We performed a meta-analysis on over 100 studies applying remote sensing (RS) and geographic information systems (GIS) to understand treeline dynamics. A literature search was performed in multiple online databases, including Web of Knowledge (Thomson Reuters), Scopus (Elsevier), BASE (Bielefeld Academic Search Engine), CAB Direct, and Google Scholar using treeline-related queries. We found that RS and GIS use has steadily increased in treeline studies since 2000. Spatial-resolution RS and satellite imaging techniques varied from low-resolution MODIS, moderate-resolution Landsat, to high-resolution WorldView and aerial orthophotos. Most papers published in the 1990s used low to moderate resolution sensors such as Landsat Multispectral Scanner and Thematic Mapper, or SPOT PAN (Panchromatic) and MX (Multispectral) RS images. Subsequently, we observed a rise in high-resolution satellite sensors such as ALOS, GeoEye, IKONOS, and WorldView for mapping current and potential treelines. Furthermore, we noticed a shift in emphasis of treeline studies over time: earlier reports focused on mapping treeline positions, whereas RS and GIS are now used to determine the factors that control treeline variation.
RNA-seq and single-cell genomic research emerge as an important research area in the recent years due to its ability to examine genetic information of any number of single cells in all living organisms. The knowledge gained from RNA-seq and single-cell genomic research will have a great impact in many aspects of plant biology. In this review, we summary and discuss the biological significance of RNA-seq and single-cell genomic research in plants including the single-cell DNA-sequencing, RNA-seq and single-cell RNA sequencing in woody plants, methods of RNA-seq and single-cell RNA-sequencing, single-cell RNA-sequencing for studying plant development, and single-cell RNA-sequencing for elucidating cell type composition. We will focus on RNA-seq and single-cell RNA sequencing in woody plants, understanding of plant development through single-cell RNA-sequencing, and elucidation of cell type composition via single-cell RNA-sequencing. Information presented in this review will be helpful to increase our understanding of plant genomic research in a way with the power of plant single-cell RNA-sequencing analysis.
Root/shoot (R/S) ratio is an important index for assessing plant health, and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents. The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession, where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients. We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress, typical of hormesis. The R/S ratio in response to stress has been widely compared among species and ecological succession classes. It is constrained by a variety of factors such as ontogeny. Furthermore, the current literature lacks dose–response studies incorporating the full dose–response continuum, hence limiting scientific understanding and possible valuable application. The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations. Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions.
Raster type of forest inventory data with site and growing stock variables interpreted for small square-shaped grid cells are increasingly available for forest planning. In Finland, there are two sources of this type of lattice data: the multisource national forest inventory and the inventory that is based on airborne laser scanning (ALS). In both cases, stand variables are interpreted for 16 m × 16 m cells. Both data sources cover all private forests of Finland and are freely available for forest planning. This study analyzed different ways to use the ALS raster data in forest planning. The analyses were conducted for a grid of 375 × 375 cells (140,625 cells, of which 97,893 were productive forest). The basic alternatives were to use the cells as calculation units throughout the planning process, or aggregate the cells into segments before planning calculations. The use of cells made it necessary to use spatial optimization to aggregate cuttings and other treatments into blocks that were large enough for the practical implementation of the plan. In addition, allowing premature cuttings in a part of the cells was a prerequisite for compact treatment areas. The use of segments led to 5–9% higher growth predictions than calculations based on cells. In addition, the areas of the most common fertility classes were overestimated and the areas of rare site classes were underestimated when segments were used. The shape of the treatment blocks was more irregular in cell-based planning. Using cells as calculation units instead of segments led to 20 times longer computing time of the whole planning process than the use of segments when the number of grid cells was approximately 100,000.
The stand density index, one of the most important metrics for managing site occupancy, is generally calculated from empirical data by means of a coefficient derived from the “self-thinning rule” or stand density model. I undertook an exploratory analysis of model fitting based on simulated data. I discuss the use of the logarithmic transformation (i.e., linearisation) of the relationship between the total number of trees per hectare (N) and the quadratic mean diameter of the stand (QMD). I compare the classic method used by Reineke (J Agric Res 46:627–638,
Numerous studies have shown that intact tropical forests account for half of the total terrestrial sink for anthropogenic carbon dioxide. Here, we analyzed and compared changes in three main tropical forest regions from 2000 to 2014, based on time-series analysis and landscape metrics derived from moderate-resolution imaging spectroradiometer data. We examined spatial-pattern changes in percentage of tree cover and net primary production (NPP) for three tropical forest regions—Amazon basin, Congo basin, and Southeast Asia. The results show that: the Amazon basin region had the largest tropical forest area and total NPP and a better continuity of TC distribution; the Southeast Asia region exhibited a sharp decrease in NPP and had comparatively separate spatial patterns of both TC and NPP; and the Congo basin region exhibited a dramatic increase in NPP and had better aggregation of forest NPP distribution. Results also show that aggregative patterns likely correlate with high NPP values.
Allometric equations are important for quantifying biomass and carbon storage in terrestrial forest ecosystems. However, equations for dry deciduous woodland ecosystems, an important carbon sink in the lowland areas of Ethiopia have not as yet been developed. This study attempts to develop and evaluate species-specific allometric equations for predicting aboveground biomass (AGB) of dominant woody species based on data from destructive sampling for Combretum collinum, Combretum molle, Combretum harotomannianum, Terminalia laxiflora and mixed-species. Diameter at breast height ranged from 5 to 30 cm. Two empirical equations were developed using DBH (Eq.
