The impact of shade on morphology,growth and biomass allocation in <Emphasis Type="Italic">Picea sitchensis</Emphasis>, <Emphasis Type="Italic">Larix</Emphasis> × <Emphasis Type="Italic">eurolepis</Emphasis> and <Emphasis Type="Italic">Thuja plicata</Emphasis>     

Seamus Kennedy  Kevin Black  Conor O’Reilly  Áine Ní Dhubháin 《New Forests》2007,33(2):139-153

To determine the effect of shade on morphology, growth and biomass allocation in Picea sitchensis, Larix × eurolepis and Thuja plicata, seedlings were grown in the open or under shadehouses providing 25%, 50% and 75% reductions of full-light for two growing seasons. For most of the characteristics assessed there was no significant interaction between species and shade indicating that the morphological responses to changing shade treatments were not species-dependent. After two growing seasons the mean height increment for the three species was significantly greater in 25% (76.1 cm) and 50% shade (74.9 cm) than in the open (69.5 cm). Root collar diameter increment, shoot, root and total biomass declined significantly with increasing shade while the opposite was true for the height:diameter ratio. In both western red cedar and hybrid larch the shoot:root ratio was significantly greater in the shade while in Sitka spruce this characteristic was not influenced by shade. While all species had significantly greater specific shoot areas in 75% shade than in 0% shade, this trend was particularly pronounced in hybrid larch. In hybrid larch and western red cedar, the normalised specific projected shoot area increased significantly with increasing shade. The opposite trend was observed for Sitka spruce. We conclude that in the main the species studied demonstrated similar shade acclimation responses despite their reported differences in shade tolerance.  相似文献   

Proteins in Norway spruce thermomechanical pulp     

Jonas Hafrén 《Journal of Wood Science》2007,53(2):143-146

Two methods of cytochemical staining using Coomassie dye and Cu⁺-bicinchoninic acid, respectively, showed that there are proteins in thermomechanical pulp (TMP) of Norway spruce. Protein isolated from TMP was analyzed for amino acid composition. There was about twice the amount of acidic amino acid material compared with basic amino acids, and the presence of glucosamine indicated that the isolated polypeptides also contained glycoproteins. The presence of proteins in ray cells and fiber tracheids in TMP adds to the chemical heterogeneity of the structurally complex high-yield pulp.  相似文献   

Rural livelihood benefits from participation in the taungya agroforestry system in Ondo State of Nigeria     

Victor A. J. Adekunle  Yekini Bakare 《Small-Scale Forestry》2004,3(1):131-138

This study examines the strategies and benefits of the taungya farming system to both the government and the rural economy in Nigeria. An interview survey was conducted in which data were collected from 115 randomly selected farmers in five villages in the Oluwa forest reserve, Ondo State, Nigeria. The study examines the extent of participation of rural dwellers in plantation development through taungya farming and the degree of success of this system as an afforestation method. The farmers were predominantly illiterate, within the age bracket of 35–54 years and with small farm holdings. Twenty nine percent relied totally on food from the forest reserve for their livelihood, while 71% also had farm holdings in free areas. Land within the reserve is allocated to farmers free of charge but compensation is paid to landlords on land from free areas. A statistically significant difference was detected in income from the two sources of farmland for the households and but not in the size of land allocated under taungya and free areas. About 184 farmers are involved in taungya annually, and 410 ha of Tectonia grandis has been established for the government of Ondo State.  相似文献   

A variance-covariance structure to take into account repeated measurements and heteroscedasticity in growth modeling     

Mathieu Fortin  Gaétan Daigle  Chhun-Huor Ung  Jean Bégin  Louis Archambault 《European Journal of Forest Research》2007,126(4):573-585

