Secondary Forest Species Research Articles

Rove beetle species diversity and the patterns of interactions with their host plants in primary and secondary tropical forests

AbstractIn tropical disturbed forests, it is relatively unknown the extent insect communities are experiencing shifts in species diversity and the consequences for ecosystem functions and services. In southern Mexico, we used the rove beetle community associated to Heliconia wagneriana bracts, as a model system, to investigate differences in community attributes and feeding habits between old-growth and human induced secondary forests. We tested if the beta diversity components of rove beetle communities were influenced by forest type and bract traits. Furthermore, we described the topology of individual-based heliconia-rove beetle ecological networks. Overall, we recorded 26 rove beetle species with significantly greater abundance in secondary forests. High compositional dissimilarity between forest types was observed with saprophagous species being more likely detected in old-growth forests; whereas predatory species in secondary forests. Heliconia-rove beetle networks showed a significant nested pattern with incidence data for old-growth forests and incidence and abundance data for secondary forests. Compared to old-growth forests, the rove beetle community in secondary forests showed strong shifts in species composition, diversity and differences in the detection probability of feeding habits, with consequences for ecosystem functioning. We further discuss these findings according to the forest disturbance and phytotelm systems. Implications for insect conservation: Individuals of H. wagneriana represent biodiversity reservoirs for invertebrates, especially in human-modified landscapes.

Nutrient Contribution and Carbon Sequestration of an Agroforestry System of Coffea canephora Cultivated by Conventional and Organic Management in the Ecuadorian Amazon

Agroforestry systems (AFSs) seek synergies that improve productivity, sustainability, and environmental benefits. This is achieved through the supplying of nutrients to the soil, carbon storage, and sequestration. In the Ecuadorian Amazon, Coffea canephora is planted together with leguminous, woody, forest, and secondary forest species, where the continuous incorporation of vegetative residues from shade species represents a substantial addition of nutrients within these systems. This study was carried out from 2018 to 2022 to determine the contribution of nutrients contained in the biomass and C sequestration in agroforestry systems of coffee with conventional (high use of agrochemicals) and organic (without the use of chemicals) management. The study was carried out with a randomized complete block design, using a factorial arrangement (2 × 4 with three replications). This arrangement included two types of systems (agroforestry and monoculture) and four agronomic management practices (high and medium for conventional, and intensive and low organic). The biomass and nutrient content were measured twice a year (every 180 days); in addition, the yield was also recorded. A multivariate and univariate analysis was used for data analysis through R and SAS software. After five years of evaluation, it was determined that the N, K, Ca, and Mg contents were higher in the agroforestry systems than the monocultures. In the AFSs, the highest nutrient content was obtained with the medium conventional and low organic agronomic management, while in the monocultures, it was obtained with the high and medium conventional management. In addition, at a soil depth of 20 cm, the total storage and CO2 were 38.12 and 139.8 t ha−1, respectively. The highest yields were obtained with conventional management in AFSs (1599 kg ha−1) and monoculture (1789.45 kg ha−1). Overall, AFSs showed a significant contribution of nutrients, such as N, K, Ca, and Mg, for coffee cultivation; moreover, yields were similar in the AFS and monoculture with both conventional and organic management, which is positive, since AFSs also contribute environmental benefits.

Trophic position determines the persistence of neotropical understory birds after forest disturbance.

