Native Tree Species Research Articles

Identification and functional analysis of the DOF gene family in Populus simonii: implications for development and stress response.

Populus simonii, a notable native tree species in northern China, demonstrates impressive resistance to stress, broad adaptability, and exceptional hybridization potential. DOF family is a class of specific transcription factors that only exist in plants, widely participating in plant growth and development, and also playing an important role in abiotic stress response. To date, there have been no reported studies on the DOF gene family in P. simonii, and the expression levels of this gene family in different tissues of poplar, as well as its expression patterns under cold, heat, and other stress conditions, remain unclear. In this study, DOF gene family were identified from the P. simonii genome, and various bioinformatics data on the DOF gene family, gene structure, gene distribution, promoters and regulatory networks were analyzed. Quantitative real time PCR technology was used to verify the expression patterns of the DOF gene family in different poplar tissues. This research initially pinpointed 41 PSDOF genes in P. simonii genome. The chromosomal localization results revealed that the PSDOF genes is unevenly distributed among 19 chromosomes, with the highest number of genes located on chromosomes 4, 5, and 11. A phylogenetic tree was constructed based on the homology between Arabidopsis thaliana and P. simonii, dividing the 41 PSDOF genes into seven subgroups. The expression patterns of PSDOF genes indicated that specific genes are consistently upregulated in various tissues and under different stress conditions, suggesting their pivotal involvement in both plant development and response to stress. Notably, PSDOF35 and PSDOF28 serve as pivotal hubs in the interaction network, playing a unique role in coordinating with other genes within the family. The analysis enhances our comprehension of the functions of the DOF gene family in tissue development and stress responses within P. simonii. These findings provide a foundation for future exploration into the biological roles of DOF gene family.

Predicting temperature ranges for the initial development of two native Brazilian tree species using multiple sowing dates

Accurate data on development responses to air temperature are essential to feed development and productivity models through which it is possible to analyze the global warming impacts. The cardinal temperatures – base (Tb), optimum (Topt), and maximum (TB) - delimit the temperature range in which development occurs, while the phyllochron (ºC day per leaf) defines the thermal requirements necessary for leaf appearance and development rate of tree species. Field experiments employing multiple sowing dates provide a wide range of temperature regimes closer to natural field conditions and, at the same time, allow obtaining accurate and reliable estimates of cardinal temperatures and phyllochron values. This study estimated the cardinal temperatures – Tb, Topt, and TB – and the phyllochron of tree species Cybistax antisyphilitica (Mart.) Mart. and Platycyamus regnellii Benth., both native to Brazil, using multiple sowing dates. For this, leaf appearance data from field experiments conducted outdoors during the 2017 and 2018 growing seasons with twelve sowing dates were used. C. antisyphilitica develops properly among 13 °C (Tb), 20 °C (Topt), and 48.4 °C (TB) temperature ranges, and P. regnellii among 13.7 °C (Tb), 21.5 °C (Topt) and 43.4 °C (TB). The phyllochron for leaf appearance was different between the two species. On average, C. antisyphilitica needs to accumulate 88.2 °C day to emit a leaf on the main stem, while P. regnellii needs to accumulate 109.7 °C day per leaf, and both values correspond to a development rate of 0.0134 and 0.0091 leaf per ºC day, respectively. Information about cardinal temperatures provides valuable insights into the development patterns and thermal requirements, which can be used in development models to project the development under future climates.

Identifying the generalizable controls on insect associations of native and non-native trees.

Trees growing outside their native geographic ranges often exhibit exceptional growth and survival due in part to the lack of co-evolved natural enemies that may limit their spread and suppress population growth. While most non-native trees tend to accumulate natural enemies over time, it remains uncertain which host and insect characteristics affect these novel associations and whether novel associations follow patterns of assembly similar to those of native hosts. Here, we used a dataset of insect-host tree associations in Europe to model which native insect species are paired with which native tree species, and then tested the model on its ability to predict which native insects are paired with which non-native trees. We show that native and non-native tree species closely related to known hosts are more likely to be hosts themselves, but that native host geographic range size, insect feeding guild, and sampling effort similarly affect insect associations. Our model had a strong ability to predict which insect species utilize non-native trees as hosts, but evolutionarily isolated tree species posed the greatest challenge to the model. These results demonstrate that insect-host associations can be reliably predicted, regardless of whether insect and host trees have co-evolved, and provide a framework for predicting future pest threats using a select number of easily attainable tree and insect characteristics.

