Silvicultural approaches at forest plantations with wider initial tree spacing have created potential for increased understory vegetation growth in response to increased light and greater nutrient resources. In consequence understory vegetation can fill a more important role in forest ecosystems, especially in interactions (competition or facilitation) between understorey vegetation and forests trees that might affect tree growth and nutrition. Considerable research has been carried out on plant interference. However, the experimental designs used in these studies vary from one study to another, and from species to species depending on the aims, objectives and practicalities of the studies. Thus there is no optimum design for competition experiments. This review discusses designs available in studying plant interferences in a glasshouse, particularly the effects of below-ground interaction of understorey vegetation and forest trees.
Early flowering and flower abundance have long been considered desirable traits in eucalypt breeding programs. In particular, flowers of Eucalyptus cladocalyx provide a nectar source for the production of honey in arid ecosystems. To identify inter-simple sequence repeat (ISSR) markers that are associated with early flowering and flower abundance in the southern Atacama Desert, we used a sample of 47 trees, representing five Australian provenances of E. cladocalyx. A unified mixed linear model (which considered the effect of genetic structure and the kinship relationship among trees) revealed that three loci were significantly associated with early flowering, which accounted for 10–16 % of the phenotypic variation, while two loci accounted for 11–13 % in flowering intensity. Locus ISO1–500 bp was associated with both flowering traits. This result is consistent with our previous findings indicating that marker-assisted selection on early flowering should have significant and positive impact on flowering intensity. The application of marker-assisted selection to identify trees that flower early and intensively may increase honey production, a resource that generates additional income for the local farmers of the southern Atacama Desert.
Expansins are cell-wall-loosening proteins that have multiple roles during plant development and stress-related processes. In this study, a novel expansin gene PwEXP2 was cloned by rapid amplification of cDNA ends based on the cDNA library of Picea wilsonii and EST fragment of PwEXP2. It was found that PwEXP2 coded 253 amino acids, and putative signal peptides exist at the N-terminal, followed by 8 cysteines, a HFD (His-Phe-Asp) conserved domain, and 4 tryptophan residues at the C-terminal. PwEXP2 was located in cytoplasm and nucleus when transformed in an onion epidermal cell. Quantitative real-time PCR assays showed that PwEXP2 was expressed in various tissues with a relatively high level in needles and low level in mature pollen. The expression level of PwEXP2 dramatically increased after seed germination. Gene expression profiles in abiotic stresses showed that PwEXP2 was induced by high temperature and osmotic stress but not involved in ABA-dependent signaling pathway. These results display the important roles of the PwEXP2 in plant development and multiple adversity stresses.
Microsporogenesis and flower development in Eucalyptus urophylla × E. grandis were examined using chromosome tableting to provide a method to predict the meiotic stages in this species. Although microsporogenesis was normal, cytokinesis during meiosis of pollen mother cells occurred simultaneously, with strong asynchronism observed in the two different lengths of stamens in a flower bud. In a single flower, the developmental period of microsporogenesis in anthers on the longer stamens was always ahead of those on the shorter stamens. Flower development was also asynchronous at different locations on a branch. Flower buds on the upper side of the branch were larger in diameter than those on the lower side. In addition, a correlation was observed between microsporogenesis development and flower bud diameter growth. The pachytene stage was first observed when the diameter of the flower buds increased to 3.0 mm, and the majority of the meiotic stages were observed when bud diameters ranged from 3.5 to 5.0 mm. This study showed that the developmental stages of microsporogenesis in Eucalyptus urophylla × E. grandis could be distinguished readily, which may be applicable to future breeding studies.
Palmatine is a valuable ingredient in Chinese medicine that is produced by Phellodendron amurense Rupr. The contents of palmatine content in root bark, trunk bark, perennial branch bark, annual branches, and leaves of the trees with different ages and geographies in Northeast China were measured by high-performance liquid chromatography. The contents of palmatine in the barks of root, trunk, and perennial branch were significantly higher than those in annual branches and leaves. The contents of palmatine in trunk bark and root bark from Lesser Khingan Mountains increased with age, which is significantly opposite to other three vegetation types. The contents of palmatine in perennial branch bark, annual bark and leaves had no significant regularity. Moreover, the contents of palmatine in samples of root bark, trunk bark, perennial branch bark and annual bark varied significantly with latitude. The nature populations of P. amurense growing at low latitude contained significantly more palmatine than those growing at high latitude. These results provide a scientific basis for the reasonable cultivation and efficient utilization of P. amurense.