Habitat loss and degradation are key drivers of the current biodiversity crisis. Most research focuses on the question of which traits allow species to persist in degraded habitats. We asked whether a species' trophic position or niche width influences the resilience of species in degraded habitats and to what extent habitat degradation affects trophic interactions between species. We used nitrogen isotope ratios (15N:14N, expressed as δ15N value) to quantify and compare trophic positions and niche widths of understory birds inhabiting old-growth and young secondary forests in the Pacific lowlands of Costa Rica. We found that a species' trophic position rather than its trophic niche width determined its persistence in secondary forests. Species feeding at lower trophic levels in old-growth forests were less likely to persist in secondary forests than those occupying a higher trophic position in old-growth forests. This pattern is likely induced by the occurrence of relatively large-bodied habitat specialists with a flexible and high-trophic level diet in secondary forests. These habitat specialists likely caused generalist bird species to lower their trophic position relative to conspecifics in old-growth forests. Regarding trophic niche widths, species in secondary forests tend to have larger niche widths than old-growth forest species. However, as old-growth forest specialists and generalists did not differ in their niche widths, no systematic effect of trophic niche width on species persistence after forest disturbance was found. This is the first study that shows a systematic effect of trophic position on the persistence of a wide range of bird species in a disturbed forest ecosystem. It therefore provides important insights into species' responses to habitat degradation and the conservation value of secondary forests. To improve habitat quality for old-growth forest birds and facilitate avian seed dispersal, the creation of large contiguous forest patches should be prioritised when implementing reforestation measures.

Status, Diversity, and Feeding Guilds of Avifauna in the Mining Area

Birds contribute to the ecosystem by delivering a variety of ecological services. Birds help the ecology by performing a number of ecological functions. Specific habitats determine bird distribution and community structure. The variety and feeding guilds of birds in various land covers were studied at PT. Vale Indonesia’s mining concession. We studied birds’ variety, status, and feeding guilds in three distinct land covers using the point count methods: i) primary dryland forest; ii) secondary dryland forest; and iii) shrubs. Data were obtained from January 20th to February 24th, 2020. There were 38 species from 24 families reported. We discovered 11 Sulawesi endemic species, and 1 vulnerable species. Secondary dryland forest species composition was more similar to primary dryland forest than to shrubs. Carnivores, frugivores, granivores, insectivores, nectarivores, and piscivores make up the fowl. The insectivore bird composition was the highest, while the piscivore bird composition was the lowest. The availability of food supplies and vegetation characteristics may be critical to the diversity of birds in any ecosystem. As a result, this study indicates that land-cover alteration and modification may have an impact on bird diversity structure. Maintaining vegetation as a source of food and habitat for birds is crucial for bird conservation.

Rhizosphere effects of moso bamboo and dominant tree species of secondary broadleaved forest on soil organic carbon mineralization.

The rhizosphere effect of plants affects soil organic carbon (SOC) mineralization. It is still unclear for the mechanism by which the rhizosphere effect of dominant plants in secondary broadleaved forest habitats invaded by moso bamboo affects SOC mineralization. Taking broadleaved tree species (Quercus glauca and Cunninghamia lanceolata) and moso bamboo, dominating respectively in uninvaded secondary broadleaved forest and bamboo forest formed after the invasion as test materials, we investigated rhizosphere effect of plants on the SOC mineralization in laboratory incubation experiments. The results showed that carbon mineralization rates of Phyllostachys edulis (PE), Quercus glauca (QG) and Cunninghamia lanceolata (CL) rhizosphere soils were 20%, 26%, and 21% higher than bulk soils, respectively. Carbon mineralization of bulk soils of QG and CL was 22% and 26% higher, while that of rhizosphere soils was 14% and 11% higher than PE, respectively. The contents of water-soluble organic carbon and organic carbon in rhizosphere soils of the three species were significantly higher than those of bulk soil, and the abundance of rhizosphere soil bacteria was higher than that of non-rhizosphere. The contents of microbial biomass carbon, water-soluble organic carbon, and total nitrogen were important factors influencing carbon mineralization in rhizosphere, while water-soluble organic carbon and microbial metabolic quotient were important factors influencing carbon mineralization in non-rhizosphere. On the whole, the rhizosphere effect increased total SOC mineralization, driving by changes in microbial biomass carbon, water-soluble organic carbon, and total nitrogen content. The results could provide a theoretical basis for plant-soil interaction on soil carbon cycling in bamboo invasion habitats.

