Thick Bark Research Articles

Evidence for bark thickness as a fire-resistance trait from desert to savanna in fire-prone inland Australia

Although bark thickness and fire-activity are correlated in many ecosystems worldwide, substantial data-gaps remain, especially for dryland biomes, preventing generalisation of this relationship at the global scale. We examined bark thickness trends in trees and shrubs across a large-scale fire-rainfall gradient from desert to dry savanna in northern Australia. Bark thickness increased with local fire activity but was unrelated to mean annual rainfall or the mean normalised difference vegetation index (surrogates of resource-productivity). In high-fire regions, thin-barked trees were restricted to localised low-fire patches. Thicker bark was associated with sites characterised by flammable Triodia hummock grassland (spinifex). Within this flora, bark thickness reflected a trade-off in trait allocation to fire resistance versus fire resilience. For trees, thicker bark (fire resistance) was strongly associated with epicormic resprouters. In contrast, fire-resilient species that were either basal resprouters or reseeders had thinner bark. With increasing aridity there was a shift in dominance from epicormic resprouters to thinner-barked shrub and mallee species that either basally resprout or are killed by fire. Pairwise congeneric species comparisons showed a consistent relationship of thicker bark under high fire activity. This same pattern also emerged from a multi-species comparison within the dominant tree genus Eucalyptus. Overall, for this system, species with thick bark at the sapling stage dominate where fire is frequent. Thus, we confirm that fire can be a major driver of plant traits in fire-prone drylands.

Using trait‐based ecology to restore resilient ecosystems: historical conditions and the future of montane forests in western North America

AbstractHistorical reference conditions have provided empirical benchmarks for guiding ecological restoration but the relevance of historical conditions has been questioned in this era of rapid global change. Trait‐based ecology offers an alternative approach for setting restoration objectives. If we understand which phenotypic traits confer high survival in a given environment, then we can restore assemblages of species with favorable trait combinations to reduce mortality risk, achieve functional outcomes, and enhance restoration success. Our objective was to compare restoration prescriptions based on historical reference conditions versus trait‐based objectives in southwestern United States mixed conifer forests. To optimize survival and enhance resilience under projected increasing frequencies of fire and drought, we constructed and evaluated models based on combinations of three traits: thick bark, dense wood, and moderate leaf nitrogen concentration. Models with multiple traits accurately derived historical species abundance distributions, which is a necessary condition for the application of trait‐based models under less certain future conditions. Model results indicated that trait‐based restoration objectives could be achieved in two ways: by manipulating abundances of species that already coexist at a site or by adding native species from warmer climates to the local species pool. The latter approach may create no‐analog communities of native species. Restoration goals based on either historical reference conditions or future projections are special cases of a more general class of desired future conditions that are derived from trait‐based objectives. Functional ecology provides a general, flexible, and theory‐based approach to restoring resilient ecosystems at a time of rapid environmental change.

Spinescent East African savannah acacias also have thick bark, suggesting they evolved under both an intense fire and herbivory regime

Spinescent East African savannah acacias also have thick bark, suggesting they evolved under both an intense fire and herbivory regime

Trees, grass, and fire in humid savannas—The importance of life history traits and spatial processes

We develop a model to investigate how trees can invade the grass stratum in humid savannas despite repeated fires. In the literature, it is clear that fire reduces tree canopy in savannas. However, fire alone may not be sufficient to prevent tree invasion because there are ecological mechanisms that hamper fire spread by undermining the continuity and density of the grass stratum, which is the means of fire propagation in savannas. Our model is spatially explicit and individual-based, and includes two important factors characterizing the interactions between fire, trees, and grass in savannas, viz. space and the strategies that trees use to cope with fire. The strategies that trees employ against fire emerge from life history traits. According to these strategies, we classify savanna trees into three categories: resprouters, which are able to resprout after their aboveground biomass is burned; resisters, which are able to resist fire due to a thick bark even in the juvenile stages; avoiders, which are very fire-vulnerable in the juvenile stages, but are able to grow fast in the absence of fire. Our results show that trees can invade the grass stratum and finally suppress fire spread because one of the following occurs: (1) trees may resprout and form a population that persists despite repeated effective fires; (2) trees may be fire-resistant; (3) if trees are fire-vulnerable they may cluster and grow in density until fire is prevented. Our results show that fire can be effective in preventing the initiation of the invasion process in the grass stratum. However, once the invasion process has begun, fire alone is not able to reverse this process because of the strategies employed by trees. Furthermore, when a high tree density is reached, grass density is insufficient to allow effective fire spread. From a management point of view, our results imply that fire must be coupled with other factors (browsing, mechanical thinning) to reduce tree density in encroached areas.

