Successional patterns of woody plants in catchment areas in a semi-arid region

Patterns of woody plants dispersal in a semi-arid nature reserve situated in Eastern Transvaal, South Africa, revealed that trees have spread from core areas and converted previously open grasslands to densely vegetated woodlands. These patterns were found in catchment areas of the gently undulating terrain which characterizes the region.Two plant communities dominated by Acacia senegal-Acacia tortilis and Euclea divinorum-Acacia nilotica were distinguished. Analysis of nearest-neighbour distances, dispersal patterns of seedlings and mature woody plants identified successional processes. These were manifested through intra and interspecific competition among the dominant tree species. Within each plant community, a transition of relative abundance was occurring namely, A. senegal became dominant in areas previously dominated by A. tortilis while E. divinorum was replacing previous A. nilotica dominance.Comparative assessment of the two plant communities was facilitated by the summary of competition and seedling dispersal indices in a multivariate analysis. Results indicated that tree species had characteristic dispersal strategies. Identification the patterns of woody plants establishment could advance the evaluation of successional dynamics and management of savannas in areas prone to bush encroachment.     

Natural rhizobial populations and nodulation status of woody legumes growing in diverse Kenyan conditions

The rhizobial populations and nodulation status of both indigenous (mainly Acacia species) and some introduced woody legume species were assessed under glasshouse conditions in soils collected from 12 sites located in different ecological zones of Kenya. The populations among the sites, as estimated by the MPN technique, varied from <3.6 to>2.3×10⁵ cells g^-1 of soil. There were some intrasite variations in population estimates depending on the trap host species, date of soil collection and the method used in sampling the soils. Nodulation in whole soil also varied across the sites with test species frequently showing higher nodulation ability in native soils. Sesbania sesban (L.) Merr. was the most prolific nodulating species while Acacia tortilis (Forsskal) Hayne was very erratic in nodulation. Nodulation of most species showed interplant and intraspecific variability within a single soil source.     

Spontaneous development of urban woody vegetation on differing soils

The general aim of the study was to follow the development of spontaneous woody vegetation on man-made urban habitats in Berlin, Germany. In spring 1968, the vegetation was removed completely in five groups of plots, which had been filled with five different transferred soil material in 1928. The spontaneous vegetation was monitored annually from 1968 to 2006. Especially, the development of shrubs and trees was followed. In addition the growth of the most important herbaceous species, Solidago canadensis, was investigated.

The soils varied from moderately rich sandy soils to rich sandy or loamy soils. On the two sandy soils S. canadensis developed poorly. Tree species dominated (>50% of total cover) on these plots after 14–18 years. On the soils rich in nutrients, S. canadensis developed strongly. Tree species did not dominate there before 21–25 years. The diversity of woody species increased over time and reached 33 species altogether. Indigenous Acer, Quercus and Betula species prevailed. Alien species, typical for urban ruderal sites, were rare.

The results support the idea of establishing urban woodlands by spontaneous succession as a cheap way to develop near-natural plant communities rich in species.     

Rotifers of the Kalahari Gemsbok National Park,South Africa

The Kalahari Gemsbok National Park in the Northern Cape Province, South Africa, is bounded by two dry river beds in which 39 artificial water sources have been provided for the use of the wild animals. The water in these sources varies from fresh to highly saline and an opportunity is thus provided to determine, not only which rotifer species are able to colonise such sources, but what their salinity tolerances are. The rotifer fauna, studied in summer and winter, is dominated by mixed populations of Brachionus calyciflorus, B. plicatilis and Hexarthra jenkinae, with only a few other monogononts and bdelloids. The most striking feature of the rotifer fauna in these troughs is the very low species diversity encountered.     

