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1.
分析了中国水资源短缺的现状,探讨了虚拟水和水足迹理论,指出了该理论为水资源的研究提供了新的方向,详细地阐述了水足迹理论在中国的应用研究,为研究虚拟水和水足迹理论提供参考。 相似文献
2.
就能源结构和各部门的能源消费进行研究,推算了辽宁省2000～2005年各种能源消费量及其引起的CO2排放量。辽宁省的主要的能源消费类型是煤炭和石油,在2005年,煤炭和石油的消费量都最多,分别为2 470.16×104t.a-1标准煤和2 932.18×104t.a-1标准煤,也是主要的CO2排放源。以煤炭为原料生产的焦炭的CO2排放量由于技术的提高而减少。从消费部门看,工业部门的能源消费量最多,从2000年的431.55×104t.a-1标准煤增加到2005年的1 096.1×104t.a-1标准煤。交通部门的消费比例从2000年的9%增加到2005年的20%,未来还有增加的趋势。不同部门排放的CO2量也不同,工业部门每年排放的CO2最多,都在2 500×104t.a-1以上,2005年达到了3 020.48×104t.a-1,农林渔牧业部门由于机械化的操作使得CO2排放量增加。 相似文献
3.
为了解退耕还林这一重大林业生态工程的效果,以河北省退耕还林工程为例,依据森林生态系统定位观测站及河北省退耕还林工程生态效益评估专项监测站监测的数据,从涵养水源、保育土壤、固碳释氧、积累营养物质、净化大气环境等5个方面,对河北省退耕还林工程生态效益进行研究。结果表明:(1)涵养水源功能生态效益为4915.00×105m3/a,涵养水源总物质量占该省年均水资源总量的26.54%。(2)固土物质量为30824.4×104t/a,保育土壤总物质量为31111.2×104t/a。(3)固碳为3686.1×104t/a,释氧为8509.7×104t/a。(4)林分积累营养物质量为187.6×104t/a。(5)提供负离子效益为1142.75×1022个/a,滞尘效益为267.08×108kg/a,吸收污染物效益为1827.22×106g/a。总体来说,河北省的退耕还林工程取得了较好的生态效益,也为河北省新一轮退耕还林工程的科学发展提供理论依据和指导。 相似文献
4.
鹅掌楸属杂交测定林的生长状况进行分析,结果表明5 a生树高、胸径、材积年平均生长量为1.92 m,2.5 cm,0.009 2 m3;生长最快杂交组合是T11×C8,其平均年生长量分别为2.39 m,3.4 cm和0.018 3 m3。3个生长性状杂交组合间都呈极显著的差异,为优良杂交组合的选择奠定基础。树高、胸径和材积的杂交组合(家系)遗传力分别为0.501,0.631和0.687,分别进行优良杂交组合选择,其现实遗传增益为16.3%,32.9%和116.1%。几种交配模式之间的材积生长比较结果是T×CC×TT自由授粉C自由授粉C×CT×S。优良杂交组合T11×C8、T12×C8、C9×T12的杂种优势率分别为108.7%,64.3%和110.7%。 相似文献
5.
对11~13年生西南桦纯林(初植密度包括2 m×2 m,2 m×3 m,2 m×4 m,2 m×5 m,2 m×6 m,3 m×3 m和2 m×3 m×7 m)、12年生西南桦与高阿丁枫(初植密度2 m×3m)和11年生西南桦(初植密度3 m×3 m)与山桂花(初植密度3 m×1.5 m)混交林的生长分析显示,西南桦造林后迅速进入速生期。7年生前尤为速生,速生期可延续至10年生林分,在速生期内,平均木的胸径、树高和木材年平均生长量分别为1.17~2.50 cm.yr-1、1.20~3.60 m.yr-1和0.000 11~0.018 04 m3.yr-1,其连年生长量分别为0.50~2.65 cm.yr-1、0.5~4.0 m.yr-1和0.000 11~0.018 68 m3.yr-1。西南桦纯林中,2 m×5 m和2 m×4 m的初植密度较为有利于林木生长和木材生产,其13年生林分生长量分别达:(1)年平均胸径1.42 cm.yr-1和1.72 cm.yr-1,年平均树高1.77 m.yr-1和1.72 m.yr-1;(2)单位面积材积为209.807 1 m3.hm-2和208.933 8 m3.hm-2,并且胸径>16 cm的林木分别占80.00%和60.00%。混交林的木材产量:(1)12年生西南桦与高阿丁枫混交林单位面积木材产量是同林龄西南桦纯林(初植密度2 m×3 m×7 m)的1.845倍(172.363 7 m3.hm-2比94.978 9 m3.hm-2);(2)11年生西南桦与山桂花混交林单位面积木材产量是同林龄西南桦纯林的2.774倍(158.742 0m3.hm-2比57.219 0 m3.hm-2)。在西南桦与高阿丁枫混交林中,1行西南桦与2行高阿丁枫混交模式能提高西南桦高生长和木材产量。高阿丁枫和山桂花是可以同西南桦相匹配营造混交林的两个云南热带乡土树种。 相似文献
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7.
