Fast-growing Tree Species Research Articles

Spatially analysed expansion of individual street tree crowns enables species-specific crown expansion predictions in different rainfall zones

Many cities are developing ambitious future canopy cover targets in recognition of urban trees' numerous benefits. Selecting fast-growing and climate-adapted tree species is important to help achieve these targets. The assessment of growth performance of tree species is challenging, but essential for selecting species that grow in different environments. Often, remote sensing is used to measure canopy cover change at a landscape or neighbourhood scale in urban forests, but rarely at individual tree or species scales. In this study, we developed a novel spatial analysis method combining remotely sensed canopy cover mapping with georeferenced urban tree inventory data to identify individual tree crowns and measure crown expansion rates. We developed species-specific models of crown expansion rates for 20 most common street tree species growing in two rainfall zones (478–665 mm). Predicted crown areas at 10 years after planting ranged from 6.6 m2 to 43.7 m2. The species showed four different crown expansion responses at 10 years after planting: Fast and consistent growth; Fast but sensitive growth; Slow and consistent growth; Slow and sensitive growth. This study demonstrates a simple, but robust method to delineateindividual tree crowns that can be used to develop species-specific crown expansion models. It also shows the importance of developing species specific crown expansion models in different rainfall zones, as some tree species were clearly sensitive to rainfall differences. Using this spatial analysis method, urban forest managers can make informed decisions regarding tree species selection, considering rainfall zone specific environmental growth conditions, as well as space constraints and water availability.

Carbon sequestration in a bamboo plantation: a case study in a Mediterranean area

In the Mediterranean region, despite bamboo being an alien species that can seriously alter plant and animal biocoenosis, the area occupied by bamboo plantations continues to increase, especially for the purpose to sequester carbon (C). However, the C dynamics in the soil–plant system when bamboo is grown outside its native area are poorly understood. Here we investigated the C mitigation potential of the fast-growing Moso bamboo (Phyllostachys edulis) introduced in Italy for climate-change mitigation. We analyzed aboveground (AGB) and belowground (as root/shoot ratio) biomass, litter and soil organic C (SOC) at 0–15- and 15–30-cm depths in a 4-year-old bamboo plantation in comparison with the former annual cropland on which the bamboo was established. To have an idea of the maximum C stored at an ecosystem level, a natural forest adjacent the two sites was also considered. In the plantation, C accumulation as AGB was stimulated, with 14.8 ± 3.1 Mg C ha–1 stored in 3 years; because thinning was done to remove culms from the first year, the mean sequestration rate was 4.9 Mg C ha–1 a–1. The sequestration rates were high but comparable to other fast-growing tree species in Italy (e.g., Pinus nigra). SOC was significantly higher in the bamboo plantation than in the cropland only at the 0–15 cm depth, but SOC stock did not differ. Possibly 4 years were not enough time for a clear increase in SOC, or the high nutrient uptake by bamboos might have depleted the soil nutrients, thus inhibiting the soil organic matter formation by bacteria. In comparison, the natural forest had significantly higher C levels in all the pools. For C dynamics at an ecosystem level, the bamboo plantation on the former annual cropland led to substantial C removal from the atmosphere (about 12 Mg C ha–1 a–1). However, despite the promising C sequestration rates by bamboo, its introduction should be carefully considered due to potential ecological problems caused by this species in overexploited environments such as the Mediterranean area.