Simulating the diameter growth responses of Larix gmelini Rupr. and Betula platyphylla Suk. to biotic and abiotic factors in secondary forests in Northeast China

Key messageThe diameter growth of Dahurian larch (Larix gmelini Rupr.) and white birch (Betula platyphylla Suk.) species in secondary forest of Northeast China was not only influenced by biological factors such as tree size and stand characteristics, but also significantly affected by topographic and climatic factors such as temperature and precipitation. It is necessary to consider the abiotic factors in simulating the diameter growth.ContextClimate change, such as global temperature rise, increased frequency of extreme weather events, and rising sea levels, has put forest ecosystems in an unstable state and has an impact on species composition, growth harvest, productivity and other functions of forests. And this impact varies in climate scenarios, regions and forest types.AimsTo gain a comprehensive understanding of the adaptation for key species to their environment in secondary forests in Northeast China, the diameter growth responses of Dahurian larch and white birch to biotic and abiotic factors were simulated to assess the effects of climate on diameter growth.MethodsChina’s National Forest Continuous Inventory (NFCI) data from 2005 to 2015 were used to develop linear mixed-effects diameter growth models with plot-level random effects, and leave-one-out cross-validation was applied to evaluate the developed models. At the beginning of modeling, correlation analysis and best-subset regression were used to analyze the correlation between the diameter increment and the biotic and abiotic factors.Results(i) Sorting the categories of predictors in descending order based on the relative importance of the significant predictors, diameter growth of Dahurian larch was affected by competition, tree size, topographic conditions, stand attributes, diversity index, and climate factors, while the white birch species was affected by competition, tree size, stand attributes, climate factors, diversity index, and topographic conditions; (ii) the plot-level mixed-effects model, which achieved better fit and prediction performance than did basic linear models of individual-tree diameter growth in the cases of prediction calibration, was preferable for modeling individual-tree diameter growth; (iii) the prediction accuracy of the mixed-effects model increased gradually with increasing size of calibration sample, and the best sampling strategy was the use of nine random trees to calibrate and make predictions with the mixed-effects model for the larch and birch species; (iv) Dahurian larch was dominant in terms of interspecific competition, and the growth of this species was enhanced when it was grown with the birch.ConclusionIn addition to biotic factors such as tree size and stand characteristics, the impact of climate on the growth of Dahurian larch and white birch should be considered in future management policies.

Sap flow responses in pioneer and late-successional tree species in secondary tropical montane forests of Eastern Himalaya, India.

The interactive role of life-history traits and environmental forcing on plant-water relations is crucial for understanding species response to climate change but remains poorly understood in secondary tropical montane forests (TMFs). Comparing contrasting life-history traits (pioneer vs late-successional species) in a biodiverse Eastern Himalayan secondary TMF, we investigated sap flow responses in co-occurring pioneer species, Symplocos racemosa (n=5) and Eurya acuminata (n=5), and late-successional species, Castanopsis hystrix (n=3), using modified Granier's Thermal Dissipation probes. The fast-growing pioneers S. racemosa and E. acuminata) had 2.1- and 1.6-times higher sap flux density than the late-successional C. hystrix, respectively, and exhibited characteristics of long-lived pioneer species. Significant radial and azimuthal variability in sap flow (V) between species was observed and attributed to life history traits and the canopy's access to sunlight. Nocturnal V (1800-0500hr) was 13.8 % of daily V and is attributed to stem recharge for evening V (1800-2300hr) and to endogenous stomatal controls for pre-dawn V (0000-0500hr). Both the shallow-rooted pioneer species exhibited midday depression in V attributed to photosensitivity and diel moisture stress response. In contrast, deep-rooted C. hystrix transpired unaffected across the dry season likely accessing groundwater. Thus, the secondary broadleaved TMFs, with the dominance of shallow-rooted pioneers, are more prone to the negative impacts of drier and warmer winters than primary forests, which are dominated by deep-rooted species. The study provides an empirical understanding of life-history traits and microclimate modulating plant-water use in widely distributed secondary TMFs in Eastern Himalaya and highlights their vulnerability against warmer winters and reduced snowfall due to climate change.

