher carbon stock had higher species richness than plots composed of single species. Therefore, plantations of mixed native species should be preferred for future restoration activities as they are more efficient in sequestrating carbon than monoculture plantations.

Long-Term Effects of Forest Plantation Species on Chemical Soil Properties in Southern Rwanda

Understanding the long-term effects of tree species on soil properties is crucial for the development of forest restoration policies in relation to the choice of species that meet both environmental and local livelihood needs. This study was performed in the Arboretum of Ruhande, Southern Rwanda, where monocultures of 148 deciduous and 56 conifer species have been established in 0.25 ha replicated plots from 1933 onwards. We investigated the effects of six exotic and two native tree species planted in monoculture plots and native species mixed within one self-regenerated plot on soil properties in two layers (0–5 cm and 5–10 cm depth). We measured general soil properties (pH, SOM, exchangeable base cations) and water-soluble C and N as a proxy for soil functioning. Changes in soil properties were observed in the upper soil layer for all tree species. Planting Eucalyptus species caused soil acidification, whereas soil exchangeable cations and pH were higher under native species (Entandrophragma excelsum and Polyschias fulva) and mixed native species. The effects of tree species were more pronounced for hot water-extractable C and N than for other soil properties. Their analyses could be used for detecting changes in soil functioning linked to vegetation types.

Impact of soil properties, tree layer and grass cover on forest regeneration in a mixed native species reforestation

Impact of soil properties, tree layer and grass cover on forest regeneration in a mixed native species reforestation

Long‐term restoration altered edaphic properties and soil microbial communities in forests: evidence from four plantations of southern China

Afforestation has been an important approach to mitigate land deterioration and biodiversity reduction. There are increasing interests in understanding the responses of soil microbial communities under long‐term forest restoration, since they play a crucial role in the mediation of ecosystem functions while interacting with plants. Here we examined the effects of four forests (Acacia species [AM], Eucalyptus species [EE], mixed coniferous species [MC], mixed native broadleaf species [NS]) after 35‐year restoration (1986–2015) on soil environmental factors and soil microbial communities. Our results showed that afforestation significantly increased soil organic carbon (SOC) and total N (TN) while decreasing soil pH. Among the four forest types, there were significant differences for TN and TK (total K) but not for pH, sSOC, and TP (total P). Bacterial species richness and phylogenetic diversity in Acacia forest significantly declined more than those of other forests, but those of fungal communities were remarkably higher in the Acacia forest. Both the bacterial and fungal communities' structure of each forest were strongly related to soil TK and TP. Besides, TK and SOC were primary edaphic properties that respectively affected the distribution pattern of bacterial and fungal communities in four forests. Network structures in AM and MC compared with EE and NS were more complex and closely linked, hence more resistant to extrinsic interference. Our results demonstrate that afforestation altered soil properties and microbial communities during long‐term restoration, which may provide insight into ecological restoration practices and biodiversity maintenance.

Temporal stability of cavity‐nesting bee and wasp communities in different types of reforestation in southeastern Amazonia

Global initiatives to recover degraded areas have intensified in recent years. However, the effectiveness of different reforestation practices in restoring habitat stability and essential resources for species over time is poorly known. We tested the degree of temporal stability of bee and wasp communities reestablishiment in different types of forest regeneration compared to intact primary forest in southern Amazonia. Using trap‐nest sampling, we collected, during 12 months, information about the nesting species in six different types of treatments: pastures, teak reforestation, fig and mixed native species, natural regeneration forest, and forest primary. We observed that in all reforested treatments, the abundance and richness of both bees and wasps were greater than in pasture sites. However, not all reforestation strategies had the same degree of effectiveness in maintaining the stability of bee and wasp communities over time than observed in primary forest communities. The high temporal variation in teak structure promoted high instability in bee and wasp communities over time. In contrast, reforestation using perennial species, such as fig or mixed species, resulted in a greater temporal stability of bee and wasp communities, although dissimilarity to primary forest remained high. Communities in natural regeneration were the most similar to primary forest, with high similarity of species composition and high temporal stability across seasons. Our findings suggest that reforestation strategies that promote increased complexity of vegetation structure, and better resemble “natural” forests in the provision of habitat resources throughout the year, will better restore and maintain communities through time.

