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991.
992.
J. Heuveldop H. W. Fassbender L. Alpízar G. Enríquez H. Fölster 《Agroforestry Systems》1988,6(1-3):37-48
During 7 years (1979–1985) cacao harvests (beans and husks) have been recorded for the agroforestry systems ofTheobroma cacao underCordia alliodora andErythrina poeppigiana shade trees. The mean oven dry cacao yields were 626 and 712 kg.ha−1.a−1 cocoa beans underC. alliodora andE. poeppigiana respectively. Harvests have gradually increased over the years and the plantation has now reached maturity.
Annual extraction of N, P, K, Ca and Mg in fruits, which is relatively small, was calculated on the basis of chemical analyses.
The following average values were found (kg.ha−1.a−1):
At the age of 8 years, theC. alliodora trees have reached 26.7 cm diameter (DBH) and 14.0 m in height. Mean annual growth (from age 5 to 7) is 14.6 m3.ha−1.a−1.
Natural plant residue production has been measured for 4 years (Nov. 1981–Oct. 1985). UnderE. poeppigiana it has reached a value of 8.91 t.ha−1.a−1 and underC. alliodora 7.07 t.ha−1.a−1. The shade trees have contributed 57 and 47% respectively. Transference and decomposition rates are high and important in
the nutrient cycles.
The nutrient content of the litter was analysed and corresponding average yearly transfers were (kg.ha−1.a−1):
For part I see Vol. 4, No. 3, 1986.
Agroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesselschaft für Technische Zusammenarbeit),
Turrialba, Costa Rica 相似文献
993.
天牛成虫胸部的发音和行为(鞘翅目:天牛科) 总被引:3,自引:0,他引:3
本文研究了15种天牛成虫的发音及其有关的行为。天牛两性对外界不同强度的刺激能作出反应,并借助胸部发音器的摩擦而发音。波形照片显示:天牛的声波信号因种不同差异极大,其频率范围约3000—10000Hz。楝星天牛可借助鞘翅的运动而发出强烈的声音以恐吓敌害,其胸部摩擦发音器则趋于退化。某些天牛雄虫在争夺雌虫、交配前和交配中,可发出不同的声波,这类声波的生物学意义尚待进一步研究。 相似文献
994.
我国刨花板生产现状与市场分析 总被引:1,自引:0,他引:1
介绍了刨花板产品特性、我国刨花板生产现状,指出我国刨花板发展中存在的问题,并根据我国现阶段市场的实际情况,预测我国刨花板的市场前景。 相似文献
995.
996.
M. Prez-Surez J.T. Arredondo-Moreno E. Huber-Sannwald J.J. Vargas-Hernndez 《Forest Ecology and Management》2009,258(7):1307-1315
Litterfall is an important ecological process in forest ecosystems, influencing the transfer of organic matter, carbon (C), nitrogen (N), phosphorous (P) and other nutrients from vegetation to the soil. We examined the production of different litterfall fractions as well as nutrient content and nutrient inputs by senesced and green leaf-litter in a semiarid forest from central Mexico. From September 2006 to August 2007, monthly litter sampling was carried out in monospecific and mixed stands of Quercus potosina and Pinus cembroides. Litterfall displayed a marked bimodal pattern with the largest annual amount (5993 ± 655 kg ha−1 yr−1) recorded in mixed stands, followed by Q. potosina (4869 ± 510 kg ha−1 yr−1), and P. cembroides (3023 ± 337 kg ha−1 yr−1). Leaves constituted the largest fraction of total litterfall reaching almost 60%, while small branches contributed with 20–30%. Overall, N content in leaf-litter was higher while lignin content was significantly lower for Q. potosina than for P. cembroides. Thus, greater litter quality together with higher litter production caused the largest C, N and P inputs to forest soils to occur in monospecific Q. potosina stands. Green leaf fall displayed significantly lower lignin:N and C:N ratios in Q. potosina than P. cembroides suggesting faster decomposition and nutrient return rates by the former. Although we recorded only two green leaf fall events, they accounted for 18% and 11% of the total N and P input, respectively, from leaf-litter during the study period. Apart, from the large spatiotemporal heterogeneity introduced by differences in litter quantity and quality of evergreen, deciduous and mixed stands, green litterfall appears to represent a much more important mechanism of nutrient input to semiarid forest ecosystems than previously considered. 相似文献
997.
论述目前我国林源活性物质提取的固形剩余物利用问题。在分析我国林源生物质利用的产业现状和林源生物质提取活性物质生产中固形剩余物的利用现状的基础上,重点介绍固形剩余物热解利用的方法与发展趋势,提出通过生物质固化成型与热解转化技术处理固形剩余物,将林源活性物质提取生产中固形剩余物转化为生物质炭、生物焦油、生物醋液和生物燃气等具市场价值的产品。在利用过程中不产生二次污染,实现清洁生产,提出将节约资源和环境友好落实到林源生物质生态化学利用工程的各个环节,论证这一利用技术的经济价值以及现实意义。 相似文献
998.
文章介绍河源市油茶生产现状及未来产业规划,总结河源市油茶产业发展在历史上的经验教训,并在此基础上进行思考,提出了河源市发展油茶产业的相关措施。 相似文献
999.
Ciro Abbud Righi Vincent S. J. A. Couderc Carlos Rodrigues Pereira Hilton Thadeu Zarate do Couto Luciana Duque Silva 《Journal of Sustainable Forestry》2013,32(1):75-87
ABSTRACTEucalyptus is widely cultivated in homogeneous monocultures throughout the world alongside plants of the same age. Furthermore, the productivity of forest stands is highly dependent on how solar radiation is intercepted and used. Meanwhile, it is possible to consider cultivating trees of different ages in the same area, and thus under different regimes of available solar radiation, creating a sequence of plantings and harvestings and to develop Eucalyptus-based agroforestry systems. We have examined biomass accumulation of Eucalyptus camaldulensis along a shade gradient. Eucalyptus trees presented power-law responses to increasing irradiance for biomass, indicating it has low plasticity and is unable to maintain growth under lower irradiance levels. Biomass partitioning showed no dependence on available irradiation. Leaf density presented very little increase toward sunnier places meaning that an increment in Eucalyptus biomass would be mostly due to its increase in size and thus higher radiation interception. Careful management of shade will be a key consideration for the integration of Eucalyptus into agroforestry. With knowledge of the growth habits of different species, we will have the potential to propose more perennial ways in which to manage land and reduce anthropogenic disturbances by avoiding clear-cuts of areas that removes all plant structures. 相似文献
1000.
《Journal of Sustainable Forestry》2013,32(2-3):123-140
Summary This study, in die Chilean Magellan Region, undertook the structural and biométrie characterization of Nothofagus betuloides (Mirb.) Blume (coihue de Magallanes) production forests to provide information for sustainable forest management. Six locations were surveyed, five on the continent and one on Tierra del Fuego Island. A total of 6,102 ha were photointerpreted and then checked and described in the field according to their location, environmental characteristic, and vegetation type. The degree of disturbance, stage of development, status of regeneration, and composition and cover of the understory were also described. From the surveyed locations, a total of 3,807 ha were production forests of which a 76% area had Nothofagus pumilio (lenga) and N. betuloides mixed forests. The remaining areas (24%) were pure N. betuloides forests. Nondisturbed, old-growth forests covered 47% of the surveyed area. The remaining area (53%) had some disturbance. In the nondisturbed forests, mean volume stocks were 438 m3 ha-1, and in disturbed forests, mean volume stocks were 316 m3 ha-1. 相似文献