Light‐demanding tree species are more susceptible to lianas than shade‐tolerant tree species in a subtropical secondary forest

Abstract Tree‐tree competition has been widely studied as a mechanism responsible for maintaining forest plant species diversity. Other common plant types, such as lianas, may influence tree species competition. Previous studies reported the negative effects of lianas on trees; however, variation in susceptibility to lianas among tree species and the species‐specificity of liana species for tree hosts remain unclear. If lianas have species‐specific interactions with trees, based either on tree or liana species identity, then lianas may influence tree‐tree interactions by altering tree species‐specific competitiveness. We surveyed 5676 lianas (DBH ≥ 0.5 cm) and 61,538 trees (DBH ≥ 1 cm) in a 12‐ha subtropical secondary forest plot to assess liana‐tree interactions. We tested variation among the 20 most common tree species in their susceptibility to lianas, including whether light‐demanding and shade‐tolerant tree species differed. We quantified liana‐tree network structure and evaluated the specificity between the 20 most common tree species and the 15 most common liana species. We expected that: (1) tree species would vary in their susceptibility to lianas, and the extent of this variation would be predicted by tree shade‐tolerance; and (2) liana species would have distinct species‐specific interactions with host trees. Tree species differed greatly in their susceptibility to lianas, with some tree species accumulating many more lianas than others. Light‐demanding tree species particularly had greater susceptibility to lianas than shade‐tolerant tree species. Both the liana‐tree network structure and the interaction intensity between the 15 liana species and 20 tree species showed distinct specialization of liana‐tree interactions. Synthesis. Variation in trees species' susceptibility to lianas implies that lianas may alter tree species‐specific competitive abilities by disproportionately affecting some tree species more than others. In contrast to studies in neotropical forests, light‐demanding tree species were more susceptible to lianas than shade‐tolerant tree species, suggesting that lianas could reduce light‐demanding tree performance in this forest. The distinct species specialization between liana and tree species suggests that increases in the relative abundance of liana species, which is occurring in many forests, may alter the tree community composition by reducing the relative abundance of preferred host tree species.

Changes in floristic composition, diversity and anthropogenic perturbations in an east African tropical forest

AbstractWe assessed changes in floristic composition, diversity and anthropogenic activities in an East African forest; Echuya Central Forest Reserve (ECFR). Using 272 permanent sample plots, comparisons between 2015 and 2021 were made. Twenty‐two tree species were recorded with Macaranga capensis being the most dominant. Tree species density increased significantly from 152 stems/ha in 2015 to 306 stems/ha in 2021. Similarly, trees basal area increased significantly from 19 m2/ha in 2015 to 38 m2/ha in 2021. The bamboo stem density decreased significantly from 11,931 stems/ha in 2015 to 1807 stems/ha in 2021. Shrubs, lianas, vines and herbs' densities did not show significant differences between 2015 and 2021. Furthermore, a number of human activities significantly increased from 22 activities per hectare in 2015 to 83 per hectare in 2021. The Non‐Metric Multidimensional Scaling (NMDS) ordination shows that the human activities with the strongest impact on tree species composition and basal areas were fuelwood collection, human trails, livestock grazing and pole cutting. In conclusion, ECFR is floristically poor; secondary forest tree species are replacing the bamboo forest and human activities could be negatively affecting the ECFR flora. We recommend interventions of increasing people's livelihood incomes to decrease their dependence on forest resources.

Effects of warming on seed germination of woody species in temperate secondary forests.

Seed germination, a critical stage of the plant life cycle providing a link between seeds and seedlings, is commonly temperature-dependent. The global average surface temperature is expected to rise, but little is known about the responses of seed germination of woody plants in temperate forests to warming. In the present study, dried seeds of 23 common woody species in temperate secondary forests were incubated at three temperature sequences without cold stratification and after experiencing cold stratification. We calculated five seed germination indices and the comprehensive membership function value summarized the above indicators. Compared to the control, +2 °C and +4 °C treatments without cold stratification shortened germination time by 14% and 16% and increased the germination index by 17% and 26%, respectively. For stratified seeds, +4 °C treatment increased germination percentage by 49%, and +4 °C and +2 °C treatments increased duration of germination, germination index, and shortened mean germination time by 69%, 458%, 29% and 68%, 110%, 12%, respectively. The germination of Fraxinus rhynchophylla and Larix kaempferi were most sensitive to warming without and with cold stratification, respectively. Seed germination of shrubs were the least sensitive to warming among functional types. These findings indicate warming (especially extreme warming) will enhance the seedling recruitment of temperate woody species primarily via shortening germination time, particularly for seeds undergone cold stratification. In addition, shrubs might narrow their distribution.

