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1.
酸沉降对森林生态系统影响的研究现状及展望   总被引:14,自引:0,他引:14  
刘菊秀 《生态学杂志》2003,22(5):113-117
酸沉降影响下物质循环及其不平衡研究;酸沉降对土壤理化性质的影响;森林水化学方面的研究;酸沉降下重金属的活化研究;酸沉降对植物生长的影响研究;酸沉降和气候变化对森林的影响;模拟酸雨对土壤理化性质和植物生长的影响;酸沉降下土壤风化问题的研究;运用模型对酸化问题的研究;森林土壤人为和自然的酸化;酸沉降临界负荷的研究;酸沉降和其它污染物对植物的联合影响;酸化土壤恢复研究等方面介绍了酸沉降对森林生态系统影响的研究现状,并阐明了今后研究的方向及应该注意的问题。  相似文献   

2.
The effects of Bt transgenic cottons (Bt-I expressing cry1Ac and Bt-II expressing cry1Ab and cry2Ab or cry1Ab and cry1Fa) and non-Bt cottons on feeding, oviposition and longevity of adults, and development and survival of Liriomyza trifolii larvae were studied under laboratory conditions; and infestation on four Bt and two non-Bt cotton traits were investigated under field conditions. Laboratory choice and no-choice tests showed that L. trifolii adults were capable of distinguishing between Bt cottons and non-Bt cottons. In a choice test on younger plants (4-5 leaves), the adults were found more often and made more feeding punctures (FP) on non-Bt cottons than on Bt cottons. On older plants (8-9 leaves), adults made the most FP on non-Bt cotton followed by those on Bt-II cottons and the least on Bt-I cotton. The females oviposited more eggs (6.7 eggs per leaf) on non-Bt cotton than on Bt-I (1.7 eggs per leaf) and Bt-II (0.8 eggs per leaf) cottons on younger plants and oviposited similar numbers of eggs (0.7-1.3 eggs per leaf) on non-Bt and Bt cottons on older plants. In a no-choice test, the females also fed more FP on non-Bt cottons than on Bt cottons on both younger and older plants. The females oviposited more eggs (15.6 eggs per leaf) on non-Bt cotton than on Bt-I (8.2 eggs per leaf) and Bt-II (6.5 eggs per leaf) cottons on younger plants and similar numbers of eggs (2.5-3.3 eggs per leaf) on non-Bt and Bt cottons on older plants. Larval and puparial survivals were not different among Bt and non-Bt cottons. The occurrence and damage of leafminers on cottons in the field showed that L. trifolii infested more plants and leaves and had more mines on non-Bt cotton than on Bt cottons.  相似文献   

3.
Abstract. The vegetation on a wet mountain slope on Haleakala (an oceanic island) is compared with that on Kinabalu (a continental island) to examine relationships between regional floristic richness and α- and β-diversities. The two mountains are similar in their constant tropical climate, generic and family-level floristic elements and geological age of the summit regions, but different in regional floristic richness (rich on Kinabalu vs. poor on Haleakala). α-diversity of canopy and subcanopy tree species was much higher on Kinabalu than in comparable zones on Haleakala. Average turnover rate of species (as logarithmic community similarity) on the slope was one order of magnitude greater on Kinabalu than on Haleakala (0.127 vs. 0.017 per 100 m alt.). While there were genera with wide altitudinal ranges on both mountains, a large proportion of the genera was differentiated into parapatric altitudinal congeners on Kinabalu. By contrast, most genera are altitudinally monotypic on Haleakala. The number of sympatric congeners per genus, and the frequency of multi-specific genera per plot were high on lower slopes but decreased with increasing altitude on Kinabalu, whereas the values were low across all altitudes on Haleakala. These patterns suggest that sympatric and parapatric species radiation was less on Haleakala than on Kinabalu. This may be related to Haleakala's initially poor and disharmonic flora.  相似文献   