粮食上木霉菌的分离鉴定及其生防效果

【背景】粮食在生长和收储期极易受到病原真菌或产毒真菌的污染,造成严重的损失。众多实践证明木霉属(Trichoderma)可以有效防治植物病原真菌。【目的】鉴定和筛选能有效抑制粮食常见危害真菌的木霉生防菌株,开发生防菌剂,保障粮食生产安全。【方法】从粮食上分离筛选出35株木霉,通过多基因系统发育分析和形态学观察方法进行菌种鉴定,利用平板对峙试验筛选出对粮食常见危害真菌有抑制作用的菌株。【结果】35株木霉分属于8个种,分别为非洲哈茨木霉(Trichodermaafroharzianum)、类棘孢木霉(Trichodermaasperelloides)、 Trichoderma amoenum、近深绿木霉(Trichoderma paratroviride)、Trichoderma obovatum、长枝木霉(Trichoderma longibrachiatum)、东方木霉(Trichodermaorientale)和深绿木霉(Trichodermaatroviride)。对峙试验结果表明,这8种木霉对于粮食上分离到的10种危害真菌均具有较好的抑制效果。非洲哈茨木霉(T.afroharzi...     

Phenology of nine common woody species in semi-arid,deciduous Kalahari Sand vegetation

The phenological patterns of 9 woody species that are common components of Kalahari Sand communities were observed over a period of 32 months. The observations were made on plants adjacent to the soil moisture study sites which have been described earlier (Childes & Walker 1987). A pre-rain flush was noted in the 2 shrub/small tree species Ochna pulchra and Terminalia sericea. Leaf fall in all species was related to a decrease in soil moisture and minimum temperature. The rooting habits and other adaptations of the species resulted in a sequential leaf fall in the communities. Open woodland and scrub species such as Pterocarpus angolensis showed a generally synchronised pre-rain flowering, while the closed woodland species e.g. Baikiaea plurijuga had protracted asynchronous flowering periods. Fruit ripening generally occurred in the dry season when conditions were ideal for fruit and seed dispersal.     

Bat species diversity and distribution in three vegetation communities of Meru National Park, Kenya

Diversity and distribution of bats was determined in four vegetation types in and around Meru National Park, Kenya between September 2000 and February 2001. Bat‐habitat studies were based on plant species dominance, cover and farming activities. Bats were captured using standard mist nets (18 m long × 2 m high) erected on poles averaging 3 m. Vegetation was broadly grouped as Acacia or Combretum wooded grassland, or Acacia–Commiphora bushland and studied using the Braun‐Blanquet method. Analysis of floristic similarity showed five vegetation species assemblages in the three broad categories. Four hundred and ninety‐five bats representing eleven genera in seven families were recorded. These were Epomophorus labiatus, E. wahlbergi, Cardioderma cor, Lavia frons, Myotis welwitschii, Scotoecus hirundo, S. leucogaster, Pipistrellus kuhlii, Mops condylurus, Chaerephon bemmeleni, Mormopterus sp., Hipposideros caffer, H. commersoni, Nycteris arge and Rhinolophus landeri. This was the first record of N. arge, M. welwitschii, C. bemmeleni and a Mormopterus species in eastern Kenya. The Combretum community was most equitable (E = 0.51) with nine bat species records, while farming areas had only four. The low species richness and increased dominance of a few generalist species on farms may be indicative of different levels of disturbance.     

A classification of subtropical riverine grassland and forest in Chitwan National Park,Nepal