Growth and Biomass Models for Three Fast-growing Tree Species under High-density Plantation

Three fast-growing trees, viz., Populus deltoides, Eucalyptus spp. and Casuarina equisetifolia were studied, in high-density plantation at Padilla, Prayagraj, Uttar Pradesh with following treatments viz., T1: Poplar (1×1m), T2: Eucalyptus (1×1m), T3: Casuarina (1×1m), T4: Poplar (1.2×1.2 m), T5: Eucalyptus (1.2×1.2 m), T6: Casuarina (1.2×1.2 m), T7: Poplar (1.5×1.5 m), T8: Eucalyptus (1.5×1.5 m) and T9: Casuarina (1.5×1.5 m). The experiment was established in year July 2021 and data was collected in June 2022. The result indicate the maximum height was recorded in T2: Eucalyptus (1×1 m) 3.81 m followed by T5: Eucalyptus (1.2×1.2 m) 3.78 m, T8: Eucalyptus (1.5×1.5 m) 3.40 m which was at par with each other and minimum in T9: Casuarina (1.5×1.5 m) 2.42 m whereas the maximum girth was found in T4: Poplar (1.2×1.2 m) 6.91 cm followed by T2: Eucalyptus (1×1 m) 6.61 cm, T5: Eucalyptus (1.2×1.2 m) 6.16 cm, T1: Poplar (1×1 m) 5.91 cm which was at par with each other and minimum in T9: Casuarina (1.5×1.5 m) 3.22 cm after one year. Various linear function was attempted to predict biomass based on GBH (G) and Height (H). Prediction accuracy of Height, girth model was slightly better than the height and girth model. Linear model (Y=a + bH + cG), where Y denotes dependent variable (biomass) and H and G denotes independent variable (Height or Girth), performed better (than the remaining tested models) in terms of estimation precision and prediction accuracy. The AGB was maximum was found in T2: Eucalyptus (1×1m) 0.676 kg tree-1 followed by T5: Eucalyptus (1.2×1.2 m) 0.598 kg tree-1 and minimum in T9: Casuarina (1.5×1.5 m) 0.214 kg tree-1. After completion of one year Eucalyptus (1×1 m) showed best growth among all treatments.

Uji Patogenisitas Cendawan Penyebab Penyakit Daun Pada Sengon Di Persemaian Permanen Dramaga Bogor

Sengon (Paraserianthes falcataria (L.) Nielsen) is a fast-growing tree species, and its wood is readily available because it has been widely cultivated in Indonesia. Efforts to propagate sengon plants are carried out through breeding activities in the nursery. The study aimed to identify the fungus that causes leaf disease on sengon plants and calculate the extent and intensity of attacks by the fungus that causes leaf disease on sengon in the Dramaga Bogor Permanent Nursery. This research consisted of pathogenicity test activities, including field observations, Koch's postulates, and the identification of fungal species. The study used a Completely Randomized Factorial Design. The disease symptoms found around 2 months of sengon leaves at the observation site were leaf fall, leaf spot, and leaf blight. The identified fungus that caused leaf fall was Rhizoctonia sp. The fungus that caused leaf spots was Colletotrichum sp., and the fungus that caused leaf blight was Fusarium sp. Fusarium sp. resulted in the highest percentage of attacks, with a disease incidence of 67% and a disease severity of 57%.
 
 Keywords: characteristics, identification, Koch`s postulates, morphology

Growing Eucalypt Outside its Native Range: A Review on Suitability and Beneficial Role

Eucalypt is an industrial short rotation fast growing tree species (SRFGTs), having wide range regarding climatic and edaphic requirements in Indian subcontinent. Eucalyptus camaeldulensis, E. globulus, E. grandis, E. tereticornis and E. citriodora are the widely planted eucalyptus species for different purposes in the country. Oil extracted from E. globulus has medicinal value and used to inhibit the avian influenza virus H11N9, and has wide scope in cosmetics, perfume, food, beverages, phytotherapy and aromatherapy. Oil contain p-coumaric, gallic, gentisic, p-hydroxybenzoic, syringic and vanillic acids and catechol are the responsible for retarding seed germination growth and survival of Parthenium, Solanum lycopersicum, Lactuca sativa and Agrostis stolonifera. Burning of eucalypt leaves used as mosquito repellent and compound 1, 8 cineole of eucalypt oil damage and kills Pediculus humanus capitis and lice. Aqueous solutions extracted from different parts of eucalypt showed nematocidal properties. Maize, wheat, mustard, berseem, potato, lentil are agricultural crops widely grown under eucalypt based agroforestry systems. Wider spacing of eucalypt in block plantations or boundary plantation mostly adopted in the agroforestry systems. Eucalypt sequester carbon 6 – 43 Mg C ha-1 yr-1 under plantations and agroforestry systems. The species has potential to reclaim waterlogged sites and escalate soil health through improving soil physical, chemical and biological properties. In case of economic returns from eucalypt based agroforestry systems, it gives nearly 1.5 B:C ratio.