Impact of exotic plantation on native Grassland Biodiversity: A 30-Year analysis in Tanzania’s southern highlands

Exotic trees have been introduced in various parts of the world for commercial and environmental reasons such as restoring degraded land and regulating the climate. Despite their economic benefits, they have been found to cause habitat loss and fragmentation, affect soil nutrient cycling, and deplete water quality and quantity. This study examined the extent of land use and land cover changes over the past 30 years, as well as the influence of exotic plant species on native grassland plant composition and diversity in Tanzania’s southern highlands. Drivers and the extent of changes were studied using Landsat imagery in 1990, 2000, 2010 and 2020. The study examined understory native plant species in 12 study sites, including grasslands as control sites near exotic plantations. The study used transects and rectangular plots to compare native plant species with those in exotic tree plantations. Trees with a stem diameter at breast height (DBH) of 10 cm or more were documented in 25 x 20 m plots, while shrubs with a DBH of 5 cm or more but less than 10 cm were recorded in 5 x 2 m sub-plots and grass as well as herbs were recorded in sub-sub plots of 2 x 0.5 m. The native plant composition and diversity were compared among exotic plantations (pine, eucalyptus and black wattle) and neighbouring grasslands. The generalised linear model (GLM) calculated the species abundance, while the native plant diversity in exotic plantations and grasslands was compared using a one-way analysis of variance (ANOVA). The study found that native species diversity is negatively impacted by exotic tree plantations, which displace natural grasslands (p < 0.05). Thus, wild medicinal plants, edible foods and habitats for flora and fauna, including pollinators, have decreased. The study recommends that afforestation and reforestation should emphasise native tree species for nature conservation.

Local ecological knowledge of forage plants for goat farming and perceptions about pollination of tree species in the arid Chaco

Local ecological knowledge (LEK) of forage resources available in the forest is crucial in the sustainability of extensive grazing systems in the arid Chaco region. Here, we document goat farming management strategies of local peasants, assess their LEK about forage plants and evaluate the local perception related to pollination of native tree species. We used semi-structured interviews to obtain ethnoecological information and a cognitive approach to inquire about the plant species considered as fodder and their relative importance. Peasants listed a total of 48 ethnospecies (60 species from 23 botanical families) used as fodder. The most important forage plants in our study were Neltuma spp., Sarcomphalus mistol and Castela coccinea, which provide high quality fruits and also leaves as forage at different moments of the year. Local producers did not identify pollination as a key factor for the production of forage fruits, but they did emphasize the importance of climatic factors for fruit production. This ethnoecological information related to forage plants and factors that determine fruit production is important to understand peasant management systems that sustain local communities and play an important role in forest persistence.

Complex drivers of geomorphic response and habitat formation revealed in multiyear monitoring of Cosumnes River experimental floodplain reconnection

In this study, we examine a novel levee breach experiment that reconnected a floodplain along the Cosumnes River, California to determine the decadal impact of removing 250 meters of levee and assess the recruitment of large wood. This is the latest study in an ongoing series of investigations 40 years in the making along the largest river on the western slope of the Sierra Nevada without a major dam. We present the findings of this multi-modal investigation here by first measuring the geomorphic alteration of the floodplain surface to quantify the depletion and accretion of sediment across the excavated site. We then identify and quantify the deposition of large wood. Results indicate initiation of anastomosing channel formation and distinct areas of large wood recruitment supporting a naturally evolving lateral levee. Accretion resulted in more than 25,000 m3 of sediment deposition within the original excavation site, the development of multiple sand splays, and natural recruitment of native riparian tree species. We conclude by discussing implications following other approaches to floodplain restoration as a Nature-based Solution. In episodic flow regimes, like in California’s Mediterranean-montane hydroclimatic regime, restoring lateral hydrologic connectivity facilitates ecosystem function. Large flood pulse events drive sediment dynamics and geomorphic heterogeneity while enriching biodiversity through biogeochemical fluxes and habitat creation on reconnected floodplains that store floodwaters and reduce peak discharge. These findings support the importance of long-term monitoring efforts of floodplain restoration.