Spatial distribution of soil microbial activity and soil properties associated with

Although much work has been completed in Australia to examine the effects on aboveground ecology of environmental plantings using mixed species of native trees, only limited attention has been focused on their effects on soils and soil microbial population. A study was conducted to determine the spatial distribution of microbial activity, total soil organic carbon (TOC), total nitrogen (TN) and extractable phosphorus (P) in soils under Eucalyptus camaldulensis and Acacia pendula. A 13-year-old environmental planting with mixed native tree species at Gunnedah, New South Wales, was used as a study site. Soil samples were taken from both inside and outside the tree canopy at each of the four compass points (N, S, E and W) at depths of 0–5, 5–10, 10–20, 20–30 and 30–50 cm. The soil was tested for heterotrophic respiration (MicroRespTM), TOC and TN (LECO) and P (Colwell). Microbes were more active inside compared with outside the tree canopy in both A. pendula and E. camaldulensis. The basal respiration rate was significantly higher under A. pendula canopy compared with E. camaldulensis canopy. The relative activity of the microbes and concentrations of TOC, TN and P declined with soil depth. Further, TOC, TN and P contents under the canopy of A. pendula were higher than those of E. camaldulensis and showed a significant positive correlation with basal respiration. However, no difference was detected in the various soil properties measured and microbial activity at four compass points around trees. Changes in soil TOC, TN and extractable P due to the tree plantings were significant only for the 0–5 cm soil depth and changes in microbial activity were mostly confined to the upper 20 cm depth. The improved levels of soil microbial activity and soil nutrients under the tree canopy could be used to measure restoration success of environmental plantings.

Using dendrogeomorphology to estimate soil erosion in mixed native species and pine forests on Ultisols in Piracicaba, Brazil

This work aims to study and date the erosion process in a gully located at the Experimental Station of Tupi (Piracicaba, São Paulo, Brazil) using dendrogeomorphology. Dendrogeomorphology is a relatively new science that relates the growth of tree-rings with geomorphological processes allowing chronological reconstruction and occurrence of events. The relevance of this study is to know the potential of this science in tropical areas because currently this type of study is lacking in these areas. This technique was applied using exposed roots of species of Pinus ssp. The dating of the erosion process was based on the changes in the pattern of root growth, such as the width of the ring, eccentric growth, percentage of latewood and density of the wood that occur after exposure by erosion. Through the study of these changes the first year of root exposure was determined, and the annual rate of erosion was estimated. Erosion rates of 0.65 and 2.39 m/year were found, characterizing the longitudinal advancement of the gully. Finally, dendrogeomorphology demonstrates great potential as a tool in tropical areas. The data and information obtained can be translated into a dendrogeomorphological database and contribute to the expansion of this science in Brazil and areas of tropical environments.

Species dominance rather than species asynchrony determines the temporal stability of productivity in four subtropical forests along 30 years of restoration

Understanding biodiversity and its relationship with ecosystem functioning along forest succession is extremely important to assessing dynamics of community stability and ecosystem integrity. Previous studies have revealed that increases in species richness, phylogenetic diversity (PD), species asynchrony and dominance can stabilize the temporal stability of community biomass in grasslands. However, how these determinants influence the stabilizing effect of biodiversity on forest productivity remains poorly understood. We analyzed the relationships between woody plant diversity and productivity stability along 30 years of restoration (1985–2015) in four types of subtropical forest: a mixed Eucalyptus plantation (EE), an Acacia mangium monoculture (AM), a mixed native species plantation (NS), and a mixed coniferous plantation (MC). Our results showed that community stability in three mixed species plantations (EE, NS, and MC) rather than the AM monoculture augmented remarkably as restoration proceeded. Both species richness and phylogenetic diversity significantly stabilized community productivity in the mixed species plantations instead of the monoculture during the 30-year restoration period. Species asynchrony was not a significant factor contributing to the forest productivity stability. Instead, community stability was mainly driven by that of the dominant tree species, and to a lesser extent, by the species richness. We demonstrated the more important role of species dominance in maintaining the temporal stability of forest productivity, which differs from that (species asynchrony) for grassland communities.

