Mining alters the natural landscape and discharges large volumes of wastes that pose serious pollution hazards to the environment, to human health and to agriculture. As a result, the recent 2 decades have witnessed a global surge in research on post-mining landscape restoration, yielding a suite of techniques including physical, chemical, biological (also known as phytoremediation) and combinations. Despite the long history of mining in Africa, no systematic review has summarized advances in restoration research and practices after mining disturbance. Thus, the aim of this review was to document the state-of-knowledge and identify gaps in restoration of post-mining landscape in Africa through literature review. We found that: (1) there has been substantial progress in identifying species suitable for phytoremediation; (2) few studies evaluated the feasibility of organic amendments to promote autochthonous colonization of mine wastelands or growth of planted species; and (3) restoration of limestone quarries in Kenya, sand mining tailings in South Africa, and gold mine wasteland in Ghana are successful cases of large-scale post-mining restoration practices in Africa. However, the pace of post-mining landscape restoration research and practice in Africa is sluggish compared to other parts of the global south. We recommend: (1) mainstreaming the restoration of mine wastelands in national research strategies and increased development planning to make the mining sector “Green”; (2) inventory of the number, area, and current status of abandoned mine lands; (3) expanding the pool of candidate species for phytostabilization; (4) further evaluating the phytostabilization potential of organic amendments, e.g., biochar; (5) assessing the impacts of mining on regional biodiversity.

To determine if reduced tree densities (number of trees per unit area) lead to changes in micro-meteorological and tree physiological characteristics, two areas with different tree densities were assessed. One was an agrosilvopastoral system (AGP) with low tree density, and the other, a secondary forest (SF) with greater tree numbers, both located in a semiarid region of Brazil. Data were collected simultaneously by two automated weather stations: rainfall, air (T_a) and soil temperatures (T_s5cm), relative humidity (RH_air), photosynthetically active radiation (PAR), soil moisture at two depths (M_s30cm and M_s50cm), and wind velocity (V_w). Net photosynthesis in Cordia oncocalyx Allemão trees was measured with an infrared gas analyzer in February, March, May, July, August and September 2011, which encompasses a rainy period followed by a dry period. Average values of T_a, T_s5cm, V_w and PAR were greater and average values of RH_air and M_s50cm were lesser in the AGP. Photosynthetic rates were greater in plants growing under the AGP at the onset of the dry season when V_w, PAR and T_s5cm were greater and M_s50cm was lesser. Photosynthetic rates correlated strongly with physical parameters during the dry season, especially under SF. Differences in tree numbers between AGP and SF led to differences in physical environmental parameters; however, the latter had less influence on photosynthetic rates in C. oncocalyx during the rainy season. During the dry season, all physical parameters had an impact on net photosynthesis under SF but not under AGP. This indicates a certain independence of plants in AGP.

Populus × euramericana “Neva” is the main poplar species in China, where drought stress is becoming extremely urgent. We carried out this research to study the effects of drought stress on the photosynthesis of Populus × euramericana “Neva”. Drought stress was induced by 58–62% (light), 48–52% (moderate), and 38–42% (severe) relative soil moisture content (RSMC). The effects of drought stress on photosynthetic rate, chlorophyll fluorescence parameters, and other related physiological parameters were investigated during treatment. Net photosynthetic rate (P _N), and stomatal conductance decreased significantly and intercellular CO₂ concentration initially increased and then declined, whereas the stomatal limitation factors showed opposite trends in the light under moderate drought stress. Photosystem II (PSII) maximum photochemical efficiency, actual photochemical efficiency, and photochemical quenching decreased gradually under drought stress, whereas nonphotochemical quenching initially increased and then declined. Superoxide dismutase, peroxidase, and catalase activities initially increased and then decreased as RSMC was reduced, whereas malondialdehyde (MDA) content and relative electric conductivity (REC) increased gradually. These results suggest that stomatal factors accounted for the decline in P _N under light and moderate drought stress, whereas leaf P _N decreased mainly due to non-stomatal factors under severe drought stress. PSII was damaged; thus, photosynthetic electron transfer was restricted, indicating that heat dissipation is important for the light protection mechanism of plants. Antioxidant enzymes increased at the beginning of treatment, and the increased MDA and REC led to cell membrane damage. These results suggest that poplar seedlings stabilized their photosynthetic apparatus by reducing the light trapping ability under light and moderate drought stress conditions. This helped dissipate heat and enhance antioxidant enzyme activity. Stomatal factors accounted for the decline in P _N, whereas damage to PSII and antioxidant enzymes under severe drought stress suggested that the decline in P _N was caused by non-stomatal restrictive factors.

Leaf nitrogen resorption is very important to Phyllostachys edulis development because the withdrawn nitrogen can help newly emerging and growing culms. However, few studies have focused on the ontogenetic changes in leaf nitrogen resorption of P. edulis. Here, we examined the variability in mature leaf nitrogen concentrations (N_m), nitrogen resorption efficiency (NRE) and proficiency (NRP or N_s) and leaf-level nitrogen use efficiency (NUE) of the current-, 3rd- and 5th-year culms in P. edulis stands under extensive management. Analyses of variance and correlation indicated that patterns of N_m, NRP, NRE and NUE were markedly affected by culm age and leaf nitrogen status. N_m, N_s and NRE were significant higher in younger (current-year) culms with 1-year lifespan leaves, while NUE was markedly higher in older (3rd- or 5th-year) culms with 2-year lifespan leaves. Significant linear correlations between N_m and NRP, NRE and NUE, N_m and NUE, N_s and NRE were found for each culm age, and N_m was significantly positively correlated to NRE for all culms pooled. Higher proficiency in older culms led to higher NUE and lower NRE, these relationships can be modulated by N_m, which in turn, is restrained by leaf N availability and acquisition. Our results revealed that at the intraspecific level, P. edulis can adjust its leaf NRE, NRP, and leaf-level NUE in concert with culm development. Understanding nitrogen resorption characteristics and NUE of P. edulis can help decision-makers design appropriate deforestation strategies and achieve precise N fertilization for sustainable bamboo forest management.

