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利用青浦地区1959~2016年的观测资料对青浦地区主要旅游气象灾害和旅游舒适度进行了分析,主要旅游气象灾害为大雾、霾、雷暴、高温、暴雨、台风,逐类进行气候特征研究,分别得出了各类气象灾害影响时段、基本特征及对旅游业主要危害。根据人体舒适度及户外活动指数分析,结果表明:青浦地区3月下旬至7月上旬、8月下旬至11月下旬较适宜旅游活动;适宜户外活动的时间段为3月下旬至6月中旬及9月中旬至11月中旬。 相似文献
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杨干透翅蛾的研究 总被引:1,自引:0,他引:1
杨干透翅蛾是杨树的一种新的蛀干害虫。在西宁地区蛀害指数达43—79%,2年1代。成虫分主、副两组,6月和8月为发生盛期,幼虫侵蛀期主要在7月中、下旬和9月下旬—10月中旬。幼虫计有8龄。当年侵蛀后可长至1—4(5)龄;第二年可长至6—7(8)龄,在林木边材中造成“L”形蛀道;于第三年相继在蛀道内作茧化蛹、羽化。因有二个发生年度不同的群体相互演替,故每年都有一批成虫和初孵幼虫出现。树龄10年左右,胸径17.77±4.42厘米的四旁杨树最易受害;树干胸高1米以内和树冠基部分枝点附近,着卵最多,蛀害也最严重。侵蛀盛期喷布50%磷胺乳剂50—100倍液,毒杀小幼虫;辅以40%乐果乳剂或80%敌敌畏乳剂原液注孔,熏杀中、老龄幼虫。 相似文献
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利用2016~2019年宿迁市中心城区国控站点臭氧(O3)监测数据,分析了宿迁市臭氧(O3)的污染状况以及时空分布特征。结果表明:2016~2019年,宿迁市区的臭氧浓度和超标天数均呈上升态势。臭氧超标出现时间由2016年的6~9月延长至2019年的2~10月,全年污染最为严重的时段为5、6月份;小时浓度变化呈单峰型分布,超标日峰值出现时间由2016年的15时延迟至2019年的17时。 相似文献
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通过对油茶主要良种的标定植株进行果实生长和含油量分析研究,探索油茶果实油脂形成与转化的内在机理.结果表明果实体积生长主要在6月中旬至7月下旬.油茶果实质量的增加主要在6月中旬至7月下旬和9月中旬至10月下旬采收前两个高峰期,其质量增加值超过油茶果实总质量的2/3.油茶种仁含油率、鲜籽含油率和鲜果含油率均随果实生长逐渐增加,年周期内存在两个增长高峰期,为8月中旬至9月初与9月下旬至10月下旬采收前.油茶鲜果含油率在9月20日至10月20日的高峰期的增幅达鲜果总含油量的68.9%,指出霜降籽油茶果实不宜提前采收,否则会对产油量造成很大的损失. 相似文献
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M. Hubbes 《Forest Pathology》1973,3(3):163-168
The seasonal fluctuation in the production of coremia by Ceratocystis ulmi (Buis.) was studied on elm stem discs taken from trees felled in April, June, July, September, October and November 1971 at Valcartier, Quebec. More coremia formed on stem discs of trees felled during the growing season. Except for trees felled in October and November, more coremia formed on sapwood than on heartwood. Evidence obtained during the study showed that the compounds, which trigger coremia formation, are not uniformly distributed within and between trees or throughout the period from April to November. 相似文献
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Yoshio Awaya Nobuhiko Tanaka Kunihiro Tanaka Gen Takao Eiji Kodani Satoshi Tsuyuki 《Journal of Forest Research》2000,5(4):247-258
The relationship between the stand parameters (top layer height (H1) and volume/ha (Vha)) and digital number (DN) were evaluated
for evergreen conifer stands using three airborne images with 4-m spatial resolution, which were taken in June 1995, September
1993, and October 1994 using the Compact Airborne Spectrographic Imager (CASI). Estimation accuracy of the stand parameters,
their seasonal changes, and suitable wavelength were analyzed using correlation coefficients and a regression analysis. The
minimum DN of stands, which showed the darkness of a canopy shadow, had a higher correlation with H1 than the average and
maximum DN while the average DN had a higher correlation with Vha. The green channels gave the highest correlation coefficients
with H1 and Vha, which exceeded — 0.9 for the September and October images. However, the red channels had a consistently high
correlation with the stand parameters for the three images. The near infrared channels gave poor correlations with H1 and
Vha for the June image. Spectral variations among trees may affect the relationship between DN and the stand parameters in
the leaf maturation period in June. Consequently, the late growing season was better at giving consistent results for the
stand parameter studies. There was a linear relationship between the measured and the estimated stand parameters for the validation
plots especially for the H1 case of September with sufficient accuracy. Nadir viewing images, which had high spatial resolution
and a wide dynamic range such as the CASI images, were necessary to estimate the stand parameters accurately.