Plant Taxonomic Diversity Better Explains Soil Fungal and Bacterial Diversity than Functional Diversity in Restored Forest Ecosystems.

Plant attributes have direct and indirect effects on soil microbes via plant inputs and plant-mediated soil changes. However, whether plant taxonomic and functional diversities can explain the soil microbial diversity of restored forest ecosystems remains elusive. Here, we tested the linkage between plant attributes and soil microbial communities in four restored forests (Acacia species, Eucalyptus species, mixed coniferous species, mixed native species). The trait-based approaches were applied for plant properties and high-throughput Illumina sequencing was applied for fungal and bacterial diversity. The total number of soil microbial operational taxonomic units (OTUs) varied among the four forests. The highest richness of fungal OTUs was found in the Acacia forest. However, bacterial OTUs were highest in the Eucalyptus forest. Species richness was positively and significantly related to fungal and bacterial richness. Plant taxonomic diversity (species richness and species diversity) explained more of the soil microbial diversity than the functional diversity and soil properties. Prediction of fungal richness was better than that of bacterial richness. In addition, root traits explained more variation than the leaf traits. Overall, plant taxonomic diversity played a more important role than plant functional diversity and soil properties in shaping the soil microbial diversity of the four forests.

Survival, growth, aboveground biomass, and carbon sequestration of mono and mixed native tree species plantations on the Coromandel Coast of India

ABSTRACT In India, reforestation programs with native indigenous tree species are a recent activity. Information on experiences comparing mono- and mixed-species plantations is limited. This study aims to estimate growth, aboveground biomass, and carbon sequestration between the mixed-species plantation and mono-species plantation. The growth, survival, height, aboveground biomass, and carbon sequestration of 82 native mixed species plantations were compared with Casuarina equisetifolia an exotic species planted in this region after over a decade (2006–2016). In the mixed species plantation, 7 species showed 100% survival rate and 19 species were not survived after over a decade intervals. While in the mono plantation, C. equisetifolia showed 92% of the survival rate. The growth rate of mixed species when compared to mono plantation, it showed highly significant differences (P < 0:05) values. Simple linear regression between annual girth increment and height produced very strong positive relations (R 2 0.759). The aboveground biomass estimated for the mixed native plantation was 8.007 tonnes and the mono plantation Casuarina had 5.585 tonnes. The total carbon stock estimated for the tree plantation in the two plots (both mixed native and mono) was 7.492 tonnes. A positive correlation was observed between the carbon stock and density of the top 10 species which contributed predominantly to the total carbon stock (rs = 0.773, p < 0.05). Plantation of C. equisetifolia seems to be well adapted and had more carbon stocking potential. On the other hand, mixed plantation with indigenous species would contribute more to sustainable management and they provide great shelters for many faunal communities and provide a greater range of ecological goods and ecosystem services than the mono plantations.

Changes in taxonomic and phylogenetic dissimilarity among four subtropical forest communities during 30 years of restoration

Enhancement and conservation of biodiversity in recovering communities is one of the primary goals of forest ecology and restoration. To achieve a better understanding of the mechanisms underlying community assembly during restoration, we examined changes in taxonomic and phylogenetic dissimilarity in four types of subtropical forests, consisting of a Eucalyptus plantation (EE), an Acacia mangium plantation (AM), a mixed native species plantation (NS), and a mixed coniferous plantation (MC), over 30 years of restoration (1985–2015). Temporal variation in taxonomic and phylogenetic dissimilarity patterns were found to differ among the four plantation types, although their taxonomic diversity (species richness) and phylogenetic diversity (PD) increased monotonically as succession proceeded. Community dissimilarity decreased nonlinearly over the 30 years, and species composition within each plantation tended to stabilize at around 20 years. Overall, the phylogenetic structure of each plantation was random during the succession period. Taxonomic and phylogenetic rates did not vary markedly along the 30 years of restoration, but the taxonomic turnover rate of MC increased significantly while the phylogenetic turnover rate of NC augmented remarkably. These results indicated that deterministic processes played a more important role in determining the temporal dynamics of community composition while stochastic processes were more important for phylogenetic structure. Our findings further inform the development and design of appropriate restoration strategies, and provide insights into understanding the mechanisms regulating community assembly during the process of forest restoration.