Epicuticular waxes have vital roles in the growth and development of plants and in defense. Conifers have a considerable amount of waxes on their cones and leaves. Here we characterized the n-alkane composition of Iranian conifers, including Juniperus oblonga, J. foetidissima, J. sabina, J. communis subsp. hemisphaerica, J. excelsa, Cupressus sempervirens, Platycladus orientalis from Cupressaceae and Taxus baccata from Taxaceae for the first time using GC-FID analyses. In the waxes, 25 n-alkane homologs with chain lengths ranging from C₇ to C₃₂ were identified. Short-chain n-alkanes were dominant in almost all samples with some exceptions. Complementary studies to elucidate complete wax constituents of Iranian conifers and n-alkane distribution pattern as a function of geographical and bioclimatic variables are recommended.

Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains limited. Accordingly, we measured sap flow velocity of Populus euphratica using the heat ratio method between 2012 and 2014. Nocturnal stem sap flow was separated into nighttime and stem refilling using the “forecasted refilling” method. Nighttime transpiration was observed for each phenophase. The highest value was during the full foliation period but lowest during leaf expansion and defoliation periods. The contribution of nighttime transpiration to daytime transpiration was an average of 15% but this was comparatively higher during the defoliation period. Relationships between nighttime transpiration, vapor pressure deficits, and air temperatures were more closely associated than with wind speed in all phenophases. Moreover, we found that nighttime transpiration linearly correlated to vapour pressure deficit during the first and the full foliation periods, but nighttime transpiration showed exponential correlations to air temperatures during the same phenophases. Additionally, environmental drivers of transpiration were significantly different between nighttime and daytime (P < 0.05). Driving forces behind nighttime transpiration were characterized by many factors, and integrated impacts between these multiple environmental factors were complex. Future studies should focus on these integrated impacts on nighttime transpiration, and the physiological mechanisms of nighttime transpiration should be investigated, given that this could also influence its occurrence and magnitude during different phenophases.

To select maternal parents with high fertility and high combining ability during cross breeding of Populus tomentosa Carr., the ploidy level of 75 female clones was determined using flow cytometry. In addition, genetic variations and phenotypic correlations of seed traits and early growth traits, as well as the general combining ability (GCA) for seedling height (SH) and basal diameter (BD) of all diploid half-sib families were examined. A total of 26 natural triploid clones were identified. For all diploid families, family effects were significant for inflorescence length (IL), thousand kernel weight (TKW), seedling emergence rate (SER), and for SH and BD. There was a positive correlation between TKW and other traits, excluding IL. The seed-bearing coefficient (NS × SER) ranged from zero to 32.4%. Clones 3-10-2, 2-8, 3119, 3206, and 3-10-1 had the best performance of the GCA for SH and BD. Based on the fertility and GCA for SH and BD, clone 3-10-2 and clone 3119 could be used as female parents for controlled cross-breeding of P. tomentosa.

Populus caspica Bornm. (section Leuce and subsection Albida), one of the most endangered endemic tree species in the Hyrcanian Forest in Iran, has numerous morphological characteristics that are closely similar to Populus alba; to clarify their taxonomic relatedness and genetic differentiation and thus inform conservation strategies, we used the noncoding regions of chloroplast DNA (cpDNA; trnL-F and trnH-psbA) and the internal transcribed spacer (ITS). Leaf samples were collected from six populations across northern Iran. cpDNA and ITS fragments were amplified by universal primers using the PCR technique and directed sequencing. The results showed that P. caspica is genetically differentiated from P. alba, and two ITS variants were detected within some P. caspica individuals. Conflicts between topologies from ITS and plastid genomes were observed. High differentiation of P. caspica from the other Populus species shown in this study confirmed the diverging taxonomic status of this endangered species. We recommend in situ conservation measures (e.g., protected areas) for at least several populations of this species, especially in the plain regions of the Hyrcanian forest.

Flavonoid 3′-hydroxylase (F3′H) and 3′,5′-hydroxylase (F3′5′H) generate precursor molecules for the synthesis of cyanidin-based anthocyanins (red) and delphinidin-based anthocyanins (blue to purple) in Ribes nigrum L. (black currant). In this study, full-length 1780 and 1650-bp cDNA homologs of RnF3′5′H1 and RnF3′H1 from black currant were identified and cloned using a homologous cloning technique. Data revealed that Rn F3′5′H1 and RnF3′H1 are homologs that encode enzymes involved in anthocyanin synthesis from different plants, which phylogenetically cluster with the CYP75B and CYP75A families in the P450 superfamily, respectively. The enzymes encoded by these two genes also shared a high homology with flavonoid hydroxylases identified from other plants. Furthermore, RnF3′5′H1 and RnF3′H1 levels were upregulated during fruit maturation. RnF3′5′H1 levels were associated with both anthocyanin and soluble carbohydrate levels in blackcurrant, while RnF3′H1 expression did not have such an association. The structure and expression patterns of RnF3′5′H1 and RnF3′H1 in blackcurrant were also characterized. Further studies should aid understanding of anthocyanin biosynthesis in black currant to develop molecular approaches and manipulate anthocyanin production in blackcurrant.