Selecting Suitable Tree Species for Direct Seeding to Restore Forest Ecosystems in Northern Thailand

To upscale restoration of tropical forest ecosystems, direct seeding—sowing seeds directly into the ground—is potentially a more cost-effective technique than tree planting. However, its success is limited by seed predation, the harshness of environmental conditions on restoration sites and particularly by a lack of information about suitable tree species. Therefore, this study tested the suitability of 23 native forest tree species for direct seeding, to restore a biodiversity-rich, upland, evergreen forest in northern Thailand. Three replicate seed batches of each species were sown randomly in two degraded sites and in a tree nursery under controlled conditions. Seed removal and germination were monitored weekly until no further germination had occurred for more than a month. Subsequently, seedling yield, growth and species performance score were also monitored at appropriate intervals. Nine months after sowing, seed removal differed significantly among species but was generally low, with a cross-species average of 3.4% (±0.5 SE). Seed size was negatively correlated with seed removal. Eight species failed to germinate. Seed germination percentage varied widely among species. Cross-species average germination of the 15 species that germinated was 25% (±6.2 SE). Two species (Adenanthera microsperma and Alangium kurzii) were ranked as having high germination (&gt;50%), five species (Choerospondias axillaris, Spondias pinnata, Diospyros glandulosa, Melia azedarach and Phyllanthus emblica) had medium germination (20–50%) and eight species had low germination (&lt;20%). Following the first dry season, two of the fifteen germinated species failed to establish. Germination and establishment were influenced by seed size, seed storage behavior and successional status. A. microsperma, S. pinnata and C. axillaris are recommended for direct seeding based on their high species performance index values. This study further concluded that selecting desiccation-tolerant seeds, particularly those with medium-to-large sizes, could increase the chances of successful seedling establishment.

The greater the proportion of Robinia pseudoacacia in a stand the greater its effect on the population characteristics of Erythronium dens-canis

Management of invasive alien plants is an increasing problem throughout the world. In some cases native rare or protected species can appear or even prefer habitats dominated by invasive alien plants, which raises questions about the optimal treatment of such areas. Erythronium dens-canis in Hungary is a protected species which only have several occurrences in the country and a number of these populations situated in Robinia pseudoacacia stands developed after harvesting native forests. In this study a total of five populations of E. dens-canis were surveyed between 2020 and 2022 in southwestern Hungary examining and comparing the ongoing demographic changes under native and Robinia stands by monitoring individual plants. Two populations were situated in forests composed of native tree species, two in Robinia pseudoacacia-dominated stands and one in a Robinia-native tree species mixed stand. We categorized the plants into five age-state categories: dormant, seedling, juvenile, vegetative adult, and reproductive adult. We found some considerable differences (e.g. leaf size, reproduction rate) between the populations situated in native and in Robinia stands, whereas the population in mixed forest showed intermediate character in most examined factors. Based on our results, R. pseudoacacia have a significant effect on the phenology and life history of E. dens-canis, and this effect is greater with higher proportion of R. pseudoacacia in a forest stand where the E. dens-canis occurs.

Induction of epicormic sprouts of Schizolobium parahyba var. amazonicum (paricá): effect of seasonality and stump height

Coppicing technique is recognized as an effective method for inducing epicormic sprouts and promoting reinvigoration in Brazilian native tree species. However, there remains a knowledge gap regarding efficient reinvigoration techniques for vegetative rescue of paricá trees. This study aimed to evaluate the coppicing technique's efficacy in inducing epicormic sprouts in paricá trees, considering different seasons and stump heights. A 2x3 factorial experimental design was employed, encompassing two seasons (rainy and dry) and three stump heights (0 = root collar; 10 cm above root collar; 30 cm above root collar). Stumps were monitored over a 90-day period. Results showed that all stumps remained viable, with significant differences observed in sprouting frequency between the rainy and dry seasons at 15 and 30 days, favoring the former. Furthermore, the number of sprouts per stump varied significantly across seasons at 15, 30, and 45 days, with higher counts recorded during the rainy season. Notably, the high percentage of stumps producing sprouts underscores the species' robust response capacity. Additionally, the occurrence of two sprouts per stump suggests a species-specific trait at these stump heights. Evaluation of sprout length and circumference revealed significant differences between seasons, with greater growth observed during the rainy season. These findings are crucial for informing management decisions related to epicormic sprout development through the coppicing technique in paricá trees. Overall, the results indicate the technique's potential to induce epicormic sprouts across all seasons and stump heights evaluated, with superior outcomes observed during the rainy season.

