Future Tree Research Articles

Mild Water Stress Makes Apple Buds More Likely to Flower and More Responsive to Artificial Forcing— Impacts of an Unusually Warm and Dry Summer in Germany

Climate change may result in increasingly frequent extreme events, such as the unusually dry conditions that occurred in Germany during the apple growing season of 2018. To assess the effects of this phenomenon on dormancy release and flowering in apples, we compared irrigated and non-irrigated orchard blocks at Campus Klein-Altendorf. We evaluated bud development, dormancy release and flowering in the following season under orchard and controlled forcing conditions. Results showed that irrigated trees presented longer (39.2%) and thinner shoots compared to non-irrigated trees. In both treatments, apical buds developed a similar number of flower primordia per cyme (4–5), presenting comparable development and starch dynamics during dormancy. Interestingly, buds on non-irrigated shoots exposed to low chill levels responded earlier to forcing conditions than those on irrigated shoots. However, chill requirements (~50 Chill Portions) and bud phenology under field conditions did not differ between treatments. In spring, buds on non-irrigated trees presented a higher bloom probability (0.42) than buds on irrigated trees (0.30). Our findings show that mild water stress during summer influenced vegetative growth during the same season, as well as the response of buds to forcing temperatures and flowering of the following season. The differences between irrigation levels in the phenological responses of shoots under low-chill conditions point to a so-far understudied impact of water supply on chilling requirements, as well as subsequent bud behavior. Accounting for the effects of both the water status during summer and the temperature during the dormant season may be required for accurately predicting future tree phenology in a changing climate.

Economic Comparison between Pasture-Based Beef Production and Afforestation of Abandoned Land in Swedish Forest Districts

Large areas of agricultural land have been abandoned or are at risk of being abandoned such as small scattered fields and pastures in forest-dominated landscapes are unsuitable for modern mechanized agriculture and cost-efficient grazing. These areas have therefore become unprofitable to cultivate and graze. Spruce planting has been seen as the obvious alternative on these lands but is today questioned from landscape points of view. Now most abandoned land is left for natural afforestation. This study aims to compare the profitability in use of abandoned or marginal agricultural land in Swedish forest districts for spruce planting, natural birch afforestation, or organic beef cattle grazing large pasture-forest mosaics. The pastures consist of remaining semi-natural pastures, abandoned and marginal agricultural land, and adjacent forest land. Calculations of contribution to land, management, and risk suggest that, given present supports and environmental payments, organic beef production with herds of more than 20 suckler cows in large pasture-forest mosaics could be more profitable than forestry, except for in the most fertile areas of southern Sweden, where spruce planting has the highest contribution. Future tree breeding progress and possible decrease of livestock-related support and environmental payments would however increase the competitiveness of resumed afforestation relative to beef production.

Trees do not always act their age: size-deterministic tree ring standardization for long-term trend estimation in shade-tolerant trees

Abstract. With increasing awareness of the consequences of climate change for global ecosystems, the focus and application of tree ring research have shifted to reconstruction of long-term climate-related trends in tree growth. Contemporary methods for estimating and removing biological growth trends from tree ring series (standardization) are ill-adapted to shade-tolerant species, leading to biases in the resultant chronologies. Further, many methods, including regional curve standardization (RCS), encounter significant limitations for species in which accurate age estimation is difficult. In this study we present and test two tree ring standardization models that integrate tree size in the year of ring formation into the estimation of the biological growth trend. The first method, dubbed size-deterministic standardization (SDS), uses tree diameter as the sole predictor of the growth trend. The second method includes the combined (COMB) effects of age and diameter. We show that both the SDS and COMB methods reproduce long-term trends in simulated tree ring data better than conventional methods; this result is consistent across multiple species. Further, when applied to real tree ring data, the SDS and COMB models reproduce long-term, time-related trends as reliably as traditional RCS and more reliably than other common standardization methods (i.e. C-method, basal area increments, conservative detrending). We recommend the inclusion of tree size in the year of ring formation in future tree ring standardization models, particularly when dealing with shade-tolerant species, as it does not compromise model accuracy and allows for the inclusion of unaged trees.