Long-term variations of rainfall interception in different growth stages of Chinese fir plantations

The dynamic properties of rainfall interception were investigated at three growth stages in Chinese fir plantations. The results showed that the annual interception ratio was significantly higher in mature stands than in young stands. For a storm event, interception rainfall amount increased with increasing rainfall, but interception ratio decreased. In contrast to dry season conditions, the interception amount was high in the wet seasons, while the interception ratio was low. The rates of change in interception ratio were extremely rapid in small rainfall events. There was little stemflow in Chinese fir forests due to the pyramid-shaped crowns and thick rough bark of the trees. The power model was suitable to describe the interception process for an individual rainfall event for stands of any age. Our results indicate that the interception process varied for stands of different ages in Chinese fir plantations due to contrasting canopy structures.

Functional and environmental determinants of bark thickness in fire-free temperate rain forest communities.

In fire-prone ecosystems, variation in bark thickness among species and communities has been explained by fire frequency; thick bark is necessary to protect cambium from lethal temperatures. Elsewhere this investment is deemed unnecessary, and thin bark is thought to prevail. However, in rain forest ecosystems where fire is rare, bark thickness varies widely among species and communities, and the causes of this variation remain enigmatic. We tested for functional explanations of bark thickness variation in temperate rain forest species and communities. We measured bark thickness in 82 tree species throughout New Zealand temperate rain forests that historically have experienced little fire and applied two complementary analyses. First, we examined correlations between bark traits and leaf habit, and leaf and stem traits. Second, we calculated community-weighted mean (CWM) bark thickness for 272 plots distributed throughout New Zealand to identify the environments in which thicker-barked communities occur. Conifers had higher size-independent bark thickness than evergreen angiosperms. Species with thicker bark or higher bark allocation coefficients were not associated with "slow economic" plant traits. Across 272 forest plots, communities with thicker bark occurred on infertile soils, and communities with thicker bark and higher bark allocation coefficients occurred in cooler, drier climates. In non-fire-prone temperate rain forest ecosystems, investment in bark is driven by soil resources, cool minimum temperatures, and seasonal moisture stress. The role of these factors in fire-prone ecosystems warrants testing.

Beating the blaze: Fire survival in the fan aloe (Kumara plicatilis), a succulent monocotyledonous tree endemic to the Cape fynbos, South Africa

AbstractFire is central to the ecology of Mediterranean‐type climate ecosystems, but little is known about the fire ecology of succulent plants therein. This study investigated the fire ecology of an arborescent succulent monocot, Kumara plicatilis (L.) G. D. Rowley (Asphodelaceae), a Cape fynbos endemic. Habitat suitability was assessed to determine whether the species tolerates or ‘avoids’ fire, and fire survival traits (bark thickness and tissue water content) were measured. The population size structure and density of three K. plicatilis populations were assessed after natural fires, and resprouting potential was investigated. Kumara plicatilis adopts a dual fire survival strategy, occupying rocky sites to ‘avoid’ fire and possessing morphological features that afford fire tolerance, e.g. well‐protected apical meristems and thick corky bark. Bark thickness of burned individuals in situ was similar to unburned plants, suggesting that K. plicatilis bark provides effective insulation against fire. Mortality rates were 64%, 40% and 11%, and decreased as rock cover at the population level increased. All three populations showed reduced plant density post‐fire, with greater density reductions associated with lower rock cover. Small plants appear most vulnerable to fire damage due to lower absolute bark thickness and plant heights within the flame zone. Kumara plicatilis is an apical sprouter, recovering after fire or mechanical stem damage by onward growth from surviving stem apices, rather than resprouting. Post‐fire population recovery therefore likely depends on inter‐fire recruitment.

