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1.
上海绿地群落冠层的UVB屏蔽作用   总被引:3,自引:0,他引:3  
文章选择上海绿地典型植物群落类型进行UVB屏蔽效率测定,分析绿地类型、植物配置方式对屏蔽效率的影响作用,并对群落优势种高度、枝下高等特征与群落屏蔽效率相关关系进行了初步研究。研究结果表明:(1)所测定植物群落中UVB屏蔽效率较高的为毛竹群落、水杉群落、香樟群落、女贞群落、朴树群落和雪松群落,UVB屏蔽效率最高为98.4%的女贞群落,最低为17.1%的红叶李群落(2)所测定群落UVB平均屏蔽效率为76.9%,即群落内2m高处UVB辐射值仅为全光照旷地20.2%。(3)植物群落内UVB辐射通量与群落郁闭度呈极显著负相关关系,相关系数为0.749,而与群落优势种平均高度和平均冠幅相关性不显著。    相似文献   

2.
绿色基础设施作为城市建设生态支撑体系的可持续发展途径,近20年来在欧美国家的不断研究与实践,取得了大量的成果。低影响开发的绿色基础设施对于解决城市雨洪问题有很好的效果,而合适的植物选择正是低影响开发的绿色基础设施中较薄弱的环节。本文以中小尺度的绿色基础设施中植物的选择为切入点点,运用低影响、低成本、低技术的规划设计理念对绿色基础设施进行构建,针对绿色屋顶、生物滞留设施、植被浅沟、嵌草砖及雨水湿地五种不同类型的低影响绿色基础设施自身的条件,选择最为合适的植物,使绿色基础设施的构建能以较少的投入获得较大的效益,实现城乡生态可持续的发展,进而提升城市土地的生态服务功能。  相似文献   

3.
The experiment with the green shoot cutting propagation ofLarix olgensis was made in the Maoer Mountain Forestry Farm on July 5, 1990. After the callus formed of the cutting base before adventitious roots came out the materials were collected from the cutting base and fixed in FAA solution. By the paraffin sections and anatomical observation, the results indicted that it needed 40 days from the cutting to the rooting. The induced primordium of the cutting was endogenous in origin, which came from: (1) vascular cambium of the callus, and became roots; (2) meristematic cell population in the intersect between the cambium and xylem ray of the cutting base. There were extruding, crushing process and enzymolysis when the adventitious roots broke through the outer layers in two rooting types.  相似文献   

4.
Four known lactones were isolated from Tithonia diversifolia: furanoheliangolides 1,3-dihydroxy-3,10-epoxy-8-(-2-methylpropanoyloxy)-germacra-11(13)-ene-6,12-olide (1), 1,3-dihydroxy-3,10-epoxy-8-(2-methylpropanoyloxy)-germacra-4,11(13)-diene-6,12-olide (2), 1,3-dimethoxy-3,10-epoxy-8-(2-methylpropanoyloxy)-germacra-4,11(13)-diene-6,12-olide (3) and, observed in natural source for the first time, furanoheliangolide 1-hydroxy-3-methoxy-3,10-epoxy-8-(2-methylpropanoyloxy)-germacra-4,11(13)-diene-6,12-olide (4). The activity of sesquiterpene lactones on superoxide anion (O(2)(o)(-)) generation from PMA-activated neutrophils was evaluated. Compound 1 did not show a full dose dependent behavior. The IC(100) was 8+/-1, 12+/-1, and 17+/-3 microM for 2 to 4, respectively.  相似文献   

5.
It was hypothesized that maximum living crown removal can be determined from experimental data using linear statistical models. Pruning experiments were carried out in four Scots pine (Pinus sylvestris L.) stands. Zero to nine living branch whorls were removed in three stands in southern Finland, and 0–4.5 m of the living crown was removed in a stand in northern Finland. Only dead branch whorls were removed from the control trees. A total of 517 trees were analyzed. Diameter increment was measured five years after pruning. The growth reduction was statistically significant when 40% or more of the living crown was removed by pruning. According to the linear models, green pruning decreased diameter growth by 0 to 33% at defoliation levels below 40%. This loss in diameter growth is, from an economical point of view, compensated by the knotfree timber resulting from pruning 2–3 years earlier.  相似文献   

6.
Allergy is an abnormal immune response to an allergen. Type I hypersensitivity is an immunoglobulin (Ig) E-mediated allergic disorder. Fructus piperis is derived from the ripe fruit of the pepper, which is widely used as a spice in human diets and is also administered as a medicine in many countries. Piperine has been shown to have anti-oxidant, anti-depressant, anti-tumor, and anti-inflammatory activities. However, the effect of piperine on IgE-mediated allergic responses has not been reported. Here, the rat basophilic leukemia cells by membrane chromatography (RBL-2H3/CMC) coupled to high performance liquid chromatography/mass spectrometry (HPLC/MS) to discover and identify piperine can bind to RBL-2H3 cell membranes. Piperine inhibited the expression of cytokines, and the release of both β-hexosaminidase and histamine, which could be stimulated by antigen in RBL-2H3 mast cells. We found that the levels of intracellular Ca2 + also decreased. Furthermore, RT-PCR showed that the mRNA expression levels of IL-4, IL-13, and TNF-α were significantly suppressed by piperine. The inhibitory effect of piperine on IgE-mediated degranulation and cytokine production by RBL-2H3 cells may be caused by the inhibition of IgE-mediated signaling pathways, including the phosphorylation of Lyn, p38, Erk, and Ras. In summary, piperine can inhibit antigen-induced allergic reactions that control degranulation.  相似文献   