不同株行距对35杨生长的影响试验初报 总被引：1，自引：0，他引：1
对东台市林场5年生35杨人工林在2m×3m、2m×4m、3m×4m、3m×5m、4m×4m和4m×6m等6种株行距下的生长情况进行了调查。树高平均值为13．22～15．70m;胸径平均值为14．68～19．46cm。35杨树高和胸径的,值分别为47．40和32．21,差异达极显著水平。树高指标处理2～6的增幅分别为0．57％,10．45％,18．73％,4．46％和13．96％,其中,处理4的增幅最大,达18．73％。胸径指标处理2～6的增幅分别为-1．22％,23．88％,27．05％,12．43％和30．93％,其中,处理6的增幅最大,达30．93％。综合相关分析结果,初步认为3m×4m、3m×5m和4m×6m等3种株行距造林对东台沿海地区35杨初期生长较为有利。 相似文献
8.
不同群体结构苹果园光照分布状况研究 总被引：2，自引：0，他引：2
为了确立乔砧红富士苹果园合理的群体结构,探讨群体结构对光照分布的影响,对临城县赵庄乡南沟村不同栽植密度、树形为改良纺锤形的盛果期乔砧红富士苹果园的群体结构以及树体不同部位的光照情况进行了调查,结果表明：株行距2m×3m、3m×4m、3m×5m的郁闭度分别为0.88、0.70和0.58;行间近地面相对光照强度分别为0.94、0.46和0.13;行间地面向上0.5m处相对光照强度随株行距加大而加大,其值分别为0.12、0.40、0.95;行间地面向上1.0m、1.5m、2.0m不同株行距的相对光照强度除株行距2m×3m的果园的行间地面向上1.0m处为0.17外,其他都在0.76以上。每666.7m2总枝量、树高、叶面积系数以株行距2m×3m的为最大,分别为345 210根、3.23m和3.4;株行距3m×5m的为最小,分别为139 920根、2.81m、2.6;株行距2m×3m、3m×4m、3m×5m行内地面向上1.5m、2.0m处的相对光照强度均在0.49以上。 相似文献
9.
杨树林分密度对材积生长量的影响 总被引：1，自引：0，他引：1
对杨树进行窄宽行 (3m× 2m与 3m× 8m交替 )、3m× 6m和 3m× 5m 3种营林密度对比试验 ,从第 1年到第 4年林龄的生长量调查和试验分析表明 ,3种林分密度单位面积年平均材积生长量的比值分别为 198∶116∶10 0 ,杨树利润比值为 2 33∶1 13∶1。证明窄宽行的林分密度能产生最佳的经济效益 ,为营造杨树速生丰产林提供科学的林分密度。 相似文献
10.
《西部林业科学》2015,(3)
基于2013年深圳市森林资源二类调查的更新数据,在样地调查和平均木生物量、含碳率、土壤有机碳含量测定基础上,对深圳市经济林生物量和碳储量进行测算。结果表明,2013年深圳市经济林生物量103.66×104t,其中植被生物量94.74×104t,枯落物生物量8.92×104t;总碳储量232.31×104t,其中土壤碳储量、植被碳储量和枯落物碳储量分别占总碳储量的78.25%、19.79%和1.96%;荔枝林碳储量占经济林总碳储量的92.26%。在空间分布上,宝安区的经济林生物量和碳储量最高,分别为41.54×104t和94.07×104t,其余依次为龙岗区(41.14×104t,91.68×104t)、南山区(16.49×104t,36.70×104t)、罗湖区(1.95×104t,4.34×104t)、福田区(1.59×104t,3.54×104t)和盐田区(0.94×104t,1.99×104t)。经济林生态系统碳密度104.17 t/hm2,其中植被碳密度20.62 t/hm2,枯落物碳密度2.03 t/hm2,土壤碳密度81.52 t/hm2。深圳市经济林生态系统碳密度较低,固碳潜力大。 相似文献
11.
Yongtao He Qingwen Min Wenhua Li Guicai Li Liwei Jin 《Frontiers of Forestry in China》2006,1(1):43-47
The ecological water requirement of forests is defined as the water resources used to maintain and improve the natural balance
of forest ecosystems, which can be expressed by evapotranspiration of trees during the growing season. The relationship of
evapotranspiration and soil moisture of forestland with tree growth showed that, if the soil moisture was above the temporary
wilting point or the point of growth retardation, the growth of trees can, respectively, be basically or normally sustained.