Eight grassland associations with ten phases and two riverine forest associations were identified on the floodplains of Chitwan National Park in lowland Nepal. TwoThemeda arundinacea associations were primarily stable edaphic associations on mollic soils, often with aquic moisture regimes.Themeda associations were floristically similar to adjacent sal forest. Four mixed tall-grass associations primarily ofNarenga porphyrocoma, Saccharum bengalense, andSaccharum spontaneum were identified. These andThemeda arundinacea types were characterized by a very weak component of woody species. Two grass-shrub associations ofSaccharum bengalense andNarenga porphyrocoma with a strong woody species component typical of riverine forest were described.Trewia nudiflora-Bombax ceiba riverine forest and mixed riverine forest types also were identified on the basis of understory composition. Mixed tall-grass and grass-shrub associations appeared to represent early and late phases of grassland succession to riverine forest. Trajectories of succession are controlled primarily by fire and wildlife grazing. The classification refines the general classifications applied to the central Terai of Nepal and India, and should provide insight for classification of other Terai riverine grasslands.Abbreviations DS Dabadghao and Shankarnarayan's 1973 grassland classification for India - IMCY Imperata cylindrica - NAFA Narenga fallax - NAPO Narenga porphyrocoma - PHKA Phragmites karka - SABE Saccharum bengalense - SASP Saccharum spontaneum - THAR Themeda arundinacea     

New records of entomopathogenic fungi infecting Bemisia tabaci and Trialeurodes vaporariorum, pests of horticultural crops, in Argentina

The whiteflies Bemisia tabaci (Gennadius) and Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) are major crop pests throughout the world. Although extensive research about biological control of whitefly by parasitoids and predators has been conducted, also entomopathogenic fungi can be considered as potential biological control agents. Surveys for entomopathogenic fungi were carried out in organic and conventional horticultural crops in greenhouses and open fields in Buenos Aires and Corrientes provinces, Argentina. These surveys resulted in the recovery and isolation of the following fungi from whiteflies: Lecanicillium lecanii (Zimmerm.) Zare & W. Gams, L. muscarium (Petch) Zare & W. Gams, L. longisporum (Petch) Zare & W. Gams, Isaria fumosorosea Wize and I. javanica (Frieder. & Bally) Samson & Hywel-Jones. Pathogenicity tests were conducted against T. vaporariorum nymphs using a conidial suspension (1 × 10⁷ conidia/ml) of the fungi. A mortality rate between 26.6% and 76.6% was obtained at 7 days post-infection. These are the first records of natural infections in the southernmost region of the South American continent of L. lecanii, L. muscarium, L. longisporum and Isaria javanica (Ascomycota: Hypocreales) on T. vaporariorum and also the first report of I. fumosorosea on B. tabaci.     

Assessing the extent and diversity of riparian ecosystems in Sonora, Mexico

Conservation of forested riparian ecosystems is of international concern. Relatively little is known of the structure, composition, diversity, and extent of riparian ecosystems in Mexico. We used high- and low-resolution satellite imagery from 2000 to 2006, and ground-based sampling in 2006, to assess the spatial pattern, extent, and woody plant composition of riparian forests across a range of spatial scales for the state of Sonora, Mexico. For all 3rd and higher order streams, river bottomlands with riparian forests occupied a total area of 2,301 km². Where forested bottomlands remained, on average, 34% of the area had been converted to agriculture while 39% remained forested. We estimated that the total area of riparian forest along the principal streams was 897 km². Including fencerow trees, the total forested riparian area was 944 km², or 0.5% of the total land area of Sonora. Ground-based sampling of woody riparian vegetation consisted of 92, 50 m radius circular plots. About 79 woody plant species were noted. The most important tree species, based on cover and frequency, were willow species Salix spp. (primarily S. goodingii and S. bonplandiana), mesquite species Prosopis spp. (primarily P. velutina), and Fremont cottonwood Populus fremontii. Woody riparian taxa at the reach scale showed a trend of increasing diversity from north to south within Sonora. Species richness was greatest in the willow-bald cypress Taxodium distichum var. mexicanum—Mexican cottonwood P. mexicana subsp. dimorphia ecosystem. The non-native tamarisk Tamarix spp. was rare, occurring at just three study reaches. Relatively natural stream flow patterns and fluvial disturbance regimes likely limit its establishment and spread.     

Studies on five species of Pythium parasitic on mustard and cabbage in India

Diseased seedlings and roots of cabbage and mustard of Khurpatal (Nainital), were surveyed for zoosporic plant pathogens. Pythium aphanidermatum and P. debaryanum were isolated from cabbage and P. middletonii, P. spinosum and P. undulatum were isolated from mustard. Pathogenicity tests conducted in the glasshouse indicated that P. debaryanum and P. spinosum are the most virulent pathogens of cabbage and mustard respectively.     