Syringa is an important aromatic woody angiosperm that is widely planted in gardens. Its dry flowers are traditionally used to manufacture infusions and spices in China. In this study, the floral volatiles emitted from nine different Syringa species and varieties, viz. S. chinensis, S. p rotolaciniata, S. o blata, S. o blata var. giraldii, S. o blata var. plena, S. v ulgaris ‘Mrs Harry Bickle’, S. v ulgaris ‘Bright Centennial’, S. v ulgaris ‘White Spires’, and S. v ulgaris ‘President Lincoln’ were collected by the dynamic headspace technique, and then identified by automated thermal desorption–gas chromatography/mass spectrometry. There were significant differences in components and corresponding contents of floral scent emitted from the nine Syringa species and varieties. Among the detected components, β-ocimene exhibited the highest content, accounting for more than 70 % of the floral scent of S. p rotolaciniata, S. o blata var. giraldii, and S. v ulgaris ‘Bright Centennial’. A significant daytime variation of floral scent emitted from S. p ekinensis was recorded, especially for benzaldehyde, whose content first increased and then decreased. We studied the scent emitted from the in vitro flowers of S. v ulgaris ‘Pres Lincoln’ during the process of natural drying. Alcohol compounds were released in the greatest content, and the content of 2-ethyl-1-hexanol accounted for about 40 % of the total release amount. The results described the emission pattern and mechanisms of floral scent in Syringa.
We studied seed germination and early seedling growth of Pinus densata to explore the range of variability within the species and to inform afforestation practices. Phenotypes were evaluated at a forest tree nursery under conditions that support Pinus yunnanensis, one of the presumed parental species of P. densata. Seeds were collected from 20 open-pollinated trees within each of eight autochthonous populations representing the natural distribution of P. densata in China to assess variation in germination traits and early seedling growth, and to examine the relationships among these traits. Results showed that seeds from all populations germinated and seedlings established successfully. There were significant differences among populations in 13 of 14 traits evaluated. Seed germination and early seedling growth were strongly related to seed size and seed weight. Bigger seeds germinated earlier and faster than small seeds, and seedling size was positively correlated with seed size. Some germination traits were strongly and significantly correlated with climatic variables associated with the provenance of the studied populations. Based on these observations, we conclude there were large, significant, and biologically important differences among P. densata populations in seed germination and seedling growth traits. The observed variability probably reflects a high degree of adaptive differentiation among populations that is likely to be relevant for future afforestation.
From four Korean pine (Pinus koraiensis) orchards, 60 clones were selected and analyzed for the fatty acid and amino acid components of the seeds to reveal the variations and correlations of the seed characteristics among the clonal source orchards and clones. The nutritional components of the seeds of the P. koraiensis trees exhibited rich genetic variation; the variation coefficient of the fatty acids was 2.24–66.83 %, while the variation coefficient of the amino acids was 14.70–38.88 %. Relatively high genetic-improvement potential exists for the nutritional components of the seeds. The phenotypic differentiation of the fatty acid and amino acid components reveals that variation within the population (85.18 %) was the primary source for the variation of the fatty acid components; variation among the orchards (63.08 %) was the primary source of the variation of the amino acid components. Data drawn from various clonal source orchards all showed that the seed characteristics were highly controlled by heritability (h2 > 80 %), and the seed characteristics of the P. koraiensis trees exhibited a similar genetic gain trend. The principal components were analyzed to obtain the comprehensive principal component value for each clonal seed orchard. Twelve clones were selected based on a clonal selection rate of 20 %. Correlation and multiple stepwise-regression analyses were conducted, considering different location conditions, to reveal the stable correlations between the seed characteristics to facilitate improvements of the seed yield of P. koraiensis trees and the clonal selection. Species of real characteristics in P. koraiensis were controlled by higher heritability. Genetic gain was obtained by selecting of superior clones.