4.
不同寄主植物对云南紫胶虫自然种群的影响   总被引:7,自引:1,他引:6  
研究了云南紫胶虫(Kerria yunnanensis)在聚果榕、南岭黄檀、钝叶黄檀和偏叶榕上的发育、存活和繁殖情况.结果表明:在自然条件下,云南紫胶虫在钝叶黄檀上的种群初始密度最高,为181.17头·cm-2,聚果榕上最低,为145.27头·cm-2;雄虫占的比例以在南岭黄檀上最少,为0.19,偏叶榕和聚果榕上最多,为0.24;从幼虫到成虫的累积死亡率,南岭黄檀上最高,为90.03%,偏叶榕上最低,为87.05%;完成世代时间以在南岭黄檀上最长,为156 d,聚果榕上最短,为140 d;平均怀卵量以在南岭黄檀上最高,为536粒,聚果榕上最低,为345.86粒;虫体质量以在南岭黄檀上最大,为12.62 mg,偏叶榕上最小,为9.03 mg;世代净增值率以在南岭黄檀上最高,为48.51,聚果榕上最小,为32.79.综合比较4种不同寄主植物,南岭黄檀是云南紫胶虫夏季世代种群生长发育和繁殖最适宜的寄主.  相似文献   

5.
目的了解实验所用常见致病真菌能否在常用医用原材料上生存及生存时间。方法选择8种常见致病真菌,活化后将它们分别接种在5种常用的医用原材料上,接种后及以后的每24h将接种有真菌的医用材料放入巯基乙酸盐液体培养基中并观察能否生存,记录存活时间。结果红色毛癣菌和须癣毛癣菌在棉布、纸板、铁皮、玻璃表面存活25~28d,在地板胶表面存活14~15d;新生隐球菌在棉布、纸板、铁皮表面存活24~27d,在玻璃和地板胶表面存活14~18d;茄病镰刀菌在上述5种材料上存活22~27d;石膏样小孢子菌在棉布、纸板、铁皮和玻璃表面存活20~27d,在地板胶表面存活8d;申克孢子丝菌在棉布、纸板、玻璃和地板胶表面存活17~24d,在铁皮表面存活10d;白念珠菌在棉布、纸板、铁皮和地板胶表面存活15~20d,在玻璃表面存活4d;犬小孢子菌在棉布、纸板、铁皮、玻璃和地板胶上存活时间分别为10d、9d、3d、2d和1d。结论实验所用各种真菌在医用原材料上都能存活,其时间长短不仅与菌种有关,还与所存在的材料有关。真菌在吸水性强、表面粗糙的材料(棉布、纸板)上的平均存活时间长于在吸水性差、表面光滑的材料(玻璃、铁皮和地板胶)。  相似文献   

6.
We investigated plant-mediated effects of the stem gall wasp, Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), on other herbivores on the chestnut tree Castanea crenata. In the early season, leaves emerged earlier and in greater numbers on galled shoots than on ungalled shoots. On galled shoots the leaf to shoot biomass ratio was lower and the leaves were physically different. In May and June the concentration of nitrogen in leaves was higher on galled shoots than on ungalled shoots. In July, the water content of leaves was lower on galled shoots. In May and June, the number of aphids, Myzocallis kuricola Matsumura (Homoptera: Aphidoidea), on leaves was higher on galled shoots than on ungalled shoots, but the opposite was true at the end of July. Laboratory experiments showed that aphid fecundity and body weight decrease were higher in May and June when aphids fed on leaves on a galled shoot than when they fed on those on ungalled shoots. In contrast, aphid performance in July was greater on ungalled leaves than on galled leaves. Our findings suggest that gall initiation in a chestnut tree affected aphid performance by affecting host plant quality.  相似文献   

7.
Continuous long-term somatic embryogenesis in alfalfa   总被引:6,自引:0,他引:6  
Summary Somatic embryogenic callus was induced on two induction media, B5h and SH4K. Embryos formed on the callus induced on B5h medium when the callus was still on the induction medium. On the other hand, embryos could not form on the callus induced on SH4K medium unless the callus was transferred to a growth regulator-free medium. Callus induced and maintained on B5h medium lost embryogenic capability quickly during the subculture. Callus induced and maintained on SH4K medium, however, consistently remained highly embryogenic. The callus mass showed steady increase during its maintenance on SH4K medium. The embryos induced on SH4K medium showed vigorous germination. Normal and fully fertile plants were recovered from the embryos developed from the callus maintained on SH4K medium.  相似文献   

8.
A panel of 18 rat x mouse somatic cell hybrid clones segregating individual rat chromosomes in different combinations was used to assign 23 biochemical loci to rat chromosomes. The chromosomal locations for these 23 loci were determined as follows: GOT1 on rat chromosome 1; HAGH on 2; ACP2, ADA, GANC, ITPA, and SORD on 3; LDHB on 4; PEPB on 7; GLB1 and HEXA on 8; IDH1 on 9; UMPH2 on 10; GUSB on 12; FH and PEPC on 13; PEPS on 14; ESD and NP on 15; DIA4 on 19; and PP on 20. In addition, ACP1 and GLO1 were reassigned to rat chromosomes 6 and 20, respectively. The chromosomal assignments of these loci extends the known syntenic homologies among rats, mice, and humans.  相似文献   

