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81.
统计分析1963 ~ 2009年广西省沿海气象台站雾的观测资料和NCEP再分析资料,从气候特征、天气形势和气象条件3个方面分析广西沿海雾的气候特征和形成条件.结果表明,广西沿海雾出现最频繁时间段为08:00 ~09:00;主要发生在冬春季,其中以3月为最多,夏秋季很少;雾日数年际变化幅度大.广西沿海出现雾过程的天气形势主要有地面高压后部和弱冷空气影响2种.统计广西沿海雾和各气象要素的关系发现,广西处于水汽通量的大值区,水汽十分充沛;广西沿海雾形成要有适当的风速、风向;出现雾时地面气温在11 ~25℃;逆温层是出现大雾的有利条件,但并不是必要的条件. 相似文献
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83.
6种不同沿海防护混交林凋落叶持水性能比较 总被引:1,自引:0,他引:1
[目的]了解并比较沿海地区6片木麻黄与竹子防护混交林凋落叶持水性能状况,为沿海防护林树种选择提供理论依据。[方法]通过设置标准地,样方搜集和室内浸水试验,测量凋落叶自然含水率、持水率、吸水速率、失水率和失水速率,比较分析混交林凋落叶持水性能。[结果]木麻黄与花吊丝竹混交林凋落叶的最大持水率较高,其次为吊丝单竹+木麻黄、勃氏甜龙竹+木麻黄、绿竹+木麻黄、麻竹+木麻黄和大头典竹+木麻黄;而自然含水率从高到低依次为勃氏甜龙竹+木麻黄花吊丝竹+木麻黄绿竹+木麻黄大头典竹+木麻黄吊丝单竹+木麻黄麻竹+木麻黄;从凋落叶的吸水和自然风干过程来看,6种混交凋落叶的持水率、吸水速率、失水率和失水速率在浸泡或自然风干的0~2h有一个迅速变化的趋势,2h后凋落叶持水率和吸水速率逐步变缓,16h后逐渐趋于平稳。[结论]回归分析结果表明,持水率和浸泡时间及失水率和风干时间之间的关系均为对数函数关系,而吸水速率与浸泡时间及失水速率与风干时间的关系均为幂函数关系。 相似文献
84.
中国浙江省上虞市滨海盐土的物理化学性质及其实验超级光谱反射 总被引:4,自引:2,他引:4
45 and 50 composite soil samples were collected, respectively, from two agricultural fields, that were enclosed and reclaimed from coastal tidal-flat areas in 1996 and 1984 respectively, in Shangyu of Zhejiang Province, China, to investigate the physico-chemical properties and the hyperspectral characteristics of the saline soils and to make an assessment on their relationships. The reflectance spectra of saline soils were measured using a spectroradiometer in laboratory. The mean spectral curves of the saline soils from the two sites different in reclamation year showed that the saline soil taken from the recently reclaimed land with higher salinity demonstrated a lower reflectance intensity in the spectral region from about 550 nm to 2300 nm. In addition, nine absorption bands, i.e., 488 nm, 530 nm, 670 nm, 880 nm, 940 nm, 1400 nm, 1900 nm, 2 200 nm and 2 300 nm, were chosen as the spectral bands to investigate the relationships between soil physico-chemical properties by means of Pearson correlation analysis. Finally, the first two principal components were calculated from nine absorption bands and used to discriminate the saline soil samples taken from two sampled fields. The results indicate that it is feasible to detect physico-chemical properties of saline soils from fields reclaimed for varying time periods on the basis of the hyperspectral data. 相似文献
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86.
We monitored breeding bird communities and vegetation both before and after Hurricane Katrina category 2 winds severely damaged extensive bottomland hardwood forest of the Pearl River basin, south Louisiana. Many trees were felled by wind, most others were stripped of leaves and branches, and the canopy opened considerably (57%). Blackberry thickets sprouted and expanded to cover almost all of what was previously a patchily open forest understory. The bird community changed distinctively following the hurricane, driven primarily by increased density of species that prefer dense understory (regenerating) habitat. Individual species that increased significantly in density included one year-round resident, Carolina wren, and five breeding migrants, white-eyed vireo, Swainson's warbler, Kentucky warbler, hooded warbler, and yellow-breasted chat. These patterns were predictable responses to the opened canopy and increased density of understory vegetation. However, over three years following the storm, most species, especially canopy breeders, showed no distinct numerical response to the hurricane, which suggests that the initial bird community was resistant to hurricane disturbance. Only one species, Acadian flycatcher, declined significantly after the hurricane, presumably because of loss of its preferred open understory breeding and feeding habitat. Our results thus document and reinforce the important role hurricanes play along the Gulf coast in structuring forest bird communities by altering understory habitat. We expect habitat changes will continue as invasive plant species further change forest community structure, and as large storms increase in frequency in relation to global climate change. Thus, we also expect continued changes to the bird community, which may include additional future declines. 相似文献
87.
泥质海岸防护林土壤酶活性与理化性质关系的研究 总被引:14,自引:0,他引:14
通过对泥质海岸防护林土壤酶活性和理化性质关系的研究得出:(1)四种土壤酶(蔗糖酶、碱性磷酸酶、脲酶、蛋白酶)与土壤水稳性团粒含量、容重、孔隙率、有机质含量、盐分含量、全氮含量、速效磷含量、pH值有着密切的关系,而与物理性粘粒含量、含水量、速效钾含量不相关;(2)通过典型相关分析,土壤酶与理化性质之间关系密切,第一对典型变量的相关系数达0.9443。在土壤酶中起主要作用的是脲酶和蛋白酶,在理化性质中 相似文献
88.
杭州湾漕泾沿岸水化学状况 总被引:6,自引:2,他引:6
报道了 2 0 0 1年 1- 12月杭州湾畔金山漕泾地区用于水产养殖的河口沿岸水化学状况 :总含盐量 (12 .2 4± 1.92 )g/L ,碱度 (2 .12± 0 .2 7)mmol/L ,pH值为 7.99± 0 .11,阴阳离子中含量最高者分别为Cl-(6 .6 4± 1.0 4)g/L与Na+ +K+ (3.76± 0 .6 0 )g/L ,属典型河口区水质特点 ,系海水水质类型 (ClNaⅢ)。常规水质指标如下 :Nt为 (1.32± 0 .44 )mg/L ,其中NH3 Nt占 19.7%,NO-3 N占 78.8%,NO-2 N占 1.6 %,活性磷PO3 -4 P含量为 (2 .0 4± 1.5 7) μg/L ,氮磷比 (N/P)为 6 47(原子比 ) ;化学需氧量 (CODMn)为 (6 .89± 1.76 )mg/L ;五日生化需氧量(BOD5)为 (2 .5 6± 0 .5 2 )mg/L ;溶解氧 (DO)为 (7.95± 0 .5 6 )mg/L。 相似文献
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90.
采用路线调查和样点统计相结合的方法,调查泉州湾乌屿海滩及海岸的鸟类资源,共记录鸟类58种,隶属于10目22科,其中留鸟19种(32.8%),夏候鸟6种(10.3%),冬候鸟25种(43.1%),旅鸟8种(13.8%)。区系组成:东洋种25种(43.1%),古北种30种(51.7%),广布种3种(5.2%)。12月鸟类的数量和种类均达到高峰。与历史资料进行对比分析,提出加强鸟类相关生境的保护与建设,建立鸟类监测站,开展科学研究等保护建议。 相似文献