Tree species classification in a typical natural secondary forest using UAV-borne LiDAR and hyperspectral data

ABSTRACT Recent growth in unmanned aerial vehicle (UAV) technology have promoted the detailed mapping of individual tree species. However, the in-depth mining and comprehending of the significance of features derived from high-resolution UAV data for tree species discrimination remains a difficult task. In this study, a state-of-the-art approach combining UAV-borne light detection and ranging (LiDAR) and hyperspectral was used to classify 11 common tree species in a typical natural secondary forest in Northeast China. First, comprehensive relevant structural and spectral features were extracted. Then, the most valuable feature sets were selected by using a hybrid approach combining correlation-based feature selection with the optimized recursive feature elimination algorithm. The random forest algorithm was used to assess feature importance and perform the classification. Finally, the robustness of features derived from point clouds with different structures and hyperspectral images with different spatial resolutions was tested. Our results showed that the best classification accuracy was obtained by combining LiDAR and hyperspectral data (75.7%) compared to that based on LiDAR (60.0%) and hyperspectral (64.8%) data alone. The mean intensity of single returns and the visible atmospherically resistant index for red-edge band were the most influential LiDAR and hyperspectral derived features, respectively. The selected features were robust in point clouds with a density not lower than 5% (~5 pts/m2) and a resolution not lower than 0.3 m in hyperspectral data. Although canopy surface features were slightly different from original LiDAR features, canopy surface information was also important for tree species classification. This study proved the capabilities of UAV-borne LiDAR and hyperspectral data in natural secondary forest tree species discrimination and the potential for this approach to be transferable to other study areas.

Different responses of growth and physiology to warming and reduced precipitation of two co-existing seedlings in a temperate secondary forest.

Warming and precipitation reduction have been concurrent throughout this century in most temperate regions (e.g., Northeast China) and have increased drought risk to the growth, migration, or mortality of tree seedlings. Coexisting tree species with different functional traits in temperate forests may have inconsistent responses to both warming and decreased precipitation, which could result in a species distribution shift and change in community dynamics. Unfortunately, little is known about the growth and physiological responses of coexisting species to the changes in these two meteorological elements. We selected two coexisting species in a temperate secondary forest of Northeast China: Quercus mongolica Fischer ex Ledebour (drought-tolerant species) and Fraxinus mandschurica Rupr. (drought-intolerant species), and performed an experiment under strictly controlled conditions simulating the predicted warming (+2°C, +4°C) and precipitation reduction (-30%) compared with current conditions and analyzed the growth and physiology of seedlings. The results showed that compared with the control, warming (including +2°C and +4°C) increased the specific area weight and total biomass of F. mandschurica seedlings. These were caused by the increases in foliar N content, the activity of the PSII reaction center, and chlorophyll content. A 2°C increase in temperature and reduced precipitation enhanced root biomass of Q. mongolica, resulting from root length increase. To absorb water in drier soil, seedlings of both species had more negative water potential under the interaction between +4°C and precipitation reduction. Our results demonstrate that drought-tolerant species such as Q. mongolica will adapt to the future drier conditions with the co-occurrence of warming and precipitation reduction, while drought-intolerant species will accommodate warmer environments.