9.
本文以GK12、33B和SGK3213种转基因棉和对应的3种常规棉泗棉3号、33及石远321为材料,通过室内测定,研究了取食转基因棉的棉蚜却h/sgossypiiGlover对龟纹瓢虫Propylaea japonica Thunberg1—4龄幼虫功能反应的影响。结果指出,龟纹瓢虫对来自转基因棉田蚜虫的捕食量大多高于常规棉田,且捕食量随猎物密度的增加而增大。在1、2龄幼虫期,龟纹瓢虫取食转双价基因棉田蚜虫的数量多高于取食转单价基因棉田的蚜虫数量,但是在3、4龄幼虫时,龟纹瓢虫取食转双价棉田蚜虫的数量多低于取食转单价棉田的蚜虫数量。龟纹瓢虫对来自转基因棉田棉蚜的捕食功能反应符合HollingII型。龟纹瓢虫1龄幼虫取食GK12和SGK3212个转基因棉田蚜虫的最大日捕食量大于对照,处理时间短于对照;龟纹瓢虫P.japonica2、3龄幼虫取食33B和SGK3212个转基因棉田蚜虫A.gossypii的日最大捕食量大于对照,处理时间短于对照;4龄时取食转基因棉田蚜虫的数量都大于对照,处理时间均短于对照,其中取食转双价基因棉SGK321棉田蚜虫的日最大捕食量小于取食单伊棉田蚜虫的日最大捕食量。  相似文献   

10.
Two new species of Leporinus are described from tributaries of the Rio Amazonas in Brazil. One species is known from the Jari and Tapajós River basins, and is identified on the basis of a gas bladder reduced in size, a dark midlateral stripe on the body, dark transverse bars on the dorsum, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle. The second new species is known from the Tocantins, Xingu and Tapajós River basins, and is identified on the basis of three dark longitudinal stripes on the body, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 12 scale rows around the caudal peduncle. In addition, Leporinus striatus is redescribed based on type and additional specimens from the Río de La Plata, Amazonas, Orinoco, Atrato, Magdalena and Sinu River basins. Leporinus striatus is identified on the basis of four dark longitudinal stripes on the body, a subterminal mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle.  相似文献   

11.
The biology of the pentatomid Dichelops melacanthus (Dallas) feeding on cultivated and non-cultivated plants was studied in the laboratory. Nymph mortality varied from approximately 60 on corn (seed mature) to 77% on wheat (ear immature); no nymphs survived on seedlings of corn or wheat. Nymph developmental time on soybean, corn or wheat (seed, pod or ear) varied from 25.5 to 32.8 days. Body weight at adult emergence was similar and greater on most foods than on wheat ear. Nymphs fed preferentially on soybean (pod immature). On non-cultivated hosts, nymphs showed high mortality (73%) on crotalaria (pod immature); on tropical spiderwort (stem) all nymphs died. Nymphs took longer time to develop on crotalaria and/or on spiderwort than on soybean. Body weight at adult emergence did not differ on crotalaria or soybean. Survivorship decreased with time on most foods, with approximately 50% of adults alive at day 30. On corn and wheat seedlings approximately 80% of adults were dead on day 20. Adult longevity ranged 31-43 days, except on corn and wheat seedlings < 15 days. Females % ovipositing peaked ( approximately 76%) on soybean (pod or seed immature), and was minimum ( approximately 9%) on wheat ear (immature); no females reproduced on seedlings of corn or wheat. Preoviposition period was shorter ( approximately 12 days) on soybean (immature pod or seed) and longer ( approximately 37 days) on wheat (ear immature). Fecundity was similar and higher on all foods than on wheat (ear immature). Body weigh gain occurred on all foods, but on corn and wheat seedlings. Adults fed preferably on soybean (pod immature and seed mature); wheat (seedling) was the least preferred food.  相似文献   

