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991.
Water adsorption capacities were evaluated for moso bamboo samples that were heated at 200°C for various times and conditioned in a closed container at 97% relative humidity at 20°C. Logistic regression analysis was used for curve fitting to the adsorption data and its parameters were analyzed. These parameters were compared with those derived previously from the Dubinin and Radushkevich theory. The properties of the heat-treated samples changed after 5 h of heating. With less than 5 h of heating, hydroxyl groups provided the main adsorption sites but their numbers decreased on heating. After 5 h, gasifi cation of the bamboo increased and capillaries formed. Part of this article was presented at the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, August 2007  相似文献   
992.
In agroforestry systems, the distribution of light transmitted under tree canopies can be a limiting factor for the development of intercrops. The light available for intercrops depends on the quantity of light intercepted by tree canopies and, consequently, on the architecture of the tree species present. The influence of tree architecture on light transmission was analysed using dynamic 3D architectural models. The architectural analysis of Acacia mangium and Tectona grandis was performed in Indonesian agroforestry systems with trees aged from 1 to 3 years. 3D virtual trees were then generated with the AmapSim simulation software and 3D virtual experiments in which tree age, planting density, planting pattern and pruning intensity varied were reconstructed in order to simulate light available for the crop. Canopy closure of trees was more rapid in A. mangium than in T. grandis agroforestry systems; after 3 years the quantity of light available for A. mangium intercrops was three times lower than under T. grandis. Simulations with A. mangium showed that practices such as pruning and widening tree spacing enable to increase the total transmitted light within the stand. On T. grandis, modification of the tree row azimuth resulted in changes in the spatial and seasonal distribution of light available for the intercrops. These results are discussed in terms of agroforestry system management.
Sylvie SabatierEmail:
  相似文献   
993.
神农架地区珍衡植物沿河岸带的分布格局   总被引:2,自引:0,他引:2  
Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian zone in basic study and practical management. In this study, 42 sampling belts (10 m×100m) parallel to the bank of Xiangxi River at different elevations in Shennongjia Area were selected to investigate the riparian vegetation and rare plants. 14 species of rare plants were found distributing in riparian zone, accounting for 42.4% of the total rare plant species in Shennongjia Area. The main distribution range of the 14 rare plant species was the evergreen and deciduous mixed broadleaved forest at elevation of 1200–1800 m, where, species diversity of plant community was the maximum at the moderate elevation. The analysis of TWINSPAN divided the 14 rare species into 3 groups against the elevation, namely low elevation species group, moderate elevation species group, and high elevation species group. The analysis of DCA ordination showed similar results to that of TWINSPAN. In the paper, the authors discussed the reasons forming the distribution pattern of rare plant species, and pointed out that the important function of riparian zone on rare plant species protection. Foundation item: This project was supported by National Natural Science Foundation of China (NSFC39970123), and Changbai Mountain Open Research Station, Chinese Acadamy of Science. Biography: JIANG Ming-xi (1965-), male, associate professor in Wuhan Institute of Botany, Chinese Academy of Sciences, Wuhan 430074, P. R. China Responsible editor: Chai Ruihai  相似文献   
994.
王宪成 《林业研究》2002,13(4):323-326
本文概要介绍了吉林省生态环境概况、林业建设成就与问题,论述了本省森林生态网络建设面临的任务及亟待解决的八个方面的问题,并对生物技术、信息技术、新材料技术及无公害森林保健技术在森林生态网络建设的应用前景进行了展望。参9。  相似文献   
995.
This paper analyses the governance characteristics of an innovative policy instrument for sustainable forest management in Flanders, namely a mechanism based on social learning and collaborative planning within joint forest management organizations. These organizations have been successful in involving non-industrial private forest owners in managing the transition towards sustainable management in small-scale forestry. Why was this innovative scheme successful? And what are its shortcomings and possible limitations? The hypothesis developed in this paper is that the success of the forest groups has been made possible by the explicit organization of a process of social learning, leading to change in the beliefs and the social norms of forest owners and users. Based on the analysis of this case of cooperative forestry, and on theoretical insights from governance theory, the contribution to fostering social learning from three distinct mechanisms is established, these being (1) the recourse to sustainability criteria and indicators as an open-ended learning device, (2) the experimentation with disruptive action strategies to put new beliefs into practice, and (3) the building of new forms of social cooperation around these new beliefs and practices.  相似文献   
996.
The relationship between early root and shoot formation at the beginning of the vegetation period and cutting survival on sandy and loamy fluvisol for 14 genotypes of black poplars was analyzed. Considerable cutting mortality was observed only within the first 80 days since planting. Intensive root formation in the first 20 days since the planting and vigorous shoot growth and development in subsequent 20 days was observed in easy-to-root genotypes. Coefficients of correlation revealed close relationship between early root and shoot growth and development and cutting survival of tested genotypes. The obtained results could be used in the breeding process, as well as for the design of cultivar-adjusted nursery and plantation establishment technology. Tested shoot characteristics, were found to be especially interesting since they could be measured rapidly, by non-destructive means.  相似文献   
997.