The 9-cis-epoxycarotenoid dioxygenase (NCED) gene is rate-limiting in abscisic acid (ABA) biosynthesis. In this study, an NCED gene, designated FvNCED3 (KY008746), was cloned from velvet ash (Fraxinus velutina Torr.) with a RACE method. The full length cDNA of FvNCED3 encodes a 573-amino acid polypeptide. Sequencing analysis showed that the FvNCED3 protein was highly homologous to other NCED proteins. The expression patterns of FvNCED3 in different ash organs were analyzed by real-time PCR which revealed that FvNCED3 expression levels were highest in leaves and lowest in roots. The gene expression patterns of FvNCED3 under abiotic stress indicated that its expression increased under drought, salt and ABA stress and decreased due to high and low temperatures. There were no obvious changes under ultraviolet light. The 1094-bp upstream sequence 5′ flank regulation region of the FvNCED3 gene was also cloned from ash using the Genome Walking method. To assess the activity of the FvNCED3 promoter, a pFvNCED3p::GUS plant expression vector was constructed for tobacco transformation. GUS expression of the FvNCED3 GUS enzyme activity was detected in almost all transgenic tobacco tissues, especially in the young leaves, stigma, anther, ovule and ovary. After treating the transgenic tobacco with NaCl and placing it under drought stress, GUS staining of tobacco leaves increased compared with that under normal growth conditions. This result indicates that gene expression driven by the FvNCED3 promoter can be induced by salt and drought stress.

Arbuscular mycorrhizal fungi (AMF) can colonize and form associations with the roots of Amorpha fruticosa L. (desert false indigo). Various genes are induced during the symbiotic process. In this study, de novo transcriptome sequencing using RNA-seq was conducted for the first time for a comprehensive analysis of AMF-A. fruticosa symbionts at the transcript level. We obtained 12G of raw data from illumina sequencing and recovered 115,786 unigenes with an average length of 547 bp, among them 41,848 of significance. A total of 2460 diffexpression genes were identified, including 1579 down-regulated and 881 up-regulated genes. A threshold for false discovery rate of < 0.001 and fold change of > 1 determined significant differences in gene expression. Using these criteria, we screened 285 significant differentially expressed genes, of which 82 were up-regulated and 203 down-regulated. The 82 up-regulated genes were classified according to their functions and assigned into seven categories: stress and defense, metabolism, signaling transduction, protein folding and degradation, energy, protein synthesis, and transcription. The 203 down-regulated genes were screened according to fold change > 2, and 50 highly significant down-regulated genes were obtained related to stress and defense. The results of this study will provide a useful foundation for further investigation on the metabolic characteristics and molecular mechanisms of AMF associations with leguminous woody shrubs.

We studied the dominant species by age category of re-growth, and how subsistence forest use through shifting cultivation impacted on the floristic composition of Baikiaea forest. For re-growth stands, variable sampling method was adopted in data collection while in mature stands, a sample plot size of 50 m × 50 m was used at each of three study sites. Distribution of species by age categories showed that shrub, herb, and grass species were abundant in young re-growth stands while woody vegetation became common with increasing age of the re-growth stand. Hierarchical clustering for common woody species showed several species associations with age categories and also with relatively undisturbed woodland. Common regeneration mechanisms of key woody species were mainly by seed (48%), coppicing (40%) and root suckers (12%). The young re-growth stands of 6–10 and 11–15 years were characterized by B. petersiana, B. massiensis, Combretum zeyheri, and Guibourtia coleosperma. Older stands (16–20 years after abandonment) were characterized by B. plurijuga, Pterocarpus antunesii, and Baphia massiensis, thus closely mimicking the relatively undisturbed forest whose dominant key woody species were B. plurijuga, P. antunesii, and G. coloesperma. There were many stems in younger stands (2–5 years) and fewer stems in older re-growth stands of 16–20 years after abandonment following shifting cultivation. Older re-growth stands (16–20 years) were similar to undisturbed stands (P < 0.005). The similarity between re-growth stands of 16–20 years and control stands demonstrates the recovery of Baikiaea forest over time after cessation of shifting agriculture. Baikiaea forest requires some disturbance to perpetuate the dominant species and begins to show signs of recovery from shifting cultivation within 16–20 years after abandonment. This is contrary to assertions that this ecosystem could take up to about 100 years for abandoned fields to begin showing signs of recovery

This study presents the structural characteristics and regeneration potential of mangrove patches in the estuarine and coastal areas of Kerala, a tropical maritime state in India. Field surveys were carried out at 46 selected sites during August 2015 to May 2016. In each site, the vegetative structure and regeneration status were assessed using the quadrat method. Altogether 219 quadrates were laid out and a total of 13 true mangrove species, belonging to 5 families and 8 genera, were recorded. The total tree density and stand basal area of the study region was 1678.08/ha and 20.33 m²/ha respectively. The low basal areas indicate the reduced structural development in mangroves. Of the 13 tree species, Avicennia constitutes 56% of the total Important Value Index (IVI) and Avicennia officinalis represents 41% of the IVI in Kerala, followed by Avicennia marina (15%), Rhizophora mucronata (15%), Sonneratia alba (8%) Rhizophora apiculata (7%) and Excoecaria agallocha (7%). The diameter at breast height (DBH) in the study area revealed that 47% of the tree species came under the 1–10 cm DBH class. Total sapling and seedling density in Kerala was 2238.35 and 3232.42 individuals/ha respectively. Density of young plants (seedlings + saplings) was only 31% greater of tree density and varied from 3–63%, which indicates poor regeneration potential. The Maturity index value (MIV) and complexity index (Ic) value of mangroves were 18.30 and 109.81 respectively. However, the low Ic value (< 10) observed in seven out of ten coastal districts indicated poor structural development of mangroves in Kerala. Therefore, location-specific conservation and management measures, guided by the knowledge on spatial distribution and habitat requirements of mangrove varieties should be taken to preserve the mangrove diversity of Kerala.