12.
Endophytic and epiphytic phyllosphere fungi associated with red-osier dogwood (Cornus stolonifera), a deciduous shrub, were examined in coastal British Columbia, Canada. Current-year shoots were divided into four types based on the absence or presence of inflorescence and secondary elongated shoots at the apex of primary shoots. Leaves on these shoots were then classified into six categories so as to examine the effect of flowering, secondary shoot elongation, and shoot order within current-year shoots on the occurrence of phyllosphere fungi. Species composition of fungi was markedly different between the interior and surface of leaves, whereas it was relatively similar among the six leaf categories in the interior or on the surface. Frequencies of the eight major species were not different between leaves on flowering and nonflowering shoots. The frequency of Colletotrichum gloeosporioides in the leaf interior was greater on leaves on the primary shoots that elongated the secondary shoots than on those that did not, and was greater on leaves on the primary shoots than on those on the secondary shoots. On the other hand, secondary shoot elongation and shoot order had no effect on the frequencies of C. gloeosporioides and the other seven epiphytes on leaf surfaces.  相似文献   

13.
Abstract The invasive Q biotype whitefly was first detected in the US on poinsettia in 2004 and is still not a pest outside of greenhouse environments in the US. To assess the potential for the establishment of the Q biotype on field crops, population cage experiments were conducted to compare the performance of a poinsettia‐derived Q population named P’06 on poinsettia and six field crops (alfalfa, tomato, melon, cotton, cowpea and cabbage). P’06 adults reared on poinsettia as nymphs laid eggs on all six field crops. Significantly more eggs were laid on alfalfa, tomato, melon and cotton than on cabbage, cowpea and poinsettia. These eggs hatched and the nymphs developed to adults on the six field crops. Relative to poinsettia, whitefly survival was similar on cowpea, alfalfa, tomato and cabbage, but significantly higher on cotton and melon. Moreover, P’06 had significantly shorter development times from egg to adult on cotton, melon, cowpea, tomato and alfalfa than they did on poinsettia. However, the F1 adults raised on the six field crops had significantly shorter lifespans and laid 11‐ to 18‐fold fewer eggs than did the F1 adults raised on poinsettia. Taken together, while P’06 may have some potential to establish on field crops, the shorter lifespans and extremely low fecundities of the F1 adults raised on the six field crops suggests that P’06 is incapable of rapidly adapting to them. Poor adaptation to field crops may explain, at least partially, why the Q biotype has not established in the US field system.  相似文献   

14.
鸟类群落研究进展   总被引:28,自引:3,他引:28  
崔鹏  邓文洪 《动物学杂志》2007,42(4):149-158
鸟类群落的研究一直是鸟类生态学研究的重要领域,研究内容主要集中在以下几个方面:群落的组成结构、集团结构、生态位与种间关系、动态与演替、群落与栖息地关系以及城市化对鸟类群落影响。群落的组成与结构、动态与演替以及群落与栖息地关系的研究是过去20年间的研究热点,但有关城市化对鸟类群落影响的研究还比较少。本文在总结国内外鸟类群落生态学研究的基础上,重点讨论了目前的研究热点和今后的发展趋势,以期促进我国鸟类群落生态学的研究。  相似文献   

15.
浙江海岛鸟兽地理生态学的初步研究   总被引:6,自引:1,他引:5  
对浙江洞头岛及舟山五岛的鸟兽调查表明,海岛动物的种数较相邻大陆为低,但种群密度却高于大陆,岛上的某些种类出现生态位扩展的现象。舟山五岛兽类的种数和岛屿面积呈正相关,其关系式为S=2.12A~(0.29),但种群密度随着岛屿面积的增大而下降。文中据此提出了保护和发展岛屿动物资源的某些措施。  相似文献   

16.
Redistribution (capping) of normal and tumor-associated surface antigens was studied on murine and human cells by the indirect membrane immunofluorescence (MIF) technique. The capping of H-2 isoantigens was compared on normal mouse T-lymphocytes and on YAC cells, a Moloney leukemia virus (MLV) induced lymphoma. H-2 and Moloney virus induced cell surface antigen (MCSA) capping was compared on three YAC lines with different MCSA concentrations. H-2 and tumor-associated surface antigen capping was compared on two polyoma induced sarcoma lines and five methylcholanthrene induced sarcoma lines. In the human system, IgM-capping was compared on normal lymphocytes and on the Burkitt lymphoma derived Daudi line. Capping of HL-A and the Epstein-Barr virus (EBV) determined membrane antigen (MA) was compared on the Burkitt lymphoma derived line Maku and on EBV-superinfected Daudi cells. H-2 antigens on normal murine cells capped more promptly and on a larger fraction of the cell population on the various tumor cells. Surface associated IgM showed a better capping on normal lymphocytes than on Daudi cells. All tumor associated antigens except MCSA, showed good capping. MCSA was almost completely refractory to capping. Increasing concentrations of MCSA appeared to inhibit the capping of H-2 on the YAC sublines with different concentrations of MCSA. The polyoma induced ascites sarcoma (SEWA) did not cap either with regard to H-2 or the polyoma determined surface antigen.  相似文献   