Therefore, they can be taken as the minimum and the suitable ecological water requirements of the forest. These points can
be estimated by introducing the soil factor (K
s) and tree species factor (K
t) to potential evapotranspiration with the Penman formula. With geographic information system (GIS), the ecological water
requirement for forests in the Jinghe watershed, western China was estimated. The results revealed that the minimum and suitable
ecological water requirements of the forests in the Jinghe watershed were approximately 204×107 and 340×107 m3, respectively.
Translated from Journal of Soil and Water Conservation, 2004, 18(6) (in Chinese) 相似文献
12.
This study suggests that Iceland may be able to produce sufficient liquid hydrocarbon fuels from biological sources in the future to substitute the Icelandic 2016 consumption of fossil fuels, by using forest products. The authors evaluate a strategy to put forest on up to 35,000 km2 in Iceland to 2050. The preliminary study shows that Iceland could reach climate neutrality around 2050 and be a significant net carbon sequester for the next 250 years. Approximate estimates suggest that the total forest biomass production could reach about 10 million m3yr?1, comprising 3.1 million m3yr?1 of roundwood, 3.1 million m3yr?1 for generic biomass, and about 4.2 million m3yr?1 woody material for biofuel use. This could result in a net annual carbon dioxide sequestration of 2–2.5 mill ton CO2 yr?1 by 2100. The calculations suggest that such an afforestation and land restoration undertaking would be long term profitable in economic terms and that the payback time would be about 2050. The method applied in this study is that of a static mass balance calculations at different time points into the future. Parallel to this work, a full integrated regional forest production model is being developed and will be applied to this issue. 相似文献
13.
The water conservation capacities of main forests in Beijing,China were estimated through the quantitative analysis.Various methods developed in published papers on forest hydrology were employed.The forests in Huairou,Yanqing,Miyun,Mentougou and Fangshan districts are the main contributors to water conservation(the cumulative ratio reaches 65%),and the forests in Tongzhou,Chaoyang,Shunyi and Daxing districts have the highest water conservation capacity(3000 m3/ha).Altitude and slope are the key factors to affect the water conservation capacity.The forests located in Plain Area,Hilly Area,Low Mountain,and Middle Mountain contributes 27%,28%,24% and 21% of the conserved water,respectively.The water conservation capacity of forests in Plain Area(2 948 m3/ha),is superior to the forests in other regions.And the forests situated on Flat Slope,Moderate Slope and Gentle Slope constitute the largest proportion(nearly 93%) of water conservation,while the forests on Flat Slope has the highest water conservation capacity(2 797 m3/ha),and the forest on Steep slope has the lowest water conservation capacity(948 m3/ha). 相似文献
14.
G. B. Douglas A. S. Walcroft S. E. Hurst J. F. Potter A. G. Foote L. E. Fung W. R. N. Edwards C. van den Dijssel 《Agroforestry Systems》2006,67(2):177-186
Silvopastoral systems involving poplars are common to rural landscapes in many parts of New Zealand. The effect of widely
spaced trees of Populus nigra × P. maximowiczii, aged 8–11 years, on the surrounding micro-environment in a tree-pasture system was determined over 3 years at a southern
North Island hill country site. Relative to open (unshaded, no trees) pasture, understorey pasture received 33% less radiation
while radiation on the north side of trees (North) was similar to that on the south side of trees (South). Around one tree,
soil temperature averaged 14.9°C annually on the North and 13.8°C on the South. Soil water content was highest in spring and
winter (0.35–11;0.39 m3 m−3) and lowest in summer and autumn (0.21–11;0.26 m3 m−3), and differences occurred between plots in open pasture and those beneath trees in all seasons except spring. Soil water
content of tree aspects differed slightly (<10%) in summer (South > North) and autumn (North > South), but not in spring and
winter, when contents were similar. Soil pH was 0.2 units higher beneath trees than in open pasture in one of 2 years. Concentrations
of Ca, K, Mg, P, and S were similar in tree and open environments. The study results complement those collected for mature
trees, and will be useful in developing tree-pasture models. 相似文献
15.