This study was also partly supported by the research project, ‘A Study of Accurate Biomass Estimation using Airborne Imagery,’
of the Science and Technology Agency of Japan. Comments from the editors helped improve the contents of the paper. 相似文献
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福建柏苗高生长期划分的有序样本聚类分析 总被引:1,自引:0,他引:1
以福建柏苗高15 d净生长量为样本,采用有序样本聚类分析方法,将福建柏苗高生长过程划分为5个时期:出苗期为3月1~30日,幼苗期为4月1日~5月30日,速生前期为6月1~15日,速生期为6月16日~9月30日,生长后期为10月1日~12月30日。速生前期和速生期的净生长量只占全年总生长量的28.5%,而幼苗期、生长后期的净生长量分别占全年总生长量的30.0%、34.9%。因此结合福建柏的生理特性提出幼苗期、生长后期的管理措施,为培育福建柏优质壮苗提供依据。 相似文献
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通过对叶林模式杜仲6—10月的生物量动态变化的调查分析,结果表明:杜仲枝条长度和粗度前期增长较快,而到8、9月以后,增长缓慢,在10月份达到最大值,分别为115.57 cm和1.971 cm。6—8月为杜仲枝条皮干重的缓慢增长期,8—10月为杜仲枝条皮干重的快速增长期,在10月份最高,达到15.99 g;不同月份杜仲枝条皮含水率从高到低顺序为:6月>8月>9月>7月>10月,6月份最高可达74.7%,而10月份最低为68.88%。6—7月杜仲剥皮枝条干重增长不明显,7—10月为杜仲剥皮枝条干重的快速增长期,在10月份最高,达到111.63 g。不同月份杜仲剥皮枝条含水率从高到低顺序为:6月>7月>8月>9月>10月,6月份最高可达66.95%,而10月份最低为50.16%。6—9月为杜仲叶(单枝)总干重的增长期,9—10月为稳定期,9月份最高,达到48.96 g;不同月份杜仲叶(单枝)含水率从高到低顺序为:9月>8月>6月>10月>7月,9月份最高可达72.44%,而7月份最低为69.91%。不同月份杜仲叶片数量(单枝)从多到少顺序为:8月>9月>10月>7月>6月,8月份最多可达59片,而6月份最少为39.7片。建议以杜仲叶子为原料的加工产业,应在9月采摘叶子。 相似文献
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Frederik J. Lerm Melanie Blumentritt Willem H. Brink C. Brand Wessels 《European Journal of Forest Research》2017,136(3):411-420
Information on the external shape, internal properties and defects of a tree is important for the forest and wood-processing industries. Resin pockets are internal defects, associated with some softwood species, and are especially undesirable in furniture, joinery and veneer products. In this study, we propose a new lower-cost method for measuring tree shape and macroscopic internal characteristics. The objectives of this study were to: (1) design, construct and test a mobile system that can be used in field to obtain a three-dimensional model of a log or tree stem indicating selected macroscopic internal characteristics and (2) to use the system to investigate the occurrence and causes of resin pockets in Pinus patula from the Mpumalanga escarpment in South Africa. In order to establish the cause of resin pocket formation in Pinus patula, four 3-m logs from 24 trees from three compartments were dissected and digitally reconstructed into three-dimensional models. The results from the study suggest that the formation of Type 1 resin pockets in Pinus patula was due to bending stresses caused by wind sway. It was not possible to establish with certainty the cause of Type 2 resin pocket formation. However, there was evidence that damage events, and specifically thinning damage, have been the cause of some of the Type 2 resin pockets observed. 相似文献
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樟子松枯梢病的侵染发生规律 总被引:1,自引:0,他引:1
在辽宁省章古台 ,松枯梢病 Sphaeropsis sapinea主要发生在樟子松 Pinussylvestrisvar.mongolica苗木和中老龄树木上 ,树龄越大 ,病害越重。病菌孢子在整个生长季节均能放散与传播 ,降雨节律和降雨量直接影响到孢子的扩散期、高峰期和数量。降雨量大的年份 ,孢子放散数量多 ,病害发生重。人工接种树木发现 ,从新梢伸长至针叶发育完全期间 ,病菌无需伤口即可直接侵入当年新梢并使之枯萎。病菌的侵入时期主要在 5月下旬至 6月下旬 ,此间也是化学防治的最佳时期。野外自然条件下 ,病害自 7月份开始发生 ,8月中下旬发展最快 ,1 0月份停止。樟子松是最易感染松枯梢病的树种之一。 相似文献
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松树高产脂力遗传改良的研究进展 总被引:6,自引:0,他引:6
松脂是重要的林产品,我国松脂产品无论在生产和贸易上都占全球40%以上的份额,在世界松脂产品贸易中占重要的地位,经营好松脂产业对我国经济建设具有重要的意义,选择高产树脂树木进行遗传改良,并在此基础上建立高产优质松脂基地是实现可持续经营松脂产业的重要途径。本文回顾和介绍了国内外松树高产脂力遗传改良研究的历程和成果,并提出迫切需要对我国主要采脂树种开展高产脂力遗传的改良工作。以建立优质高产采脂林基地,确保我国松脂产业的可持续经营。 相似文献