Potencial Simbiótico de Microrganismos do Solo na Promoção do Crescimento de Espécies Arbóreas da Mata Atlântica

The objective of this study was to evaluate the potential of topsoil obtained from a natural forest fragment in the Brazilian Atlantic Forest to serve as a source of symbiotic microorganisms capable of promoting the growth of native tree species in ecological restoration projects. In greenhouse conditions, 14 experiments in a completely randomized design were conducted in 1,700 cm³ pots filled with sterilized substrate. The effect of adding 80 g of topsoil, either in natura or sterilized, to the substrate was tested on the growth of 14 tree species. Plant height, stem diameter, mycorrhizal colonization and dry masses of shoot, roots, and nodules of tree species were measured. Applying the topsoil to the pots generally resulted in significant increases in height and stem diameter of seedlings compared to the control group during the four to six-month evaluation period. This effect was particularly greater in the nodulating species Plathymenia reticulata, Dalbergia nigra and Mimosa bimucronata, with increases in height and stem diameter of up to 328% and 484%, respectively. Forest topsoil also had a positive impact on the growth of shoot, roots, and nodules of the plants, significantly differing from the control groups. Only the plants that received the topsoil in natura exhibited mycorrhizal colonization and the formation of nodules in nitrogen-fixing species. These plants that established mycorrhizas and nodules presented higher concentrations of phosphorous and nitrogen in their biomass, respectively. Under controlled conditions, the use of forest topsoil proved to be a promising strategy for the introduction of microorganisms that can enhance the growth of tree species, thereby holding potential for implementation in nurseries and field settings.&#x0D; &#x0D;

Evaluating the Landscape and Ecological Aspects of Urban Planning in Byblos: A Multi-Faceted Approach to Assessing Urban Forests

Byblos, designated as a UNESCO World Heritage site, stands as one of Lebanon’s most ancient urban centers, known for its expansive green spaces. However, ongoing urbanization threatens these valuable areas. This study uses a multi-faceted approach to evaluate the structure and landscape attributes of Byblos’ urban and peri-urban forests (UPFs). Landscape canopy cover, diversity indices, forest structure, and a silhouette perceptual test were assessed across 24 streets in the city center, residential zones, and areas with heavy vehicular traffic. Findings reveal that 28% of Byblos’ canopy cover is concentrated mostly in the northeastern region. Native tree species account for 30% of the total, and a notable variation in tree diversity exists among different land-use types (Shannon diversity index (H) was 1.02 for the city center, 1.35 for residential streets, and 0.64 for vehicular areas). Additionally, a normal J-shaped distribution of tree diameters was identified across all street types. This study highlights a correlation between tree silhouettes and visual preferences, with densely spreading canopies being favored. Residential trees demonstrate the highest structural diversity and varied blossoming seasons. This research represents the first investigation into the current state of urban forestry in Byblos and offers recommendations for sustainable management and planning strategies.

The first draft genome sequence of Russian olive (Elaeagnus angustifolia L.) in Iran

Russian olive (Elaeagnus angustifolia L.) is a native tree species of Iran and the Caucasus region growing in both wild habitats and cultivated settings. The area under cultivation of this tree has been increasing in recent years due to its ability to withstand drought and soil salinity. Revealing the complete genome of this tree holds great importance. To achieve this, a local cultivar of Russian olive was sampled from the northwest region of Iran for whole genome sequencing using the Illumina platform resulting in approximately 6GB of raw data. A quality check of the raw data indicated that approximately 45,011,388 read pairs were obtained from sequences totalling around 6.7×109bp with CG content of 31%. To assemble the genome of the Russian olive tree, the raw data was aligned to a reference sequence of the jujube (Ziziphus jujuba) genome, which is the taxonomically closest plant to the Russian olive. Assembly of alignments yielded a genome size of 553,696,299bp consisting of 339,701 contigs. The N50 value was 5,300 with an L50 value of 24,921 and GC content of the Russian olive genome was 31.5%. This research represents the first report on the genome of the Iranian cultivar of the Russian olive tree.