Fire regime, soil fertility and growth form interact to shape fire and growth traits in two co-occurring Banksia species

Inter- and intra-specific comparisons were made between several co-occurring populations of two Banksia species growing in Eastern Australian dry sclerophyll open woodland that experiences a grass-fueled surface-fire regime. The two species differ in life-history from a short basal resprouter (B. Neoanglica) to a tall fire-survivor (B. integrifolia). Growth (LMA = leaf mass per unit mass area), persistence (bark thickness) and recruitment (serotiny) traits were determined across independent gradients in soil fertility and fire frequency. Trait correlations for the two species showed distinct patterns, from each other and across environments, with the resprouter having higher LMA and infructescence retention but lower bark thickness. However, there were no consistent intra-specific patterns with variation in fire and soil nutrients. LMA only varied in B. integrifolia with soil fertility, and fire frequency had no effect on either species. Relative bark thickness varied with plant size but not among sites. There was a trend of increasing pyriscence with fire in B. neoanglica and with lower nutrients soils but not in B. integrifolia. Clearly the two species respond differently to variability in nutrients and fire. Nevertheless, growth form appears to be the strongest determinant of both growth (LMA) and fire traits (thicker bark; pyriscence) in these co-existing Banksia species.

Effect of landscape fires on the demography of the endangered New Caledonian conifer Callitris sulcata

New Caledonia is a global biodiversity hotspot and an epicentre for Gondwanan conifers, many of which are threatened by mining and by altered fire regimes. We studied the distribution, abundance and demography of the endangered Callitris sulcata. The largest populations are restricted to one river system in the south-east of the island, with satellite populations in adjoining rivers. The local distribution is controlled by the fire protection afforded by terrain features such as scree slopes, creeklines and small cliffs. Adult trees, which have comparatively thick bark, are able to tolerate and recover from infrequent surface fires, but severe fires kill trees and the seeds they store, a pattern similar to that in many Australian Callitris species. Radiocarbon dating revealed the species is slower growing than Australian Callitris species, possibly due to the extreme infertility of the ultramafic soils. The species is of high cultural value to the indigenous population who also prizes the durable and aromatic timber, and harvests have been traditionally regulated. Illegal cutting of trees has become a problem, but uncontrolled fires, which have caused substantial population declines, dwarf this threat. Given these threats, conservation of the species hinges on ensuring some populations remain remote and rarely visited by humans.

Habitat selection by an arboreal lizard in an urban parkland: not just any tree will do

The nocturnal, arboreal Marbled Gecko, Christinus marmoratus, is a common reptile in urban areas in southern Australia. This study compared the demographics and the distribution of geckos occupying different tree species in a modified urban park, the Adelaide Parklands, with those of a population occurring in Ferguson Conservation Park, a nearby native vegetation remnant surrounded by suburbia. The geckos in the modified urban and native remnant parks demonstrated different demographic characteristics. These differences were explained by tree circumference and the amount and type of bark cover on the tree trunk. In the Parkland, geckos were limited by the availability of thick exfoliating bark, its clearly preferred microhabitat as demonstrated by a laboratory choice experiment. The preference for trees with larger circumference, more cover, and thick bark were probably linked to thermoregulation, predator avoidance, and food resources. This study supports the premise that to support populations of urban animals, tree species selection needs careful consideration with regard to its microhabitat capabilities as well as food provision and other resource supports it can provide.

Relative Bark Thickness is Correlated with Tree Species Distributions along a Fire Frequency Gradient

AbstractThe probability of stem survival after fire is strongly influenced by energy allocation to bark because bark thickness affects heat transfer during fire. Greater relative investment in inner bark versus outer bark should also enhance survival because of greater moisture content of inner bark. We measured stem diameter, bark thickness, and habitat preference of five species typical of long-leaf pine savannas, and six species characteristic of adjacent wetlands (pocosins), and calculated relative bark thickness, the inner bark proportion, radial growth, and bark accumulation of each species. We hypothesized that savanna species have thicker bark and greater relative investment in inner bark than pocosin species, because fires occur more frequently in savannas than pocosins. As hypothesized, savanna species have relatively thicker bark than pocosin species. Relative bark thickness and the rate of bark accumulation were correlated with the mean location of a species along the pocosin-to-savanna gradient. However, the inner bark proportion did not differ between savanna and pocosin species. Our results indicate that relative bark thickness is likely the primary bark trait affecting fire-induced topkill and influencing the distribution of species along the pocosin-to-savanna gradient.