On the Plurality of Environmental Regimes of Anticipation

In recent years, the social sciences have increasingly investigated ways in which futures are anticipated, fostered, and pre-empted. However, less attention has been given to how various predictive approaches inform different ways of acting in the present. Our article presents the results of an investigation into the current practices and agendas of forest scientists and managers in France. We first suggest how an anticipation of environmental futures is coming to the fore as an emerging field of expertise and practices in forest sciences, including predicting but also monitoring, preparing and adapting to projected futures. We then account for the co-existence of three “micro-regimes” of anticipation combining a certain approach to the forest, a certain vision of the future, and a certain type of scientific predictive approach, including different anticipatory objectives, different modelling practices, and different interactions between research and management: i/ Adapting forestry to future climates; ii/ Predicting Future Tree Biology; iii/ Monitoring forests as indicators of climate change.

Habitat fragmentation in a Mediterranean-type forest alters resident and propagule mycorrhizal fungal communities

AimsAnthropogenic activities disturb forests and their associated mycorrhizal fungi. The combination of climate change and habitat fragmentation are linked to increased incidence of a canker disease in a Mediterranean-type forest tree in Western Australia. As changes in communities of mycorrhizal fungi could predispose these Mediterranean-type forest trees to decline, we investigated how two aspects of mycorrhizal fungal community structure, soil propagules and resident communities on mature trees, respond to habitat fragmentation. MethodsRoots were collected from a forest tree (Corymbia calophylla) across a disturbance gradient. Soil collected from the same disturbance gradient was used in a glasshouse bioassay with C. calophylla as the bioassay host (i.e., soil propagule community). After four months, we harvested the seedlings and collected roots. DNA was extracted from the field roots (resident community) and glasshouse roots (propagule community), amplified with fungal specific primers, labelled with specific barcodes and subjected to 454 pyrosequencing. ResultsMycorrhizal fungal community composition overlapped substantially between the soil propagule and resident communities. However, the resident community had greater mycorrhizal fungal richness than the soil propagule community. Habitat fragmentation had a similar effect on each community structure: communities along highly fragmented areas had different community compositions than communities in a healthy forest. ConclusionWith the increased mortality of C. calophylla forest trees in recent years along edge habitats, understanding the effects habitat fragmentation has on communities of mycorrhizal fungi will further elucidate host-mutualist interactions in these forest ecosystems. The changes in community composition of mycorrhizal fungal species in both propagule and resident pools can have cascading effects on future tree establishment and health by predisposing forest trees to other abiotic or biotic factors.

Edge Effects on Seedling Diversity Are Mediated by Impacts of Fungi and Insects on Seedling Recruitment but Not Survival

Growing awareness of the role of enemies in plant community dynamics has led to ecologists exploring how plant-enemy interactions change in human-modified systems. Proximity to forest edges was found to weaken the role of two groups of plant enemies—insect herbivores and fungal pathogens—in increasing plant diversity during the seed-to-seedling transition. However, it is less clear whether edge effects similarly compromise the diversifying effects of fungi and insects on established seedlings. We examined this question in a human-modified wet tropical forest in the Western Ghats of southern India. Over an annual cycle of recruitment, in 730 seedling plots (1 × 1 m each) arrayed at distances 0–100 m from the forest edge across 15 locations in a 30 km2 landscape, we suppressed the activity of fungal pathogens and insect herbivores by applying fungicide and insecticide to soil, seeds, and seedlings in a subset of plots. Suppressing fungi and insects reduced diversity mainly for seedling recruits and not for seedlings that had already established. However, pesticide effects were only apparent at 90–100 m from forest edges. Specifically, in the interior sites, fungi and insect activity increased recruit diversity, which helped maintain local seedling diversity even though diversity of established seedlings declined with annual mortality. By comparison, canopy openness affected neither the diversity of survivors from the initial seedling cohort nor total seedling diversity after an annual cycle of recruitment. Our results indicate that insects and fungi promote diversity more prominently during early seedling establishment rather than through impacts on post-establishment seedling survival. Thus, edge effects can weaken the diversifying effects of plant-insect and plant-fungal interactions during recruitment and thereby modify the seedling template available for the future tree community in human-modified forests.