Morphological and phylogenetic analyses reveal three new species of Fusarium (Hypocreales, Nectriaceae) associated with leaf blight on Cunninghamialanceolata in China.

Chinese fir (Cunninghamialanceolata) is a special fast-growing commercial tree species in China with high economic value. In recent years, leaf blight disease on C.lanceolata has been observed frequently. The diversity of Fusarium species associated with leaf blight on C.lanceolata in China (Fujian, Guangxi, Guizhou, and Hunan provinces) was evaluated using morphological study and molecular multi-locus analyses based on RNA polymerase second largest subunit (RPB2), translation elongation factor 1-alpha (TEF-1α), and RNA polymerase largest subunit (RPB1) genes/region as well as the pairwise homoplasy index tests. A total of five Fusarium species belonging to four Fusarium species complexes were recognized in this study. Two known species including Fusariumconcentricum and F.fujikuroi belonged to the F.fujikuroi species complex, and three new Fusarium species were described, i.e., F.fujianense belonged to the F.lateritium species complex, F.guizhouense belonged to the F.sambucinum species complex, and F.hunanense belonged to the F.solani species complex. To prove Koch's postulates, pathogenicity tests on C.lanceolata revealed a wide variation in pathogenicity and aggressiveness among the species, of which F.hunanense HN33-8-2 caused the most severe symptoms and F.fujianense LC14 led to the least severe symptoms. To our knowledge, this study also represented the first report of F.concentricum, F.fujianense, F.fujikuroi, F.guizhouense, and F.hunanense causing leaf blight on C.lanceolata in China.

Seven new species of Alternaria (Pleosporales, Pleosporaceae) associated with Chinese fir, based on morphological and molecular evidence.

Chinese fir (Cunninghamialanceolata) is a special fast-growing commercial tree species in China and has significant ecological and economic value. However, it experienced damage from leaf blight caused by pathogenic fungi of the genus Alternaria. To determine the diversity of Alternaria species associated with leaf blight of Chinese fir in China, infected leaves were collected from five major cultivation provinces (Fujian, Henan, Hunan, Jiangsu and Shandong provinces). A total of 48 fungal strains of Alternaria were obtained. Comparison of morphology and phylogenetic analyses, based on nine loci (ITS, SSU, LSU, GAPDH, RPB2, TEF1, Alt a1, endoPG and OPA10-2) of the representative isolates as well as the pairwise homoplasy index tests, revealed that the fungal strains belonged to seven undescribed taxa of Alternaria, which are described here and named as Alternariacunninghamiicolasp. nov., A.dongshanqiaoensissp. nov., A.hunanensissp. nov., A.kunyuensissp. nov., А. longqiaoensissp. nov., A.shandongensissp. nov. and A.xinyangensissp. nov. In order to prove Koch's postulates, pathogenicity tests on detached Chinese fir leaves revealed significant pathogenicity amongst these species, of which A.hunanensis is the most pathogenic to Chinese fir. This study represents the first report of A.cunninghamiicola, A.dongshanqiaoensis, A.hunanensis, A.kunyuensis, A.longqiaoensis, A.shandongensis and A.xinyangensis causing leaf blight on Chinese fir. Knowledge obtained in this study enhanced our understanding of Alternaria species causing leaf blight on Chinese fir and was crucial for the disease management and the further studies in the future.