A healthier water use strategy in primitive forests contributes to stronger water conservation capabilities compared with secondary forests

Water conservation is an important ecological function of forest ecosystems, plant water use strategy is a key factor in regulating forest ecosystem water balance. However, there are still insufficient studies on the water conservation capacity and water use strategies of different forest types, especially in climate-sensitive areas. In this study, we determined the stable isotope values (δD, δ18O and d-excess) of plant water, soil water and precipitation from two typical stand types (primary forest and secondary forest) on Changbai Mountain to reveal plant water use and evaluated the water conservation capacity. The results indicated that rainwater infiltrated into the soil combined with piston flow and preferential flow in the primary forest, and preferential flow was the only form of flow in the secondary forest. The main tree species in the primary forest formed a relatively stable water use niche. Among them, the water use pattern of Quercus mongolica Fisch. ex Ledeb (Qm.) was transformed between shallow and deep soil layers with strong ecological plasticity. The dominant species in secondary forest derived water from similar soil layers with intense interspecific competition. By comparing the water use patterns, the secondary forest conformed to the hypothesis of “two water worlds”, while the primary forest conformed to the hypothesis of one reservoir. The primary forest ecosystem had stronger water conservation capacity than secondary forest ecosystem due to the regulable water use strategies of plants and the stable water conservation capacity of the soil. These results will provide theoretical support and a reference for plan future forest management strategies in the climate-sensitive areas.

Negative Density Restricts the Coexistence and Spatial Distribution of Dominant Species in Subtropical Evergreen Broad-Leaved Forests in China

Negative densification affects the spatial distribution of species in secondary evergreen broad-leaved forests and is a key mechanism governing species coexistence. We investigated the effects of habitat heterogeneity and density on the spatial distribution of populations of dominant woody species in a secondary evergreen broad-leaved forest in Wuchaoshan using spatial univariate point pattern analyses. This 6 ha forest dynamic monitoring sample area in Hangzhou, China is a typical secondary subtropical evergreen broad-leaved forest. We found (1) a strong effect of habitat heterogeneity that led to the spatial aggregation of dominant species in the plot. Habitat heterogeneity had a strong impact on mature individuals at different life history stages and of different species on a large scale. (2) Negative density dependence (NDD) generally affected spatial distributions of most dominant species and decreased in magnitude with age class. Therefore, different species of subtropical evergreen broad-leaved forests in China have formed unique spatial structures due to their habitat preferences but are generally subjected to density-dependent effects.

Herb assemblage dynamics over seven years in different cocoa production systems

Both agronomic practices and spatial position can determine the assemblage of herbaceous species. We assess the dynamics and the contribution of these two aspects over time to the herb assemblages of different cocoa production systems. Braun-Blanquet surveys were performed over seven years in a long-term trial in Bolivia to compare different cocoa production systems: successional agroforestry (SA) with no external inputs, organic agroforestry (OA) and organic monoculture (OM), both including a leguminous perennial cover crop, conventional agroforestry (CA) and conventional monoculture (CM), where agrochemicals were applied. Using general linear models and multivariate analysis we found that assemblages were mainly driven by spatial position only at the beginning. After this, a very dynamic selection process related to the different management practices took place, which became more stable over the years. We observed a decline in species in both the CA and OA systems, due to the loss of heliophilous species and the low number of new species established in them. The OM presented the most conservative pattern, with the lowest number of new species and species lost, due to the presence of the cover crop. Both the most intensively managed system (CM) and the most diverse and least intensive one (SA) had the highest number of new species recorded over time, which led to highly specialized assemblages, with worldwide distributed and herbicide resistant species in the first case and secondary forest species, in the second. We conclude that the promotion of organic management and agroforestry systems, especially highly divers and successional agroforestry sytems would favour herb assemblages with high conservation value and prevent the establishment of globally distributed species.

Data of ant community compositions and functional traits responding to land-use change at the local scale.

