绵阳地区肺吸虫第二中间宿主——淡水蟹类感染情况的调查

为了探索绵阳地区肺吸虫自然疫源地与人群感染的关系,自1981年起,我们先后对青川、平武、广元、江油、剑阁、梓潼、北川、安县等山丘地区10个县进行了调查,现将结果报告如下。 一、一般情况 绵阳地区位于四川盆地西北边缘,东经104°45′—107°45′,北纬30°20′—33°05′,由龙门山脉、大巴山脉构成北高南低垂直梯度较大     

唐山地区的蝗虫种类及其分布

<正> 地理概貌 唐山地区位于河北省东部,东经117°31′—119°19′,北纬38°55′—40°28′。全地区包括10个县3个区和芦台、汉沽两个农场,耕地面积890万亩,境内以小麦、水稻、玉米、高梁、甘     

江苏省沿海水鸟资源

江苏省沿海地区位于东径119°27′—120°56′,北纬31°33′—35°07′,地处北亚热带向暖温带过渡地区,面积为3.5万km~2,两端为丘陵山地,中部为广阔的滩涂沼泽,长年受海洋性气候的影响,年平均温度14.1℃,冬季月平均温度在0℃以上,年均相对湿度达80％以上,气候     

云南蝶类调查及其地理分布

云南地处我国西南边陲,东经97°9′—106°12′,北纬21°09′—29°15′之间。北回归线横贯本省南部,基本上属于低纬度地带的内陆地区。地势、气候复杂,自然条件优越,蝴蝶种类繁多,区系复杂多样。多年来,在本研究室同志共同努力下,对云南及邻近地区,进行了野外考察采集,共获蝴蝶标本12,000余号,初步鉴定出432种,隶属于11科,188属。为今后进一步研究云南昆虫区系的全貌,现对云南蝶类区系及地理分布作一初步分析。     

试论陕西关中地区新石器时代遗址的地理环境与人类生产活动的关系

渭河是黄河的一条主要支流。陕西关中地区主要包括渭河中下游及其支流下游地区,约在东经106°45′—110°13′,北纬34°0′—35°12′之间,位于黄土高原东部边缘,南倚秦岭山脉,北界关中北山山系,面积约二万一千平方公里,属暖温带大陆性季风气候区域。这一地区虽然自第四纪全新世以来,总的气候变化趋势是由温暖湿     

神农架的部分大型真菌

(一)基本特征湖北省西部的神农架地区,位于东经109°56′—110°58′,北纬31°15—31°57′之间。地处我国亚热带向北温带过渡地带,又是东部低山丘陵区向西部高山区过渡区域。神农架系大巴山之余脉,最高的无名峰     

云南老君山鼠类的垂直分布

1980年6月至8月,我们对云南老君山的鼠类进行了垂直分布的调查研究。现介绍如下。 自然概况 老君山位于云南省的剑川、丽江和兰坪三县交界处;北纬26°30′—26°52′,东经99°42′—100°26′。属于著名的横断山脉的云岭山系中的大山之一。最高峰海拔4,247m.,山麓(金坪)海拔2,500m.。山势南北走向,北高南低,有纵横交错的高山、山间峡     

鄂西南山地植被的基本特征

本文系湖北省区划办委托进行的湖北植被类型图、植被区划图过程中的一个阶段性小结。鄂西南山地位于中国亚热带东部(湿润)常绿阔叶林亚区域,为湖北植被区划中鄂西南山地植被区,所属范围包括整个鄂西自治州、宜昌地区的大部及神农架南坡。约当北纬29°05′—31°22′,东经108°30′—111°47′的地理位置。     

云南陇川地区啮齿类及食虫类动物调查报告

我们于1982年8—9月,1983年6—9月,1984年5—9月的疫源调查工作中采集了大量啮齿类及食虫类动物标本,经分类鉴定,现整理如下。 自然地理概况 陇川位于云南西部,北纬24°08′—24°40′,东经97°39′—98°17′。西与缅甸接界,面积为1931平方公里。地处滇西山原、高黎贡山西坡,地势东北高,西南低。山川均为东北—西南走向,为侵蚀山地与宽谷相间的地     

大兴安岭北部火烧迹地人工更新造林鼠害调查报告

黑龙江省大兴安岭北部的塔河、阿木尔、图强和西林吉4个林业局地处北纬52°30′—54°51′,东经121°51′—125°5′之间,属大兴安岭寒温带明亮针叶林区,寒温带大陆性气候。气候严寒干燥,动植物组成种类贫乏,乔     

Forest restoration following a windthrow: how legacy retention versus plantation after salvaging alters the trajectory of initial recovery