To accelerate the breeding and selection of Pinus densiflora Siebold and Zucc. resistance to pine wilt disease, a micropropagation system was established and nematode resistance evaluated in vitro. Cotyledon-hypocotyl explants from 28-day-old seedlings were first cultured on Gresshoff and Doy medium supplemented with 4.0 mg L⁻¹ 6-benzyladenine and 0.2 mg L⁻¹ α-naphthaleneacetic acid (NAA) to stimulate the formation of buds. Induced buds were subsequently subcultured on Gupta and Durzan medium supplemented with 0.1% (w/v) activated charcoal for elongation. Stem sections derived from shoots were used as explants for the further multiplication. Roots were formed from shoots transferred to woody plant medium containing 0.2 mg L⁻¹ NAA for 4 weeks. The nematode resistance test showed that symptoms in micropropagated shoots after infection with pine wood nematode (PWN) were similar to those in plants infected in the field. The wilting rate varied from 20 to 100% among different clones 18 days after inoculation. The most susceptible clone was Clone 6-4 with a 100% wilting rate, while Clone 8-4 showed a relatively high resistance with a 20% wilting rate. The number of nematodes recovered from Clone 8-4 shoots was significantly lower (P = 0.05) than from Clones 5-10 and 16-4. This work contributes to the breeding of PWN resistance in P. densiflora.

Density effects on the growth and self-thinning of Eucalyptus urophylla stands were examined for 7 years. The reciprocal equation of the competition-density (C–D) effect was used to describe the C–D effect in even-aged pure stands of E. urophylla during course of self-thinning and showed a good fit to the data. The time trajectories of mean stem volume-density nearly paralleled the y-axis during early growth stages of stands, and then began to curve left. Finally, the mean stem volume-density trajectories of the low-, middle- and high-density stands tended to follow the self-thinning lines with slopes of − 2.01, − 1.90 and − 1.99, respectively. With increasing physical time t, the biological time τ increased rapidly during early growth stages and became slow gradually during later growth stages. Realized density-initial density curves tended to become more or less flat with increasing initial density, indicating the existence of an asymptotic value for density at a given time. The coefficient ε, the reciprocal of which represents the asymptotic density at a given time, increased with increasing biological time τ, indicating that the asymptotic density decreased with increasing stand age. Final yield Y(t) increased gradually with increasing stand age.

In silvopasture system, the coexistence of eucalyptus seedlings with other species may result in growth reduction, especially during eucalyptus early development. Therefore, studies elucidating how forage species affect the eucalyptus growth can provide important information for their rational management aiming to obtain the maximum gain of the system. The aim of this work was to evaluate the effect of increasing densities of Urochloa brizantha cv. Marandu in the early development of Eucalyptus urograndis. An experiment was conducted in 20 L pots, in an open and semi-controlled area, during 90 days after planting of eucalyptus. A completely randomized design with four replications was used, in a 6 × 7 factorial system, meaning six evaluation periods and seven densities of U. brizantha: 0 (control), 22, 33, 44, 67, 89 and 111 plants m⁻². Fortnightly, eucalyptus height, stem diameter and chlorophyll fluorescence (F _v/F _m) were evaluated. At the end of experimental period, the net assimilation rate, stomatal conductance and transpiration rate of eucalyptus plants were determined, in addition to the dry matter of eucalyptus (leaves and stem) and U. brizantha (leaves). In coexistence with 111 plants m⁻², eucalyptus had reduction of 63.9% on total dry matter and 72.7% on leaf area, compared to the control. From the density of 22 plants m⁻², U. brizantha negatively interfere significantly the growth of E. urograndis. Up to 8 plants m⁻² there are no reductions greater than 5% in eucalyptus height and stem diameter.

Nectandra is one of the most representative genera of Lauraceae in the subtropical Atlantic Forest of Brazil. The objective of this work was to study the dendrochronological potential of Nectandra oppositifolia Nees and Mart. from two sites in Santa Catarina State in southern Brazil. A tree-ring chronology of 34 trees was developed. The time span ranged from 1843 to 2013. The oldest and youngest trees were 171 and 47 years-old and the average length of the series was 103 years. Average diameter and annual increment were 20.64 cm and 0.74 mm a⁻¹; diameter and age were unrelated. The species has good dendrochronological potential with an intercorrelation of 0.61 between sites, indicating the existence of a synchronous pattern in the development of the trees. The climate response of the species could be seen by negative tree growth effects for previous hot and current rainy growth seasons.

Kaynasli District in the western Black Sea region of Turkey has long been vulnerable to frequent flood damage due to the establishment of settlements within and around stream channels without regard to fluctuating peak-streamflow frequencies. The aim of this research was to determine the measures needed to protect the towns and villages from this type of damage. Daily total precipitation data for 1975–2010 were analysed, and rainfall-runoff models developed to estimate the potential yearly maximum discharge from each stream of sub-watersheds dominated by forests and/or agriculture. This was then calculated for different frequencies of the yearly maximum discharge. Flood analysis and mapping was modified via the one-dimensional Hydrologic Engineering Centers-River Analysis System software to produce potential maximum discharge and geometric data for Kaynasli Creek. As the main creek of the sub-watershed, its cross-section was shown to be insufficient and incapable of containing the maximum discharge at the 100-year frequency presumed for the watershed, and subsequently was seen as having a high level of casualty risk. It was concluded that the one dimensional model could be useful, but 2D models were more suitable for these types of watersheds.