Azamal Husen 《New Forests》2009,38(2):117-129
About 19 clones of shisham (Dalbergia sissoo Roxb.) were raised by using healthy coppice shoot cuttings. After 2 year of establishment and growth, they were examined to identify suitable clone of shisham at nursery stage. Clones were studied for growth (height and basal diameter), chlorophyll fluorescence (Fv/Fm) and biochemical contents (chlorophyll a, b, total chlorophyll, free amino acids, total soluble proteins, total soluble sugars, starch and reducing sugar) in the leaves. Clone C2 and C3 (Gonda, Uttar Pradesh, India) had the highest growth and the chlorophyll fluorescence rate among examined clones. Between these two clones, C2 gave the highest response on height, basal diameter and Fv/Fm. Except free amino acids, all other biochemical contents were greater in the clones belonging to Gonda, Uttar Pradesh, India. Growth parameters, i.e. height and basal diameter increment at nursery stage had a positive correlation with all the studied parameters, except free amino acid and total soluble protein. These findings have demonstrated that there are remarkable clonal variations in growth, physiological and biochemical responses at nursery stage. Thus, physiological and biochemical markers can enhance selection efficiency, in addition to growth characteristics such as height and basal diameter as these have practical value in the tree improvement. The study suggests that clones of Gonda, Uttar Pradesh, India had the best performance and could be further tested in plantation programs.  相似文献   
998.
This report describes in vitro shoot induction and plant regeneration from nodal segments of Balanites aegyptiaca on Murashige and Skoog (MS) medium fortified with 6-benzyladenine (BA), thidiazuron (TDZ) and kinetin (Kin) (0.5–20.0 μM). MS medium supplemented with BA (12.5 μM) was the most effective in inducing bud break and growth and also in initiating multiple shoot proliferation. However, the optimal level of TDZ supplementation to the culture medium was 5.0 μM. Shoot cultures were established by repeatedly subculturing the original nodal explants on the same medium. Highest number of shoots (11.5 ± 0.7) and shoot length (5.0 ± 0.2 cm) were achieved when cultures were subcultured on MS medium supplemented with 12.5 μM BA and 1.0 μM α-naphthalene acetic acid (NAA). The shoots regenerated from TDZ supplemented medium when subcultured to hormone free MS basal medium considerably increased the rate of shoot multiplication and shoot length by the end of fifth subculture. Rooting of the shoots was achieved on MS medium augmented with 1.0 μM indole-3-butyric acid (IBA) plus 0.5% activated charcoal followed by their transfer to half strength MS basal medium. The in vitro raised plantlets with well developed shoots and roots were successfully established in earthen pots containing garden soil and were grown in greenhouse with 70% survival rate. The results of this study provide the first successful report on in vitro direct plant regeneration of B. aegyptiaca.  相似文献   
999.
On three sites in coastal northwestern Oregon, USA, seedling root and shoot development were assessed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western red-cedar (Thuja plicata Donn ex D. Don) container seedlings under varying sulfometuron methyl (Oust XP®) herbicide application treatments. Treatments consisted of application of 0.16 kg active ingredient (ai) ha?1 as a site preparation in fall 2003, a release application in fall 2004, or a control treatment with no application. Seedlings were planted in winter 2004 and measurements recorded in summer 2004, winter 2005, and summer 2005. During first season growth, western red-cedar seedlings showed the greatest negative impact to site preparation compared to the control with overall average new root length outside the root plug reduced by 67%. Significant reductions in root length also occurred for western hemlock (47%) and Douglas-fir (40%) seedlings. About 9 months after the release treatment, and 21 months after the site preparation application, there were no significant differences between treatments for any measured parameter. These findings suggest that seedlings under the site preparation treatment recovered from initial damage incurred to the root system. Lack of seedling response under the release treatment may be the result of opposing influences from the herbicide application associated with seedling phytotoxicity and enhanced seedling development resulting from effective vegetation control. Although our study was limited to 21 months following planting, reduced vegetation cover in the site preparation and release treatments suggests that these treatments may benefit future seedling growth.  相似文献   
1000.
Holm oak (Quercus ilex L.) seedlings were exponentially (E) nutrient loaded using incremental increases in fertilizer addition or conventionally (C) fertilized using a constant fertilizer rate during nursery culture. The fertility treatments (mg N plant−1) were control (0), 25E, 100E, and 100C. Subsequently, 1-year-old plants were transplanted under simulated soil fertility gradients in a greenhouse to evaluate effects of nutrient loading and post-transplant fertility on seedling performance. Post-transplant fertility consisted of fertilizing plants at two rates (0 vs. 200 mg N plant−1). A water-soluble fertilizer 20-20-20 was supplied in both nursery and post-transplant experiments. Nutrient loading increased plant N content by 73% in 100E and by 75% in 100C relative to controls, although no significant differences were detected between constant and exponential fertilization regimes at the 100 mg N plant−1 rate. When transplanted, nutrient loading promoted post-transplant root growth relative to shoot, implicating potential to confer competitive advantage to loaded holm oak seedlings after trans-planting. In contrast, post-transplant fertility increased new shoot dry mass by 140% as well as N, P and K content relative to controls. Results suggest that holm oak seedlings can be successfully nutrient loaded in the nursery at higher fertility rates, improving its potential to extend new roots, but alternative fertilization regimes and schedules that better fit nutrient availability to the growth rhythm and conservative strategy of this species must be tested.  相似文献   
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