Forest carbon storage and sink estimates under different management scenarios in China from 2020 to 2100

Forests play a crucial role in mitigating climate change through carbon storage and sequestration, though environmental change drivers and management scenarios are likely to influence these contributions across multiple spatial and temporal scales. In this study, we employed three tree growth models—the Richard, Hossfeld, and Korf models—that account for the biological characteristics of trees, alongside national forest inventory (NFI) datasets from 1994 to 2018, to evaluate the carbon sink potential of existing forests and afforested regions in China from 2020 to 2100, assuming multiple afforestation and forest management scenarios. Our results indicate that the Richard, Hossfeld, and Korf models provided a good fit for 26 types of vegetation biomass in both natural and planted Chinese forests. These models estimate that in 2020, carbon stocks in existing Chinese forests are 7.62 ± 0.05 Pg C, equivalent to an average of 44.32 ± 0.32 Mg C/ ha. Our predictions then indicate this total forest carbon stock is expected to increase to 15.51 ± 0.99 Pg C (or 72.26 ± 4.6 Mg C/ha) in 2060, and further to 19.59 ± 1.36 Pg C (or 91.31 ± 6.33 Mg C/ha) in 2100. We also show that plantation management measures, namely tree species replacement, would increase carbon sinks to 0.09 Pg C/ year (contributing 38.9 %) in 2030 and 0.06 Pg C/ year (contributing 32.4 %) in 2060. Afforestation using tree species with strong carbon sink capacity in existing plantations would further significantly increase carbon sinks from 0.02 Pg C/year (contributing 10.3 %) in 2030 to 0.06 Pg C/year (contributing 28.2 %) in 2060. Our results quantify the role plantation management plays in providing a strong increase in forest carbon sequestration at national scales, pointing to afforestation with native tree species with high carbon sequestration as key in achieving China's 2060 carbon neutrality target.

Resistance against tree encroachment is driven by richness and identity of herbaceous resident species

AbstractAimsHerbaceous plant cover can be used to inhibit tree encroachment in many managed and semi‐natural grasslands. Ideally, herbaceous seed mixtures should reduce the establishment and growth of many invading tree species over several years. Theory predicts that invasion resistance can be maximized by both: (a) increasing the diversity (taxonomic and/or functional) of resident seed mixtures, and (b) including species that are especially efficient at blocking further colonizers. We established an experiment in a regularly mown old field within a deciduous forest region in southeastern Canada. Our overall goal was to examine the relative contribution of old field community composition and diversity (taxonomic and functional) to resistance against encroachment by two undesirable native tree species over time.LocationVarennes, southern Québec, Canada (45°37′01.24″ N, 73°23′03.57″ W).MethodsWe tested our hypotheses by seeding experimental plots with different levels of taxonomic diversity (from one to nine species) and functional group richness (grasses, legumes, and forbs). Our herbaceous species comprised four native species and five introduced and naturalized species. We then seeded the plots with two model tree colonizers, Acer rubrum and Betula populifolia, during three consecutive years. We also transplanted seedlings of Acer and Betula to determine the effect of herbaceous diversity on post‐emergence growth and seedling survival.ResultsOverall, herbaceous species identity (presence and absence) better predicted the resistance of resident herbaceous seed mixtures to tree encroachment than the other diversity measures assessed in our study. Fast‐growing herbaceous species, such as Lolium, substantially inhibit resistance to woody encroachment in the first year. Achillea millefolium and Solidago canadensis were by far the most efficient in blocking tree seedling establishment and growth, particularly during the second and third years. These effects highlight the potential for a combination of fast‐growing species, along with slower‐growing but highly inhibitive species, as a way to limit tree encroachment in real field applications. Functional group richness was a poor predictor of tree encroachment. Species richness reduced tree encroachment, especially when considering a multidimensional tree encroachment index integrating all aspects of tree establishment and growth over the three years of our experiment.ConclusionsSeeding highly inhibiting herbaceous species is the most efficient approach against specific tree invaders. However, it is difficult to implement in practice because it relies on a priori knowledge of the species’ inhibitory effects. In the absence of this knowledge, the taxonomic richness of seed mixtures should be increased to prevent tree encroachment.

Green deserts, but not always: A global synthesis of native woody species regeneration under tropical tree monocultures.