Recently, the conversion of plantations into natural forests has attracted increasing attention, but little is known about how to convert a windthrown plantation into a natural forest. We examined the initial 3-year effects of salvage logging, site preparation, planting, and weeding in comparison with the effects of legacy retention after a typhoon blowdown on the changes in terrestrial environments and plant compositions and the similarity of the species composition to that of the intact natural forest. Our major findings are as follows: (1) A homogeneous, sunny, and flat environment continued for 3 years in the planted and weeded plot, whereas a heterogeneous environment was observed in the legacy retention plot; however, the light environment changed slightly in the planted plot. (2) The species composition in the planted plots changed greatly due to invasion by annual, biennial, and perennial herbs and early successional trees. Alien species also invaded the planted row. Conversely, the species composition changed little in the legacy retention, which was likely due to the presence of residual plants that prevented shade-intolerant species from being established. (3) The legacy retention, followed by the residual row, was the closest to the natural forest with respect to species composition, whereas the planted row was the most dissimilar from the natural forest. Legacy retention appears to be the most appropriate way to restore a natural forest immediately after a windthrow, yet supplemental planting may be necessary to restore the desired broadleaved species.     

Experimental and Ecological Studies on the Rubber-tea Artificial Community

This paper sums up the ecological data recorded in the south of Yunnan on our experiment of the rubber-tea artificial community during 1960 to 1980. It is a part of our studies of the tropical artificial ecosystem. The following results concern its dynamic productivity, stability, interspecific relationships, structure and function. 1. By the introduction of tea into the rubber plantation, its annual productive period has been prolonged from seven to ten months, while the non-productive period of young plants has also been shortened by three to four years. Its monthly productivity curve shows a change corresponding to the monthly variation of local solar radiation. In contrast, the monthly productivity curve of the monocultural tea plantation is not so. This is due to the fact that a tea-plantation must possess a certain amount of shade before it can grow well. 2. The rubber-tea community has a comparatively high stability in productivity. Low temperature is the major problem of rubber plantations in the south of Yunnan. It often causes cracks in the root collar barks of rubber trees and may even cause the death of the trees. We believe that the problem is caused by lack of heat from sun light, and have found that the critical least amount of heat necessary is 123 calories/sq em per day. In order to obtain more amount of heat, during the past twenty years, we have compared the annual productivity variations of various rubber-tea community structures, and are convinced that the cold-resistant ability of one kind of rubber-tea community structure has been greatly improved. This is achieved by discovering and applying two kinds of heat effects; namely, the directional heat effect of side rows and the lower story heat effect in the community. By adopting the wide row and thick planting structure of rubbertea community, arable land suitable for the rubber tree has been raised from 800 m. to 1000 m. in altitude. 3. The rubber-tea community possesses a high environmental protection capability. Owing to the introduction of the tea plants in the lower story, the annual rate of water loss in the community decreases by 42%, and that of soil erosion by 23.8%. Before the dry season sets in, the rubber-tea community contains 150 tons more water per hectare than that of a rubber plantation, and 322.5 tons more than that of a tea plantation (2.2 m thickness of Soil). The content of the organic matter in the soil of the rubber-tea community is 0.15% higher than that of a rubber plantation, and 0.2% higher than that of a tea plantation. Moreover, the soil unit weight of the rubber-tea community is comparatively lighter. 4. A corresponding relationship of the underground story-formation has been found in rubber-tea community; for example, rootlets of the rubber trees are concentrated in soil 0–20 cm below the surface, and those of the tea trees in soil 20–50 cm in depth. This shows the possibility of mutual aceomodation of the two species. 5. In conformity with the changes in altitute and latitude, the proportion of rubber and tea should also be changed accordingly. In the plains, the rubber trees will play a dominant part in the community. As the altitude rises, tea trees will gradually replace the rubber trees in playing the dominant role. Finally, the rubber trees entirely disappear from the scene and are replaced by plants such as camphor tree (Cinnamomum porrectum (Roxb.) Kosterm.). A camphor-tea community is formed. In fact, it is a type of artificial community welcomed by people in the south of Yunnan. Now, rubber-tea community is being rapidly spread in the southern part of our country, amounting to more than 10,000 hectares in area.     

A Study on Manganese Content in Soils and Leaves of Rubber Trees in Rubber Plantation Areas of China

The present paper deals with the status of manganese (Mn) in rubber trees on 110 rubber plantation at 46 counties in the rubber tree growing regions of China. The content of Mn in rubber tree leaves ranges from 31 to 2167 ppm, averaging 390 ppm which is higher than that in the leaves of normal rubber trees (150–300 ppm). Thus it can be concluded that the present status of Mn in China's rubber trees is higher. Nevertheless, the content of Mn of soil of rubber plantations in China varies significantly according to different soil types, fertilization and management. The difference between the highest and the lowest contents of total Mn could be as high as 140 times and an even greater difference of 200–1240-fold between the highest and the lowest contents of replaceable and reducible Mn has been observed. The storage of reducible Mn is generally insufficient in the soil. Therefore, the symptom of leaf yellowing due to deficiency of Mn has developed in rubber trees in certain parts of rubber tree growing regions in China. The essential oure for leaf yellowing of rubber trees is to raise Mn content in the tree by proper application of fertilizer. The procedures, dosage and timing of the fertilizer for leaf yellowing treatments are suggested.     