Soil fertility induces coordinated responses of multiple independent functional traits

Summary A central goal of functional ecology is to determine how independent functional traits are selectively filtered by environmental conditions to improve our understanding of the mechanisms of community assembly. Soil fertility clearly influences community composition, but it is unclear which plant functional traits are most strongly associated with gradients of increasing nutrient limitation. We hypothesized that leaf economic traits and stem tissue density would be strongly associated with soil fertility given their direct relationship to soil resource acquisition and use. In contrast, we hypothesized that functional traits that are commonly associated with competition for light (maximum height), shade tolerance (seed mass) and resistance to disturbance (bark thickness) would be unrelated to soil fertility. We measured 13 functional traits from 30 tree species occurring in 40 plots across a soil fertility gradient in a mature warm temperate rain forest in Northland, New Zealand. Principal component analysis was used to assess the dimensionality and independence of the functional traits and the soil properties, and regression was used to determine the relationships between community‐weighted mean traits and the soil fertility gradient. We observed a coordinated response of multiple independent traits to soil fertility. Consistent with our hypothesis, species associated with low‐fertility soils had comparatively ‘slower’ leaves (i.e. low SLA and leaf N and P, and high LDMC and thickness) and higher stem tissue density than species associated with high‐fertility soils. Unexpectedly, we observed that species associated with low‐fertility soils had larger maximum heights, thicker bark and lower seed mass. Tall trees can persist on poor soils. Thick bark may be a defensive strategy for trees growing in resource‐limited sites and large‐seeded shade‐tolerant species can persist in fertile soils where light is more limiting. Synthesis. Species sorting can occur over short distances in ecosystems where topographically driven variation in soil fertility leads to complete compositional turnover. Inferences about species distributions based on single‐trait spectrums can be misleading when environmental gradients sort species by filtering multiple independent traits simultaneously. Identifying the multidimensional trait combinations that promote fitness will advance both theory development and ecological restoration.

Outer bark thickness decreases more with height on stems of fire-resistant than fire-sensitive Floridian oaks (Quercus spp.; Fagaceae).

• In ecosystems maintained by low-intensity surface fires, tree bark thickness is a determinant of fire-survival because it protects underlying tissues from heat damage. However, it has been unclear whether relatively thick bark i S: maintained at all heights or only near the ground where damage is most likely.• We studied six Quercus species from the red and white clades, with three species characteristic of fire-maintained savannas and three species characteristic of forests with infrequent fire. Inner and outer bark (secondary phloem and rhytidome, respectively) thicknesses were measured at intervals from 10 to 300 cm above the ground. We used linear mixed-effects models to test for relationships among height, habitat, and clade on relative thickness (stem proportion) of total, inner, and outer bark. Bark moisture and tissue density were measured for each species at 10 cm.• Absolute and relative total bark thickness declined with height, with no difference in height-related changes between habitat groups. Relative outer bark thickness showed a height-by-habitat interaction. There was a clade effect on relative thickness, but no interaction with height. Moisture contents were higher in inner than outer bark, and red oaks had denser bark than white oaks, but neither trait differed by habitat.• Quercus species characteristic of fire-prone habitats invest more in outer bark near the ground where heat damage to outer tissues is most likely. Future investigations of bark should consider the height at which measurements are made and distinguish between inner and outer bark.

