The effect of mesoclimate on Collembola diversity in the Zádiel Valley, Slovak Karst (Slovakia)

In 2002–2004 an investigation of Collembola communities in the Zádiel Valley (Slovak Karst, Slovakia) was carried out. The karst valley is characterised by climatic and vegetation inversion. To assess the effect of mesoclimate inversion upon soil Collembola five sites were selected in hypsometric sequence from the karst plateau down the valley: (1) subxerophilous pasture – ass. Glechomo–Festucetum, (2) lime wood – ass. Mercuriali–Tilietum, (3) beech wood – ass. Dentario bulbiferae-Fagetum, (4) maple–hornbeam wood – ass. Aceri–Carpinetum, and (5) secondary oak wood. In total 152 soil Collembola species were collected, the numbers for particular sites ranging between 70 and 108. Evidently higher species richness was observed in soil of the beech wood compared to other selected forest plots. Thirteen species revealed affinity to inversed (wet and cold) stands of beech (3) and maple–hornbeam wood (4), four of them represented montane species, whereas five species clearly preferred thermophilous sites (1, 2, 5). The presence of 11 montane species at the bottom of the gorge (4) documented the inverse character of the site: Ceratophysella sigillata, C. silvatica, Friesea albida, Deutonura albella, D. stachi, Superodontella lamellifera, Tetrodontophora bielanensis, Heteraphorura variotuberculata, Kalaphorura carpenteri, Orthonychiurus rectopapillatus and Plutomurus carpaticus. Abundance of Folsomia quadrioculata significantly correlated with the soil microclimate – moisture (p < 0.01, r = 0.92). Distribution data on Collembola were performed by cluster (PC-ORD) and CCA ordination techniques. Collembolan communities of two neighbouring forest stands with identical soil type (rendzina) – lime (2) and beech wood (3) – were the most similar in species composition. Meso-/microclimatic gradients within a karst landscape play an important role in determining diversity and community structure of the soil Collembola.     

藏北羌塘牧民家庭人口特征和收入构成之间的关系

为探讨牧民家庭人口特征和收入构成之间的关系，通过半结构式访谈调查了藏北羌塘高寒草甸、高寒草原和荒漠草原区682户牧民，比较了其家庭规模、劳动力、抚养比、草场面积、放牧强度、家庭收入及其多样性的差异，结合多元线性回归评价了家庭人口特征对收入构成的影响。结果显示：羌塘地区牧民家庭规模大（5.3人·户^-1）、抚养比高（0.62）、劳动力充足（3人·户^-1）但受教育年限短（2.3年），高度依赖政策性收入；高寒草甸区牧民家庭规模、劳动力数量及受教育年限、抚养比和放牧强度等指标显著高于高寒草原和荒漠草原区（P<0.05），后两者之间无显著差异；荒漠草原区牧民家庭草场面积和政策性收入较高（P<0.05）；家庭规模、文盲率和抚养比是影响高寒草原和荒漠草原牧民收入构成的主要因子，人口特征对高寒草甸牧民收入影响不显著。综上所述，建议分区精准施策以提高牧民生计。     

Rate-specific responses of prokaryotic diversity and structure to nitrogen deposition in the Leymus chinensis steppe