7.
Ma bamboo (Dendrocalamus latiflorus Munro) treated with chromated phosphate (CP) exhibits an excellent green color. To understand the effects of the treatment sequence of CrO3 and H3PO4 and their interactions regarding green color protection, CrO3-H3PO4 and H3PO4-CrO3 two-step treatments plus a H3PO4-CrO3-H3PO4 three-step treatment were carried out in this study. Results revealed that the treatment sequence of CrO3 and H3PO4 definitely affects the effectiveness of bamboo color protection. Green color protection of ma bamboo culm could not be achieved by treating it with CrO3 or H3PO4 alone or with the H3PO4-CrO3 two-step treatment. Only by treating it with the CrO3-H3PO4 two-step treatment or the H3PO4-CrO3-H3PO4 three-step treatment did ma bamboo exhibit an excellent green color. The results indicated that bamboo reacts first with CrO3 and then forms an insoluble complex with H3PO4, which produces the green color on its epidermis. Chlorophyll analyses demonstrated that chlorophyll is not a key factor for green color protection. The green pigment was also formed when chlorophyll-free bamboo was treated with 2% CP at 60°C for 3h.  相似文献   

8.
该文以宁杭高速公路互通绿地及相关环境为研究区域,选取节点不同景观样地,以绿量作为研究生态效能的指标,通过对不同类型植物绿量的科学测定及其单位面积植物绿量综合比较得出:以乔木为主体,乔灌草搭配复层式绿地其单位面积绿量通常大于单一结构的绿地。由此借助绿量从光合、蒸腾和滞尘效应方面,研究高速公路绿地植物群落在环境绿化中发挥的生态效能,为科学合理建设高速公路绿地提供理论依据。  相似文献   

9.
为了解退耕还林工程对黄土高原生态脆弱区米脂县综合效益的影响,采用生态经济分析法、问卷调查法、修正的Bossel定位理论方法,2009年10~11月,对米脂县退耕还林工程实施前后的生态、社会和经济效益进行评价。研究结果表明,(1)自1998~2009年,退耕造林地土壤有机质(0~20 cm)平均含量和土壤有机碳密度分别比临近(﹤30 m)的坡耕地高出0.478%和0.574 kg/m2;(2)退耕还林经济净效益主要体现在退耕造林后劳动力转移劳务创收。即:69%的被调查农户家庭纯收入上涨了2~5倍,56%被调查农户种植业纯收入上涨0~1倍,44.5%的农户劳务收入占了家庭纯收入的50%以上,36.6%农户劳务收入超过了家庭纯收入的10%~20%,87.5%农户的退耕补贴占家庭纯收入的10%以下;(3)退耕还林提高了社会整体协调性0.81。国家实施退耕还林工程以来,初步改善了区域生态环境,整体提高了农户经济收入,优化了经济收入结构,但农业产业结构调整空间潜力很大。  相似文献   

10.
植物不同配置模式对绿地小气候温湿度的影响   总被引:2,自引:0,他引:2  
经过选择密林、灌草、乔草、草坪、乔灌草、水生植物、灌木绿篱、硬化地面绿化共8种植物配置模式,并以硬化地面作为对照进行温、湿度的测量。运用SAS软件进行分析发现,在和硬化地面的温度差异性比较中,草坪、灌草、乔草、灌木绿篱、硬化地面绿化、乔灌草、密林皆差异性显著。在和硬化地面的湿度差异性比较中,灌木绿篱、乔灌草、密林、草坪、灌草差异显著。密林的不同水平位置之间,温度的差异显著,但湿度的差异并不显著。经过相关性分析发现,气温和植物的高度呈线性负相关,但是湿度与植物高度的相关性不明显。  相似文献   

11.
分别以浓度为0.05%和0.1%的秋水仙素溶液处理一串红植株3d和6d,研究秋水仙素处理对一串红生长的影响.结果表明:以浓度为0.05%秋水仙素处理一串红生长点6d,一串红植株变异率较高,而且保持稳定,同时处理后植株死亡率低;发生变异的植株花色红艳,呈大球型.  相似文献   

12.
Load sharing between the stringers in gravel-decked log bridges is an important design factor when small- diameter stringers are used with thin gravel decks. In order to estimate the load sharing between the stringers, it is necessary to consider the deflection of the stringers; therefore, accurate estimates of the apparent modulus of elasticity (MOE) for full-size log stringers are required. In this paper, load and displacement data from the full- size bending tests are used to demonstrate that taper near midspan has the greatest effect on the MOE used in common log bridge design methods, where the logs are assumed to have constant cross sections. This paper proposes a method to estimate a MOE that can be used in a constant cross-section model given the geometry of the particular log of interest, and the MOE from full-size bending tests calculated when considering actual log geometry.  相似文献   