In the Sahel of Africa, where 90 % of the population depends on natural resources for their livelihood, a large part of the soils are structurally unstable, prone to crusting and hard setting, and have low water holding capacity, which hamper vegetation establishment. The effect of soil restoration techniques on survival and growth of seedlings of Acacia nilotica, Acacia tortilis and Jatropha curcas was tested in completely barren, degraded land in a Sahelian ecosystem in Burkina Faso. A total of 522 seedlings (174 plants of each plant species) were planted in a randomized complete block design with three replicates combining three soil preparation techniques: half-moon, zaï and standard plantation. Survival and growth rates evaluated over 20 months were significantly higher using the half-moon technique compared with the other two techniques. Survival rates of plant species planted using half-moon technique were 62.5, 28.57 and 10.71 % for A. nilotica, A. tortilis and J. curcas respectively, but in zaï and standard planting, seedling survival was zero. The low survival rate of J. curcas using the half-moon technique may indicate that J. curcas is unsuitable for barren and degraded land, whereas A. nilotica and A. tortilis appear to be promising tree species for rehabilitation of degraded land.
Plant roots have been recognized to be modular, and a third order root cluster has been proposed to be the basic root module unit based upon the life cycle. This experiment examines root modularity of the nutrient-uptake function using stable isotope 15N. Solidago canadensis root clusters of second or third orders—from the same third or fourth order roots, respectively—were treated with 15NH4 15NO3, NH4NO3, and de-ionized water for 15 and 180 min. The δ15N values of the root clusters were then analyzed and compared. The δ15N values of 15N-treated root clusters of both second and third orders were hundreds of times higher than that of the 15N untreated root clusters. However, the differences of the δ15N values among 15N untreated root clusters (though expressed some significant variations), did not indicate the 15N shared by the sister root clusters came from a common higher-order root. These results demonstrated functional modularity of root nutrient uptake, revealed a second order root, perhaps even a first order root to be a base module unit in terms of root nutrient uptake. The results also suggested that the concept of root modularity is function-specific. This experiment further revealed the importance of treatment timing in stabilizing the internal 15N/14N ratio in roots and avoiding top-down transportation of 15N back into roots to secure unbiased measurements.
The effects of understory plant litter on dominant tree litter decomposition are not well documented especially in semi-arid forests. In this study, we used a microcosm experiment to examine the effects of two understory species (Artemisia scoparia and Setaria viridis) litter on the mass loss and N release of Mongolian pine (Pinus sylvestris var. mongolica) litter in Keerqin Sandy Lands, northeast China, and identified the influencing mechanism from the chemical quality of decomposing litter. Four litter combinations were set up: one monoculture of Mongolian pine and three mixtures of Mongolian pine and one or two understory species in equal mass proportions of each species. Total C, total N, lignin, cellulose and polyphenol concentrations, and mass loss of pine litter were analyzed at days 84 and 182 of incubation. The chemistry of pine litter not only changed with the stages of decomposition, but was also strongly influenced by the presence of understory species during decomposition. Both understory species promoted mass loss of pine litter at 84 days, while only the simultaneous presence of two understory species promoted mass loss of pine litter at 182 days. Mass loss of pine litter was negatively correlated with initial ratios of C/N, lignin/N and polyphenol/N of litter combinations during the entire incubation period; at 182 days it was negatively correlated with polyphenol concentration and ratios of C/N and polyphenol/N of litter combinations at 84 days of incubation. Nitrogen release of pine litter was promoted in the presence of understory species. Nitrogen release at 84 days was negatively correlated with initial N concentration; at 182 days it was negatively correlated with initial polyphenol concentration of litter combinations and positively correlated with lignin concentration of litter combinations at 84 days of incubation. Our results suggest that the presence of understory species causes substantial changes in chemical components of pine litter that can exert strong influences on subsequent decomposition of pine litter.