Occurrence of Yeasts in Cloacae of Migratory Birds

Several species of yeast have been reported as pathogens in humans based on increases in immunodeficiency syndromes and as a result of immunosuppressant chemotherapy in cancer treatment. Domestic and wild birds are known to act as carriers of human pathogenic fungi. To gain additional information on the yeasts present in the cloacae of some species of migratory birds, 421 wild birds (24.39% out of 1726 birds caught in Romania, Hungary and Bulgaria) were sampled with the permission of the local judicial authority. The state of conservation of the birds (i.e. post-mortem alterations, colour of the mucosae etc.), along with their age and sex were determined. Samples were collected directly from the cloacae and cultured, and colonies were identified in each positive sample. Yeasts were isolated from 15.7% of the animals sampled, with the highest percentage found in coots (Fulica atra −58.8%) and the lowest in quails (Coturnix coturnix −1.7%). A total of 131 isolates belonging to 15 species of yeast were identified. Rhodotorula rubra was the yeast with the highest number of isolates (28.2%), followed by Cryptococcus albidus (18.4%), Candida albicans (9.2%), Trichosporon cutaneum (8.4%), Candida guilliermondii (6.1%), Candida tropicalis (6.1%) and other species. The present study represents the first survey on the occurrence of yeasts in the cloacae of migratory birds. The prevalence and species of yeasts isolated is discussed on the basis of the ecology, diet, and habitat of the birds.     

Superior quality agar from <Emphasis Type="Italic">Gracilaria</Emphasis> species (Gracilariales,Rhodophyta) collected from the Gulf of Mannar,India

Gracilaria edulis, G. crassa, G. foliifera, and G. corticata are naturally occurring agarophytes of Indian waters. These agarophytes were evaluated for their agar contents using an improved process recently reported by us (US Patent 2005/0267296A1). The effect of different concentrations of NaOH in the alkali treatment was studied for optimizing the extraction conditions. These Gracilaria species of Indian waters produced agars, both native and alkali treated, with different properties confirming the heterogeneity of the agar polymers in this genera, as one would expect. Among these, G. edulis and G. crassa produced agar polymers having high gel strengths of 490 ± 8.16 and 800 ± 15.4 g cm⁻², respectively, with 8% NaOH treatment as opposed the low gel strength agars that have been reported in the literature to date.     

湖南张家界国家森林公园土壤中的暗色丝孢菌

自湖南张家界国家森林公园采集的15份土样中,分离获得32个暗色丝孢菌分离物,经鉴定分别属于15属中的19个种。其中,湖南小带孢Taeniolella hunanensis为一新种,昏暗色串孢Torula caligans和小孢维郎那霉Veronaea parvispora为中国新记录种。对其它16个中国已报道种亦作了分离生境的引证。研究过的标本(干制培养物)与活菌种存放在山东农业大学植物病理学标本室(HSAUP)。     

Survey of bovine mycotic mastitis in dairy herds in the State of São Paulo,Brazil

The purpose of this study was to isolate fungi from the quarter milk of cow udders from several dairy herds and to identify the different genera and species involved in mastitis. A total of 2078 milk samples from normal, clinical and subclinical mastitis quarters from 22 dairy herds of 16 districts in the State of São Paulo, Brazil was utilized in this survey. Two hundred and fifty one (12.07%) fungi were isolated from the samples. Two hundred and eight of these (82.86%) were yeasts and 30 (11.95%) were moulds. The fungi were isolated in pure culture (24.77%) or in cultures mixed with bacteria (72.22%). The yeasts isolated were:Cryptococcus spp. (71 strains),Rhodotorula spp. (40),Candida spp. (68),Trichosporon cutaneum (21),Aureobasidium pullulans (7), andPichia ohmeri (1). Moulds classified in following genera were also isolated:Aspergillus (3),Penicillium (3),Alternaria (3),Phoma (3),Epicoccum (2), andGeotrichum (16).     