Serious nitrogen (N) deposition in terrestrial ecosystems causes soil acidification and changes the structure and function of the microbial community. However, it is unclear how these changes are dependent on N deposition rates, other factors induced by N (e.g., pH), and their interactions. In this study, we investigated the responses of soil prokaryotic community structure and stability after a 13-year N addition in the semi-arid Leymus chinensis steppe in Inner Mongolia, China. Our results demonstrated that the prokaryotic community structure changed at the low N addition rate of 1.75 g N m⁻² yr⁻¹; however, dramatic changes in microbial abundance, respiratory quotient, and prokaryotic diversity occurred at N addition rates of more than 5.25 g N m⁻² yr⁻¹ when the soil pH dropped below 6.0. The two patterns indicated the difference in driving forces for different microbial properties. The N-driven and pH-driven processes are likely the most important mechanisms determining the responses of bacterial community to N. Some copiotrophic/oligotrophic bacteria, e.g., Proteobacteria and Acidobacteria, changed their relative abundances with the N addition continuously even at a low rate, indicating that they were more sensitive to N directly. Some bacterial groups significantly changed their relative abundance at a high N addition rate when pH dropped below 6.0, e.g., Verrucomicrobia and Armatimonadetes, indicating that they were more sensitive to pH below 6.0. N addition altered the prokaryotic community structure through enrichment of copiotrophic bacteria (species adjustment) at low N addition rates and through enrichment of nitrophilous taxa and significant loss of diversity at high N rates. The results also demonstrated that a high N addition diminished the stability of the prokaryotic community structure and activity through reduction in species diversity and bacterial interaction. Overall, this study supported the hypothesis that the responses of prokaryota to N were dependent on deposition rates, and N-driven and pH-driven processes were the important mechanisms to control the shift of the prokaryotic community.     

西藏地区青稞籽粒营养品质分析及评价

为探明西藏地区青稞品种间的性状差异及性状间的相关性，筛选优异品质青稞种质，以251个西藏青稞种质资源为材料，测定了籽粒淀粉、粗蛋白、β-葡聚糖、γ-氨基丁酸、大量元素（Ca、P）、微量元素（Fe、Zn、Se）含量共9个品质指标，分析了被测指标间关系。结果表明，所测定的9项品质指标在供试种质资源间均存在不同程度的差异，淀粉含量的变异系数最小，Se含量的变异系数最大；粗蛋白与淀粉含量呈极显著负相关（r= -0.54），粗蛋白与γ-氨基丁酸、Ca、P、Zn、Fe含量均呈极显著正相关。对被测指标进行主成分分析发现，可将9项品质指标简化成3个主成分，其累积方差贡献率为74.5%，其中第一主成分因子的贡献率达到了 48.0%，第一主成分中因子载荷量大的品质指标是Zn、P、Ca、粗蛋白、γ-氨基丁酸、淀粉、Fe含量。综合评价筛选出10个营养品质较高的种质，分别为BJX152、BJX008、BJX149、BJX004、BJX003、BJX015、BJX005、藏青2000、BJX227、喜马拉22号。     

桑树内生真菌的分离、鉴定及其多样性分析

用组织分离法从不同桑树品种的器官组织中共分离出内生真菌114株,经显微形态观察,鉴定114株内生真菌分别归属于镰孢霉属Fusarium、链格孢属Alternaria、柱霉属Scytalidium等21个属,表明桑树内生真菌具有丰富的生物多样性。不同桑树品种树体内的内生真菌分布有一定差异。同一桑树品种不同器官组织的内生真菌种类和数量差异较大,根中最多,茎中次之,叶中最少。其中:镰孢霉属为根中优势种群,链格孢属为茎、叶中的优势种群;丛梗孢属Monilia和镰孢霉属菌株在根、茎、叶中均能分离到,其它属的菌株只存在于其中的某一个或两个器官组织。研究结果有助于进一步探讨桑树内生真菌与生理活性物质的关系。     

Genetic survey of 10 Indian coconut landraces by simple sequence repeats (SSRs)

A rich genetic diversity of coconut exists in farmer's fields, which represent valuable genetic resource for breeding. The study was conducted to assess the pattern of diversity in 102 coconut palms representing 10 landraces from 3 coconut-growing communities of India using 14 simple sequence repeat (SSR) markers. A total of 90 alleles were detected with an average of 6.42 alleles per locus and an average polymorphism information content of 0.61. Expected heterozygosity (H_e) was highest for the two tall landraces from Pallikkara community, while the least heterozygosity was observed for the dwarf coconut landraces from Vayalar community. Mean fixation index (F_ST) of 0.42 indicates a high level of population differentiation. A low gene flow (N_m) of 0.37 was observed. Based on molecular data, genetic similarities were calculated. The unweighted pair group method with arithmetic averages (UPGMA) cluster analysis grouped the landraces according to their geographical locations and breeding behaviour. The practical implications of this study in farmer participatory evaluation and conservation of coconut genetic resources are highlighted.     