In the headwater catchments of the Hun River, Northeast China, secondary forests (SF) have been replaced by plantations since the 1960s. Concern has been growing over this loss and the decline in water quality caused by the plantations. To test the effects of plantations on water quality, we selected two separate catchments covered by SF and Pinus koraiensis plantations (KP) to monitor physical and chemical properties of various hydrological variables including throughfall, stemflow, through-litterfall and runoff (flowing out of outlets of the catchments). The physical properties of water declined after water flowed through the two catchments as compared with rainwater. The pH of runoff in both catchments also dramatically decreased. The concentrations of Cl⁻, NO₃ ⁻ and NH₄ ⁺ in the runoff from the two catchments were similar (concentrations of Cl⁻ and NH₄ ⁺ in both catchments were similar to those in rainwater). Total P concentration in runoff of the SF catchment was higher than that of the KP catchment (P concentrations in both catchments were also higher than in rainwater) because P concentrations in litter and soil of the SF catchment were higher than those in the KP catchment. In summary, the rainwater became acidic in both catchments, but the responses of most water quality variables were similar in the two catchments, suggesting that appropriate ratios of KP in SF are feasible for secondary forest recovery and for preserving water quality (KP did not cause a decline in quality) in the headstream regions in Northeast of China.

Fuel moisture content is an important variable for forest fires because it affects fuel ignition and fire behavior. In order to accurately predict fuel ignition potential, fuel moisture content must be assessed by evaluating fire spread, fireline intensity and fuel consumption. Our objective here is to model moisture content of surface fuels in normally stocked Calabrian pine (Pinus brutia Ten.) stands in relation to weather conditions, namely temperature, relative humidity, and wind speed in the Mugla province of Turkey. All surface fuels were categorized according to diameter classes and fuel types. Six fuel categories were defined: these were 0–0.3, 0.3–0.6, and 0.6–1 cm diameter classes, and cone, surface litter, and duff. Plastic containers 15 × 20 cm in size with 1 × 1 mm mesh size were used. Samples were taken from 09:00 to 19:00 h and weighed every 2 h with 0.01 g precision for 10 days in August. At the end of the study, samples were taken to the laboratory, oven-dried at 105 °C for 24 h and weighed to obtain fuel-moisture contents. Weather measurements were taken from a fully automated weather station set up at the study site prior to the study. Correlation and regression analyses were carried out and models were developed to predict fuel moisture contents for desorption and adsorption phase for each fuel type categories. Practical fuel moisture prediction models were developed for dry period. Models were developed that performed well with reasonable accuracy, explaining up to 92 and 95.6% of the variability in fuel-moisture contents for desorption and adsorption phases, respectively. Validation of the models were conducted using an independent data set and known fuel moisture prediction models. The predictive power of the models was satisfactory with mean absolute error values being 1.48 and 1.02 for desorption and adsorption as compared to the 2.05 and 1.60 values for the Van Wagner’s hourly litter moisture content prediction model. Results obtained in this study will be invaluable for fire management planning and modeling.

Forest fire risk estimation constitutes an essential process to prevent high-intensity fires which are associated with severe implications to the natural and cultural environment. The primary aim of this research was to determine fire risk levels based on the local features of an island, namely, the impact of fuel structures, slope, aspects, as well as the impact of the road network and inhabited regions. The contribution of all the involved factors to forest fires ignition and behavior highlight certain regions which are highly vulnerable. In addition, the influence of both natural and anthropogenic factors to forest fire phenomena is explored. In this study, natural factors play a dominant role compared to anthropogenic factors. Hence essential preventative measures must focus on specific areas and established immediately. Indicative measures may include: the optimal allocation of watchtowers as well as the spatial optimization of mobile firefighting vehicles; and, forest fuel treatments in areas characterized by extremely high fire risk. The added value of this fire prediction tool is that it is highly flexible and could be adopted elsewhere with the necessary adjustments to local characteristics.

Leaf area index (LAI) is a key factor that determines a forest ecosystem’s net primary production and energy exchange between the atmosphere and land surfaces. LAI can be measured in many ways, but there has been little research to compare LAI estimated by different methods. In this study, we compared the LAI results from two different approaches, i.e., the dimidiate pixel model (DPM) and an empirical statistic model (ESM) using ZY-3 high-accuracy satellite images validated by field data. We explored the relationship of LAI of Larix principis-rupprechtii Mayr plantations with topographic conditions. The results show that DPM improves the simulation of LAI (r = 0.86, RMSE = 0.57) compared with ESM (r = 0.62, RMSE = 0.79). We further concluded that elevation and slope significantly affect the distribution of LAI. The maximum peak of LAI appeared at an aspect of east and southeast at an elevation of 1700–2000 m. Our results suggest that ZY-3 can satisfy the needs of quantitative monitoring of leaf area indices in small-scale catchment areas. DPM provides a simple and accurate method to obtain forest vegetation parameters in the case of non-ground measurement points.

Object-based classification differentiates forest gaps from canopies at large regional scale by using remote sensing data. To study the segmentation and classification processes of object-based forest gaps classification at a regional scale, we sampled a natural secondary forest in northeast China at Maoershan Experimental Forest Farm. Airborne light detection and ranging (LiDAR; 3.7 points/m²) data were collected as the original data source and the canopy height model (CHM) and topographic dataset were extracted from the LiDAR data. The accuracy of object-based forest gaps classification depends on previous segmentation. Thus our first step was to define 10 different scale parameters in CHM image segmentation. After image segmentation, the machine learning classification method was used to classify three kinds of object classes, namely, forest gaps, tree canopies, and others. The common support vector machine (SVM) classifier with the radial basis function kernel (RBF) was first adopted to test the effect of classification features (vegetation height features and some typical topographic features) on forest gap classification. Then the different classifiers (KNN, Bayes, decision tree, and SVM with linear kernel) were further adopted to compare the effect of classifiers on machine learning forest gaps classification. Segmentation accuracy and classification accuracy were evaluated by using Möller’s method and confusion metrics, respectively. The scale parameter had a significant effect on object-based forest gap segmentation and classification. Classification accuracies at different scales revealed that there were two optimal scales (10 and 20) that provided similar accuracy, with the scale of 10 yielding slightly greater accuracy than 20. The accuracy of the classification by using combination of height features and SVM classifier with linear kernel was 91% at the optimal scale parameter of 10, and it was highest comparing with other classification classifiers, such as SVM RBF (90%), Decision Tree (90%), Bayes (90%), or KNN (87%). The classifiers had no significant effect on forest gap classification, but the fewer parameters in the classifier equation and higher speed of operation probably lead to a higher accuracy of final classifications. Our results confirm that object-based classification can extract forest gaps at a large regional scale with appropriate classification features and classifiers using LiDAR data. We note, however, that final satisfaction of forest gap classification depends on the determination of optimal scale (s) of segmentation.