Vigna mungo, V. radiata and V. unguiculata plants sampled in different agronomical–ecological–climatic regions of India are nodulated by Bradyrhizobium yuanmingense

Vigna mungo, Vigna radiata and Vigna unguiculata are important legume crops cultivated in India, but little is known about the genetic resources in native rhizobia that nodulate these species. To identify these bacteria, a core collection of 76 slow-growing isolates was built from root nodules of V. mungo, V. radiata and V. unguiculata plants grown at different sites within three agro-ecological-climatic regions of India. The genetic diversity of the bacterial collection was assessed by restriction fragment length polymorphism (RFLP) analysis of PCR-amplified DNA fragments of the 16S–23S rDNA intergenic spacer (IGS) region, and the symbiotic genes nifH and nodC. One rDNA IGS type grouped 91% of isolates, but more diversity was found at the symbiotic loci (17 symbiotic genotypes). Overall, no host plant specificity was shown, the three host plant species sharing common bradyrhizobial genotypes that represented 62% of the collection. Similarly, the predominant genotypes were found at most sampling sites and in all agro-ecological-climatic regions. Phylogenies inferred from IGS sequencing and multi-locus sequence analysis of the dnaK, glnII and recA genes indicated that all isolates but one were clustered with the Bradyrhizobium yuanmingense species. The nifH phylogeny also grouped the different nif haplotypes within a cluster including B. yuanmingense, except for one infrequent nif haplotype which formed a new lineage within the Bradyrhizobium genus. These results may reflect a long history of co-evolution between B. yuanmingense and Vigna spp. in India, while intra-species polymorphism detected in the symbiotic loci may be linked with the long history of diversification of B. yuanmingense coinciding with that of its host legumes.     

Using soil profiles of seeds and molecular markers as proxies for sawgrass and wet prairie slough vegetation in Shark Slough, Everglades National Park

We measured the abundance of Cladium jamaicense (Crantz) seeds and three biomarkers in freshwater marsh soils in Shark River Slough (SRS), Everglades National Park (ENP) to determine the degree to which these paleoecological proxies reflect spatial and temporal variation in vegetation. We found that C. jamaicense seeds and the biomarkers Paq, total lignin phenols (TLP) and kaurenes analyzed from surface soils were all significantly correlated with extant aboveground C. jamaicense biomass quantified along a vegetation gradient from a C. jamaicense to a wet prairie/slough (WPS) community. Our results also suggest that these individual proxies may reflect vegetation over different spatial scales: Paq and kaurenes correlated most strongly (R ² = 0.88 and 0.99, respectively) with vegetation within 1 m of a soil sample, while seeds and TLP reflected vegetation 0–20 m upstream of soil samples. These differences in the spatial scale depicted by the different proxies may be complementary in understanding aspects of historic landscape patterning. Soil profiles of short (25 cm) cores showed that downcore variation in C. jamaicense seeds was highly correlated with two of the three biomarkers (Paq, R ² = 0.84, p<0.005; TLP, R ² = 0.97, p<0.0001), and all four of the proxies indicated a recent increase in C. jamaicense biomass at the site. Using a preliminary depth-to-age relationship based on matching charcoal peaks with available ENP fire records (1980-present) specific to our coring site, we found that peak-depths in C. jamaicense seed concentration appeared to correspond to recent minimum water levels (e.g., 1989 and 2001), and low seed abundance corresponded to high water levels (e.g., 1995), consistent with the known autecology of C. jamaicense. In summary, the combination of C. jamaicense seeds and biomarkers may be useful for paleoecological reconstruction of vegetation change and ultimately in guaging the success of ongoing efforts to restore historic hydrologic conditions in the South Florida Everglades.