In selectively logged forests, trees are more likely to expand their diameters (D) at the expense of height (H) growth, resulting in variations in H:D relationships. This study examines how selective logging affects the H:D allometric relationships of five common tree species and whether the effects vary with functional groups (shade-intolerant or shade tolerant) in seasonal semi-deciduous forests. Individuals of five species in a 3000 m2 (0.3 ha) plot were marked and heights and diameters recorded. Most of the species, with one exception, showed greater investment in diameter per increment of height compared to an unlogged forest, possibly because of the greater light available. This study shows the effects of selective logging on species populations as evidenced by increases in H:D ratios. Comparison of forest fragments with different degrees of human impact is important because it allows us to understand the differences in architectural characteristics caused by selective logging.
Artificial neural network models are a popular estimation tool for fitting nonlinear relationships because they require no assumptions about the form of the fitting function, non-Gaussian distributions, multicollinearity, outliers and noise in the data. The problems of back-propagation models using artificial neural networks include determination of the structure of the network and over-learning courses. According to data from 1981 to 2008 from 15 permanent sample plots on Dagangshan Mountain in Jiangxi Province, a back-propagation artificial neural network model (BPANN) and a support vector machine model (SVM) for basal area of Chinese fir (Cunninghamia lanceolata) plantations were constructed using four kinds of prediction factors, including stand age, site index, surviving stem numbers and quadratic mean diameters. Artificial intelligence methods, especially SVM, could be effective in describing stand basal area growth of Chinese fir under different growth conditions with higher simulation precision than traditional regression models. SVM and the Chapman–Richards nonlinear mixed-effects model had less systematic bias than the BPANN.
Continuously growing populations and rapid economic development have led to the excessive use of forest resources, and the forest ecosystem is threatened. In response, forest ecological security (FES) has attracted attention. In this study, an integrated dynamic simulation model was constructed using the system dynamic method, and it was used to evaluate the FES in China from 1999 to 2014. A scenario analysis was then used to evaluate the changes in the FES under five forestry policy scenarios for the 2015–2050 period, including the baseline, afforestation policy, harvesting policies, management policy, investment policy, and a policy mix. The results showed that the evaluation values of the FES increased during the period from 1999 to 2002, the period from 2004 to 2010 and the year 2014, and they decreased in 2003 and during the period from 2011 to 2013. During the 2015–2050 simulation period, the FES improved continuously. In particular, China would enter a new stage when the economic systems, social systems and ecosystems were in harmony after 2040. To improve the FES and the current status of the FES, a scenario analysis showed the most suitable scenario to be Scenario 5 from 2015 to 2020 and Scenario 2 from 2021 to 2050. To relieve pressure, the most suitable scenario would be Scenario 5 from 2015 to 2040 and from 2046 to 2050, and the most suitable scenario would be Scenario 4 for 2041–2045. A policy mix (Scenario 5) would be most efficient under current conditions, while the effects of all the benefits of the forestry policies would weaken over the long term. The integrated method can be regarded as a decision support tool to help policy makers understand FES and promulgate a reasonable forestry policy.
Canadian boreal mixedwood forests are extensive, with large potential for carbon sequestration and storage; thus, knowledge of their carbon stocks at different stand ages is needed to adapt forest management practices to help meet climate-change mitigation goals. Carbon stocks were quantified at three Ontario boreal mixedwood sites. A harvested stand, a juvenile stand replanted with spruce seedlings and a mature stand had total carbon stocks (± SE) of 133 ± 13 at age 2, 130 ± 13 at age 25, and 207 ± 15 Mg C ha−1 at age 81 years. At the clear-cut site, stocks were reduced by about 40% or 90 Mg C ha−1 at harvest. Vegetation held 27, 34 and 62% of stocks, while detritus held 34, 29 and 13% of stocks at age 2, 25 and 81, respectively. Mineral soil carbon stocks averaged 51 Mg C ha−1, and held 38, 37 and 25% of stocks. Aboveground net primary productivity (± SE) in the harvested and juvenile stand was 2.1 ± 0.2 and 3.7 ± 0.3 Mg C ha−1 per annum (p.a.), compared to 2.6 ± 2.5 Mg C ha−1 p.a. in the mature stand. The mature canopies studied had typical boreal mixedwood composition and mean carbon densities of 208 Mg C ha−1, which is above average for managed Canadian boreal forest ecosystems. A comparison of published results from Canadian boreal forest ecosystems showed that carbon stocks in mixedwood stands are typically higher than coniferous stands at all ages, which was also true for stocks in vegetation and detritus. Also, aboveground net primary productivity was typically found to be higher in mixedwood than in coniferous boreal forest stands over a range of ages. Measurements from this study, together with those published from the other boreal forest stands demonstrate the potential for enhanced carbon sequestration through modified forest management practices to take advantage of Canadian boreal mixedwood stand characteristics.
Forest disturbance and recovery are critical ecosystem processes, but the temporal patterns of disturbance have not been studied in subtropical China. Using a tree-ring analysis approach, we studied post-logging above-ground (ABG) biomass recovery dynamics over a 26-year period in four plots with different degrees of logging disturbance. Before logging, the ABG biomass ranged from 291 to 309 t ha−1. Soon after logging, the plots in primary forest, secondary forest, mixed forest and single-species forest had lost 33, 91, 90 and 100% of their initial ABG biomass, respectively. Twenty-six years after logging, the plots had regained 147, 62, 80 and 92% of their original ABG biomass, respectively. Over the 26 years following logging, the mean C AI (Current annual increment) were 10.1, 5.5, 6.4 and 10.8 t ha−1 a−1 and the average M AI (Mean annual increment) 8.7, 2.5, 5.6 and 7.8 t ha−1 a−1 for the four forest types, respectively. The results indicate that subtropical forests subjected to moderate logging or disturbances do not require intensive management and single-species plantings can rapidly restore the above-ground biomass to levels prior to heavy logging.