Quality attributes of commercial charcoals produced in Amapá, a Brazilian state located in the Amazonia

The charcoals of Amapa, a Brazilian state located in the Amazonia forest, have been produced from wastes of high-quality native and exotic wood species. However, there is no control to avoid mixing raw materials with different potentials for bioenergy. This work aimed to compare the quality of two brands of Amapa charcoals for domestic use, besides to analyze the variability of properties within and among packages. Charcoals of brands A and B were produced from harvesting wastes of Acacia mangium wood and sawing wastes of mixed native wood species, respectively. Five packages of each brand were acquired, from which thirteen samples were randomly selected for physical and chemical analyses. The higher heating value was estimated from the chemical composition. The brands were compared by analysis of variance or Wilcoxon–Mann–Whitney test. The variability within and between packages was investigated through box plots. The Amapa charcoals showed moisture content (≈ 7.3%) somewhat above the stipulated (5%) by the Brazilian standardization for domestic use. The proper quality of the charcoals was attested by high apparent density (≈ 0.568 g/cm3), high fixed carbon (≈ 87.2%), low volatile matter (≈ 11.7%), low ash content (≈ 1.0%) and high higher heating value (≈ 32,925.40 kJ/kg). The charcoal of the brand B showed better quality considering significant higher average apparent density, no outlier of ash content above the maximum ideal value and overall lower variability within and among packages of the properties. The apparent density greatly varied among packages, while a greater variation within packages was observed for the other properties.

Different plant covers change soil respiration and its sources in subtropics

Heterotrophic soil respiration (RH) and autotrophic soil respiration (RA) by a trenching method were monitored in four vegetation types in subtropical China from November 2011 to October 2012. The four vegetation types included a shrubland, a mixed-conifer, a mixed-legume, and a mixed-native species. The average RH was significantly greater in soils under the mixed-legume and the mixed-native species than in the shrubland and the mixed-conifer soils, and it affected the pattern of soil total respiration (RS) of the four soils. The change in RH was closely related to the variations of soil organic C, total N and P content, and microbial biomass C. The RA and the percentage of RS respired as RA were only significantly increased by the mixed-native species after reforestation. Probably, this depended on the highest fine root biomass of mixed-native species than the other vegetation types. Soil respiration sources were differently influenced by the reforestation due to different changes in soil chemical and biological properties and root biomass.

Eco-exergy and emergy based self-organization of three forest plantations in lower subtropical China

The bio-thermodynamic structures of a mixed native species plantation, a conifer plantation and an Acacia mangium plantation in Southern China were quantified over a period of 15 years based on eco-exergy methods. The efficiencies of structural development and maintenance were quantified through an integrated application of eco-exergy and emergy methods. The results showed that the storage of eco-exergy increased over 3 times in all three plantations, as predicted by the maximum eco-exergy principle. This trend was primarily seen due to the accumulation of biomass, instead of an increase in the specific eco-exergy (eco-exergy per unit biomass), although species richness did increase. The eco-exergy to emergy and eco-exergy to empower ratios of the three plantations generally increased during the study period, but the rate of increase slowed down after 20 years. The dominant trees are the largest contributors to the eco-exergy stored in the plantations, and thus, the introduction of suitable indigenous tree species should be considered after the existing trees pass through their period of most rapid growth or around 20 years after planting. The combined application of C-values and suggested weighting factors in the eco-exergy calculation can imply opposite results, but may also supply useful information for forest management.

Quantifying carbon sequestration on sheep grazing land in Australia for life cycle assessment studies