In the Ethiopian highlands, communal grazing lands are one of the major land uses, and are source of livelihood for the rural people. Free and uncontrolled grazing in the communal grazing lands is the dominant grazing system. The traditional uncontrolled and free grazing system has caused severe degradation of the grazing lands. As a result, communities have started to establish exclosures and support the restoration of degraded communal grazing lands. Studies have shown that exclosures are effective to restoring degraded communal grazing lands and improving ecosystem services. However, studies that investigate the changes in aboveground biomass following the establishment of exclosures and compare it with fuelwood demand of the beneficiaries in our study area is lacking. Therefore, our study aimed at: (1) quantifying yearly biomass accumulation in exclosures and compare it to fuelwood demand of households that manage the exclosures; (2) assessing household energy sources and their consumption levels. To monitor changes in biomass production with over time, replicated (n = 3) 5 and 10 year-old exclosures were sampled. To investigate fuelwood sources and consumption patterns, household surveys, key informant interviews and focus group discussion were conducted. Our results demonstrated that total biomass production increased with exclosure age. In both exclosure, biomass production from Vachellia etbaica was significantly (p < 0.05) greater than that from Euclea. racemosa. Average daily fuelwood consumption per person was (0.63 ± 0.2) kg day⁻¹. This means that the total biomass (27.5 Mg year⁻¹) obtained from 114.6 ha of exclosures covers only 9.4% of yearly fuelwood demand of the residents who manage the sampled exclosures. Nearly all respondents (95%) confirmed that they travel more than 10 km day⁻¹ to gather fuelwood from surrounding degraded forest patches. We recommend plantings of fast growing native tree species within exclosures and around homesteads to provide a sustainable fuelwood supply and using improved stoves to address the problem of fuelwood shortage. District agricultural offices could provide seedlings of native plant species, while communities provide unpaid labour for planting and managing plantations.

The use of Eucalyptus trees, in association with other plants, has the potential to reduce the growth of neighbouring plants or grasses by competing for resources or releasing allelochemicals that may cause other plants to grow slowly. Our purpose here is to assess whether border planting of Eucalyptus is harmful to the establishment, growth, and production of Cymbopogon winterianus at various distances from tree lines in the Wondo Genet Agricultural Research Center in Southern Ethiopia. Several factors were studied: growth performances and yield of aromatic grasses; soil properties, including total nitrogen, organic carbon, and moisture content; and plant leaf nutrient content (NPK) at various distances away from the Eucalyptus citriodora border line were studied. Chemical compositions of hydro-distilled essential oils obtained from selected C. winterianus grasses leaves were analysed by gas chromatography. Plant height, biomass yield, amount of essential oil yield, and essential oil composition all were significantly affected due to Eucalyptus effect in the first 10-m distance as compared to beyond 10 m from the tree border line. There were increases in soil total nitrogen, organic carbon, and moisture content with decreasing distances to the Eucalyptus tree border. The result of plant leaf nutrient content (NPK) differed across treatment and distance. The pot experiment (15 cm × 20 cm), shoot length, and number of leaves of aromatic plants varied in the degree of inhibition based on the concentration of the aqueous extract. Significantly higher inhibitions of the shoot length and number of leaf parameters were observed when using 25% fresh leaf extract compared to other extract levels.

Secondary forests, created after heavy logging, are an important part of China’s forests. We investigated forest biomass and its accumulation rate in 38 plots in a tropical secondary forest on Hainan Island. These secondary forests are moderate carbon sinks, averaging 1.96–2.17 t C ha⁻¹ a⁻¹. Biomass increment is largely by medium-sized (10–35 m) trees. Tree mortality accounts for almost 30% of the biomass and plays a negligible role in biomass accumulation estimates. Mortality rate is highly dependent on tree size. For small trees and seedlings, it is related to competition due to elevated irradiance after logging. Regarding prospective biomass and rates of accumulation, recovery is not as rapid as in secondary forests of cleared land. Therefore, tropical forests are susceptible to logging operations and need careful forest management.

Bamboo forest is an important forest type in subtropical China and is characterized by fast growth and high carbon sequestration capacity. However, the dynamics of carbon fluxes during the fast growing period of bamboo shoots and their correlation with environment factors are poorly understood. We measured carbon dioxide exchange and climate variables using open-path eddy covariance methods during the 2011 growing season in a Moso bamboo forest (MB, Phyllostchys edulis) and a Lei bamboo forest (LB, Phyllostachys violascens) in Zhejiang province, China. The bamboo forests were carbon sinks during the growing season. The minimum diurnal net ecosystem exchange (NEE) at MB and LB sites were − 0.64 and − 0.66 mg C m⁻² s⁻¹, respectively. The minimum monthly NEE, ecosystem respiration (RE), and gross ecosystem exchange (GEE) were − 99.3 ± 4.03, 76.2 ± 2.46, and − 191.5 ± 4.98 g C m⁻² month⁻¹, respectively, at MB site, compared with − 31.8 ± 3.44, 70.4 ± 1.41, and − 157.9 ± 4.86 g C m⁻² month⁻¹, respectively, at LB site. Maximum RE was 92.1 ± 1.32 g C m⁻² month⁻¹ at MB site and 151.0 ± 2.38 g C m⁻² month⁻¹ at LB site. Key control factors varied by month during the growing season, but across the whole growing season, NEE and GEE at both sites showed similar trends in sensitivities to photosynthetic active radiation and vapor pressure deficit, and air temperature had the strongest correlation with RE at both sites. Carbon fluxes at LB site were more sensitive to soil water content compared to those at MB site. Both on-year (years when many new shoots are produced) and off-year (years when none or few new shoots are produced) should be studied in bamboo forests to better understand their role in global carbon cycling.