Bark thickness and fire regime

Summary Bark is a vital and very visible part of woody plants, yet only recently has bark characteristics started to be considered as key traits structuring communities and biomes. Bark thickness is very variable among woody plants, and I hypothesize that fire is a key factor selecting for a thick bark, and thus, at the global scale, a significant proportion of the variability in bark thickness is explained by the variability in fire regimes. Previous research has focused on the importance of bark thickness mainly in surface‐fire regimes; here I generalize this idea and present a conceptual framework to explain how the different drivers that affect fire intensity have shaped bark thickness, in conjunction with other plant traits. I first review methods used to study bark thickness and then provide examples of bark thickness patterns from a wide range of ecosystems subject to different fire regimes (understorey fires, grass‐fuelled surface fires, grass‐fuelled crown fires and infrequent fires). There are some fire regimes that select for thick barks, while some only in the base of the trunk (e.g. understorey fires), others select for a thick bark on the whole plant (e.g. grass‐fuelled crown fires). There are also fire regimes in which allocating resources to a thick bark is not adaptive (e.g. woody‐fulled crown fires). Fire regime can explain a large proportion of the variability of bark thickness at the global scale, and thus, this trait varies across ecosystems in a predictable manner; however, the current paucity of data limits a fully accurate analysis.

Identifikasi Jenis Epifit Dan Tumbuhan Yang Menjadi Penopangnya Di Blok Perlindungan Dalam Kawasan Taman Hutan Raya Wan Abdul Rachman

Epiphytic is one among the plants that attaches and grows on other plants for sunlight, water, air, and minerals. The existence of epiphytes is very important for forest ecosystems due its ability to provide a place for the ants and the other organisme. The objective of this study were to identify the species of epiphytes, species of cantilever plant, and to know the number of cantilever plant species associated with the species of epiphytes in Wan Abdul Rahman Great Forest Park. This research was conducted at the protection block, Wan Abdul Rahman Great Forest Park, particularly in the area of Way Balau Sub-watershed. This research was conducted during September to October 2013. Epiphytes and cantilever plants species were inventoried in a sampling intensity of 0,2% taken from 796,50 ha of total area of protection blocks, therefore the large of sample plot is 1,593 ha. The size of each sample plot is 400 m2 or 20 m x 20 m, therefore the total number of sample plots are 40 plots. Observed variables were the species and the number of epiphytes , species of cantilever plant and its number, and the importance alue index for each species. The result of the study showed that plant are 7 species of epiphytes and 16 species of cantilever plant. The highest importance value index (IVI) of epiphytes is paku sepat (59,14%). The highest IVI of cantilever plant is pulai (30,91%). The most abundant cantilever plant growed by epiphytes is pulai (Alstonia scholaris), pinangsi (Villebrunea rubescens), enau (Arenga pinnata), and medang gabong (Litsea firma). Result of the study showed that epiphytic mostly found on the cantilever plant that has thicker bark, groove bark, stringy bark, and a tough bark.

The remarkable congruence of New and Old World savanna origins.

The remarkable congruence of New and Old World savanna origins.

Characterization of Overwintering Sites of the Invasive Brown Marmorated Stink Bug in Natural Landscapes Using Human Surveyors and Detector Canines

Halyomorpha halys is an invasive species from Asia causing major economic losses in agricultural production in the mid-Atlantic region of the United States. Unlike other crop pests, H. halys is also well-known for nuisance problems in urban, suburban, and rural areas, as massive numbers of adults often invade human-made structures to overwinter inside protected environments. Research efforts have focused on populations in human-made structures while overwintering ecology of H. halys in natural landscapes is virtually unknown. We explored forested landscapes in the mid-Atlantic region to locate and characterize natural overwintering structures used by H. halys. We also evaluated the use of detector canines to locate overwintering H. halys to enhance the accuracy and efficiency of surveys. From these studies, we indentified shared characteristics of overwintering sites used by H. halys in natural landscapes. Overwintering H. halys were recovered from dry crevices in dead, standing trees with thick bark, particularly oak (Quercus spp.) and locust (Robinia spp.); these characteristics were shared by 11.8% of all dead trees in surveyed landscapes. For trees with favorable characteristics, we sampled ∼20% of the total above-ground tree area and recovered 5.9 adults per tree from the trees with H. halys present. Two detector canines were successfully trained to recognize and detect the odor of adult H. halys yielding >84% accuracy in laboratory and semi-field trials. Detector canines also found overwintering H. halys under field conditions. In particular, overwintering H. halys were recovered only from dead trees that yielded positive indications from the canines and shared key tree characteristics established by human surveyors. The identified characteristics of natural overwintering sites of H. halys will serve as baseline information to establish crop economic risk levels posed by overwintering populations, and accordingly develop sustainable management programs.