Understanding the relationship between tree height (H) and diameter at breast height (D) is vital to forest design, monitoring and biomass estimation. We developed an allometric equation model and tested its applicability for unevenly aged stands of moso bamboo forest at a regional scale. Field data were collected for 21 plots. Based on these data, we identified two strong power relationships: a correlation between the mean bamboo height (H m) and the upper mean H (H u), and a correlation between the mean D (D m) and the upper mean D (D u). Simulation results derived from the allometric equation model were in good agreement with observed culms derived from the field data for the 21 stands, with a root-mean-square error and relative root-mean-square error of 1.40 m and 13.41 %, respectively. These results demonstrate that the allometric equation model had a strong predictive power in the unevenly aged stands at a regional scale. In addition, the estimated average height–diameter (H–D) model for South Anhui Province was used to predict H for the same type of bamboo in Hunan Province based on the measured D, and the results were highly similar. The allometric equation model has multiple uses at the regional scale, including the evaluation of the variation in the H–D relationship among regions. The model describes the average H–D relationship without considering the effects caused by variation in site conditions, tree density and other factors.
Turkey ranked third place in the world for chestnut production after China and South Korea and the country has unique chestnut forests including valuable and diverse chestnut genotypes. This study was conducted to select superior chestnut genotypes within seedling populations found in natural wild grown chestnut forest located in Isparta province in Turkey during 2010–2011 years. A total of 2500 wild grown chestnut trees were examined on the field first year and among them the most promising 22 genotypes were chosen according to relatively high yield capacity, earliness, tolerance to chestnut blight (Cryphonectria parasitica), ink disease (Phytopthora cambivora), and fruit quality characteristics. The selected 22 genotypes were evaluated for their detailed morphological, phenological and pomological traits in 2010 and 2011. According to average of 2 years, nut weight, the number of nut per kilogram, nut width, nut length, nut height and nut shell thickness of 22 promising genotypes ranged from 10.26 to 22.32 g, 97.47 to 44.80/kg, 26.80 to 42.47, 16.92 to 25.91, 27.74 to 39.73, and 0.26 to 1.01 mm, respectively. The ash, crude protein, and total fat content of kernels were between 0.85 to 1.94, 3.69 to 7.06 and 1.32 to 4.52, respectively. The genotypes were evaluated with weighted ranking method and the highest general quality score was observed in genotypes of IY17, IY01, IY42, IY43 and IY12.
Biomass production and nutrient (N, P, K, Ca and Mg) accumulation, distribution and cycling were quantified in young, mature and over-mature (10-, 22-, and 34-year old) Chinese fir [Cunninghamia lanceolate (Lamb.) Hook] plantations in southern China. Total stand biomass of young, mature and over-mature stands was 38, 104 and 138 t ha−1 respectively. Biomass production increased significantly with age. Stem wood represented the highest percentage of stand biomass, accounting for 41, 55 and 63 % in the young, mature and over-mature plantations respectively. Nutrients concentration was highest in live needles and branches, and lowest in stem wood. The plantations accumulated more N, followed by K, Ca, Mg, and P. Nutrient return amount, nutrient utilization efficiency, nutrient turnover time, the ratio of nutrient return and uptake increased with stand age, which implies that young Chinese fir deplete soil nutrients to maintain growth, and efficiently utilize nutrients to decrease dependence on soil nutrients as they age. Harvesting young Chinese fir plantations would therefore lead to high nutrient loss, but prolonging the rotation length could improve soil recovery, and help sustain productivity in the long-term. Improved nutrient return through litterfall as stands get older may also be beneficial to nutrient pool recovery.
Forest fire, an important agent for change in many forest ecosystems, plays an important role in atmospheric chemical cycles and the carbon cycle. The primary emissions from forest fire, CO2, CO, CH4, long-chained hydrocarbons and volatile organic oxides, however, have not been well quantified. Quantifying the carbonaceous gas emissions of forest fires is a critical part to better understand the significance of forest fire in calculating carbon balance and forecasting climate change. This study uses images from Enhanced Thematic Mapper Plus (ETM+) on the Earth-observing satellite LANDSAT-7 for the year 2005 to estimate the total gases emitted by the 2006 Kanduhe forest fire in the Daxing’an Mountains. Our results suggest that the fire emitted approximately 149,187.66 t CO2, 21,187.70 t CO, 1925.41 t C xH y, 470.76 t NO and 658.77 t SO2. In addition, the gases emitted from larch forests were significantly higher than from both broadleaf-needle leaf mixed forests and broadleaf mixed forests.
