Highest Similarity Index Research Articles

Gene Expression Profiling of the Irinotecan Pathway in Colorectal Cancer

The exact mechanism responsible for large variation of response to chemotherapy remains unclear. This study profiled the gene expression for the entire irinotecan pathway to provide insights into individualized cancer therapy. The RNA expressions of 24 irinotecan pathway genes were measured in paired tumor and normal tissues from 52 patients with Dukes' C colorectal cancer using a real-time quantitative reverse transcription-PCR assay. The relative expression levels across the 24 pathway genes varied considerably, with a 441-fold range from highest to lowest expression levels for the tumor tissues and a 934-fold range for the normal tissues. Interpatient variability was also quite large, with a 33.6 median fold change in the tumor tissue genes and a 30.1 median fold change in the normal tissue genes. Six of the 24 irinotecan pathway genes had dramatically lower expression levels in the tumor samples than did the genes in the normal tissues (median range, 1.28-4.39 folds; P = 0.001-0.029). Eight genes had significantly higher levels (median range, 1.35-2.42 folds; P = 0.001-0.011). Using hierarchical clustering, three gene clusters and three patient groups were observed with high similarity indices by the RNA expressions in colorectal tumors. The three patient groups had no unique clinical pathologic features but could be differentiated by the statistically significant differences in RNA expression level of seven genes. Our study indicates that gene expression profiling could be valuable for predicting tumor response to chemotherapy and for tailoring therapy to individual cancer patients.

Community analysis of a full-scale anaerobic bioreactor treating paper mill wastewater

To get insight into the microbial community of an Upflow Anaerobic Sludge Blanket reactor treating paper mill wastewater, conventional microbiological methods were combined with 16S rRNA gene analyses. Particular attention was paid to microorganisms able to degrade propionate or butyrate in the presence or absence of sulphate. Serial enrichment dilutions allowed estimating the number of microorganisms per ml sludge that could use butyrate with or without sulphate (10 5), propionate without sulphate (10 6), or propionate and sulphate (10 8). Quantitative RNA dot-blot hybridisation indicated that Archaea were two-times more abundant in the microbial community of anaerobic sludge than Bacteria. The microbial community composition was further characterised by 16S rRNA-gene-targeted Denaturing Gradient Gel Electrophoresis (DGGE) fingerprinting, and via cloning and sequencing of dominant amplicons from the bacterial and archaeal patterns. Most of the nearly full length (approximately 1.45 kb) bacterial 16S rRNA gene sequences showed less than 97% similarity to sequences present in public databases, in contrast to the archaeal clones (approximately. 1.3 kb) that were highly similar to known sequences. While Methanosaeta was found as the most abundant genus, also Crenarchaeote-relatives were identified. The microbial community was relatively stable over a period of 3 years (samples taken in July 1999, May 2001, March 2002 and June 2002) as indicated by the high similarity index calculated from DGGE profiles (81.9±2.7% for Bacteria and 75.1±3.1% for Archaea). 16S rRNA gene sequence analysis indicated the presence of unknown and yet uncultured microorganisms, but also showed that known sulphate-reducing bacteria and syntrophic fatty acid-oxidising microorganisms dominated the enrichments.

GROUND BRYOPHYTE COMPOSITION AND SYNUSIA STRUCTURE UNDER SIX TYPES OF YOUNG CONIFEROUS FOREST PLANTATIONS IN THE UPPER MINJIANG RIVER