17.
Vegetation management on levees, especially removal of trees and shrubs, might affect burrowing mammals that are considered threats to levee integrity. We evaluated habitat associations of California ground squirrels (Otospermophilus beecheyi) and Botta's pocket gophers (Thomomys bottae) on levees in the Sacramento Valley to assess the effects of levee vegetation management on these species. Using burrows as an indirect measure of mammal presence, we found that the presence of trees had a negative effect on the occurrence and abundance of ground squirrels on levees, and on the location of their burrowing activities on the levee slope, potentially because visual occlusion caused by tall woody vegetation impedes detection of predators. Similarly, trees had a negative effect on the abundance of pocket gophers on levees and on the location of their burrowing activities on the levee slope, probably because of the effect of tree cover on food availability. The conversion of woodland habitats to grasslands on levees most likely will result in increased occurrence, abundance, or both of ground squirrels and pocket gophers, and thereby increase the potential threat that their burrowing activities pose to levee integrity. © 2012 The Wildlife Society.  相似文献   

18.
The antitumor action of bovine seminal ribonuclease was evaluated with a quantitative assay based on the production of tumor foci in the spleens of mice injected with plasmacytoma cells. The antitumor action depended on the integrity of the catalytic site, and on the dimeric structure of the enzyme. A working hypothesis is proposed, based on these results, and on previous results obtained studying the antitumor action of seminal RNAase in vitro on cell cultures. According to this hypothesis, the antitumor action is based on the ability of seminal RNAase to interact at specific receptor sites on the tumor cell membrane, as well as on its RNA degrading ability.  相似文献   

19.
为了准确掌握梨小食心虫的产卵特性,研究模拟室外条件下该虫在不同寄主果树的叶片、桃枝不同部位及不同品种桃果上的产卵偏好.结果表明: 梨小食心虫成虫对7种寄主果树叶片的产卵偏好由高至低依次为:桃>樱桃>苹果>李>梨>海棠>杏.在桃树叶片上的产卵量占总产卵量的33.5%,平均单叶卵量达8.3粒;虫卵在不同寄主叶片正、反两面的分布有所差异,苹果和海棠叶片正面卵量多于背面,桃、李、梨、杏叶背面卵量多于正面,桃叶背面卵量是正面的3.3倍,樱桃叶两面卵量差异不明显;该虫在桃枝上产卵部位选择顺序为:叶片>托叶>叶柄>枝条,叶片是其主要产卵部位,占总产卵量的88.7%;梨小食心虫在桃枝上主要选择靠近顶端未展叶的前10片桃叶背面产卵,前10叶卵量占总产卵量的725%,其中第3片叶上产卵最多,占9.3%;第25叶以后仅占总产卵量的1.1%;在不同类型桃果上的产卵偏好次序为:油桃>蟠桃>毛桃;绒毛疏密及其特点是影响梨小食心虫在寄主果树叶片和果实上产卵选择的首要因素.  相似文献   

20.
为了准确掌握梨小食心虫的产卵特性,研究模拟室外条件下该虫在不同寄主果树的叶片、桃枝不同部位及不同品种桃果上的产卵偏好.结果表明: 梨小食心虫成虫对7种寄主果树叶片的产卵偏好由高至低依次为:桃>樱桃>苹果>李>梨>海棠>杏.在桃树叶片上的产卵量占总产卵量的33.5%,平均单叶卵量达8.3粒;虫卵在不同寄主叶片正、反两面的分布有所差异,苹果和海棠叶片正面卵量多于背面,桃、李、梨、杏叶背面卵量多于正面,桃叶背面卵量是正面的3.3倍,樱桃叶两面卵量差异不明显;该虫在桃枝上产卵部位选择顺序为:叶片>托叶>叶柄>枝条,叶片是其主要产卵部位,占总产卵量的88.7%;梨小食心虫在桃枝上主要选择靠近顶端未展叶的前10片桃叶背面产卵,前10叶卵量占总产卵量的725%,其中第3片叶上产卵最多,占9.3%;第25叶以后仅占总产卵量的1.1%;在不同类型桃果上的产卵偏好次序为:油桃>蟠桃>毛桃;绒毛疏密及其特点是影响梨小食心虫在寄主果树叶片和果实上产卵选择的首要因素.  相似文献   

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