Aim: Off-reserve conservation is a major contributor to China biodiversity conservation efforts, biodiversity conservation being achieved within afforestation and low-intensity agriculture in fragmented landscapes. Functional trait is more strongly related to ecological processes than taxonomic diversity and reflects ecosystem functioning and species responses to environmental changes. In this study, we selected five habitats that differ in degree of disturbance to explore the effects of land use on ant community compositions, traits distributions and functional diversity change. We assessed how habitat disturbance affects the ant community compositions and traits distributions and asked if ant functional diversity respond to disturbance at the local scale? Location: Lüchun County, Yunnan Province, southwest China. Methods: Pitfall traps were used to survey ant communities. Additionally, we measured four ant morphological traits (eyes diameter, distance between eyes, femur length of the hind-leg and Weber's length) to assess the functional traits distributions and functional diversity. Shade plot of ant relative abundance was used to explore species distribution amongst different habitats. Kernel density plot was used to explore ant traits distribution patterns amongst different habitats. Non-metric multi-dimensional scaling ordination, based on ant Weber's length, was used to explore the ant traits compositions amongst different habitats. The fourth corner model was used to evaluate the association between ant traits and environmental variables. The FRic, RaoQ and FEve indices were selected as three complementary measures of the multivariate functional traits space and functional redundancy of different habitats. Results: We collected 14258 ants, representing 89 species, 40 genera and seven subfamilies. Aphaenogasterschurri and Tetramoriumciliatum were the common species of secondary forest; P.sagei, P.pieli, Cardiocondylawroughtonii, Recurvidrisnuwa, Tapinnomamelanocephalum, Monomoriumpharaonis and M.orientale were the common species in plantations; and Iridomyrmexanceps and Cardiocondylanuda were the common species in managed farms. Ants had medium eye diameters, narrow distances between eyes, medium leg lengths and smaller body sizes in greatly-disturbed habitats; and ants had an increasing eye diameter and narrowing of the space between eyes, while the leg length and Weber's length became shorter in moderately-disturbed habitats. Ant trait composition, based on Weber's length, showed significantly differences amongst five habitats. The fourth corner analysis indicated that ant species traits were significantly correlated with environmental variables. The functional diversity of secondary forest, lac plantation and lac plantation-corn agroforest were higher than those in dryland farm and rice paddy. Functional diversities were significantly negatively correlated with bare ground cover and significantly positively correlated with leaf-litter cover, leaf-litter thickness and plant cover. Main conclusion: Our results indicated that ant traits distribution patterns were affected by land-use changes, followed by anthropogenic disturbance pressures at the local scale. Ant traits compositions in greatly-disturbed habitats also differed from the habitats with less disturbance. It is unfavourable for the survival of the large body-size ants in more open habitats with more anthropogenic disturbance. Compared with secondary forest, dryland farm and rice paddies were less resistant and more vulnerable and lac plantations had approximately functional diversity of ant communities, suggesting that lac plantations might be resistant as secondary forest to species loss.

Phylogenetic structure and diversity among herpetofaunal communities along a successional gradient of a tropical dry forest in Mexico

The tropical dry forest (TDF) is one of the most biodiverse ecosystems on earth, but also one of the most threatened. Therefore, it is critical to understand the processes that control community assembly and generate diversity during succession. We surveyed 15 herpetofaunal communities from a chronosequence of succession plots and tested whether phylogenetic structure (nonrandom distribution of species with respect to phylogeny) and phylogenetic diversity (incorporation of phylogenetic differences between species to measure biodiversity) differed among seasons and succession stages of the TDF in western Mexico. Phylogenetic structure and diversity of both groups showed temporal shifts. Our data suggest a role of environmental filtering in the first succession stages: during the rainy season in amphibians, allowing the coexistence of closely related species in water ponds, while for reptiles during the dry season, where higher exposure to solar radiation and humidity loss predominate in pastures. The more distantly related species in primary and secondary forests in later succession stages may predict ecosystem stability assuring the sufficient ecological strategies in a community to achieve the persistence of the ecosystem under changing conditions. Our results strengthen the arguments for promoting the conservation and managing of secondary forests under recovery to maintain phylogenetic diversity.