Genome-wide identification of poplar GSTU gene family and its PtrGSTU23 and PtrGSTU40 to improve salt tolerance in poplar

Glutathione S-transferases (GSTs) are abundant proteins encoded by a highly differentiated family of ancient genes. GSTs play an important role in plant cell detoxification and growth and development. However, their precise function in growth and response to abiotic stresses in poplar remains unclear. We have identified 81 GST genes from Populus trichocarpa, which have been categorized into 8 subfamilies. Among these subfamilies, the Tau subfamily stands out as the largest, consisting of 58 members. We isolated two Tau-like Glutathione S-transferases encoding genes, PtrGSTU23 and PtrGSTU40, and investigated the biological functions of these two genes in transgenic poplar to regulate salt tolerance in poplar. Under salt stress, reactive oxygen species (ROS) accumulate in plants, and overexpression of PtrGSTU23/40 in 84 K poplar (Populus alba × Populus glandulosa) could play a crucial role in regulating ROS scavenging by controlling the activity of plant GST enzyme. This regulation of GST enzyme activity enhanced the tolerance of poplar to salt stress. Ultimately, our findings contribute to the availability of genetic resources that can be utilized in the breeding of salt tolerance traits within fast-growing tree species.

IRGWP: An international network of key players for a better understanding and industrial developments in wood protection and preservation

IRGWP: An international network of key players for a better understanding and industrial developments in wood protection and preservation

The Search for Sustainability Amid Displacement: Exploring the Potential of Fast-growing Exotic Tree Species as Fuelwood Alternative for Refugees and Host Communities in Northern Uganda

Uganda hosts Africa’s largest refugee population, exceeding 1.5 million in early 2023. While commended for its progressive refugee policies, which grant freedom of movement and work opportunities, the influx of displaced people since 2015 has strained shared environmental resources, including slow-growing indigenous trees utilized for construction and fuel. Efforts to preserve indigenous biodiversity have promoted the growth and use of faster-growing exotic tree species. However, local communities often favor indigenous trees as fuel sources, despite limited evidence supporting their superiority. This study assessed fuel properties of selected indigenous and exotic tree species in Lamwo District, Northern Uganda. Laboratory analysis of wood samples revealed no significant differences in moisture content, fixed carbon, volatile matter, or Fuel Value Index (FVI) among the species. The study therefore recommends promoting fast-growing exotic species like Eucalyptus grandis, Caliandra calothyrsus, and Senna siamea, urging international agencies, NGOs, and community-led organizations to leverage the findings for behavior change campaigns. This approach would facilitate species regeneration, alleviate pressure on natural forests, and supplement Uganda’s investment strategy in Modern Energy Cooking Services (MECS) such as LPG and solar e-cooking technologies.

Spatiotemporal Dynamics of Betula pendula Crown Cover on Abandoned Arable Land in a Broad-Leaved Forest Zone of Bashkir Cis-Ural

Silver birch (Betula pendula Roth) is one of the fast-growing tree species that often colonize abandoned agricultural lands in Europe and the European part of Russia. The purpose of this article is to analyze the spatiotemporal dynamics of Betula pendula crown cover on abandoned arable lands in a zone of broad-leaved forests of the Bashkir Cis-Ural (Russia, Republic of Bashkortostan). The assessment of current and retrospective values of crown cover was carried out using a regression model of the dependence of crown cover on the values of red channel brightness in early-spring images from Landsat 5–8 and Sentinel-2 satellites from 2012–2022. To estimate the number and height of trees, a survey was carried out using a LiDAR camera mounted on a UAV. After calculating the crown cover in grid squares and their distance from the seed source in QGIS, variance analysis was carried out to assess the influence of the factor of distance from the seed source on the crown cover. The influence of the factor of distance from the seed source on the crown cover was higher at earlier stages of overgrowth of abandoned agricultural lands. An exception to this dependence was only one sample plot where the prevailing wind direction was opposite to the direction of seed dispersal. The leading factors affecting the distribution of birch on abandoned agricultural lands were wind direction, height of seed trees, and grazing. In the parts of the sample plots that were furthest away from seed sources, the trees were 1–3 years younger or the same age, and stand density was lower than in sites located closer to the seed trees. In general, the results of the present study indicate two opposite relationships between seedling survival and distance to seed trees: (1) seed fall and seedling density decrease with increasing distance from the seed tree, and (2) the probability of seed/seedling survival increases due to decreased competition.