川渝地区野生鹅观草种质资源形态多样性研究

对采自四川及重庆地区不同采集地的26份鹅观草(Roegneria kamoji Ohwi)材料的24个形态学性状进行了观察分析.结果表明:该物种在形态学上具有丰富的遗传多样性(H′=1.955).遗传多样性指数分析表明,遗传多样性主要集中在材料内(64.48%),材料间的遗传变异为35.52%.从单份材料上看,鄷都新城材料具有最高的遗传多样性(H′=1.382).聚类分析将26份材料分为4类,聚类结果与其地理分布和采集生境存在一定的关系.主成分分析表明:穗节节间长、第2颖长、外稃芒长、花序长、旗叶宽、外稃宽和小穗小花数7个性状是解释川渝地区野生鹅观草多样性的重要性状,支持聚类结果.还探讨了鹅观草的保护及其利用.     

有机化梨园不同栽培措施节肢动物多样性比较

运用生物多样性指标对北京顺义地区有机化梨园3个不同栽培区节肢动物群落多样性及其动态进行了系统研究。结果表明,在同一园区内,不同栽培区节肢动物群落的丰富度和均匀度在整个生长季中的动态变化较一致,而优势度出现了明显的时序差别。群落个体数稀植区在大部分时间内均高于其它2区。3个区的主要优势害虫及其天敌在发生时间和数量上有一定差异,早春密植区木虱发生数量较大,稀植区中砂潜、金龟子类害虫以及步甲、蜘蛛类天敌数量相对丰富,入秋后稀植区木虱发生量最大,密植区最小。据此,对主要害虫综合防治体系建立提出了讨论意见。     

甘肃省白龙江流域蕨类植物的多样性

白龙江流域位于甘肃南部,青藏高原东北边缘,地形复杂,气候条件多样,蕨类植物种类繁多。据调查蕨类植物有２６３种,隶属于３４科,７６属,分别占甘肃省蕨类总科数的１００％,总属数的９７．４％,总种烤的８７．６９％。本区地还发现有１６个特有种和３６个新纪录种。     

Earthworm communities in native savannas and man-made pastures of the Eastern Plains of Colombia

 The structure and seasonal changes of earthworm communities were evaluated in a natural savanna and in a improved grass-legume pasture in a Colombian oxisol over a period of 18 months. One plot of 90×90 m was isolated in each of the systems and each month five samples of 1 m²×0.5 m and ten of 20×20×20 cm were randomly selected from a stratified block design. Species richness was similar in the two evaluated plots (seven species), whereas diversity measured by the index, H (Shannon and Weaver 1949) was clearly different, i.e. H=2.89 in natural savanna and H=1.29 in pasture. This is explained by differences in earthworm community structure. The average annual density in the savanna was 49.8, ranging from 10.8 to 135.8 individuals (ind) m^–2, and biomass was 3.3 g m^–2 (hand-sorting method), ranging from 0.9 to 11.5 g m^–2. In the man-made pasture, density was 80.1 ind m^–2 on average, ranging from 24 to 215.8 ind m^–2 and biomass was more than tenfold higher, ranging from 29.2 to 110.4 g m^–2. This was especially due to the presence of a large glossoscolecid anecic species, Martiodrilus carimaguensis Jiménez and Moreno, which has been greatly favoured by conversion of savanna to pasture. Endogeic species were dominant in the natural savanna whereas the anecic species accounted for 88% of total earthworm biomass in the pasture. Total earthworm density and biomass were significantly different in the two systems studied (t-test). The results indicate a clearly positive response of earthworm communities to improved pastures, a type of land use that is being increasingly adopted in moist neotropical savannas. Received: 20 October 1997