Southwest China is one of three major forest regions in China and plays an important role in carbon sequestration. Accurate estimations of changes in aboveground biomass are critical for understanding forest carbon cycling and promoting climate change mitigation. Southwest China is characterized by complex topographic features and forest canopy structures, complicating methods for mapping aboveground biomass and its dynamics. The integration of continuous Landsat images and national forest inventory data provides an alternative approach to develop a long-term monitoring program of forest aboveground biomass dynamics. This study explores the development of a methodological framework using historical national forest inventory plot data and Landsat TM time-series images. This method was formulated by comparing two parametric methods: Linear Regression for Multiple Independent Variables (MLR), and Partial Least Square Regression (PLSR); and two nonparametric methods: Random Forest (RF) and Gradient Boost Regression Tree (GBRT) based on the state of forest aboveground biomass and change models. The methodological framework mapped Pinus densata aboveground biomass and its changes over time in Shangri-la, Yunnan, China. Landsat images and national forest inventory data were acquired for 1987, 1992, 1997, 2002 and 2007. The results show that: (1) correlation and homogeneity texture measures were able to characterize forest canopy structures, aboveground biomass and its dynamics; (2) GBRT and RF predicted Pinus densata aboveground biomass and its changes better than PLSR and MLR; (3) GBRT was the most reliable approach in the estimation of aboveground biomass and its changes; and, (4) the aboveground biomass change models showed a promising improvement of prediction accuracy. This study indicates that the combination of GBRT state and change models developed using temporal Landsat and national forest inventory data provides the potential for developing a methodological framework for the long-term mapping and monitoring program of forest aboveground biomass and its changes in Southwest China.
The impact of nitrogen (N) deposition on dissolved organic carbon (DOC) fractions in throughfall is not well understood. We performed a laboratory experiment and compared DOC leaching from canopy leaves after dipping leaves in pure water (control) and NH4NO3 solution (N-treatment) for 18 h. Net changes of DOC, NH4 +, NO3 −, SO4 2−, K+, Mg2+, Ca2+ and H+ contents after dipping leaves were determined by comparing solutions with and without leaves. We recorded no differences of DOC leaching between control and N-treatment, implying that N deposition had minor impacts on canopy DOC production. This confirmed that previous experiments testing the effects of N addition on DOC dynamics without considering the effects of the canopy reaction successfully described the real situation. We also confirmed the previously-reported canopy exchange process in spite of a high background N deposition at our study site. N-treatment significantly increased base cation leaching, especially K+, and the increase was positively correlated with foliar NH4 + retention. Net leaching of H+ and SO4 2− was not affected by the N-treatment.
Understanding physiological responses and drought adaptation strategies of woody plant leaf traits in sub-humid to semi-arid regions is of vital importance to understand the interplay between ecological processes and plant resource-allocation strategies of different tree species. Seasonal variations of leaf morphological traits, stoichiometric traits and their relationships of two drought tolerant woody species, live oak (Quercus virginiana) and honey mesquite (Prosopis glandulosa) and two less drought tolerant species, sugarberry (Celtis laevigata) and white ash (Fraxinus americana) were analyzed in a sub-humid to semi-arid area of south Texas, USA. Our findings demonstrate that for the two drought tolerant species, the leguminous P. glandulosa had the highest specific leaf area, leaf N, P, and lowest leaf area and dry mass, indicating that P. glandulosa adapts to an arid habitat by decreasing leaf area, thus reducing water loss, reflecting a resource acquisition strategy. While the evergreen species Q. virginiana exhibited higher leaf dry mass, leaf dry matter content, C content, C:N, C:P and N:P ratios, adapts to an arid habitat through increased leaf thickness and thus reduced water loss, reflecting a resource conservation strategy in south Texas. For the two less drought tolerant deciduous species, the variations of leaf traits in C. laevigata and F. americana varied between Q. virginiana and P. glandulosa, reflecting a trade-off between rapid plant growth and nutrient maintenance in a semi-arid environment.
In this study, 10 bacterial strains were isolated from the rhizosphere of coniferous trees on Mount Tláloc in Mexico. The strains were characterized by their capacity to produce auxins, solubilize phosphates and stimulate mycelial growth of the ectomycorrhizal fungus Suillus sp. All isolates were identified at the molecular level. Moreover, an experiment was established to evaluate the response of Pinus pseudostrobus seedlings to inoculation with the rhizobacteria strains. The isolated strains belonged to the species Cupriavidus basilensis, Rhodococcus qingshengii, R. erythropolis, Pseudomonas spp., P. gessardii, Stenotrophomonas rhizophila and Cohnella sp. All of the strains produced auxins; the best producer was R. erythropolis CPT9 (76.4 µg mL−1). P. gessardii CPT6 solubilized phosphate at a significant level (443 µg mL−1). The strain S. rhizophila CPT8 significantly increased the radial growth of the ectomycorrhizal fungus Suillus sp. by 18.8%. Five strains increased the dry mass of the shoots; R. qingshengii CPT4 and R. erythropolis CPT9 increased growth the most, by more than 20%. Inoculation with plant-growth-promoting rhizobacteria can be a very useful practice in a forest nursery to produce healthy, vigorous plants.