The occurrence of lightning-induced forest fires during a time period is count data featuring over-dispersion (i.e., variance is larger than mean) and a high frequency of zero counts. In this study, we used six generalized linear models to examine the relationship between the occurrence of lightning-induced forest fires and meteorological factors in the Northern Daxing’an Mountains of China. The six models included Poisson, negative binomial (NB), zero-inflated Poisson (ZIP), zero-inflated negative binomial (ZINB), Poisson hurdle (PH), and negative binomial hurdle (NBH) models. Goodness-of-fit was compared and tested among the six models using Akaike information criterion (AIC), sum of squared errors, likelihood ratio test, and Vuong test. The predictive performance of the models was assessed and compared using independent validation data by the data-splitting method. Based on the model AIC, the ZINB model best fitted the fire occurrence data, followed by (in order of smaller AIC) NBH, ZIP, NB, PH, and Poisson models. The ZINB model was also best for predicting either zero counts or positive counts (≥1). The two Hurdle models (PH and NBH) were better than ZIP, Poisson, and NB models for predicting positive counts, but worse than these three models for predicting zero counts. Thus, the ZINB model was the first choice for modeling the occurrence of lightning-induced forest fires in this study, which implied that the excessive zero counts of lightning-induced fires came from both structure and sampling zeros.
We described potential changes in the geographic distribution and occurrence probability of Pinus koraiensis Sieb. et Zucc. and Eleutherococcus senticosus (Rupr. et Maxim.) Maxim. in the counties of northeast China. This information was used to identify priority areas for protection and provide protection and management recommendations within each studied county. The two species were mapped in 2884 study plots throughout this region over a 4-year period (38°40′N–53°30′N, 115°05′E–135°02′E). We used the species distribution models (Maxent), systematic conservation planning models (Marxan), and Geographic Information Systems (ArcGIS 10.0). The distributions of two species were correlated in the study area, enabling unique and economically viable joint conservation measures to be implemented. Three models were combined to identify feasible priority conservation sites. We used local spatial statistics to assess all identified conservation areas in relation to potential climate change based shifts in the geographic distribution of the two species. Model-based conservation strategies were used to identify effective measures to protect and utilize these two tree species in the study region. This study presents a novel technique for assessing wild plant distributions, in addition to serving as a model for the conservation of other species within the framework of general forest management, ecological construction, and geographical surveying.
The deciduous linden tree (Tilia amurensis Rupr.) is protected at National Level II in China as a species of ecological and economic importance. The objective of this study was to assess and compare the ectomycorrhizal communities associated with T. amurensis in natural versus urban forests of central Heilongjiang Province. The percentage of T. amurensis colonisation by ectomycorrhiza was more than 60 % in urban forests, compared to 34–49 % in natural forests. Use of a combination of morphological and molecular methods documented 18 ECM (ectomycorrhizal) types among three sites; 12–13 ECM species were identified in the natural sites versus 9 species in the urban site. Four ECM species (Boletus sp., Tuber sp., Inocybe sp.2, Leccinum sp.1) were the dominant mycorrhizal symbionts, and Cenococcum geophilum and Russula sp. were found only in the natural forests.
We used thermal images of bamboo culms of Guadua angustifolia Kunth to analyze the relationship between culm surface temperature and maturity, driven by the hypothesis that young culms may exhibit lower surface temperatures than old ones. The culm surface temperature shows small but constant differences between three age classes of 1, 2, and 3 years. Our findings indicate that surface temperature may be applied as an additional indicator to support the determination of maturity of guadua culms besides the visual assessment of the culms.
We evaluated the potential use of amino silane coupling agent (SiNH) to improve physical and mechanical properties of UF-bonded wheat straw (Triticum aestivum L.) poplar wood particleboard. We examined the effects of varied content of silane coupling agent content and ratios of straw to poplar wood particles on particleboard properties. The ratios of straw to poplar wood particles were 100:0, 85:15, 70:30 and 55:45. Silane coupling agent content was tested at three levels, 0, 5 and 10 %. The experimental panels were tested for their mechanical strength, including modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding (IB) and physical properties according to procedures specified in DIN 68763 (Chipboard for special purposes in building construction: concepts, requirements, testing, 1982–03,
Chemical extraction, bioremediation, and electrodialytic processes have been extensively studied for removal of copper, chromium, and arsenic from wood treated with chromated copper arsenate (CCA). However, one problem has not been addressed: the effects of wood species and retention levels on remediation efficiency. The objectives of this study were to investigate the effects of wood species and retention levels on removal of copper, chromium, and arsenic from CCA-treated wood samples using sodium hypochlorite. Our results showed that sodium hypochlorite (NaOCl) was very effective for removal of copper, chromium, and arsenic from CCA-C treated milled wood samples for all three species used in this study. The Cu, Cr, and As extraction efficiencies for red pine were 95 % Cu, 97 % Cr and 94 % As, for maple were 95 % Cu, 97 % Cr, and 98 % As at 4.0 kg m−3 retention levels, and for aspen were 95 % Cu, 92 % Cr, and 91 % As at 9.6 kg m−3 retention level, respectively. However, the results showed that wood species and initial retention levels of CCA-treated wood products played very important roles in terms of removal of Cu, Cr, and As.