Modelling post-fire tree mortality: Can random forest improve discrimination of imbalanced data?

Predicting post-fire tree mortality is a major area of research in fire-prone forests, woodlands, and savannas worldwide. Past research has relied overwhelmingly on logistic regression analysis (LR) that predicts post-fire tree status as a binary outcome (i.e. living or dead). One of the most problematic issues for LR (or any classification problem) occurs when there is a class imbalance in the training data. In these instances, predictions will be biased toward the majority class. Using a historical prescribed fire data set of longleaf pines (Pinus palustris) from northern Florida, USA, we compare results from standard LR and the machine-learning algorithm, random forest (RF). First, we demonstrate the class imbalance problem using simulated data. We then show how a balanced RF model can be used to alleviate the bias in the model and improve mortality prediction results. In the simulated example, LR model sensitivity and specificity was clearly biased based on the degree of imbalance between the classes. The balanced RF models had consistent sensitivity and specificity throughout the simulated data sets. Re-analyzing the original longleaf pine data set with a balanced RF model showed that although both LR and RF models had similar areas under the receiver operating curve (AUC), the RF model had better discrimination for predicting new observations of dead trees. Both LR and RF models identified duff consumption and percent crown scorch as important predictors of tree mortality, however the RF model also suggested pre-fire duff depth as an important predictor. Our analysis highlights LR limitations when data are imbalanced and supports using RF to develop post-fire tree mortality models. We suggest how RF can be incorporated into future tree mortality studies, as well as possible implementation in future decision-support tools.

Phenotypic assessment of wood density and stiffness in Melia dubia plantations from three locations using non-destructive tools

Phenotyping large populations for assessing the variability for wood traits is the basic and critical step for developing improved genotypes/clones in the conventional or molecular marker-based tree improvement programmes of timber-yielding species. Melia dubia is rapidly emerging as a potential timber species with large-scale plantations being raised in different parts of India. In this study, large number of M. dubia trees (n = 940) were phenotyped for girth at breast height, wood basic density and stiffness from six plantations at three different locations, i.e. Yeshwanthpura (Kolar district), Hunsur and adjoining areas (Mysore district) and Kollegal (Mandya district) of Karnataka. Non-destructive tools namely pilodyn penetrometer and stress wave timers were used for phenotyping of wood density and wood stiffness, respectively. Across the locations, pilodyn penetration ranged from 12 to 30 mm and stress wave velocity ranged from 3.45 to 4.54 km/s. Plantations in the Hunsur area were characterized with relatively high pilodyn penetration (means low basic density), whereas stress wave velocity was uniformly distributed in all three locations. 11.68% of total number of trees (3.11% with GBH ≥ 37.5 cm from Yeshwanthpura and 8.57% trees from Kollegal) exhibiting pilodyn penetration range from 12 to 17 mm can be considered for selection for high density and 19.3% of trees (3.9% of trees from Yeshwanthpura, 4.4% trees from Hunsur and 11.02% trees from Kollegal) having stress wave velocity ranging from 4.05 to 4.46 km/s can be considered for high stiffness in the future tree improvement programmes. More than twofolds variation in pilodyn penetration and sufficiently large variation in stress wave velocity provide the opportunity for the development of trait-specific markers.