In this paper, the ultrasonic-assisted extraction process of flavonoid compounds from leaves of Amorpha fruticosa is optimized. In single factor experiments, solid/liquid ratios, ultrasonic power, ethanol concentrations and extraction cycles were experimental factors. Box–Behnken central composite design and RSM analyzed the effects of the four factors on the yield of total flavonoids. The optimal extraction parameters were solid/liquid ratio 1:50 g/mL, ultrasonic power 316 W, ethanol concentration 50%, 4 extraction cycles. In the optimized condition, the estimated value of the regression model was 66.6456 mg/g while the measured value was 66.4329 mg/g.
Total phenols, flavonoids, procyanidins, and total antioxidant capacity, measured with ferric reducing antioxidant power, radical scavenging capacity, and oxygen radical absorption capacity assays were first evaluated in the extracts of the shells, skins and kernels of 10 varieties of Pinus koraiensis. Results indicate that these varieties had strong radical scavenging capacities, ferric reducing antioxidant power and oxygen radical absorption capacities. Phenolic, flavonoid and procyanidin values ranged from 138.6 (#3 kernel) to 518.6 (#10 shell) mg GAE/g, from 23.3 (#2 kernel) to 70.8 (#5 skin) mg RE/g, from 2.5 (#2 kernel) to 142.1 (#7 skin) mg CE/g, respectively. Radical scavenging capacity and ferric reducing antioxidant power values were positively correlated to the polyphenol contents which play a major role in antioxidant properties. The varieties may be divided into two groups by cluster analysis and the variables being measured. These results will be useful for breeding varieties and guiding their production.
Intraspecific variability in morphological and ecophysiological leaf traits might be theorized to be present in declining populations, since they seem to be exposed to stress and plasticity could be advantageous. Here we focused on declining Persian oaks (Quercus brantii Lindl. var. persica (Jaub and Spach) Zohary) in the Zagros Mountains of western Iran, representing the most important tree species of this region. We selected trees with contrasting crown dieback, from healthy to severely defoliated, to investigate the relationships between canopy dieback and leaf morphology, water content and pigments. We also measured esterase and peroxidase, as enzymatic antioxidants and indicators of contrasting genotypes. Trees showing moderate to severe defoliation showed higher leaf mass area (LMA), reduced relative water content (RWC), and lower stomatal density (SD). Increasing LMA indicates a more sclerophyllic structure, according to drier conditions. We did not find significant differences in leaf pigments (chlorophyll a and b, and carotenoids) among crown dieback classes, suggesting that Persian oak trees are able to maintain accurate photochemical efficiency, while reduced RWC and SD suggest hydraulic limitations. Our results do not provide a consistent pattern as regards enzymatic antioxidant defense in Persian oak. Morphological leaf traits would be important drivers of future adaptive evolution in Persian oak, leading to smaller and thicker leaves, which have fitness benefits in dry environments. Nonetheless, drought responses may be critically affecting carbon uptake, as photosynthetic compounds are less effectively used in leaves with higher sclerophylly.
Yerba mate (Ilex paraguariensis A. St.-Hil.) is a species of great economic, social and environmental importance for the southern regions of Brazil, Uruguay and Argentina. Currently the most diverse products are obtained from mate leaves, including mate tea. The objective of this study was to establish shoot meristem cultures (meristematic dome and a few primordia) of elite clones and identify the endophytic bacteria present in the explants. We tested the effect of clones (F1, F2, A03 and A07), culture media (MS, 1/2MS, 1/4MS and WPM), cytokinins (kinetin, BA and 2iP), activated charcoal (1, 2 and 3 g L−1), and disinfecting agent (sodium hypochlorite and mercuric chloride) on in vitro establishment. F1 and F2 clones were the most responsive for shoot meristem in vitro culture. WPM medium supplemented with 8.8 µM 2iP, 0.2 µM NAA and 3 g L−1 activated charcoal was the most suitable for the in vitro establishment of the F1 clone. No phytotoxic effect of the disinfectant was observed and some meristems sprouted. The isolated endophytic bacterium was identified for the first time in yerba mate as Agrobacterium larrymoorei. To conclude, we were able to establish in vitro culture of yerba mate using meristems as explants but the tissues were not free of endophytic microorganisms which could interfere with explant response.
The exploitation of agro-industrial wastes is a strategy to add value to seedling production and reduce environmental problems. The production chain for processed peaches generates, approximately, 21,000 tons of fruit worldwide, and the pits are used mainly to generate energy. The objective of the study was to investigate the use of different proportions of ground peach pits (GPP) as a substrate component for seedling growth of Eucalyptus dunnii in the nursery and field. Different proportions of GPP mixed with either commercial substrate (CS) or with brown peat (BP) were tested. The physical and chemical properties of the substrates, the morphological and physiological attributes of the seedlings and their correlation with substrate properties were evaluated. The GPP increased the density, aeration space and pH and reduced total porosity, liquid retention and electric conductivity of the substrate. The use of this component resulted in hormesis, a biphasic dose–response model in which low levels of exposure to this component stimulated biological performance of plants and high levels of exposure inhibited performance. For improved seedling growth in the nursery and adequate post-planting development of E. dunnii, GPP with CS is recommended at 20% of the total substrate and with BP between 15 and 30%.