Determination of biotic aetiology of tapping panel dryness (TPD) syndrome of rubber tree (Hevea brasiliensis) by return-polyacrylamide gel electrophoresis (R-PAGE) technique

Tapping panel dryness (TPD) syndrome affecting rubber tree (Hevea brasiliensis) is known to reduce natural latex production. Its aetiology remains ambiguous despite long years of research. A low molecular weight RNA similar to viroid RNA was isolated from TPD-affected samples of rubber trees. In the present study, a modified return-polyacrylamide gel electrophoresis procedure was standardised. The viroid-like low molecular weight (LMW) RNA was found associated with leaf, bark and root tissues and rubber seedlings. The technique was employed to detect LMW RNA in different clones of rubber planted in different locations and in bud-grafted plants. The LMW RNA isolated from TPD-affected trees was found infectious on seedlings of tomato cv Pusa Ruby. The LMW RNA was reisolated from symptomatic tomato leaves but not from control plants. This is for the first time that a biotic agent, a viroid RNA, is found consistently associated with the syndrome. The technology developed can be useful to demonstrate the onset of TPD in untapped trees in the absence of other methods such as nucleic acid hybridisation.     

Narrow rows reduce biomass and seed production of weeds and increase maize yield

Smallholder farmers in southern African countries rely primarily on cultural control and hoe weeding to combat weeds, but often times, they are unable to keep up with the weeding requirements of the crop because of its laboriousness, causing them to incur major yield losses. Optimisation of crop planting pattern could help to increase yield and suppress weeds and to reduce the critical period of weed control and the weeding requirements to attain maximum yield. Experiments were carried out in Zimbabwe during two growing seasons to assess the effect of maize density and spatial arrangement on crop yield, growth and seed production of weeds and to determine the critical period for weeding. Planting maize at 60 cm row distance achieved higher yields and better weed suppression than planting at 75 or 90 cm row distance. Increasing crop densities beyond the customary three to four plants m⁻² gave modest reductions in weed biomass but also diminished crop yields, probably because of increased competition for water and nutrient resources. Maize planted in narrow rows (60 cm) intercepted more radiation and suffered less yield reduction from delaying hoe weeding than those planted in wider rows (75 or 90 cm), and the duration of the weed-free period required to attain maximum grain yield was 3 weeks shorter in the narrow spacing than that in the 75- and 90-cm row spacings. Weeding was more effective in curtailing weed seed production in the narrow row spatial arrangements than in the wide row planting. The results of these studies show that narrow row spacings may reduce weeding requirements and increase yields.     

西双版纳30个橡胶树品种的低温半致死温度及低温对抗氧化系统的影响

采用低温恒温槽处理离体叶片后测定其电解质外渗率,并结合Logistic方程得出低温半致死温度的方法,评价农业部景洪橡胶树种质资源圃中的30个橡胶树品种的抗寒性。结果表明,品种‘RRIM712’、‘云研80-1983’、‘云研77-4’、‘PR107’、‘RRIM524’抗寒性强,低温半致死温度在-4～0℃之间;品种‘云研76-398’、‘RRIM523’抗寒性弱,低温半致死温度在4~7℃之间;其他品种抗寒性居中。橡胶树在低温胁迫下,超氧阴离子的产生速率与橡胶树的抗寒性无直接关系,但不同温度下的变化幅度越小,抗寒性越高;SOD活性随温度降低迅速提高,CAT随温度降低表现出活性降低的趋势。     

Functional Characterization of Hevea brasiliensis CRT/DRE Binding Factor 1 Gene Revealed Regulation Potential in the CBF Pathway of Tropical Perennial Tree

Rubber trees (Hevea brasiliensis) are susceptible to low temperature and therefore are only planted in the tropical regions. In the past few decades, although rubber trees have been successfully planted in the northern margin of tropical area in China, they suffered from cold injury during the winter. To understand the physiological response under cold stress, we isolated a C-repeat binding factor 1 (CBF1) gene from the rubber tree. This gene (HbCBF1) was found to respond to cold stress but not drought or ABA stress. The corresponding HbCBF1 protein showed CRT/DRE binding activity in gel shift experiment. To further characterize its molecular function, the HbCBF1 gene was overexpressed in Arabidopsis. The HbCBF1 over expression (OE) line showed enhanced cold resistance and relatively slow dehydration, and the expression of Arabidopsis CBF pathway downstream target genes, e.g. AtCOR15a and AtRD29a, were significantly activated under non-acclimation condition. These data suggest HbCBF1 gene is a functional member of the CBF gene family, and may play important regulation function in rubber tree.     