Improving Mountain Pine Beetle Survival Predictions Using Multi-Year Temperatures Across the Western USA

Global climate change has led to an increase in large-scale bark beetle outbreaks in forests around the world, resulting in significant impacts to forest ecosystems, timber economies, and forest-dependent communities. As such, prediction models that utilize temperature for estimating future bark beetle locations and consequential tree mortality are critical for informing forest management decision-making in an attempt to mitigate and adapt to pending and current outbreaks. This is especially true for physiological models that account for the effects of overwinter temperatures on bark beetle survival, as seasonal temperatures, specifically during winter months, exert the greatest impact on bark beetle mortality during various stages of life cycle development. Yet, how temperature observations are used to predict bark beetle survival can significantly under- or over-estimate the role that temperature variability plays in annual tree mortality, especially under current climate change trajectories. This study evaluates how representations of winter temperature influence bark beetle survival estimates. Using the recent outbreak of mountain pine beetle (Dendroctonus ponderosae Hopkins) across the western USA as a case study, single-year to decade-long winter temperature averages were used as inputs into a physiological beetle survival prediction model, the results of which were compared against beetle-induced tree mortality observations using temporal autoregressive models. Results show that using longer-term survival averages of seven to ten years significantly increases the likelihood that temperature alone can predict general levels of beetle survival and hence beetle-induced mortality. These findings demonstrate the importance of considering the role of long-term temperature observations when forecasting bark beetle outbreaks, and that year-to-year temperature variability may be constrained in predicting beetle survival during outbreak periods.

Reduced tree growth in the semiarid United States due to asymmetric responses to intensifying precipitation extremes.

Earth's hydroclimatic variability is increasing, with changes in the frequency of extreme events that may negatively affect forest ecosystems. We examined possible consequences of changing precipitation variability using tree rings in the conterminous United States. While many growth records showed either little evidence of precipitation limitation or linear relationships to precipitation, growth of some species (particularly those in semiarid regions) responded asymmetrically to precipitation such that tree growth reductions during dry years were greater than, and not compensated by, increases during wet years. The U.S. Southwest, in particular, showed a large increase in precipitation variability, coupled with asymmetric responses of growth to precipitation. Simulations suggested roughly a twofold increase in the probability of large negative growth anomalies across the Southwest resulting solely from 20th century increases in variability of cool-season precipitation. Models project continued increases in precipitation variability, portending future growth reductions across semiarid forests of the western United States.

Effects of Drought on the Phenology, Growth, and Morphological Development of Three Urban Tree Species and Cultivars

Under changing climatic conditions, drought may become a critical constraint for trees in urban areas, particularly at roadsides and highly paved squares. As healthy urban trees have proven to be an important mitigation and adaptation tool for climate change as well as a significant provider of ecosystem services, there is a need for planting species and cultivars capable of coping with the limited water supply. However, data on species’ and cultivars’ response to drought, particularly their water supplying root systems remains rare. To consider the whole plant responses to drought situations, we studied the growth and phenology of three frequently planted tree species and cultivars with a diameter of 5–6 cm during a one-year rainfall exclusion experiment conducted in a nursery field as well as the dry biomass of the compartments branch, stem, and root after excavation. Our results revealed that species’ and cultivars’ performance were linked to their within-plant carbon partitioning. A high tolerance to drought was noted for Acer campestre, with a particularly high ratio of root:shoot ratio, which made it presumably less susceptible to droughts. Tilia cordata ‘Greenspire’ was highly affected by the reduced water availability visible through prematurely leaf senescence, while Carpinus betulus ‘Fastigiata’ suffered from losing a considerable part of its root biomass, which resulted in the lowest root:shoot ratio of all species and cultivars. This study demonstrated the need for investigating the reaction patterns of species and cultivars by considering both the above-and the below-ground plant parts. We recommend that, for future tree plantings at harsh and challenging urban sites, an important selection criterion should be species’ and cultivars’ capability to develop and retain strong and dense root systems even under limited water supply, as that is believed to be an important trait for drought tolerance.