Comparative Transcriptome Sequencing and Endogenous Phytohormone Content of Annual Grafted Branches of Zelkova schneideriana and Its Dwarf Variety HenTianGao

Zelkova schneideriana is a fast-growing tree species endemic to China. Recent surveys and reports have highlighted a continued decline in its natural populations; therefore, it is included in the Red List of Threatened Species by The International Union for Conservation of Nature. A new variety “HenTianGao” (H) has been developed with smaller plant height, slow growth, and lower branching points. In this study, we attempted to understand the differences in plant height of Z. schneideriana (J) and its dwarf variety H. We determined the endogenous hormone content in the annual grafted branches of both J and H. J exhibited higher gibberellic acid (GA)-19 and trans-Zeatin (tZ) levels, whereas H had higher levels of indole-3-acetic acid (IAA) catabolite 2-oxindole-3-acetic acid (OxIAA), IAA-Glu conjugate, and jasmonic acid (JA) (and its conjugate JA-Ile). The transcriptome comparison showed differential regulation of 20,944 genes enriched in growth and development, signaling, and metabolism-related pathways. The results show that the differential phytohormone level (IAA, JA, tZ, and GA) was consistent with the expression of the genes associated with their biosynthesis. The differences in relative OxIAA, IAA-Glu, GA19, trans-Zeatin, JA, and JA-Ile levels were linked to changes in respective signaling-related genes. We also observed significant differences in the expression of cell size, number, proliferation, cell wall biosynthesis, and remodeling-related genes in J and H. The differences in relative endogenous hormone levels, expression of biosynthesis, and signaling genes provide a theoretical basis for understanding the plant height differences in Z. schneideriana.

Evaluation of Gmelina Arborea (Roxb) Germplasm for Qualitative Traits and Insect Pest Resistance in Natural and Planted Population Populations of Madhya Pradesh, India

Gmelina arborea Roxb., a fast-growing tree species native to tropical and subtropical regions of Asia, has garnered attention for its potential in wood-based industries. However, its large-scale plantation in Madhya Pradesh, India, faces significant challenges. This study investigates the prevalent diseases and pests, bole form and branching habit of Gmelina arborea among different populations in Madhya Pradesh. Eextensive field surveys were carried out to identify the natural and planted populations of Gmelina arborea. Based on these surveys three natural populations viz Betul, Mandla and Jabalpur Population and five planted populations Sonaghati, Badhaura, Saraswahi, Neemkheda and Barha were selected for the present investigation. Observations of the bole form of trees was recorded visually as Crooked, less crooked, nearly straight, straight. Branch angle was visually observed and observation is recorded 300, 450, 600 and 900. Disease and pest incidence was visually assessed and intensity of the observations are recorded as Heavy infection, Moderate infection, Low infestation, A healthy tree with no attack. Considerable variation among the qualitative traits was observed among population under study. most straight and nearly straight trees found in planted population than natural populations. 900 and 600 branch angles were observed more in plantation than natural populations. More no of healthy tree and tree with low infestation was observed in plantation. Agroclimatic zones of Satpura plateau performs better for bole form. Kymore plateau and Satpura hills agroclimatic zones performs well in case of branching angle and health status. Northen hill zones of Chhattisgarh underperforms as far as qualitative traits are concerned.