Bryophytes on the ground under six types of artificial forests, Picea balfouriana forest (P), Pinus tabulaeformis forest (Y), Pinus armandii forest (H), Larix kaempferi forest (L), Picea balfouriana-Pinus tabulaeformis forest (P-Y) and Pinus tabulaeformis-Pinus armandii forest (Y-H), were investigated in the upper Minjiang River in order to understand the bryophyte composition and synusia structure of these different forest types. In the 19 bryophyte species identified, only 13, 10, 7, 11, 9 and 10 species were present in the P, L, H, Y-H, Y and P-H forests, respectively. Four mosses, Brachythecium glaciale, Thuidium cymbifolium, Entodon concinnus and Eurhynchium savatieri, were common in all six plantations. Another three mosses, Entodon macropodus, Mnium spinosum and Polytrichum formosum, occurred only in the Picea balfouriana forest. The highest frequency of bryophyte occurrence was under the P forest (90%) and the lowest frequency under the H forest ( 17.65% ). Thuidium cymbifolium had the highest frequency (60%) of all species under the P forest, and the second was Brachythecium glaciale (50%). The predominant species, based on the importance value, was Thuidium cymbifolium under the P forest and Brachythecium glaciale, occurred under the other five plantations, which indicated that Brachythecium glaciale was the most common moss species in the study area. In all forests, the P forest had the highest bryophyte diversity (Shannon-Wiener index, species richness index) and the H forest had the lowest diversity. The lowest Simpson index was calculated for the H forest and the highest one for the P forest. The highest similarity index (Sorensen similarity) occurred between the H and Y forests (0.89) and the lowest similarity index between the P and H forests (0.40). The greatest percent coverage (17.79%±1.67%), shoot density ((3 807.11±412.90) shoots·m -2 ) and thickness ((19.89±1.69) mm) of bryophytes occurred under the P forest, and the lowest values (0.41% ±1.49%, (27.99±367.95) shoots·m -2 , and (1.80±1.51) mm, respectively) under the H forest. For the Y, L, Y-H and P-H forests, ground bryophyte cover was 5.20%±1.58%, 2.44%±1.58%. 2.73%±1.61%, and 2.71%±1.61%, respectively, shoot density was (623.08±391.71), (566.13±391.71), (253.38±398.41), and (188.69±398.41) shoots·m -2 , respectively, and average bryophyte thickness was (9.60±1.61), (14.93±1.61), (9.59±1.63), and (6.69±1.63) mm, respectively. No statistical differences (p0.05) were found in any of these measures among the Y, L, Y-H and P-H forests. The low bryophyte diversity and limited structure development (density, coverage, thickness) found under all six plantations indicate that, in general, these are poorly developed bryophyte communities. Our results show that the best bryophyte community have developed under the spruce forest with a relatively open canopy and low tree density. Our results suggest that tree thinning or canopy pruning would be an effective measure for improving bryophyte development under dense forests.

Ecological features of Syllidae (Polychaeta) from shallow-water benthic environments of the Aegean Sea, eastern Mediterranean

Ecological features of Syllidae inhabiting shallow-water benthic habitats of the Aegean Sea were analysed by utilizing some univariate and multivariate statistical methods. A total of 121 benthic materials collected in a variety of substrata and depths (0–76 m) contained 90 syllid species belonging to the four subfamilies Autolytinae, Exogoninae, Eusyllinae and Syllinae. Among the subfamilies, Syllinae were characterized by a high number of species and Exogoninae by a high number of individuals. Although dominant species varied according to substrata, the two species, Grubeosyllis clavata and Syllis prolifera, accounted for up to 51% of the total syllid populations in the area. Among the biotopes sampled, Posidonia oceanica seems to be particularly suitable for the settlement of syllid species, whereas bare sand and mud harbour only a few species, mainly Exogoninae. The cluster- and ordination analyses detected species associations on soft and hard substrata, and suggested that syllid assemblages are strongly affected by the habitat structure. Species compositions associated with algae appear to be related to complexity of the algae, so that the ones with relatively small thalli, such as Padina pavonica and Halopteris spp., constituted a group with a high similarity-index value. Samples of Posidonia oceanica collected at different stations showed a high consistency in terms of syllid assemblages.

The Study on Flora and Distribution Characteristics of Orchidaceae on Moor

Total 7 moors, Yong-neup on Mt. Daeam, Chilbo Mt. moor, Dogapsa-neup on Mt. Wolchul, Wangdeungiae-neup on Mt. Jiri, Mujechi-neup on Mt. Jungjok, Buljae-neup on Mt. Kyungak and Geoinri-neup on Dongsang, were investigated by literatures and survey. Distribution, conditions, and similarity of dominant species and Orchidaceae on moor were analyzed. The results are follows; There are total 46 wetland plant species observed more than twice from 7 moors. The plants classified as constancy class V, which are appeared more than 80%, are Iris ensata var. spontane, Juncus effusus var. decipiens, Sanguisorba tenuifolia var. alba, Habenaria linearifolia, Sium ninsi, Lobelia sessilifolia, Lastrea theiyptoris, and Eupatorium chinensis var. simplicifolium. Highly appearing Orchidaceae, which was classified to constancy class IV plant, are Habenaria linearifolia, Pogonia japonica, Eipactis thunbergii, and Platanthera mandarinorum. They are the typical index plants of the moors. Habitual environment of Habenaria radiate and Platanthera hologlottis can be affected by environmental aspects such as latitude, altitude and the water quality. However those of Habenaria linearifolia, Epipactis thunbergii, and Pogonia japonica are not affected by latitude and altitude, but may be determined by water condition of wetland. As the result of similarity index analysis for appearance of Orchidaceae identifying each moors in the view of species composition, swamps at Dogapsa-neup and Buljae-neup are very similar. However Yong-neup is totally different from those of Dogapsa-neup and Buljae-neup. Yong-neup had shown the high similarity indices of 0.85 and 0.75 with Wangdeungiae-neup and Mujechi-neup, respectively. Growth properties of wild Orchidaceae at wetland were almost similar. Platanthera mandarinorum and Liparis kumokiri had characteristics of good adaptability. Most of them need light. Pogonia was the only long-day plant. The flowering time of these Orchidaceae was from May to September.