Proanthocyanidins (PAs) are the most broadly distributed secondary metabolites that play important roles in various aspects of plant development and response to biotic and abiotic stresses. In this study, we cloned a R2R3 MYB gene LoMYB29, which has a full-length coding sequence of 921 bp identified in Larix olgensis. Quantitative real-time reverse transcription polymerase chain reaction analysis indicates that LoMYB29 is expressed under mechanical wounding, high light intensity, and NaCl, PEG6000, Methyl Jasmonate, and abscisic acid treatments. Subcellular localization analysis and yeast two-hybrid assay localized LoMYB29 to the nucleus, acting as a transcriptional activator. Staining with 4-dimethylaminocinnamaldehyde showed a darker blue-purple color in LoMYB29-overexpressing Arabidopsis seeds compared to that of wild seeds. LoMYB29-overexpression resulted in a significant increase in leaf PA content. The expression of early flavonoid biosynthesis-related gene CHI and late flavonoid biosynthesis-related genes, including DFR, LDOX, and ANR (PA branch gene), were also activated in transgenic plants overexpressing LoMYB29. The results indicate that LoMYB29 plays a positive role in the regulation of PA biosynthesis by activating the expression of PA biosynthetic genes.
Camellia oleifera Abel. is an important economic tree species of southern China. In this study, we evaluated the mating system and genetic diversity of a series of cultivars of C. oleifera ‘Ruan Zhi’. A total of 159 individuals from the progenies of four cultivars were tested by simple sequence repeat molecular markers. Results reveal that 11 pairs of primers showed polymorphism and their polymorphism information content value was greater than 0.73, suggesting that these primers could be used to identify the genetic diversity of open-pollinated populations. The average number of effective alleles (N e = 4.88) was significantly different from the average number of alleles (N a = 12.18), and their distribution in the sample population was not uniform. The average observed heterozygosity (H o = 0.96) was greater than the average expected heterozygosity (H e = 0.79), and the population heterozygote was excessive. Shannon index was 1.84 and populations showed high genetic diversity. As regards to the mating system, the multilocus outcrossing rate was 0.996, and the single locus 0.866. These results indicate a high degree of outcrossing by C. oleifera ‘Ruan Zhi’. We recommend selecting individuals for high genetic gain from the progenies of cultivars because of outcrossing characteristics and genetic diversity for application to germplasm conservation and promotion.
Members of the WUSCHEL-related homeobox (WOX) transcription factor family are essential for determining cell fate and regulating diverse developmental processes in plants. Many WOX genes have been systematically investigated in woody plants such as Populus trichocarpa, but not in Salix suchowensis. Whole-genome sequence data for S. suchowensis is now available for comprehensive study of WOX genes in S. suchowensis. We thus surveyed the genome of S. suchowensis and demonstrated active expression of 15 WOX genes. In a phylogenetic analysis of WOX genes, the 15 SsWOX genes clustered among the modern/WUS, intermediate and ancient clades similar to the WOX genes of Arabidopsis thaliana. Based on the conserved intron/exon structure, SsWOX genes in the same subgroup had similar conserved exon–intron structures and motif domains. Furthermore, among several SsWOX subgroups, WUS (Wuschel)-box and EAR (the ERF-associated amphiphilic repression)-like motifs were conserved. Expression profiles of WOX genes in roots, stems and leaves indicate that SsWOX genes have various conserved roles in the tissues. Comparative analysis of the expression patterns in Salix suchowensis with that of Arabidopsis suggests that different shoot regeneration abilities are controlled by different WOX genes in plants. The analysis provide an overview of differentially expressed SsWOX genes during shoot regeneration, but also contribute to understanding the evolution of WOX genes in Salicaceae and the interrelations of WOX genes and other transcription factors, providing targets for further study.
Two threatened dipterocarp species, Dipterocarpus costatus and Dipterocarpus alatus are well-known endangered species in lowland forests of southeastern Vietnam, primarily from habitat loss and over-exploitation of their wood. To develop conservation strategies for these species, we analyzed 242 samples using nine microsatellite markers to determine the genetic variability within and among five populations of D. alatus and three of D. costatus, representing the natural range of dipterocarps in Southeast Vietnam. Results indicated low levels of genetic variability within populations with an average gene diversity of 0.223 for D. alatus and 0.152 for D. costatus. Results of bottleneck tests indicated a reduction in population size of both species (P > 0.05). Genetic differentiation among populations was high (F ST = 0.347 for D. costatus and 0.274 for D. alatus), indicating limited gene flow (N m = 0.662 for D. costatus and 0.47 for D. alatus) and isolated populations related to geographical distances. Analysis of molecular variance showed high genetic variation within populations (72.92% for D. alatus and 60.81% for D. costatus) compared to among populations. Bayesian analysis and UPGMA tree also indicated the two optimal genetic clusters related to geographical distances. These results will provide a platform for the conservation, management and restoration of these species.