Is the QBS-ar index a good tool to detect the soil quality in Mediterranean areas? A cork tree Quercus suber L. (Fagaceae) wood as a case of study

Cork oak (Quercus suber L., 1753) is a Mediterranean evergreen tree species with a thick and characteristic bark covering the trunk and branches. Despite the fact that cork oak is distributed over about 1.7 million hectares in the western Mediterranean Basin, information about soil biota in this particular habitat at present is scanty. This study was carried out in a cork tree wood in Bergeggi (Liguria, NW Italy), characterized by a Pluvioseasonal Oceanic Mediterranean bioclimate. The profile, texture, pH, total carbonate content, total organic carbon (C) and nitrogen (N) contents, soluble phosphorus (P) and cation exchange capacity were measured in order to characterize the soil. Soil biological quality was evaluated by studying microarthropod communities. Each month, from February 2007 to January 2008, 10 soil samples measuring 10 × 10 × 10 cm were collected from the wood being studied and arthropods were extracted using Berlese-Tullgren funnels. The biological quality of soil based on arthropods (QBS-ar) index, taxa abundance, Shannon diversity index (H’) and Pielou’s evenness index (J) were applied to assess soil biological quality in the cork oak being studied.A total of 29 taxonomic groups were identified. Some important groups, such as Pseudoscorpionida, Palpigradi, Miriapoda and Protura were detected every month, but only a few groups showed a clear abundance distribution trend throughout the year and globally it was impossible to define general trends. The results suggested that the condition of the soil was good, as generally observed in natural environments not subjected to significant impacts. It was also possible to demonstrate that the Mediterranean climate causes strong seasonal fluctuations in soil biota, resulting in corresponding differences in the QBS-ar index values. Therefore, the QBS-ar index could be considered to be a valid candidate for the biomonitoring of soil biodiversity in natural and anthropic soils, but in Mediterranean climates comparisons of different areas must be performed analyzing samples collected during the same period.