In South Africa, non-timber forest products, especially mopane worms (Imbrasia belina) have become an important source of food and cash income for rural people living in or near the mopane woodlands. However, the continued harvesting has implications for long term management of the mopane woodlands in the northern parts of South Africa. In order to keep a balance between mopane worm harvesting and biodiversity, an understanding of socio-economic factors influencing the harvest at household level is vital to reducing depletion and overexploitation of the mopane woodland resources. This study evaluated the socio-economic factors influencing mopane worm harvesting decisions in rural households in Limpopo Province, South Africa using a binary logistic regression model based on a household survey of 120 respondents. Age, gender, education, income from mopane worm sales, social capital (group affiliation), household size, lack of institution/law to regulate use, distance to the nearest harvesting site, and regional locations were statistically significant factors influencing household mopane worm harvest decisions. Implications for policy are discussed.
Natural, protected areas offer many possibilities for recreation in rural areas such as camping, one of the most popular activities. The system established for protected areas in Turkey aims to provide a foundation for conserving areas for recreation. One such area, Abant Natural Park, is convenient for visits from Turkey’s two most populated metropolitan areas, Istanbul and Ankara. It also attracts tourists from other regions and countries. The aim of the present study was to evaluate the vegetation loss and land cover changes due to picnic/camping, transhumance, and construction over 40 years (1966–2004) in the park using data on visitor numbers, vegetation patches, corridors and connectivity. For evaluating landscape variables, remote sensing data and aerial photos were used. When aerial photos were imported into the ERDAS Imagine program, ground control points identified, and individual images orthorectified, land degradation was not found in the use of camping areas. Moreover, manmade areas (road, car park and hotel) observably increased, thus decreasing the forest lands. The findings show that the land use types that have had the greatest ecological impact are transhumance and construction of hotels, which also require infrastructure development. The intensity of the ecological effects mandates precautions to lessen the impacts and the need for continuing assessment to ensure sustainable use of the area.
Geometric design of forest roads and design of their landscapes can reduce noise pollution and its harmful effects on human health. We investigated the effects of technical and biological parameters such as geometric road design and various roadside tree stands on reducing noise pollution according to the tree density and distance from roadway in Darabkola Forests, Sari, Iran. We recorded the noise generated by a car (Land Rover) relative to changes in longitudinal slope, horizontal curve radius and type of road pavement. We also measured noise levels according to roadside tree density and stand type (coniferous and hardwood) in 40 rectangular plots of three widths (25, 100 and 300 m) and 50 m length that were randomly demarcated along forest roads. The changes in noise level were recorded using a decibel meter with an accuracy of ±1.5 dB and resolution of 0.1 dB. Noise levels were higher alongside unpaved roads than alongside paved roads. There was an inverse relationship between the measured noise level and horizontal curve radius. The rate of noise level on horizontal curve with a radius less than 30, 30–45 m and more than 45 m were 64.8, 70.8 and 75.9 dB, respectively. The noise level increased with the increasing longitudinal slope of the road. There was a significant difference between the noise level on slopes less than 3 % (67 dB) and 3–8 % (71.2 dB) in comparison with slopes greater than 8 % (77.8 dB), (p < 0.05). Pinus brutia L. reduced the noise level more (about 6 dB) in stands of 1/3 density of mixed hardwoods within 25 m from middle of the road. Careful design of geometric properties of forest roads as well as planting coniferous trees with hardwoods is a suitable solution for reducing noise pollution.