Spatial distribution and correlation of dominant species of karst secondary forest in central Guizhou, China

We analyzed the spatial distribution pattern and correlation of the top four dominant tree species in a 2 hm2 karst secondary forest plot of Tianlong Mountain in central Guizhou, using pairwise correlation function g(r) combined with a completely random model (CSR). The results showed that the diameter structure of trees followed an inverted J-shape, and that more trees belonged to diameter class Ⅴ (≥10 cm) driven by the dominant trees of Lithocarpus confinis and Platycarya longipes. L. confinis presented an inverted J-shaped distribution, and the population could renew very well and was in the primary growth stage. The abundance of P. longipes and Itea yunnanensis increased gradually with increasing diameter class. The density of grown and large trees was far more than the young and small individuals, which indicated poor population regeneration, and the population was in the middle and late growth stages. The top dominant tree species, except L. confinis, showed clustering distribution at large scale, which was decreased gradually with scale and trended to distribute randomly. The pattern was particularly prominent in the diameter class for young trees. Different diameter classes of different tree species presented diffe-rent spatial distribution patterns which influenced by many factors. In terms of interspecific associations, the four dominant tree species showed negative or no associations. The higher importance value of tree species, the lower the degree of association with other dominant species. The two negative correlation tree species had the lowest degree of correlation at small scale. With the increase of spatial scale, the degree of negative correlation decreased gradually, and tended to be no correlation.

SPECIES AND STATUS OF BAMBOO KNOWN FOR THE CONICAL HAT OF NORTHWESTERN LAYA: A UNIQUE CULTURE IN GASA, BHUTAN

Montane bamboo is of very importance to the indigenous people inhabiting mountains of the Himalayas, and is a necessary component of highaltitude temperate forest ecosystems. Particularly, in Laya it is commonly used for weaving conical hat and other implements. Thamnocal amusspathiflorus (Trin.) Munro bamboo was documented as a main element of the conical hat making, displaying the highest altitude frost hardy bamboos in mixed coniferous forest. The cluster analysis specified major habitat of 60% significance (p-value ≤ 0.72) indicating a strong influence of bamboo density with associated species composition and other ecological factors. Unregulated harvesting of young culms and the harvesters repeatedly congregating in the same site resulted in unhealthy clump. Its narrow distribution pattern might threaten to population decline or total wipe off and also remote cause possibly by the spread of secondary forest tree species such as Picea spinulosa & Abies dens a that have gradually taken over areas previously occupied by the bamboo forest. Seventy percent of Laya pinter viewed agreed with the decline inthe production and use of conical hats. The element of this unique culture is under constant threat, for it was challenged by various factors including the stereotypical believes of the people.

Interspecific Association and Community Stability of Tree Species in Natural Secondary Forests at Different Altitude Gradients in the Southern Taihang Mountains

An interspecific association represents an inter-relatedness of different species in spatial distribution and combined with the altitude factor, is key for revealing the formation and evolution of an ecological community. Therefore, we analyzed the changes in interspecific association and community stability at different altitudes in the southern Taihang Mountains using the variance ratio (VR), χ2 test, association coefficient (AC), percentage of co-occurrence (PC) and Godron stability method. In total, 27 sample plots measuring 20 × 20 m were set up and were divided into lower altitude (700~1100 m), medium altitude (1100~1500 m) and higher altitude areas (1500~1900 m) into. The results showed that the overall interspecies association of communities exhibited an insignificant negative association in both the lower (VR = 0.79, W = 7.15) and higher (VR = 0.81, W = 7.36) altitude areas, while an insignificant positive association was observed in the medium (VR = 1.48, W = 13.34) altitude area. Besides, the χ2 test showed the ratio of positively and negatively correlated species pairs decreased as altitude increased with values of 1.39, 1.22 and 0.95 in the lower, medium and higher altitude areas, respectively. Moreover, the AC and PC indices stated that most species pairs had a weaker association in the three altitude areas, but the AC indices also suggested the number of positive association species pairs was more than that of negative association only in medium altitude area. Meanwhile, the Godron stability method showed the distances from the intersection point to the stable point (20 and 80) were still far away, with values of 22.53, 11.92 and 21.34 in the lower, medium and higher altitude areas, respectively, which indicated an unstable succession stage, though the community appeared steadier in the medium altitude area. This study can provide some guidance for effective afforestation and vegetation restoration.