四种类型栓皮栎栲胶含量

PDF HTML阅读 XML下载 导出引用 引用提醒 四种类型栓皮栎栲胶含量 DOI: 10.5846/stxb201308242145 作者: 作者单位: 西北农林科技大学西部环境与生态教育部重点实验室,西北农林科技大学西部环境与生态教育部重点实验室,西北农林科技大学西部环境与生态教育部重点实验室,西北农林科技大学西部环境与生态教育部重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家林业局林业公益性行业科研专项（201004011） The content of tannin extract in four types of Quercus variabilis Author: Affiliation: Key Laboratory of Environment and Ecology Education Ministry in West China,College of Forestry,Norwest A F University,Key Laboratory of Environment and Ecology Education Ministry in West China,College of Forestry,Norwest A F University,Key Laboratory of Environment and Ecology Education Ministry in West China,College of Forestry,Norwest A F University,Key Laboratory of Environment and Ecology Education Ministry in West China,College of Forestry,Norwest A F University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了阐明不同类型（薄皮深裂、薄皮浅裂、厚皮深裂、厚皮浅裂）栓皮栎各器官栲胶含量， 系统采集了秦岭南坡商州区4种类型的栓皮栎不同径级植株根、主干木材、叶片、枝条和树皮样品， 用紫外光分光光度法（UV Spectrophotometry）测定了4种类型栓皮栎不同器官栲胶含量， 分析了林木生长与栲胶含量的关系。结果表明， （1） 4种类型栓皮栎的根、主干木材、叶片、枝条和树皮单宁含量平均值分别为2.64%-3.02%、1.74%-2.02%、6.63%-7.21%、4.69%-5.10%、8.87%-9.46%， 叶片、枝条和树皮均可以作为栲胶生产主要原材料。（2）不同类型各器官单宁含量存在极显著差异（P < 0.01）， 4种类型的树皮、叶片、枝条单宁含量均表现为： 厚皮深裂型 > 厚皮浅裂型 > 薄皮深裂型 > 薄皮浅裂型；根部和主干木材在4种类型间单宁含量表现为： 薄皮深裂型 > 薄皮浅裂型 > 厚皮深裂型 > 厚皮浅裂型；厚皮深裂类型的栓皮栎是提取栲胶的最佳类型。（3） 4种类型栓皮栎各器官单宁含量与胸径呈显著正相关， 各器官单宁含量随着栓皮栎胸径增大而增多， 并最终趋于稳定， 在第Ⅳ径级（胸径20.1-25 cm）时，栲胶含量均值最大。因此， 栲胶生产可以高效利用第Ⅳ径级及其以上径级的栓皮栎， 并对第Ⅳ径级以下栓皮栎进行定向培育和重点保护。 Abstract:Tannin extract is one of the significant forestry chemical products. The main component of tannin extract is tannin. Tannin, which is an important chemical material for forestry, can be extracted from the organs of Quercus variabilis widely in China. To illustrate the variation of tannin content, the barks, shell buckets, fruits, roots, stems and leaves of 72 Q. variabilis trees from the four types were sampled based on different diameters at breast height were on the south slopes of Qinling Mountains in October 2012. The content of tannin in the organs were analyzed by UV spectrophotometry, and the influence of tree growth on the tannin content was detected by Pearson correlation and linear regression. The result indicated that there was a great variation between the individuals of the four types. Our aim is to provide an reference and experiment basis for the directive cultivation and effective utilization of Q. variabilis resources. It was showed concretely as follows. (1) The average tannin content of 2.31%-2.72% was found in the roots of the four typesof Q. variabilis, as well as 1.31%-1.72% in the stems, 6.32%-6.89% in the leasves, 4.49%-4.92% in the branches and 8.17%-8.86% in the barks. The content of tannin in the leaves, branches and barks are much higher than that in the roots and stems obviously. Leaves, branches and barks were suggested as the major raw materials of tannin extract. (2) The significant difference of tannin content was observed among the different organs of the four types of Q. variabilis. In the leaves, branches and barks, the content of tannin ranged from high to low as the thick bark deep crack type, the thick bark shallow crack type, the thin bark deep crack type, the thin bark shallow crack type. The tannin content in the roots and stems of the four types ranged from high to low as the thin bark deep crack type, the thin bark shallow crack type, the thick bark shallow crack type, the thick bark deep crack type. Because of the tannin content in the leaves, branches and barks with a high level, the Q. variabilis with the thick bark deep crack type was the best one in the four types for tannin extract. (3) The tannin content of the different organs in the four types augmented with the increasing DBH of the trees, and the top value was observed in the DBH of 20. 1-25cm. The DBH and the height of trees affected the tannin content positively. The suggestion is that the Q. variabilis with DBH above 25cm should be applied fully and efficiently for tannin extraction, or it should be priority for directive cultivation and special protection. 参考文献 相似文献 引证文献

Insulation capacity of three bark types of temperate Eucalyptus species

Fire plays an increasingly important role in management of native forests and plantations around the world. Thick tree bark represents the most important defence against surface fires, although other bark traits (bark-type, moisture content, density) are also involved. The interplay of bark traits to reduce heat-induced cambium necrosis and related tree death remains poorly understood. Here we introduce a novel method using multiple sensors to accurately measure conductance of heat through the periderm and secondary phloem and to detect how individual bark traits influence the transfer of heat through those tissue types. We employed this method to document the capacity for bark insulation of three Eucalyptus species with different bark-type from temperate Australia, simulating a ‘worst-case’ scenario (750°C bark surface temperature for 900s). Thickness of these different bark types ranged from 3 to 65mm. Our results clearly show the importance of thickness and type of bark for prevention of cambium necrosis due to heat. Coefficients of determination that describe how bark thickness correlates with time to reach lethal temperatures (>60°C) at the cambium ranged from 0.61 (least effective: E. tricarpa, ironbark-type bark, average moisture content=34%, average bark density=0.58gcm−3) to 0.94 (most effective: E. leucoxylon, gum-type bark, average moisture content=54%, average bark density=0.42gcm−3) and both followed linear and curvilinear trajectories. The cooling effect of water in the periderm was found to slow conduction of heat towards the cambium. This effect has not previously been documented by empirical measurements and may have significant implications to survival of trees during “cooler” prescribed fires. Our study highlights between-species variation in ability to withstand heat from surface fires. Fire temperatures and duration thus have considerable capacity to change species composition of these Box-Ironbark forests via mortality.