Plantation forests play a pivotal role in carbon sequestration in terrestrial ecosystems, but enhanced nitrogen (N) deposition in these forests may affect plantation productivity by altering soil N cycling. Hence, understanding how simulated N deposition affects the rate and direction of soil N transformation is critically important in predicting responses of plantation productivity in the context of N loading. This study reports the effects of N addition rate (0, 40, and 120 kg N ha⁻¹ a⁻¹) and form (NH₄Cl vs. NaNO₃) on net N mineralization and nitrification estimated by in situ soil core incubation and on-soil microbial biomass determined by the phospholipid fatty acid (PLFA) method in a subtropical pine plantation. N additions had no influences on net N mineralization throughout the year. Net nitrification rate was significantly reduced by additions of both NH₄Cl (71.5) and NaNO₃ (47.1%) during the active growing season, with the stronger inhibitory effect at high N rates. Soil pH was markedly decreased by 0.16 units by NH₄Cl additions. N inputs significantly decreased the ratio of fungal-to-bacterial PLFAs on average by 0.28 (49.1%) in November. Under NH₄Cl additions, nitrification was positively related with fungal biomass and soil pH. Under NaNO₃ additions, nitrification was positively related with all microbial groups except for bacterial biomass. We conclude that simulated N deposition inhibited net nitrification in the acidic soils of a subtropical plantation forest in China, primarily due to accelerated soil acidification and compositional shifts in microbial functional groups. These findings may facilitate a better mechanistic understanding of soil N cycling in the context of N loading.

Microbial indices and their spatial patterns are strongly affected by environmental factors. Spatial variability of soil properties is one of the most important causes of variability in soil microbial indices. This research was conducted in the Caspian forest to assess spatial variabilities and frequency distributions of microbial properties. Ninety soil samples were taken using a grid sampling design 40 × 40 m. Microbial indices, organic carbon, nitrogen and pH were determined. Soil variable distributions showed that microbial indices had abnormal distributions. Logarithmic transformation produced normal distribution. Spatial continuity using geostatistical (variogram) was studied and maps obtained by point kriging. The variograms revealed the presence of spatial autocorrelation. The results indicate that spatial dependence of soil microbial indices was affected by non-intrinsic factors and forest management procedures. The maps show that soil microbial indices and soil properties have spatial variability. The spatial pattern of microbial indices was correlated to organic carbon and nitrogen.

When confined to a single leaf, the larvae of most leafminers should suffer intense intraspecific competition. The survival and performance of individuals are expected to decline with increasing larval density within a leaf, showing a negative density-dependent effect. The maximum density of an Elachista Treitschke (Lepidoptera: Elachistidae) miner on Indocalamus tessellatus (Munro) Keng f. (Poaceae: Bambusoideae) under natural conditions can be greater than 40 per leaf, making this a good system for studying intraspecific competition and density effects. We counted the number of leaves with different mine densities in the field and found a clumped distribution of leafminer larvae among host leaves. The emergence rates of pupae (and last-instar larvae), adults and parasitoids were inversely correlated with larval density. Pupal weight and adult weight also showed negative relationships with larval density. However, pairwise tests showed that there might be no differences in pupal or adult weight at larval densities of 1–10 mines per leaf, indicating that density-dependent effects are more obvious at densities greater than 10 mines per leaf. Intraspecific competition could lead to stable density and consistent body size in surviving individual insects, which would help maintain a sustainable population size. The density threshold could be an indicator of the balance between intraspecific competitive detriments and conspecific aggregation benefits; however, the validity of the threshold density hypothesis requires further testing and confirmation.

Bursaphelenchus xylophilus is the pathogen that causes pine wilt disease, which has greatly damaged forests and ecosystems in countries of East Asia and Europe. Bursaphelenchus mucronatus is closely related to B. xylophilus in morphology and host plant specificity. A long-running debate has existed regarding whether these two species can successfully produce hybrid offspring. In the present study, we performed in the laboratory, hybridization of two B. xylophilus nematode isolates from China and Japan and three B. mucronatus isolates from China, Japan and France. Nematode isolates of B. xylophilus were successfully crossed with B. mucronatus isolates, and the rate of hybridization was relatively high; however, some hybrid offspring died. Successful hybridization occurred between B. xylophilus and B. mucronatus isolates from China, and 22 generations of hybrids were produced. All F1 hybrids could be backcrossed with their parents and produce offspring. Variation in mucro length among the hybrid offspring and their parents was observed. The hybrid offspring and their parents were inoculated into 3-months-old black pine (Pinus tunbergii) seedlings. Weaker pathogenicity of hybrid offspring was observed compared with that of their parents, and significantly fewer offspring nematodes than parents were reisolated from pines. Therefore, the offspring of B. xylophilus and B. mucronatus may exist in the forest and could influence disease epidemics.