Performance of particleboard from fast-growing species

Kelempayan (Neolamarckia cadamba) is a fast-growing tree species that can be cultivated in Malaysia. This species has potential as an alternative resource for the Malaysian furniture and panel board industries in the coming years because of a shortage of the current frequently used raw material (rubberwood). A study on potential as particleboard was done. In accordance with Malaysian Standards (MS), this study examined MOE, MOR, IB, and thickness swelling of particleboard with particle sizes of 0.5 and 1.0 mm, densities of 600 and 700 kgm−3, resin contents of 9 and 11 %, and hot press temperatures of 155 and 165 °C. Boards from 0.5 mm particle size, 700 kgm−3 density, and 11 % resin content at 165 °C hot press temperature had the greatest mechanical performance. The boards constructed from particle size 0.5 mm with the density 600 kgm−3 presence 9 % resin and pressed using 155 °C hot press temperature showed the least amount of thickness swelling. The boards complied with the standard requirements. In general, kelempayan wood is a potential raw material for the manufacture of wood composites.

The chromosome-level genome assembly of Fraxinus americana provides insights into the evolution of Oleaceae plants

White ash (Fraxinus americana linn.) originates from the southeastern United States. It is a tall and fast-growing tree species with strong salt-alkali resistance and cold tolerance, making it an important reforestation species and widely planted worldwide. Here, we completed the chromosome-level reference genome assembly of F. americana based on Illumina, PacBio, and Hi-C reads, with a genome size of 878.98 Mb, an N50 of 3.27 Mb, and a heterozygosity rate of 0.3 %. Based on de novo prediction, transcriptome prediction, and homology-based protein prediction, we obtained 39,538 genes. Approximately 843.21 Mb of the assembly genome was composed of 37,928 annotated protein-coding genes, with a gene function annotation rate of 95.93 %. 99.94 % of the overlap clusters (877.44 Mb) were anchored to 23 chromosomes. Synteny analysis of F. americana and other Oleaceae plants showed that F. americana underwent frequent chromosome rearrangements. The amplification of the Ale transposons effectively promoted the genome size of F. americana. Compared with other Oleaceae plants, the Glutathione S-transferase (GST) gene family in the F. americana genome has undergone significant expansion, which may help F. americana cope with adverse natural environments. Furthermore, we found that key enzyme-coding gene families related to lignin biosynthesis were expanded and highly expressed in F. americana leaves. These key genes drive lignin synthesis and benefit F. americana in fast-growing, as well as resisting biotic and abiotic stress. Overall, the F. americana genome assembly provides insights into the evolution of Oleaceae plants and provides abundant resources for breeding and germplasm conservation of white ash.

Leaf morpho-physiological traits of Populus sibirica and Ulmus pumila in different irrigation regimes and fertilizer types.

The impacts of climate change, such as increased soil dryness and nutrient deficiency, highlight the need for environmentally sustainable restoration of forests and groundwater resources. However, it is important to consider that extensive afforestation efforts may lead to a depletion of groundwater supply due to higher evapotranspiration rates, exacerbating water scarcity issues. Consequently, we conducted a study to examine how the fast-growing tree species Populus sibirica (Horth ex Tausch) and Ulmus pumila (L.) respond morpho-physiologically to varying watering regimes and types of fertilizers, aiming to better understand their specific water and nutrient requirements. We used two-year-old nursery-growth seedlings (N=512) of P.sibirica and U. pumila with initial root collar diameter (RCD) and the height of 0.51±0.02mm and 68±2.94 cm and 0.33±0.01mm and 51±1.14 cm, respectively. The leaf area (LA), specific leaf area (SLA), chlorophyll concentration, stomatal conductance (gs), chlorophyll fluorescence, and predawn and midday leaf water potential were measured across treatments. Four different irrigation regimes and two different fertilizer types were applied: no irrigation (control, 0 L h-1), 2 L h-1 = 0.25 mm m-2, 4L h-1 = 0.5mm m-2, 8 L h-1 = 1.0 mm m-2 and 120 g and 500 g tree-1 of NPK and compost (COMP). Twelve plots (600 m2) were established in the study site for each species and treatments. During the first growing season (2021), the LA of P. sibirica was larger in the 4-8 L h-1 without fertilizer, but it was smaller in the 4 L h-1+ COMP during the second growing season (2022). The 2 L h-1 without fertilizer and 2 L h-1 + NPK had larger LA compared with the control (CONT) for the first and second growing seasons, respectively, for U. pumila. P. sibirica seedlings at 4 L h-1 without fertilizer had the highest SLA for 2021 and at 2 L h-1 + NPK for 2022, whereas CONT and 4 L h-1 had the highest SLA than the other treatments for 2021 and 2022 growing seasons, respectively, for U. pumila. The chlorophyll concentration of P. sibirica seedlings in the first year was generally higher in CONT, while the 2 L h-1 without any fertilizer yielded a significantly higher chlorophyll concentration of U. pumila. Chlorophyll fluorescence parameters (PIABS and Fm) were generally lower in CONT with/without NPK or COMP for both species. The CONT with NPK/COMP generally had a higher gs compared with the other treatments in both experimental periods for U. pumila, whereas CONT and 2 L h-1+ NPK-treated P. sibirica seedlings had a significantly greater gs during the first year and second year, respectively. The predawn and midday leaf water potentials of both species were generally the lowest in CONT, followed by 2 L h-1+ NPK/COMP during the first growing season, but a different pattern was observed during the second growing season. Overall, the morpho-physiological traits of the two species were affected by watering and fertilizer treatments, and the magnitude of the effects varied depending on growing season, amount of irrigation, and fertilizer type, and their interactions.