Tree monocultures constitute an increasing fraction of the global tree cover and are the dominant tree-growing strategy of forest landscape restoration commitments. Their advantages to produce timber are well known, but their value for biodiversity is highly controversial and context dependent. Therefore, understanding whether, and in which conditions, they can harbor native species regeneration is crucial. Here, we conducted meta-analyses based on a global survey of the literature and on a database created with local, unpublished studies throughout Brazil to evaluate the regeneration potential of native species under tree monocultures and the way management influences this regeneration. Native woody species regeneration under tree monocultures harbors a substantial fraction of the diversity (on average 40% and 68% in the global and Brazilian surveys, respectively) and abundance (on average 25% and 60% in the global and Brazilian surveys, respectively) of regeneration observed in natural forests. Plantations with longer rotation lengths, composed of native tree species, and located adjacent to forest remnants harbor more species. Pine plantations harbor more native individuals than eucalypt plantations, and the abundance of regenerating trees is higher in sites with higher mean temperatures. Species-area curves revealed that the number of woody species under pine and eucalypt plantations in Brazil is 606 and 598 species, respectively, over an aggregated sampled area of ca. 12 ha. We highlight that the understory of tree monocultures can harbor a considerable diversity of regenerating native species at the landscape and regional scales, but this diversity strongly depends on management. Long-rotation length and favorable location are key factors for woody regeneration success under tropical tree monocultures. Therefore, tree monocultures can play a role in forest landscape restoration and conservation, but only if they are planned and managed for achieving this purpose.

Potential Interactions between Climate Change and Land Use for Forest Issues in the Eastern United States

Applying an interaction framework, we examined whether climate change and combined land use and disturbance changes were synergistic, antagonistic, or neutral for forest issues of wildfires, tree growth, tree species distributions, species invasions and outbreaks, and deer herbivory, focused on the eastern United States generally since the 1800s and the development of instrumental records (1895). Climate largely has not warmed during 1981–2020 compared to 1895–1980, but precipitation has increased. Increased precipitation and land use (encompassing fire exclusion and forestation, with coarse fuel accumulation due to increased tree densities) have interacted synergistically to dampen wildfire frequency in the humid eastern U.S. For overall tree growth, increased precipitation, carbon fertilization, and land use (i.e., young, fast-growing dense stands) likely have been positive, generating a synergistic interaction. Human activities created conditions for expanding native tree species distributions, non-native species invasions, and damaging native species outbreaks. No strong evidence appears to exist for recent climate change or land use influences on deer populations and associated herbivory levels. In the future, a warmer and effectively drier climate may reverse synergistic and neutral interactions with land use, although effects of climate interactions with land use will vary by species. Management can help correct non-climate stressors due to land use and support resilient structures and species against climate change.

A Comparison of the Chronologies of Introduced versus Native Coniferous Tree Species Growing in Northwestern Poland during the Period of Global Warming

The ongoing climatic changes are causing the extinction of numerous species or their withdrawal from previously occupied areas. The environmental and economic significance of introduced species may increase. The aim of the present study was to examine the rate of growth of coniferous species growing in northwestern Poland and to analyze the tree ring width–climate relationships. Six tree species were selected for this study. Two of these species have natural occurrences in Poland: Pinus sylvestris and Larix decidua. The remaining four species were introduced from North America: Chamaecyparis lawsoniana, Thuja plicata, Pseudotsuga menziesii, and Pinus strobus. Samples were collected from 131 trees using a Pressler borer at 1.3 m above ground. Tree ring widths were measured down to 0.01 mm. Climatic data were retrieved from a weather station located 23 km from the study plot. The average tree ring width reaches the lowest value for the P. sylvestris chronology (1.62 mm/year) and for P. strobus (1.69 mm/year), and the highest value is reached for T. plicata (2.80 mm/year) and P. menziesii (2.56 mm/year). The analysis of weather conditions in the designated pointer years and the response function analysis indicate that winter and early spring air temperature is the factor responsible for the formation of wide tree rings in the following species studied: P. sylvestris, C. lawsoniana, P. menziesii, and T. plicata. For L. decidua and P. strobus, the climate–growth relationships are different: weather conditions in the previous growth year are important, and it is the weather in the late spring and summer months. Two of the investigated introduced species (T. plicata and P. menziesii) are characterized by very good acclimatization and are best adapted to the new habitat during the current climate changes. These tree species can constitute a basis for replacing native species, which, due to increasingly severe droughts and higher temperatures, are doing less and less well in their current habitats. Foresters wanting to conduct sustainable forest management will look for replacement species that are well adapted to new habitat conditions in order to maintain the continuity of forest cover.

