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991.
992.
993.
Reproductive phenology was observed over three years in a Eucalyptus grandis seed orchard in Madagascar to determine the impact of geographic differences of parental selections on the expected genetic composition of seed crops. Pollen flow (observed pollen cloud) was deduced from a paternity assignment based on sampling from one year’s seed production. The two approaches were used to verify whether knowledge of phenology is sufficient to predict the genetic quality of the seeds collected. Despite the high flowering level, with a constant cycle over three years, the results demonstrated wide reproductive phenological differences associated with the parents’ origin, suggesting putative pollination disequilibrium. From both observed and expected pollen clouds, the results showed preferential mating among different provenances, which has consequences for seed crop composition. Phenological observations, which can be made inexpensively, can be used to promote methods of effective seed orchard management in order to improve the genetic quality of seeds. 相似文献
994.
This paper presents empirical evidence on the impact of socio-economic factors on the adoption of agroforestry practices in
Cameroon. The analysis uses primary farm-level data collected from June to December 1996. Three major provinces of the country
were covered, namely Centre, Southwest and Northwest Several agroforestry technologies have been promoted among farmers in
the zone, including alley farming, improved fallow, live fencing, cut-and-carry fodder and apiculture. The status of adoption
of each agroforestry practice is described and factors that affect adoption identified. These are gender of farmer, household
family size, level of education, farmer’s experience, membership within farmers’ associations, contact with research and extension,
security of land tenure, agroecological zone, distance of the village from nearest town, village accessibility and income
from livestock. Research findings indicate that since factors affecting farmers’ adoption of agroforestry practices differ
across techniques, generalisation is to be avoided. 相似文献
995.
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
996.
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
997.
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
998.
Newly recorded species of the genus Isohypsibius (Tardigrada; Hypsibiidae) from China 总被引:9,自引:0,他引:9
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
999.
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
1000.
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