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991.
福建梅花山自然保护区的竹类资源丰富,共有12个群落14属51种,经济竹种多样,竹类资源的开发利用具有广阔的前景。 相似文献
992.
开沟灌溉造林与大田平灌相比,具有总体用水量少,局部给水量多的特点,能够显著地提高灌溉效率,提高造林成活率和林木生长量。同时,利用管道和砌护渠道输水,可防止渗漏,提高水的利用率。 相似文献
993.
The nitrogen (N) cycling was elucidated in a 40-year-old subtropical evergreen broad-leaved forest dominated by Cyclobalanopsis glauca growing on red soil in Zhejiang Province, East China. The concentrations of N in the representative species ranged from 0.49%
to 1.64%, the order of which in various layers was liana and herb layers > understory layer > tree and subtree layers; in
various organs was leaf > branch > root > trunk; and aboveground parts > underground parts. The sequence of the concentrations
of N in C. glauca was understory > tree > subtree layer; young and high-growing > old organs; reproductive > vegetative organs. Seasonal dynamics
of the concentrations of N in C. glauca in the tree and subtree layers was comparatively stable. It was lower in autumn (October) in root, branch, and leaf in the
tree layer, and low in January in the understory. There was no evident change in regularity of the concentrations of N in
varying diameter classes. The concentrations of N in the litterfall, precipitation, throughfall, litter layer, and soil were
0.74%–2.30%, 0.000,038%, 0.000,09%, 1.94%, and 0.59%, respectively. The standing crop of N in the plant community was 1,025.28
kg/hm2, accumulation in the litter layer was 224.88 kg/hm2, and reserve in the soil was 55,151 kg/hm2. Annual retention of N was 119.47 kg/hm2, return was about 84.13 kg/hm2, among which litterfall was 78.49 kg/hm2 and throughfall, 5.64 kg/hm2. Annual absorption of N was 203.60 kg/hm2. Annual input of N through incident precipitation was 4.88 kg/hm2. Compared with other forest types, cycling rate of N in the community was lower than in deciduous broad-leaved forests, rain
forests, and mangroves, and was moderate in evergreen broad-leaved forests. N use efficiency of this forest was moderate among
the forest types cited. According to the characteristics of the biocycle of phosphorous, it was concluded that N availability
in the soil of this forest was not lower, and phosphorous not N was the limiting factor in the growth of plants in this community.
__________
Translated from Acta Ecologica Sinica, 2005, 25(4): 740–748 [译自: 生态学报, 2005, 25(4): 740–748] 相似文献
994.
995.
为了提高单板干燥过程中的能源利用效率,对单板干燥过程进行了分析并提出有效的节能措施与途径。提出利用单板干燥尾气余热回收系统,以减少尾气直接排入大气时的热量损失,对尾气余热回收利用;提出蒸汽梯级利用回收冷凝水的热量,达到对冷凝水余热回收利用的目的。 相似文献
996.
《The Journal of Applied Poultry Research》2015,24(2):267-282
Poultry nutritionists should constantly evaluate their feeds and feeding programs in view of the changes that continue to be made to the potential growth rate of broilers and egg production in laying hens with the objective of providing the birds with the optimum economic level of nutrients at all times. In this review, the models generated at Universidade Estadual Paulista (UNESP) Jaboticabal, to estimate the optimum intake of amino acids (AA) for broilers and laying hens are presented. These models were used to estimate the variation in AA intake within a broiler population making use of coefficients of variation that represent the real situation in a commercial broiler operation. The range of AA intakes obtained was compared to some commonly applied feeding programs and recommendations. Based on results of our developed models and other feeding programs, feeds were formulated and growth was predicted using a growth simulation model (Avinesp). The prediction of growth showed that these models are reliable and useful tools to assist the nutritionists in decision making. In a study with laying hens, the Reading model (RM) was used to establish optimum economic AA intakes in a flock of hens. The input variables were the means and standard deviations of egg output and BW, and the relationship between the marginal cost of the AA and the marginal revenue for eggs. Based on this model, the optimum intake of each AA can vary with each of the variables considered. The models proposed in our study enable important decisions to be made regarding AA intakes to be used to obtain optimum economic performance from a population of broilers and laying hens. 相似文献
997.
《The Journal of Applied Poultry Research》2015,24(1):80-90
The objective of this study was to determine the response of broilers to the combination of multi-enzymes and direct-fed microbial (DFM) under commercial production settings. A total of 7,000 1-day-old male broilers (Ross 308) were distributed over 10 pens (700 broilers/pen). Two dietary treatments were tested using complete randomized design, including a control diet and a test diet with addition of multi-enzymes (xylanase, amylase, and protease (XAP)] and DFM (a combination of spores from 3 strains ofBacillus amyloliquefaciens). Pelleted diets were offered ad libitum in 3 phases and water was freely available. During starter and grower phases (0 to 21 d), the enzyme and DFM combination resulted in improved FE (P < 0.05). During the finisher phase, higher feed intake and BW gain (P < 0.05) were observed for the test group. Overall, there were significantly higher feed intake, BW gain, and lower water-to-feed ratio in test group compared to the control group. This was related to improved (P < 0.05) modified production efficiency factor which was calculated based on final BW, survival rate, feeding period, and mortality-weight-corrected FCR. The test group had improved litter quality and a reduced foot-pad lesion score compared to the control. In addition, there was a tendency (P < 0.1) of reducingClostridium perfringens population in cecal digesta and higher lactic acid content in the ileal digesta, when expressed on an as-is basis, in the test group. In this study, we demonstrated that using a multi-enzymes and DFM combination in the diet for broilers can result in improved FE in starter/grower phases and animal welfare parameters, and lead to improved production efficiency under commercial settings. 相似文献
998.
湖南省自然条件优越,地质、地貌复杂多样,生物资源本底好,生物多样性丰富.据统计,可供利用的野生经济植物资源达2000种以上,为该省一大资源优势.本文根据野生植物资源之用途,将其分为4大类17小类,并较为详尽地论述了各类植物代表种、资源概况及开发利用前景.同时,提出了开发利用这类资源的建议,可供合理开发利用和保护这类资源时参考. 相似文献
999.
为合理开发利用九阜山省级自然保护区山茶科植物资源,对该区山茶科植物资源进行调查,结果表明该区山茶科植物共有7属28种(包括变种)。对其种类占全国与福建省的比例、属的分布区类型、优势属、生活型与生态环境条件、数量以及应用途径进行了分析,并提出保护与开发利用建议。 相似文献
1000.