How to classify forests? A case study from Central Europe

Aims: Inconsistent treatment of the vegetation layers is one of the main problems in the floristic classification of forests. In this study I investigate whether a classification based solely on woody species leads to units similar to the Braun-Blanquet system or to something completely different. Study area: Austria (Central Europe) and adjacent regions. Methods: 23,681 forest relevés from the Austrian Vegetation Database were classified using TWINSPAN. Spruce and pine plantations and stands with a cover of non-native woody species &amp;gt; 5% were excluded from the dataset. Only native tree and shrub species were used in the classification while herbs, dwarf shrubs, cryptogams and all records of woody species in the herb layer were omitted. Results: The TWINSPAN classification revealed elevation (i.e., climate) as the main floristic gradient in the data set. Within lowland communities, soil moisture was the dominant factor. The higher units of the Braun-Blanquet system were mostly well reproduced. Conclusions: The higher levels of the phytosociological forest classification (class, order, partly also alliance) can basically be defined by taking only the shrub and tree layer into account. However, all past and current classifications suffer from arbitrary exceptions to this rule. This leads to many inconsistencies and blurs the main biogeographical patterns within European forests. Here I argue that using the tree and shrub species for defining the higher levels and the understorey species for defining the lower ones is best suited to meet the properties that users would expect from a good forest classification. Taxonomic reference: Fischer et al. (2008). Syntaxonomic reference: Mucina et al. (2016) if not stated otherwise. Abbreviations: EVC = EuroVegChecklist (Mucina et al. 2016).

Functional traits to predict financial value of enrichment planting in degraded tropical forests

Demand for tropical timber is expected to rise due to an increased global need for sustainable renewable materials. However, sustainable tropical timber production remains a challenge for the global wood product supply chain, especially for high-value tropical hardwoods. Restoration of degraded lands through enrichment planting of native hardwood species could provide a solution, but the financial viability of using native tropical tree species remains largely unknown. We evaluated the financial viability of 22 hardwood tree species native to northern Borneo in enrichment plantings of a degraded forest in Sabah, Malaysia. We investigated how the species’ financial value, expressed as an internal rate of return (IRR) based on land expectation value, varied with their functional trait composition. We found that high financial value was positively correlated with trait values associated with a conservative growth strategy, i.e., financial value was negatively correlated with leaf calcium, magnesium, and nitrogen content, as well as with leaf pH and specific leaf area. Trees with these traits showed a high IRR, partly explained by relatively fast growth and high survival rates. For the most economically promising species, Shorea macrophylla, we estimated that enrichment planting for forest restoration could reach IRRs up to 7.8%. Our results showed that enrichment planting for high-value hardwood production in degraded forests can be financially viable, with variation among species, and that various traits associated with a more conservative growth strategy were linked to high financial value.

Hornbill abundance and habitat relationships in a human-impacted protected area in the Indian Eastern Himalaya

Asian forest hornbills play an important functional role as seed dispersers. Three of the large-bodied hornbill species in the Eastern Himalaya are declining globally. To understand their global population status, it is important to obtain reliable abundance estimates across their range. Protected areas are the strongholds for hornbill species in the Eastern Himalaya but differ in degree of disturbances and human pressures. We estimated the abundances of four hornbill species (Great Hornbill, Wreathed Hornbill, Rufous-necked Hornbill, and Oriental Pied-Hornbill) in the human-impacted Buxa Tiger Reserve in northern West Bengal. This is the first study in Asia to obtain abundance estimates of the hornbill species through comprehensive spatial coverage of the reserve. The densities of the three large-bodied species were low (< 1 bird per km2), while that of the small-bodied Oriental Pied hornbill was around 11 birds per km2. Abundance estimates ranged from a mean of 27 birds for the Rufous-necked Hornbill that is confined to the hilly areas to 161 for the Great Hornbill, 375 for the Wreathed Hornbill and 8050 for the Oriental Pied-Hornbill. Habitat quality was poor in most of the reserve with low tree density and basal area with only a few patches with higher tree density. Oriental Pied-Hornbills were associated with lower elevations and higher fruiting tree density. Despite the relatively low abundance of the large-bodied hornbill species, Buxa is an important site for hornbill conservation due to the presence of breeding populations and nests. While past and ongoing human pressures have resulted in habitat degradation, poaching pressures are low and hornbills are able to persist and breed in this landscape. Ecologically meaningful forest restoration with diverse native tree species is urgently needed to improve the habitat quality for hornbills and other wildlife.