Hunting for a Larger Diversity of Urban Trees in Western Europe—A Case Study from the Southern Caucasus

The primary aim of this study was to communicate a method for locating natural habitats where trees grows under conditions that are comparable to those in urban environments in terms of water stress. This is presented by analyzing five different forest reserves in the southern Caucasus (Republic of Georgia) where calculation of net water balance over the period of a year was conducted. This provided an insight into the drought at the sites during the growing season. The data were thereafter compared with similar calculations for five different cities in Western Europe in order to see if there were any matches in drought stress between the cities and the forest reserves. To extend the analysis, conditions in the five cities were assessed for high density and low density areas, and for the current climate and a future climate scenario. The comparisons revealed some matches between conditions in the forest reserves and those in different scenarios/areas in the cities. A secondary aim was to identify specific ecotypes in the wild demonstrating great potential to handle growing conditions similar to those in urban environments based on inventories of woody plants in the forest reserves. A total of 44 woody species were found in the forest reserve systems with a random distribution throughout the five study sites. Based on the commitments presented above a preliminary screening can be done where future tree selection focus can be directed towards highly promising species and ecotypes, which would undoubtedly limit the time lag before proper plant material can be released.

Assessment of morphological and genetic variability through genic microsatellite markers for essential oil in Sandalwood (Santalum album L.).

Sandalwood (Santalum album L; family Santalaceae) is a highly significant aromatic oil yielding tree. It is valued for two important traits, heartwood and essential oil obtained from the heartwood. This study was proposed to assess the morphological and genetic variability of sandalwood accessions. For this, genotypes were randomly selected (n = 177) from the 14 populations from three states in southern India. The total heartwood oil content and quality was estimated by UV method and GC-MS. Total 14 oil-specific genic SSR markers were procured to evaluate the genetic diversity among the sandalwood accessions. Total core size, heartwood content, and oil of S. album ranged from 4.4 to 19.1cm; 0.0 to 17.3cm; and 0.0 to 5.96% with covariance 27.61, 85.25, and 73.12% followed by mean 9.74, 3.77, and 2.71, respectively. Genetic diversity estimates were highly polymorphic in terms of Na 7.28, Ne 5.89, He 8.0 PIC 0.891, with little Ho, and F-0.922. AMOVA revealed that minimal genetic variation among populations and highest variation was found among individuals with Nm (58.4). The UPGMA reveals the cluster favored the grouping pattern by the PCA analysis. Structure and PCA analysis clustered the entire populations into two major groups with F ST 0.046 in which population of Kerala and Karnataka were pure and Telangana accessions were found admixtures. No significant correlation (r 2 = 0.23, P = 0.00) was observed between heartwood oil and genetic structures. A high degree of transferability of genic markers would facilitate the assessment of novel genotypes for future tree improvement and conservation of Sandalwood populations.

Chilling accumulation in fruit trees in Spain under climate change

Abstract. Growing trees are quite vulnerable to cold temperatures. To minimise the effect of these cold temperatures, they stop their growth over the coldest months of the year, a state called dormancy. In particular, endodormancy requires accumulating chilling temperatures to finish this sort of dormancy. The accumulation of cool temperatures according to specific rules is called chilling accumulation, and each tree species and variety has specific chilling requirements for correct plant development. Under global warming, it is expected that the fulfilment of the chilling requirements to break dormancy in fruit trees could be compromised. In this study, the impact of climate change on the chilling accumulation over peninsular Spain and the Balearic Islands was assessed. For this purpose, bias-adjusted results of 10 regional climate models (RCMs) under Representative Concentration Pathways (RCPs) 4.5 and 8.5 were used as inputs of four different models for calculating chilling accumulation, and the results for each model were individually compared for the 2021–2050 and 2071–2100 future periods under both RCPs. These results project a generalised reduction in chilling accumulation regardless of the RCP, future period or chilling calculation model used, with higher reductions for the 2071–2100 period and the RCP8.5 scenario. The projected winter chill decrease may threaten the viability of some tree crops and varieties in some areas where the crop is currently grown, but also shows scope for varieties with lower chilling requirements. The results are relevant for planning future tree plantations under climate change, supporting adaptation of spatial distribution of tree crops and varieties in Spain.