The miRNA-mRNA Regulatory Modules of Pinus massoniana Lamb. in Response to Drought Stress.

Masson pine (Pinus massoniana Lamb.) is a major fast-growing woody tree species and pioneer species for afforestation in barren sites in southern China. However, the regulatory mechanism of gene expression in P. massoniana under drought remains unclear. To uncover candidate microRNAs, their expression profiles, and microRNA-mRNA interactions, small RNA-seq was used to investigate the transcriptome from seedling roots under drought and rewatering in P. massoniana. A total of 421 plant microRNAs were identified. Pairwise differential expression analysis between treatment and control groups unveiled 134, 156, and 96 differential expressed microRNAs at three stages. These constitute 248 unique microRNAs, which were subsequently categorized into six clusters based on their expression profiles. Degradome sequencing revealed that these 248 differentially expressed microRNAs targeted 2069 genes. Gene Ontology enrichment analysis suggested that these target genes were related to translational and posttranslational regulation, cell wall modification, and reactive oxygen species scavenging. miRNAs such as miR482, miR398, miR11571, miR396, miR166, miRN88, and miRN74, along with their target genes annotated as F-box/kelch-repeat protein, 60S ribosomal protein, copper-zinc superoxide dismutase, luminal-binding protein, S-adenosylmethionine synthase, and Early Responsive to Dehydration Stress may play critical roles in drought response. This study provides insights into microRNA responsive to drought and rewatering in Masson pine and advances the understanding of drought tolerance mechanisms in Pinus.

Individual Tree Aboveground Biomass Estimation Based on UAV Stereo Images in a Eucalyptus Plantation