Numerous land-use policies have been implemented in China in recent decades for ecological restoration and conservation to reduce environmental disasters and promote environmental sustainability. Many of these policies follow a top-down approach to implementation and as such, emphasize the hierarchical control within government structures. An understanding of local perceptions of land-use policies is important if the disconnect between policy makers and the target population is to be reduced and if program support is to improve. This study aimed to help improve local implementation, attitude toward, and engagement by examining the influence of socio-economic characteristics on the target population’s (local farmers) perception of the conversion of cropland to forestland program (CFPP) land use policy in Jiangxi, Sichuan, and Shaanxi provinces. It uses logistical regression models, with robust aspects of perception including confidence, support, transparency, prospects, fairness, and willingness to participate. Results indicate that social aspects as well as economic aspects are most important in influencing farmers’ perceptions towards the CFPP. The farmers who have received technical support, rural male habitants, educated, and non-middle-aged farmers exhibit more positive perceptions of the program and are much more likely to support it, whereas farmers without any technical support or formal education, and female and middle-aged farmers are less likely to support the program. Importantly, this study also reveals the differences in responses, experiences and perceptions of the farmers living across different provinces. These empirical results provide insight into the influence of socio-economic characteristics on the perception of farmers towards land-use policies, which has important implications for designing targeted policy instruments and increasing farmer support for these policies. This knowledge can be harnessed and further evaluated in future research to improve citizen engagement, support, and understanding in order to help ecological restoration and conservation objectives be more effectively achieved.
Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest. It was thus essential to assess regeneration before designing optimizing strategies. To this end, we studied the overstory canopy and microhabitat conditions for recruitment of Pinus brutia Ten in 10 plots (20 × 25 m) on the southern aspects where the Zawita natural forest is still present. In total, 1540 regenerating P. brutia were recorded, 854 seedlings, 597 saplings, and 89 trees. Seedlings and saplings were more frequent beyond the canopy than under the canopy of the parent trees. Regeneration requirements differed between seedlings and saplings. The probability of the occurrence of seedlings was negatively correlated with increasing litter depth and increasing soil compaction. The density of saplings only showed a positive significant correlation with increasing slope. The nearest neighbor index showed a trend toward a positive spatial association between understory shrubs with their neighboring seedlings at a mean distance of 1.6 m. Overall, the study highlighted the requirements for seedling regeneration as a relatively open canopy cover, a light understory litter layer, and non-compacted soils. These results are a step towards designing effective management and restoration programs.
Numerous approaches have been developed to quantify forest structure modules. A variety has measured each as part of stand attributes. This study was carried out in managed mixed stands in northern Iran. The objective was to quantify stand structure and its variation before and after tree marking through the Gini index and structural triangle method. A full sampling inventory was taken in 2004 and 2014 at the beginning and end of a period, before and after tree marking operations in five stands. The results indicate that the Gini index was 39.5, 62.2, 43.0, 82.0 and 74.0% for I, II, III, IV and V stands respectively. Furthermore, approximate structural diameters were determined as a large category for I, III, IV and V stands while stand II had an intermediate-large class pre-tree marking to an intermediate-small class post-tree marking. The paired t-test results were not significant for tree numbers and growing stock changes for all species, and for beech, hornbeam, and velvet maple before and after tree harvesting in the whole stand. Therefore, the Gini index and the structural triangle method can be used for natural stand modeling, structural diversity designation, and for management practices in nature-oriented forestry strategies.
It is critical to understand how forests regenerate after the exclusion of human induced disturbances because the regenerating species drive the renewal of resources and ecosystems, which in turn support human beings locally and globally. This study of forest regeneration was conducted in the tropical coastal forest ecosystems of Tanzania at Uzigua Forest Reserve (24,730 ha) in the Pwani Region. We collected data from adult trees in 47 sampling plots (25 × 25 m) randomly established in closed forest sites (control) and in sites disturbed by farming and livestock grazing. Sapling and seedling data were collected and analyzed in 2 × 2 m nested subplots. Plots in the closed forest had higher mean basal area and volume for adult trees than those in sites disturbed by farming and livestock grazing. Plots in sites disturbed by farming had the highest Shannon–Wiener index for seedlings and saplings, followed by closed forest and livestock grazed sites. Closed plots and farmed plots had higher Simpson’s index for seedlings and saplings than in grazed sites. Plots in farmed and livestock-grazed sites had a higher Simpson index for adult trees than in closed sites. Equitability of seedlings and saplings was highest in closed forest sites, followed by farmed and livestock grazed sites. Plots disturbed by farming had higher equitability for adult trees than in livestock-grazed and closed sites. Moreover, plots disturbed by farming and grazing had a higher importance value index for seedlings than in closed sites. Plots in closed forests had higher sapling importance values than in farmed and grazed sites. Again, plots in closed forest had a higher importance value for adult trees than in farmed and grazed sites. The differences in tree species subcategories of regeneration across land-use indicates that farming and livestock grazing disturbances create heterogeneous microhabitats, which positively or negatively affects regeneration capacity of species after exclusion.
For evaluating microbial community changes in a Siberian larch stand disturbed by forest fire or clear-cutting, 357 clones were randomly selected and sequenced using a culture-independent approach and 16S rRNA sequencing to characterize the bacterial composition and diversity from the different disturbed Siberian larch stands. Interestingly, the burned larch stand had an increase in the relative amounts of β-proteobacteria and Firmicutes and a decrease in Acidobacteria, while Gemmatimonadetes increased Verrucomicrobia decreased in the harvested larch stand. Microbial diversity and richness were higher in the undisturbed larch stand than the disturbed (burned or clear-cut) larch stands, and the influence of clear-cutting was more negative than that of the forest fire. This study indicates that evaluating the microbial diversity of undisturbed, burned, and clear-cutting Siberian larch stands provides information about the impact of forest disturbances on soil microbial communities, which may be helpful for understanding and evaluating soil health and devising reafforestation strategies for larch.