Simulated Nitrogen Deposition Reduces the Concentration of Soil Base Cations in Acer velutinum Bioss. Plantation, North of Iran

The effect of simulated N deposition on concentration of soil base cations and net N mineralization was studied in Acer velutinum Bioss. plantation in Hyrcanian forest, North Iran. Nine plots were established in May 2015 and three N addition treatments were designed: N0 (control), N1 (50 kg N ha−1 year−1), and N2 (100 kg N ha−1 year−1), respectively. NH4NO3 solution was monthly sprayed on the forest floor during 1 year starting from May 2015. Soil pH, EC, organic carbon (OC), and concentrations of total N, $$ {\mathrm{NO}}_3^{-} $$ , $$ {\mathrm{NH}}_4^{+} $$ , phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were measured. Nitrogen treatments significantly decreased soil pH and EC. The concentration of N in N2 was significantly greater than N0 (control). Compared to N0, the soil P, K, Ca, and Mg decreased in N treatments, but soil OC, $$ {\mathrm{NO}}_3^{-} $$ , and $$ {\mathrm{NH}}_4^{+} $$ increased. Net N mineralization rates were positive but showed no significant difference between treatments. As the first work in Iranian Hyrcanian forests, this study showed that the concentration of soil nutrients can be changed under N additions in this area, and these new results can be considered as suitable data for predicting and modeling future trees’ growth and forest ecosystems’ production in Hyrcanian forests.

The growth and production modeling of individual trees of Eucalyptus urophylla plantations

Individual tree models (ITMs) are classified as growth and production models for projecting current and future forest stands. ITMs are more complex than other growth and production models, show a higher level of detail and, consequently, produce a better modeling resolution. However, the accuracy and efficiency of ITMs have not been properly assessed to date. In this study, we estimated the growth in height, diameter, and individual tree volume of a Eucalyptus urophylla plantation by applying an ITM. We used a continuing forest inventory dataset in which 1554 individual trees within 29 permanent plots were measured in the field over a 6-year period (24 to 72 months). Each individual tree volume was estimated for future tree age. To achieve this, we adjusted the model to predict the height and diameter growth, and the probability of mortality as a function of the competition index. The ITM accuracy was assessed based on the analysis of variance results and, subsequently, the multiple mean comparison test at the 5% significance level. The tree volumes predicted by the ITM for the forest stand aged 72 months, beginning at ages 24, 36, 48, and 60 months, were compared to the field measured tree volume acquired from the 72-month forest inventory that was used as the reference age. Estimated and observed tree volumes were similar when the estimation was based on the 48-month forest plots. These results might help to reduce financial costs of forest inventory because the ITM produces accurate future predictions of forest stand stocks. Our estimated ITM for Eucalyptus plantations using measurement intervals up to 2 years is recommended because it significantly reduced the projected volume discrepancy compared to the field measurements.

The Riparian Tree Species Composition and Diversity of the Midstream of Halda River in Chittagong, Bangladesh

Riparian vegetation has been depleting in the many river basins of Bangladesh. Consequently, this study assessed the tree species composition, structure and diversity of the midstream area of the Halda River in Bangladesh. Twenty two quadrats (20 × 20m in size) were sampled. A total of 414 individual tree stems of ≥10 cm DBH of 36 tree species belonging to 31 genera and 15 families were enumerated. Density, Basal area and volume of the tree species were measured. Different diversity indices, i.e. Shannon-Wienners Diversity Index, Simpson's Dominance Index, Pielou’s Species Evenness Index, Margalef's and Menhinick’s richness index were calculated. Fabaceae was the most represented family with nine species, followed by Moraceae, Meliaceae and Anacardiaceae. Density, basal area and volume of the trees were 470.45 stem/ha, 19.09m²/ha and 139.42m³/ha, respectively. Samanea saman was found to be dominant, showing a maximum IVI, followed by v, Mangifer aindica, Eucalyptus camaldulensis and Artocarpus heterophyllus. The findings of the study will be helpful for the posterior researchers in their research work and their future tree based planning programs and conservation. So it is recommended that greater emphasis should be taken to proper management and conservation against over extraction and illegal felling for the maintenance of existing tree species composition and density.