As one of the three fastest-growing tree species in the world, eucalyptus grows rapidly, with a monthly growth rate of up to 1 m and a maximum annual growth rate of up to 10 m. Therefore, ways to accurately and quickly obtain the aboveground biomass (AGB) of eucalyptus in different growth stages at a low cost are the foundation of achieving eucalyptus growth-change monitoring and precise management. Although Light Detection and Ranging (LiDAR) can achieve high-accuracy estimations of individual eucalyptus tree biomasses, the cost of data acquisition is relatively high. While the AGB estimation accuracy of high-resolution images may be affected by a lack of forest vertical structural information, stereo images obtained using unmanned aerial vehicles (UAVs) can not only provide horizontal structural information but also vertical structural information through derived point data, demonstrating strong application potential in estimating the biomass of eucalyptus plantations. To explore the potential of UAV stereo images for estimating the AGB of individual eucalyptus trees and further investigate the impact of stereo-image-derived features on the construction of biomass models, in this study, UAVs equipped with consumer-grade cameras were used to obtain multitemporal stereo images. Different features, such as spectral features, texture, tree height, and crown area, were extracted to estimate the AGB of individual eucalyptus trees of five different ages with three algorithms. The different features extracted based on the UAV images had different effects on estimating AGB in individual eucalyptus trees. By estimating eucalyptus AGB using only spectrum features, we found that tree height had the greatest impact, with its R2 value increasing by 0.28, followed by forest age. Other features, such as spectrum, texture, and crown area, had relatively small effects. For the three algorithms, the estimation accuracy of the CatBoost algorithm was the highest, with an R2 ranging from 0.65 to 0.90, and the normalized root-mean-square error (NRMSE) ranged from 0.08 to 0.15. This was followed by the random forest algorithm. The ridge regression algorithm had the lowest accuracy, with an R2 ranging from 0.34 to 0.82 and an NRMSE value ranging from 0.11 to 0.21. The AGB model that we established with forest age, TH, crown area, and HOM-B feature variables using the CatBoost algorithm had the best estimation accuracy, with an R2 of 0.90 and an NRMSE of 0.08. The results indicated that accurately estimating the AGB of individual eucalyptus trees can be achieved based on stereo images obtained using UAVs equipped with affordable, consumer-grade cameras. This paper can provide methodological references and technical support for estimating forest biomass, carbon storage, and other structural parameters based on UAV images.

Wood-density has no effect on stomatal control of leaf-level water use efficiency in an Amazonian forest.

Forest disturbances increase the proportion of fast-growing tree species compared to slow-growing ones. To understand their relative capacity for carbon uptake and their vulnerability to climate change, and to represent those differences in Earth system models, it is necessary to characterise the physiological differences in their leaf-level control of water use efficiency and carbon assimilation. We used wood density as a proxy for the fast-slow growth spectrum and tested the assumption that trees with a low wood density (LWD) have a lower water-use efficiency than trees with a high wood density (HWD). We selected 5 LWD tree species and 5 HWD tree species growing in the same location in an Amazonian tropical forest and measured in situ steady-state gas exchange on top-of-canopy leaves with parallel sampling and measurement of leaf mass area and leaf nitrogen content. We found that LWD species invested more nitrogen in photosynthetic capacity than HWD species, had higher photosynthetic rates and higher stomatal conductance. However, contrary to expectations, we showed that the stomatal control of the balance between transpiration and carbon assimilation was similar in LWD and HWD species and that they had the same dark respiration rates.

Using camera traps to inform reintroduction success and recovery of the Northern Aplomado Falcon (Falco femoralis septentrionalis)

Anthropogenic disturbances, including habitat changes, climate change, and pesticides, contribute significantly to species declines and extinctions worldwide. These disturbances also hinder conservation efforts like species reintroductions by creating novel ecosystems that no longer support the species that is being reintroduced. Using camera traps, we observed Great Horned Owls (Bubo virginianus), which are a dominant avian predator, perching on the nests of Northern Aplomado Falcons (Falco femoralis septentrionalis), a federally endangered species reintroduced to coastal Texas with a current breeding population of 23 pairs. The presence of Great Horned Owls on five of the twenty cameras placed on Northern Aplomado Falcon nest structures led us to consider the impact this interaction may have on occupancy and productivity of the nests. Throughout the study system, fast-growing tree and shrub species have become more prominent, which could be facilitating the interaction. We hypothesize that encroachment of woody vegetation is drawing Great Horned Owls into the open coastal grassland habitat of Northern Aplomado Falcons, which may limit the occupancy and productivity of falcon nests. Based on this hypothesis from the camera trap observations and anecdotal evidence of habitat encroachment, quantifying this relationship is a key next step in the recovery process. This will enable us to define priority areas for targeted restoration to push back woody vegetation, as well as areas best suited to release Northern Aplomado Falcons that will minimize the likelihood of predation by Great Horned Owls.