This study proposes a within-subject variance-covariance (VC) structure to take into account repeated measurements and heteroscedasticity in a context of growth modeling. The VC structure integrates a variance function and a continuous autoregressive covariance structure. It was tested on a nonlinear growth model parameterized with data from permanent sample plots. Using a stand-level approach, basal area growth was independently modeled for red spruce (Picea rubens Sarg.) and balsam fir [Abies balsamea (L.) Mill.] in mixed stands. For both species, the implementation of the VC structure significantly improved the maximum likelihood of the model. In both cases, it efficiently accounted for heteroscedasticity and autocorrelation, since the normalized residuals no longer exhibited departures from the assumptions of independent error terms with homogeneous variances. Moreover, compared with traditional nonlinear least squares (NLS) models, models parameterized with this VC structure may generate more accurate predictions when prior information is available. This case study demonstrates that the implementation of a VC structure may provide parameter estimates that are consistent with asymptotically unbiased variances in a context of nonlinear growth modeling using a stand-level approach. Since the variances are no longer biased, the hypothesis tests performed on the estimates are valid when the number of observations is large.  相似文献   

Newly recorded species of the genus Isohypsibius （Tardigrada; Hypsibiidae） from China   总被引：9，自引：0，他引：9  

WANG Li-zhi  ;LIAN Zhen-min 《林业研究》2007,18(4):322-324

This paper reports two newly recorded species, lsohypsibius lunulatus Iharos, 1966 and lsohypsibiusprosostomus Thulin, 1928, of the genus lsohypsibius （Tardigrada; Hypsibiidae） from China. The specimens of lsohysibius lunulatus were collected from Taibai Mt （34°18′N, 107°42′E） at 2,500 m a.s.1, and those oflsohypsibius prosostomus from Taibai Mt （34°10′N, 107°35′E） at 2,000 m above sea level. All specimens are deposited at the College of Life Sciences, Shaanxi Normal University, China. A key to the Chinese species of lsohypsibius was also given.  相似文献   

Dielectric properties of copper-ethanolamine treated Chinese fir (Cunninghamia lanceolata Hook.)     

Cao Jin-zhen Yu Li-li You Xiao-di Kamdem D. Pascal 《中国林学(英文版)》2007,9(4):239-245

In order to clarify the interaction between copper and wood substances in wood treated with copper containing water-borne wood preservatives, the dielectric constant ε′ and dielectric loss factor ε″ of untreated wood and wood treated with four concentration levels of copper-ethanolamine (Cu-EA) solutions were determined within a temperature range from –100 to 40°C and a frequency range from 100 to 1 MHz. Three dielectric relaxation processes were observed in the ε″ spectrum; among them R-I is based on the reorientation of methylol groups in the amorphous region of wood cell walls and R-II is related to wood extractives. R-III appeared in Cu-EA treated wood, and its magnitude decreases with the concentration of Cu-EA solutions used in this experiment. This relaxation process was considered to be based on the reorientation of copper-ethanolamine-wood complexes in wood cell walls. At low copper retention, the hydrogen in the complex can form hydrogen bonding with adjacent hydroxyl groups, which results in a strong bonding state between copper and wood; at high copper retention, the numerous copper-ethanolamine complexes not only hinder them from forming hydrogen bonding with adjacent wood molecules due to steric hindrance, but also weaken the interaction between wood molecules themselves, which corresponds to reducing ε″ values of both R-I and R-III processes. The results explain the fact of in-creasing copper leaching in wood treated with high concentration copper-based water-borne preservatives.  相似文献   

哈茨木霉天冬氨酸蛋白酶基因SA76的3＇RACE扩增和序列分析     

刘燕  杨谦 《林业研究》2007,18(2):139-143

由EST获得全长cDNA对于结构基因组学和功能基因组学都是至关重要的,cDNA末端快速扩增技术RACE是该领域中的重要研究方法.利用BD SMART RACE技术扩增编码分泌天冬氨酸蛋白酶SA76基因的3＇末端,将其与哈茨木霉cDNA文库中的SA76基因的EST序列进行序列拼接,获得2019bp的全长cDNA序列,其开放读码框长1593bp,5＇非编码区266bp,3＇非编码区201bp,编码530个氨基酸,有信号肽.哈茨木霉天冬氨酸蛋白酶基因与玉蜀黍赤霉、粗糙脉孢菌、球毛壳菌天冬氨酸蛋白酶基因的同源性分别为53%, 37%, 36%.利用BD SMART RACE技术首次从哈茨木霉中克隆天冬氨酸蛋白酶基因,为验证SA76基因的功能奠定基础,为进一步研究蛋白酶的作用机制及生物防治功能提供依据.  相似文献   