The sheep industry has played an important role in Australia’s development and economy over the 220 years since European settlement and remains an important land use in Australia, occupying an estimated 85 million ha of continental land mass. Historically, deforestation was carried out in many sheep-rearing regions to promote pasture growth but this has not occurred within recent decades and many wool producers have invested in planting trees as well as preserving patches of remnant vegetation. Although the limitations of single environmental impact studies are recognised, this paper focuses on the contribution of carbon sequestration in trees and shrubs on sheep farms to the global warming potential impact category in life cycle assessment of wool. The analysis represents three major wool-producing zones of Australia. Based on default regional yields as applied in Australia’s National Inventory model, FullCAM, CO2 removals in planted exotic pines and mixed native species were estimated to be 5.0 and 3.0 t CO2 ha–1 year–1, respectively, for the Northern Tablelands of New South Wales in the ‘high-rainfall zone’ and 1.4 t CO2 ha–1 year–1 for mixed native species in the ‘sheep-wheat zone’ of Western Australia. Applying modified factors allowing for the higher measured growth rates in regions with rainfall &gt;300 mm, gave values for native species reforestation of 4.4 and 2.0 t CO2 ha–1 year–1 for New South Wales and Western Australia, respectively. Sequestration was estimated to be 0.07 t CO2 ha–1 year–1 over 100 years for chenopod shrublands of the ‘pastoral zone’ of South Australia but this low rate is significant because of the extent of regeneration. Sequestration of soil organic carbon in improved permanent pastures in the New South Wales Northern Tablelands was evaluated to be highly uncertain but potentially significant over large areas of management. Improved data and consistent methodologies are needed for quantification of these benefits in life cycle assessment studies for wool and sheep meat, and additional impact categories, such as biodiversity, need to be included if the public and private benefits provided by good management of vegetation resources on farms are to be more fully recognised.

Improved models for estimating temporal changes in carbon sequestration in above-ground biomass of mixed-species environmental plantings

Plantings of mixed native species (termed ‘environmental plantings’) are increasingly being established for carbon sequestration whilst providing additional environmental benefits such as biodiversity and water quality. In Australia, they are currently one of the most common forms of reforestation. Investment in establishing and maintaining such plantings relies on having a cost-effective modelling approach to providing unbiased estimates of biomass production and carbon sequestration rates. In Australia, the Full Carbon Accounting Model (FullCAM) is used for both national greenhouse gas accounting and project-scale sequestration activities. Prior to undertaking the work presented here, the FullCAM tree growth curve was not calibrated specifically for environmental plantings and generally under-estimated their biomass. Here we collected and analysed above-ground biomass data from 605 mixed-species environmental plantings, and tested the effects of several planting characteristics on growth rates. Plantings were then categorised based on significant differences in growth rates. Growth of plantings differed between temperate and tropical regions. Tropical plantings were relatively uniform in terms of planting methods and their growth was largely related to stand age, consistent with the un-calibrated growth curve. However, in temperate regions where plantings were more variable, key factors influencing growth were planting width, stand density and species-mix (proportion of individuals that were trees). These categories provided the basis for FullCAM calibration. Although the overall model efficiency was only 39–46%, there was nonetheless no significant bias when the model was applied to the various planting categories. Thus, modelled estimates of biomass accumulation will be reliable on average, but estimates at any particular location will be uncertain, with either under- or over-prediction possible. When compared with the un-calibrated yield curves, predictions using the new calibrations show that early growth is likely to be more rapid and total above-ground biomass may be higher for many plantings at maturity. This study has considerably improved understanding of the patterns of growth in different types of environmental plantings, and in modelling biomass accumulation in young (<25years old) plantings. However, significant challenges remain to understand longer-term stand dynamics, particularly with temporal changes in stand density and species composition.

Bird community comparisons of four plantations and conservation concerns in South China

Plantations of non-native, fast-growing trees are increasing in the tropics and subtropics, perhaps with negative consequences for the native avifauna. We studied bird diversity in 4 types of plantations in South China to determine which plantation types are especially detrimental, and compared our findings with studies in nearby natural forests to assess the magnitude of the negative impact. A total of 57 species was recorded. The mean capture rate of understory birds was 1.7 individuals 100-net-h(-1). Bird richness and capture rate were lower in plantations than in nearby natural forests. Babblers (Timaliidae), primarily forest-dependent species in South China, were particularly under-represented in plantations. Species richness, composition and bird density, particularly of understory birds, differed between plantation types. Plantations of Schima, which is native to South China, had the highest species richness according to point count data. Plantations of Acacia (non-native) supported the highest understory species richness and produced the highest capture rate of understory birds, probably because of their complex structure and high arthropod abundance. If bird diversity is to be considered, we strongly recommend that future re-afforestation projects in South China should, as far as possible, use mixed native tree species, and especially Schima, ahead of the other species.