The response of soil fauna to the litter decomposition process has received considerable attention, but this effect has not been fully examined in agroforestry systems. A 1-year in situ decomposition experiment was carried out in a pure ginkgo plantation and two ginkgo agroforestry systems using a litterbag method (11 different treatments were tested in three systems). We found that the application of different organic materials (crop residues) produced positive effects on the number of soil fauna in the ginkgo planting systems; the mixture of ginkgo leaves and corn leaves was the best performing treatment. Collembola and Acarina were the predominant groups in the litter bags and were mainly responsible for the differences among the treatments. Litter mixing promoted the abundance, richness, and diversity of soil fauna, and significant differences regarding the Shannon–Wiener index of the soil fauna were observed among the 11 treatments in July. Significantly higher soil MBC (microbial biomass carbon) and MBN (microbial biomass nitrogen) were observed in agroforestry systems than in pure ginkgo plantations. These results suggest that the practice of intercrop residue application plays an important role in enhancing soil ecosystem function in ginkgo agroforestry systems and may ultimately contribute to sustainable intercrop production, soil fertility, and local economic diversity.
The aim of this study is to determine the influence of tree litters on soil nutrients in a managed forest in southwestern Nigeria. Mono species tree clusters consisted of indigenous species: Gmelina arborea, Tectona grandis, Leucaena leucocephala, Bambusa vulgaris, Treculia africana, Anogeissus leiocarpus were selected and analyzed for their litter and soil chemical properties at 0–5 and 15–30 cm. T. africana and T. grandis litters have the highest nutrients, while L. leucocephala and A. leiocarpus are the lowest. Soils under G. arborea, T. africana, and A. leiocarpus are more acidic due to lower calcium and magnesium contents but have higher manganese and sulphur levels. Tree litters improved soil nitrogen, phosphorous, and micro-nutrients but depleted potassium. Litter lignin and carbon appeared to hinder the release of some nutrients. Nitrogen, potassium and copper are concentrated in the topsoil while others nutrients are not differentiated with soil depth. There is a positive correlation between litter chemistry and soil chemical properties. It was concluded that tree litter chemistry differs according to species but determines soil reaction and nutrient content. The magnitude of the effect on soil properties is related to the quality of the organic litters.
To investigate the effects of biochar addition (1 or 3%) to the soil of a China fir plantation with or without litter, we conducted a 90-day incubation experiment. We also studied the C and N dynamics and the microbial community structure of the soil. In soil without litter, the application of biochar at a rate of 3% significantly decreased CO2 emissions, while addition of 1% biochar had no effect. Biochar application did not affect the net N mineralization rate but significantly reduced the NH4 + concentration after 90 days. In litter-enriched soil, biochar application had no significant effect on total CO2 emissions; however, application of 3% biochar significantly reduced the net N mineralization rate. Biochar application to soil with or without litter immediately reduced the dissolved organic carbon (DOC) concentration independent of the application rate, which was primarily due to sorption of DOC by the biochar. Phospholipid fatty acid analysis demonstrated that both concentrations of added biochar to soil (with or without litter) altered the soil microbial community structure at the end of incubation, although the effect of biochar was not as strong as the effect of time or litter application. The effect of biochar addition alone on microbial community structure was inconsistent over time. Litter added to soil significantly increased fungi and reduced Gram-positive bacteria. In the presence of litter, biochar applied at both 1% and 3% significantly increased (p < 0.05) the proportion of actinomycete only at day 90. Our results indicate biochar as a potentially effective measure for C sequestration in the test soil of a China fir plantation, even in the presence of litter.
Climate change is predicted to alter global precipitation regimes. However, the response of soil carbon and nitrogen cycles and soil microorganisms to precipitation reduction is poorly understood but is dependent on ecosystem type. To evaluate the impacts of reduced precipitation on soil respiration, soil inorganic nitrogen (i.e., NH4 +–N and NO3 −–N), nitrogen mineralization, and soil microbial community composition, a precipitation manipulation experiment was initiated in a Mongolian pine plantation and a naturally restored grassland in semi-arid northeast China. Precipitation reduction led to decreases of soil respiration rates by 14 and 8% in 2014 and 2015 in the Mongolian pine plantation but no changes in the grassland. Soil inorganic nitrogen, ammonification and nitrification rate, and soil phospholipids fatty acids were not significantly changed by reduced precipitation but significantly differed between the two ecosystems and among growing seasons. Our results suggest that the impacts of precipitation reduction on soil respiration were different between the Mongolian pine plantation and the grassland, and that ecosystem type and growing season had more pronounced impacts on soil carbon and nitrogen cycles.
Pest preference and subsequent susceptibility of a host individual is likely related to previous growth patterns in that host. Emerald ash borer (Agrilus planipennis Fairmaire) is a pestiferous beetle introduced to North America from Asia. While all species of ash are susceptible to attack, some individual trees appear to survive infestation. We selected ash trees in southeastern Michigan, collected cores and categorized trees as high tolerance to emerald ash borer attack (high overall health, low crown dieback), low tolerance (low overall health, high crown dieback) and intermediate tolerance (in-between the other categories). We artificially wounded trees and measured wound closure after 3 years. Ring width indices were not correlated between high and low tolerance trees. Regression slopes comparing growth and years were significantly different between the three tolerance categories, with high tolerance trees having the steepest slope. Wound closure was greatest in high tolerance trees. High tolerance trees demonstrating more rapid (steeper regression slope), consistent (lower variance), and effective (greater wound closure) growth. Those vigorously growing trees likely had more capacity to repair damage caused by emerald ash borer, leading to healthier trees in our categorization. Linking previous host growth patterns to health may have implications related to identifying individual trees potentially tolerant to attack.