Socio-economic significance of reed forests in a rural community: A case study from the greater Sylhet Region of Bangladesh   总被引：1，自引：0，他引：1  

Qumruzzaman Chowdhury  A. Z. M. Manzoor Rashid  Masuduzzaman Afrad 《Small-Scale Forestry》2004,3(1):121-130

The reed forests that are the subject of this study are scattered over five thanas of the Sunamganj and Sylhet Districts of the Sylhet Division of Bangladesh. Their total area is 23,590 ha and they have great ecological, economic, commercial and socio-economic importance due to the diversified resources they supply. However, the forests are commonly encroached on by local people who are perceived to be seriously depleting the resource. This paper deals with the socio-economic status of the people residing near these reed forests, and examines their dependency on the resources provided by the reed forests. A socio-economic survey, participatory rural appraisal and interviews were used to obtain baseline data of the reed forest resource and the local communities. The study reveals that the communities in the study region have higher income than other areas of Bangladesh. Most survey respondents have other occupations in addition to farming. The literacy rate is 28.8%. Among the illiterate, 68% engage in collecting reeds. Although the Forest Department has a management plan for sustainable use of the reed forests, encroachers receive backing from political leaders and local elites, so their eviction is difficult. In order to achieve long-term productivity and sustainability from the reed forests, this study recommends a strategy of developing an integrated joint management plan between the Forest Department and the local people.  相似文献   

The use of compensatory and non-compensatory multi-criteria analysis for small-scale forestry     

Ian Jeffreys 《Small-Scale Forestry》2004,3(1):99-117

Small-scale farm forestry has the potential to offer many benefits both to landholders and the wider community. As with all changes in land-use practices, there are associated benefits and costs and these are not uniformly distributed. They have varying impacts on the different values, aspirations, goals and objectives that exist within the community. Furthermore, the community does not consider these values, aspirations, goals and objectives of equal importance. The degree of concern can vary from minor to high and overriding all other considerations. When evaluating farm forestry options it is necessary to address all of these concerns. This paper examines the combined use compensatory and non-compensatory multi-criteria analyses to evaluate forestry options, in a case study for the Darling Downs region of Queensland, Australia. These aggregation techniques are found to be highly complementary and together provide a comprehensive analysis. The compensatory technique provides a sound measure of overall performance of a forestry system, whereas the non-compensatory technique alerts decision-makers to presence of particularly poor performance with respect to individual criteria. The compensatory technique used is simple and understandable even for those with non-mathematical backgrounds. This analysis can identify and aid communication of the relative benefits and costs, and trade-offs, between economic, environmental and social considerations.  相似文献   

Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber     

Jan Johansson  Olle Hagman  Bengt-Arne Fjellner 《Journal of Wood Science》2003,49(4):312-316

This study was carried out to investigate the possibility of calibrating a prediction model for the moisture content and density distribution of Scots pine (Pinus sylvestris) using microwave sensors. The material was initially of green moisture content and was thereafter dried in several steps to zero moisture content. At each step, all the pieces were weighed, scanned with a microwave sensor (Satimo 9,4GHz), and computed tomography (CT)-scanned with a medical CT scanner (Siemens Somatom AR.T.). The output variables from the microwave sensor were used as predictors, and CT images that correlated with known moisture content were used as response variables. Multivariate models to predict average moisture content and density were calibrated using the partial least squares (PLS) regression. The models for average moisture content and density were applied at the pixel level, and the distribution was visualized. The results show that it is possible to predict both moisture content distribution and density distribution with high accuracy using microwave sensors.  相似文献