Oil from seeds of Diospyros lotus was extracted using a conventional method with two different solvents: hexane and petroleum ether. A central composite design with response surface methodology were used to optimize the process. A second-order polynomial equation was employed, and ANOVA was applied to evaluate the impact of various operating parameters including extraction temperature (x ₁; 44.9–70.1 °C), extraction time (x ₂; 5.0–10.0 h) and solvent to solid ratio (x ₃; 11.6–28.4 mL g⁻¹), on oil yield. Experiments to validate the model showed decent conformity between predicted and actual values. Extraction conditions for optimal oil yield were 61 °C, 8.75 h extraction duration and 19.25 mL g⁻¹ solvent to solid ratio. Under these conditions, the oil yield was predicted to be 5.1340%. Oil samples obtained were then analyzed using gas chromatography. The fatty acid composition revealed the major fatty acids to be oleic acid (C18:1) and linoleic acid (C18:2). The analysis of oil also demonstrated a decent ratio between omega-3 and omega-6 fatty acids. The structure of seeds was imaged using scanning electron microscopy. Oil quality was analyzed thermogravimetrically and by Fourier transform infrared spectroscopy. The assigned nutritional features of the D. lotus oil suggested that it can be used as an edible oil in pharmaceutical and food industry in the future.

Gyrinops walla Gaertn. is the only species growing in Sri Lanka that belongs to the agarwood family, Thymelaeaceae. Although agarwood resin induction and extraction from Aquilaria species of the same family have been practised for many decades in Southeast Asian region, the ability of producing agarwood resins in G. walla was discovered recently. Since previous studies were on agarwood resins formed due to natural causes, the present study was conducted to identify the potential fungal species that are capable of artificially inducing agarwood resin formation in G. walla. Since this is the first ever study conducted on artificial inducement of agarwood resin formation in G. walla, Aspergillus niger and Fusarium solani were selected owing to their high abundance in the naturally formed agarwood resinous tissues collected from 25 G. walla trees. Both fungal species were separately grown in yeast extract glucose agar and used to inoculate healthy G. walla trees under aseptic conditions. Three holes were made for each tree and 2 g of fungal culture including the medium were placed in each hole. Tissue discoloration, characteristic aroma, resin content and resin constituents were checked at 10 cm intervals above and below the inoculation points for a period of 1 year. Results revealed that tissue discoloration and resin content were higher in the trees inoculated with A. niger. Other than at 10 cm above and below the inoculation points, samples collected at all locations had significantly higher resin contents when inoculated with A. niger compared to F. solani. Sixteen agarwood resin constituents, which were also recorded in Aquilaria species, were identified from the discolored tissues using GC–MS analysis. Jinkohol, agarospirol and 2(2-phenyl) chromone derivatives were found in all discolored tissues collected at 10-cm intervals of the trees inoculated with both fungi. β-Seline, γ-eudesmol and valerenal were found in nine of 10 sample points on the stem. γ-Elemene was recorded only in one sample. The characteristic aroma during burning was stronger for dark-colored tissues than the light-colored ones. The present study confirmed the potential use of certain fungal species to induce agarwood resin in G. walla and that A. niger is more effective than F. solani.

Because growth ring data have temporal features, time series analysis can be used to simulate and reveal changes in the life of a tree and contribute to plantation management. In this study, the autoregressive (AR) and moving average modeling method was used to simulate the time series for growth ring density in a larch plantation with different initial planting densities. We adopted the Box–Jenkins method for the modeling, which was initially based on an intuitive analysis of sequence graphs followed by the augmented Dickey–Fuller stationarity test. The order p and q of the ARMA (p, q) model was determined based on the autocorrelation and partial correlation coefficient figure truncated on the respective order. Through the residual judgment, the model AR (2) was only fitted to the larch growth ring density series for the plantation with the 1.5 × 2.0 m² initial planting density. Because the residuals series for the other three series was not shown as a white noise sequence, the modeling was rerun. Larch wood from the initial planting density of 2.0 × 2.0 m² was modeled by ARMA (2, 1), and ARMA ((1, 5), 3) fitted to the 2.5 × 2.5 m² initial planting density, and the 3.0 × 3.0 m² was modeled by AR (1, 2, 5). Although the ARMA modeling can simulate the change in growth ring density, data for the different growth ring time series were described by different models. Thus, time series modeling can be suitable for growth ring data analysis, revealing the time domain and frequency domain of growth ring data.

We explored the discoloration of rattan cane using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). XPS analysis showed that after the cane was stained by Lasiodiplodia theobromae, carbon and oxygen elements and the ratio of oxygen to carbon decreased. Considering atomic binding, C₁ and C₄ contents increased, while C₂ and C₃ contents decreased, and the ratio of O₂ to O₁ decreased sharply. The relative contents of lignin, cellulose and polysaccharides increased and new substances with low O₂/O₁ ratio occurred. FTIR analysis showed that the absorption peaks of O–H at 3346 cm⁻¹, aliphatic C–H at 2921, 2853 and 1464 cm⁻¹, and C=O at 1723 cm⁻¹, were characteristic peaks of fungal melanin intensified, indicating that cane discoloration was primarily caused by fungal melanin. The absorption peaks characterizing cellulose and lignin like polysaccharides at 800 cm⁻¹, C–H at 1374 cm⁻¹, C–O at 1058 and 1038 cm⁻¹, phenolic hydroxyl at 1245 cm⁻¹, aromatic ether bonds at 1270 cm⁻¹, carbon skeleton at 1608 cm⁻¹ and benzene ring at 1500 cm⁻¹ were enhanced since the fungus mainly consumed the extractives in cane cell lumens and the main composition content increased relatively. Regardless of the discoloration caused by natural fungi or inoculated fungi, the discoloring feature and composition changes were identical except that the fungus-inoculated cane had more melanin.