Tree compensation rates: Compensating for the loss of future tree values

When healthy trees are removed, common methods of compensation are either monetary or replanting new trees. Accurate monetary compensation for large healthy trees is difficult to ascertain and often uses formulas based on tree attributes such as species, size, location and condition. Compensation based on leaf area is more direct as most tree values are related to healthy leaf area. Using leaf area, a tree compensation rate can be determined (how many new trees are needed to compensate for the removal of a healthy tree). However, compensation also needs to consider the future benefits provided by both the removed tree and newly planted trees. This paper provides a new method of tree compensation based on comparing the net present value of leaf area between a removed tree and planted replacement trees. This proposed method is not intended to replace existing methods, but rather facilitate discussion and science to improve estimating tree values and compensation. Using this new approach with a three-percent discount rate and a four- percent annual mortality rate, maximum compensation rates using comparable trees reached 13.7 trees for large trees and 3.3 trees for small trees. An overall maximum compensation of 41.1 trees was reached when large trees with a one-percent mortality rate were replaced with small trees with a four-percent mortality rate. Compensation rates vary with tree size, estimated life span remaining (mortality rate), discount rates, and type of replacement tree used (large vs. small trees). Compensation for tree loss can either be through planting of replacement trees or the conversion of replacement trees to a monetary value based on local planting costs.

Characteristics of the tree shrew gut virome.

The tree shrew (Tupaia belangeri) has been proposed as an alternative laboratory animal to primates in biomedical research in recent years. However, characteristics of the tree shrew gut virome remain unclear. In this study, the metagenomic analysis method was used to identify the features of gut virome from fecal samples of this animal. Results showed that 5.80% of sequence reads in the libraries exhibited significant similarity to sequences deposited in the viral reference database (NCBI non-redundant nucleotide databases, viral protein databases and ACLAME database), and these reads were further classified into three major orders: Caudovirales (58.0%), Picornavirales (16.0%), and Herpesvirales (6.0%). Siphoviridae (46.0%), Myoviridae (45.0%), and Podoviridae (8.0%) comprised most Caudovirales. Picornaviridae (99.9%) and Herpesviridae (99.0%) were the primary families of Picornavirales and Herpesvirales, respectively. According to the host types and nucleic acid classifications, all of the related viruses in this study were divided into bacterial phage (61.83%), animal-specific virus (34.50%), plant-specific virus (0.09%), insect-specific virus (0.08%) and other viruses (3.50%). The dsDNA virus accounted for 51.13% of the total, followed by ssRNA (33.51%) and ssDNA virus (15.36%). This study provides an initial understanding of the community structure of the gut virome of tree shrew and a baseline for future tree shrew virus investigation.

Climate change and tree harvest interact to affect future tree species distribution changes

Abstract Tree harvest and climate change can interact to have synergistic effects on tree species distribution changes. However, few studies have investigated the interactive effects of tree harvest and climate change on tree species distributions. We assessed the interactive effects of tree harvest and climate change on the distribution of 29 dominant tree species at 270 m resolution in the southern United States, while accounting for species demography, competition, urban growth and natural fire. We simulated tree species distribution changes to year 2100 using a coupled forest dynamic model (LANDIS PRO), ecosystem process model (LINKAGES) and urban growth model (SLEUTH). The distributions of 20 tree species contracted and nine species expanded within the region under climate change by end of 21st century. Distribution changes for all tree species were very slow and lagged behind the changes in potential distributions that were in equilibrium with new climatic conditions. Tree harvest and climate change interacted to affect species occurrences and colonization but not extinction. Occurrence and colonization were mainly affected by tree harvest and its interaction with climate change while extinctions were mainly affected by tree harvest and climate change. Synthesis and applications. Interactive effects of climate and tree harvest acted in the same direction as climate change effects on species occurrences, thereby accelerating climate change induced contraction or expansion of distributions. The overall interactive effects on species colonization were negative, specifically with positive interactive effects at leading edges of species ranges and negative interactive effects at trailing edges. Tree harvest generally did not interact with climate change to greatly facilitate or ameliorate species extinction. Our modelling results highlight the importance of considering disturbances and species demography (e.g. post‐harvest regeneration dynamics) when predicting changes in tree distributions.