13.
This study examines certain physical, mechanical, and anatomical characteristics of coconut palm wood. The results show a correlation between the anatomical characteristics and density as well as lengthwise compression. All properties (density, frequency of vascular bundles (VBs), and mechanical properties) increase with the transverse distance from the center of the trunk. The study also tests VBs from different radial sections of the coconut palm tree (Cocos nucifera) for diameter, ultimate tensile strength, and modulus of elasticity. The influence of the VBs on the overall properties of the wood is discussed.  相似文献   

14.
Oral pre-treatment with alcoholic extract of Picrorrhiza kurroa rhizomes and roots (50 mg/kg/day for 10 days) significantly prevented the -galactosamine-induced alterations in respiration and oxidative phosphorylation of liver mitochondria.  相似文献   

15.
In this study, the effect of girdling on the moisture content of small-sized trees for heat energy production was clarified. The moisture content was measured for Scots pine (Pinus sylvestris), Norway spruce (Picea abies), and Downy birch (Betula pubescens) during two growing seasons after girdling. The trees were girdled at breast height for around 30 cm by removing the bark, phloem, and cambium from around the stem. At the beginning of the growing season the mean moisture content of the living Scots pine (P. sylvestris) and Norway spruce (P. abies) was 60%, and for Downy birch (B. pubescens) it was 50%. During the first growing season the effect of girdling on the moisture content was low, but during the second growing season the moisture content decreased significantly. The moisture content of the Norway spruce (P. abies) (23%) and Downy birch (B. pubescens) (33%) was at its lowest point at 14 months after girdling. There were no significant changes in the moisture content of the Scots pine (P. sylvestris) in this study. The results of this study can be used in basic research and in the development of energy wood production.  相似文献   

16.
微生物对杉木木材渗透性的影响   总被引:4,自引:0,他引:4  
分别在杉木产区古杉的创伤处采集被微生物感染木材样品和活体杉木上采集感染病的叶进行分离培养,培养后得到交链胞(Paeudomonas cunuinghamiae Nanjing F.)和多毛胞(Pestalotia zhirdiana P.Henn.)将两种微生物接种到杉木木材上,处理90d后,木材液体渗透性提高达55.3%-60.5%,经方差分析,对照与处理差异显著;微生物处理对心材没有作用;微生物处理改善杉木木材渗透性主要作用在边材,前6h的单位体积吸水量占总吸水量为55.3%-60.5%,达到24h后吸水量差异甚微。  相似文献   

17.
利用扩散法测定草甸土、淡黑钙土、草甸黑钙土及盐碱土碱解氮含量,结果表明:添加与不添加还原剂测定的土壤碱解氮含量,在8~24 h之间,呈上升态势,在24~30 h之间有所下降,但在30~48 h之间又呈现明显上升趋势,在扩散时间为24 h时氮含量测定值达到最好。添加与未添加还原剂所测得的土壤碱解氮含量相关极显著,进而证明两种方法都适用于这4种土壤的测定。还原剂对草甸土、淡黑钙土、草甸黑钙土碱解氮含量的测定影响不大,但在测定盐碱土碱解氮含量时采用添加还原剂的方法更加准确。  相似文献   

18.
Seedlings of Pinus pinea L. growing in plastic containers were treated with seaweed concentrate (SWC). Different concentrations of SWC were applied, 0 to 3 times, to the roots or shoots of the seedlings. Shoot application increased plant weight mainly by increasing shoot growth. This was manifested as increased shoot length and weight and a decrease in the root/shoot ratio. Root drenches did not change the total plant weight but it accelerated root growth and increased lateral root dry weight. Root growth capacity (RGC) tests for both shoot and root applications indicated an increase in root length and some increases in root number when applied as a root drench. This study indicates that root application of SWC improved seedling quality and increased the ability of seedlings to survive transplanting into pots.Abbreviations GC-MS Gas Chromatography-Mass Spectrometry - RGC root growth capacity - SWC seaweed concentrate  相似文献   

19.
Abstract

The thermal properties of wood-plastic composites with five different mineral fillers were studied. The tested mineral fillers were calcite (CaCO3), two different qualities of wollastonite, soapstone, and talc. The amount of wood, mineral, and plastic (polypropylene) was kept constant. Only the mineral type has been changed during the tests. The thermal behavior of the samples was studied by using a differential scanning calorimeter, a thermogravimetric analyzer and by determining the heat build-up. The analyzed properties were compared with a reference sample made without adding any minerals. The results show that the addition of mineral fillers does not remarkably change the thermal stability of composites. All the studied mineral fillers except soapstone had a small effect on the heat build-up.  相似文献   

20.
对上层林木采取大强度、中强度、小强度抚育,林分郁闭度分别保持在0.60、0.65、0.70左右时的林分生长量进行调查分析,结果表明:大强度抚育林分冠下红松的树高、胸径、蓄积生长量分别是小强度抚育林分的2.26倍、3.24倍和6.50倍;从整个林分蓄积生长量看,采取大强度抚育林分的生长量最高,是小强度抚育林分的1.30倍...  相似文献   

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