Ecological water requirement based on ecological protection and restoration targets in the lower reaches of the Heihe River, northern China 总被引：1，自引：0，他引：1
Li Zhang 《Frontiers of Forestry in China》2009,4(3):263-270
Owing to the irrational use of water resources in the Heihe River, northern China, the eco-environment has deteriorated seriously
in its lower reaches. Some ecological problems exist (i.e., lake shrinkage, the decline of the underground water table, vegetation
degradation, land desertification, and sandstorm damage). Subareas of ecological protection and restoration in the lower reaches
of the river are proposed, considering the course of the river, its ecosystem characteristics, and the range of impact of
water resource allocation. Based on a comprehensive decision-making method and GIS technology, the targets of ecological protection
and restoration in the lower reaches of the river were determined quantitatively. Using a phreatic evapotranspiration model
and a groundwater balance equation, the ecological water requirements of the riparian forest ecosystem, the desert ecosystem,
the water area ecosystem, and the underground ecosystem, given various eco-restoration targets in different level years, were
calculated and analyzed. The results show that the total ecological water requirements of the Shaomaying section were 548
million m3 in 2000 to maintain the normal growth of its natural vegetation and a stable groundwater table in the lower reaches of the
Heihe River. The total ecological water requirement of the Shaomaying section is expected to be 632 million m3 in 2010, 635 million m3 in 2020, and 635 million m3 in 2030. 相似文献
16.
《Southern Forests》2013,75(4):311-318
Average wood density of 38-year-old Cariniana legalis (Mart.) Kuntze, a Brazilian native forest species, was found to increase with faster growth and lower stocking, while decreasing from pith to bark. A complete randomised block design was planted with five blocks. Ten trees were harvested in each of three spacing treatments. We hypothesised that the stand stemwood production would not significantly differ depending on tree spacing. However, tree growth would be higher in the wider spacing and wood density would be higher in the narrower spacing. The diameter growth of trees was higher at 3 m × 2.5 m than at 3 m × 2 m and 3 m × 1.5 m. Nevertheless, this higher individual tree growth at 3 m × 2.5 m did not compensate for the greater tree stock density at 3 m × 1.5 m with stand stemwood production at 38 years of 530 m3 ha?1 and 649 m3 ha?1, respectively. These results suggest that C. legalis, which can produce up to 17 m3 ha?1 y?1 of medium-to high-density timber – about 800 kg m?3 – is a promising native species for forest plantations in Brazil. 相似文献
17.
The productivity and chipping cost of a low-investment small mobile chipper were investigated. The effect of capital cost on chipping cost reduction was analyzed by changing the service life of the chipper when assuming a target operational chipping cost set at 250 yen m?3. Productivity of the investigated chipper was found to be at 23.7 m3 h?1 in chip volume with fuel consumption at 14.6 L h?1. The results showed that the chipping cost of the investigated chipper was lower than that of a higher priced and more productive grinder. Neither chipper nor grinder, however, could achieve the assumed target cost of 250 yen m?3 even if their service lives were extended. It was necessary to withstand the initial grapple loader and the labor costs or raise the grinder’s productivity to 33 m3 h?1 in order to reach a comparable operational cost target with that of the investigated chipper. Similarly, the grinder would have to reduce its capital cost and fuel consumption to maintain the chipping cost of 250 yen m?3 ifproductivity could not be improved. Net chipping cost of the investigated chipper was relatively small compared to that of the tub grinder, especially under a shorter service lifespan. The investigation shows that it is feasible for small-scale forestry to introduce a low-investment mobile chipper because it does not require a large amount of material and has a low chipping cost. Moreover, lowering the capital cost or the price of chippers is a more realistic cost savings in the long term. 相似文献
18.
The dynamic change of soil water as a function of leaf area index and the soil water deficit value, prerequisites for assuring
the survival of plants, were simulated. We established a dynamic soil water model based on a theory of water balance, the
characteristics of the environment, and the physiological ecology of the plants in the Ulan Buh Desert, northwestern China.
We estimated the soil water carrying capacity of the vegetation in our study area of the desert. The results showed that the
proportion of soil evaporation in the total amount of precipitation was greater than 60% in the wandering and semifixed sands
and 44.8%in the fixed sand. When the leaf area index was less than 1.7 m2/m2, the soil water deficit was maintained at a low level, but when the leaf area index continued to increase, the soil water
deficit increased rapidly as well. In consequence, we come to the conclusion that the leaf area index of the soil water carrying
capacity of the vegetation is 1.7 m2/m2 in our study area.
__________
Translated from Scientia Silvae Sinicae, 2008, 44(9): 13–19 [译自: 林业科学] 相似文献
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20.
2010年世界木材消费预测 总被引：2，自引：0，他引：2
据FAO预测,到2010年世界木材总消费量将达46.59亿m3,比以前发表的数字少了4.1亿m3,主要林产品消费结构也有较大的变化。作者着重对2010年世界和10个不同类型国家木材消费量、消费结构和林产品在国民经济中的地位,进行了深入分析和对比研究,并对21世纪初木材消费的特点进行了评估。 相似文献