Photosynthetic Responses to Light for Rainforest Seedlings Planted in Abandoned Pasture, Costa Rica

Efforts to reforest tropical pasture with native tree species have increased in recent years, yet little is known about the physiology of most tropical trees. The goal of this study was to assess the effect of habitat on photosynthetic responses to light for seedlings of four native rainforest species (Calophyllum brasiliense, Ocotea glaucosericea, Ocotea whitei, and Sideroxylon portoricense) planted to facilitate tropical rainforest recovery in southern Costa Rica. Seedlings were planted in primary forest, in open abandoned pasture, and in the shade of remnant trees within the pasture. Growth, morphology, photosynthetic gas exchange responses to light, and chlorophyll fluorescence (an indication of the integrity of photosynthetic processes) were measured in the three habitats. Height and leaf area were generally greater for seedlings in tree shade compared to those in the forest and open pasture. Photosynthetic rates were higher for plants in open pasture and tree shade compared to those in the forest for two of the four species. Chlorophyll fluorescence results indicated flexibility in the photosynthetic processing of light energy that may help plants tolerate the bright light of the pasture. This study demonstrates that, for certain species, seedlings under remnant pasture trees do not exhibit the level of photosynthetic stress experienced in open abandoned pasture. Seedling responses to light, in combination with other factors such as increased nutrient input through litterfall, help explain the enhanced growth of seedlings under remnant pasture trees. Planting seedlings under remnant trees may increase the success of future efforts to restore tropical forest in abandoned agricultural land.     

A newly identified locus controls complete resistance to Microcyclus ulei in the Fx2784 rubber clone

Using cultivars which are genetically resistant to South American leaf blight (SALB) caused by the fungus Microcyclus ulei is the only way to plant rubber trees in disease-affected areas. Numerous field observations led to the hypothesis that the resistance of the cultivar Fx2784 to SALB is likely to be monogenic. In this study, we investigated this hypothesis by examining the distribution of the trait in a cross between the resistant cultivar and a susceptible one. The individuals resulting from this cross were planted in field trials in French Guiana and Brazil. The resistance of all the trees was assessed by field observations. Bulk segregant analysis (BSA) using microsatellite markers was performed in French Guiana to determine which markers were genetically linked to resistance, and the results were validated by field observations in Brazil. In both locations, a 1:1 segregation of the resistance trait was observed, thus reinforcing the monogenic hypothesis. BSA showed tight linkage between resistance and the microsatellite markers located in linkage group 2 in the Hevea genome and enabled to pinpoint the resistance locus. The location was confirmed by observations on the trees planted in Brazil. This result should facilitate the use of Fx2784 resistance in future breeding programs for SALB resistance. This is the third major locus conferring resistance to SALB identified in rubber tree (Hevea spp.). These three loci are genetically independent, a favorable situation for genetic improvement of SALB resistance.     

Monoterpene emissions from rubber trees (Hevea brasiliensis) in a changing landscape and climate: chemical speciation and environmental control

Emissions of biogenic volatile organic compounds (VOCs) have important roles in ecophysiology and atmospheric chemistry at a wide range of spatial and temporal scales. Tropical regions are a major global source of VOC emissions and magnitude and chemical speciation of VOC emissions are highly plant-species specific. Therefore it is important to study emissions from dominant species in tropical regions undergoing large-scale land-use change, for example, rubber plantations in South East Asia. Rubber trees ( Hevea brasiliensis ) are strong emitters of light-dependent monoterpenes. Measurements of emissions from leaves were made in the dry season in February 2003 and at the beginning of the wet season in May 2005. Major emitted compounds were sabinene, α -pinene and β -pinene, but β -ocimene and linalool also contributed significantly at low temperature and light. Cis -ocimene was emitted with a circadian course independent of photosynthetic active radiation (PAR) and temperature changes with a maximum in the middle of the day. Total isoprenoid VOC emission potential at the beginning of the wet season (94 μg gdw⁻¹ h⁻¹) was almost two orders of magnitude higher than measured in the dry season (2 μg g dw⁻¹ h⁻¹). Composition of total emissions changed with increasing temperature or PAR ramps imposed throughout a day. As well as light and temperature, there was evidence that assimilation rate was also a factor contributing to seasonal regulating emission potential of monoterpenes from rubber trees. Results presented here contribute to a better understanding of an important source of biogenic VOC associated with land-use change in tropical South East Asia.