Eight species of Pseudoligosita (Hymenoptera: Trichogrammatidae) from China are reviewed, including two new species: P. processa sp. nov. and P. qiluensis sp. nov. New distributional data for six species and a key to all the Chinese species of the genus are provided.
With environmental change and increased human activity, wild red deer (Cervus elaphus xanthopygus) populations and habitat area continue to decrease. Red deer is a main prey species of Amur tiger (Panthera tigris altaica). Factors affecting red deer winter home range in the Wanda montains of northeast China are not well understood. In this study, we aimed to better document red deer daily ranges to support conservation of red deer. A second objective was to develop a practical research method combining macro- and micro-technology for home range research on a variety of rare or endangered wild species. We collected 105 fresh fecal samples of red deer in three different periods during winter from December 2012 to March 2013 in the Wandashan region, Heilongjiang Province, China. Individual and sex identities were analyzed based on fecal DNA using microsatellite DNA. We used samples from deer farms for correction and validation of our identifications from field samples. We used a combination of molecular scatology, 3S techniques (GPS), and direct observation to estimate winter daily range areas. Based on eleven microsatellite loci, we identified 18 individuals, 10 females and 8 males, with a correction factor of 1.00 and sex ratio of 1:0.8. The mean (± SE) number of alleles was 5.1 ± 0.41, and mean polymorphism information content was 0.63 ± 0.03. Expected heterozygosity ranged from 0.46 to 0.81, with a mean of 0.69 ± 0.03, and mean observed heterozygosity was 0.73 ± 0.07. Sizes of mean daily ranges were 26.1 ± 1.1 ha in December, 89.3 ± 1.6 ha in January, and 67.5 ± 1.9 ha in March, indicating the following trend for daily range area: middle winter > late winter > early winter. Mean daily range area was insignificantly larger for males than for females. Estimated winter daily ranges were similar to those reported for Europe. Our combination of macro- and micro-technology proved useful for estimating winter home range areas of red deer.
Indian Giant Flying Squirrel (Petaurista philippensis Elliot 1839) is widely distributed in South Asia and the only species of flying squirrel found in Gujarat. We studied the seasonal variation in its feeding behaviour at selected sites of Central Gujarat. Focal sampling was employed to study the behaviours and mainly feeding behaviours. Feeding analyses were consistent with other studies and indicated Madhuca longifolia as an important food resource. The diet of the species mainly consisted of pith, twig, seed, bark, petiole, young to mature leaves, flower and fruits of 20 species of plants of 15 families along with lichens, Vanda tessellata and Dendrophthoe falcata. Madhuca longifolia (25%) contributed most to the squirrel diet, followed by Diospyros melanoxylon (10%) and Terminalia tomentosa (9%). Among the plant parts consumed, pith formed the highest bulk as a food at 23%, followed by fruits (21%), bark (16%), twig (14%), flower (10%), seed (6%), leaf (6%), and bud (4%). The findings reveal the high dependency of flying squirrel on certain tree species. These tree species are well represented and distributed throughout central Gujarat, indicating that this area is important for the survival of this species and that the area should be conserved for protection and future management of this species.
Oil palm trunk is an excellent raw material for thermally compressed wood board. However, improvements to dimensional stability during water absorption and reduced thickness swelling has been tied to losses in other mechanical properties, especially as the compression temperature is increased. Toward solving this trade-off, we analyzed the effects of a 48 h pre-soak in citric acid solutions (0, 5, 15, 25, or 35% w/v in distilled water) on the physical and mechanical properties of oil palm board compressed at 140 °C. The reference benchmark case was compressed at 200 °C without pretreatment. The oil palm board raw materials were obtained from outer, middle and inner parts of trunk. The results showed that the oven-dry density of compressed oil palm board made from different parts of trunk increased with thermal compression (maximum pressure 12.26 MPa for 8 min). The citric acid pretreatment improved water absorption and thickness swelling properties of oil palm board thermally compressed at 140 °C, consistent with the citric acid concentration. The carboxyl groups in citric acid cross-link with the hydroxyl groups in the wood. However, no significant difference was found between the benchmark (200 °C) and pretreatments with 5 or 15% citric acid. The citric acid altered the wood chemistry during hot compressing at 140 °C. Static bending strength, modulus of rupture (MOR), and modulus of elasticity (MOE) slightly decreased with the citric acid pretreatment, matching the effects of high temperature compression at 200 °C.
Rosewood (Pterocarpus erinaceus Poir.) is valued for flooring, ornaments, musical instruments and furniture-making due to its durability, strength, beauty and acoustic properties. It coppices easily which could boost its continual supply. Compression parallel to grain, Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) within coppiced and non-coppiced boles were determined. These properties decreased along both types of boles. Strength values for the heartwood were also greater than those for the sapwood of each type of bole. MOE, MOR and compression for non-coppiced stems were greater than those from the coppiced stems. The differences were significant (p < 0.05). Mechanical properties from the coppiced and non-coppiced boles are comparable. Both have strength properties comparable with those of species widely used for railway sleepers, structural supports, flooring, veneer, furniture, cabinetry, truss and mine props. Therefore, coppiced wood could supplement non-coppiced wood for industrial applications which require strength.