Genetic Diversity of Basil (Ocimum spp.) Based on RAPD Markers

Molecular markers were used to assess genetic diversity in basil (Ocimum L. spp., Lamiaceae). Using randomly amplified polymorphic DNA (RAPD) analysis, 11 primers generated 98 polymorphic bands, ranging from 300 to 2,000 base pairs, that discriminated among 37 accessions across nine Ocimum spp. Means of genetic similarities within Ocimum spp. showed that the domesticated species, O. minimum L. (0.887), O. basilicum L. (0.769), and O. ×citriodorum Vis. (0.711) had highest similarity indices within species, while the nondomesticated, O. americanum L. (0.580), O. gratissimum L. (0.408), and O. kilimandscharicum Guerke (0.559) showed the lowest similarity. RAPD results indicated that O. minimum should not be considered a distinct species but rather a variety of O. basilicum. Consistent clusters among all but one of the O. ×citriodorum spp., all containing citral as the major constituent, were identified using bootstrap analysis. RAPD analysis was useful in discriminating among Ocimum spp., although within species resolution will require a higher number of polymorphic bands.

Fitossociologia de uma área de cerrado denso na RECOR-IBGE, Brasília-DF

Foi amostrada uma área de 10ha de cerrado denso da RECOR-IBGE, Brasília-DF. Nesta foram estabelecidas parcelas experimentais de um projeto para o estudo do efeito do fogo na vegetação do cerrado com um delineamento em blocos casualizados. Este levantamento foi efetuado antes da aplicação dos tratamentos visando conhecer a composição florística e estrutura da vegetação original. Foram incluídos todos os indivíduos lenhosos e aqueles não-lenhosos pertencentes à família Velloziaceae, com diâmetro mínimo de 5cm, presentes em cinco parcelas de 1000m². Foram medidas as alturas e os diâmetros a 30cm do solo de cada indivíduo. Ao todo foram amostrados 982 indivíduos, pertencentes a 63 espécies e a 34 famílias. Cerca de 47% das famílias foram representadas por apenas uma espécie. Apenas 16 espécies foram comuns a todas as cinco parcelas. A diversidade da área foi alta (H'= 3,53) e a similaridade entre as parcelas segundo índice de Sørensen foi também alta. As espécies Sclerolobium paniculatum, Eremanthus glomerulatus, Schefflera macrocarpum, Ouratea hexasperma, Vochysia thyrsoidea, Guapira noxia, Caryocar brasiliense, Vellozia squamata, Qualea grandiflora e Emmotum nitens apresentaram os maiores valores de importância. As estimativas de densidade e de área basal por hectare foram de 1964 indivíduos e 13,28m², respectivamente. A diversidade foi equivalente a de outras áreas de cerrado sensu stricto na região, mas a densidade e a área basal foram mais elevadas.

A New Bacterial Leaf Spot Disease of Broccolini, Caused by Pseudomonas syringae pathovar maculicola, in California.

In 1998, a new disease was detected on 3-week-old commercial broccolini (Brassica oleracea L. var. botrytis × B. alboglabra) transplants in a Salinas Valley, Monterey County, CA greenhouse. Initial symptoms were small (2 to 4 mm diameter) circular to angular, water-soaked spots. As the disease progressed, spots remained relatively small, but turned tan to brown. When diseased tissues were macerated and streaked on King's medium B, a blue-green fluorescent pseudomonad was consistently isolated. Strains were levan positive, oxidase negative, and arginine dihydrolase negative. Strains did not rot potato slices, but induced a hypersensitive reaction on tobacco (Nicotiana tabacum L. 'Turk'). Fatty acid methyl ester analysis (MIS-TSBA, version 4.10, MIDI Inc., Newark, DE) indicated that strains had a high similarity index (0.82 or higher) to Pseudomonas syringae, and GN (version 3.50, Biolog, Inc., Hayward, CA) profiles also identified strains as P. syringae. The bacterium associated with the disease, therefore, was identified as P. syringae van Hall. Pathogenicity was demonstrated by growing inoculum in nutrient broth shake cultures for 48 h, misting the broth cultures (1×106 CFU/ml) onto broccolini (cv. Aspabrock), and subjecting the plants to 48 h of high humidity. Control plants were misted with sterile nutrient broth. After 4 to 5 days in a greenhouse, leaf spot symptoms developed on all inoculated broccolini plants, and reisolated strains were characterized and found to be P. syringae. Control plants remained symptomless. The results of two sets of pathogenicity tests were the same. Repetitive sequence-based polymerase chain reaction using the BOXA1R primer resulted in identical banding patterns for the broccolini pathogen and for known isolates of P. syringae pv. maculicola from crucifers. In host range testing, P. syringae pv. maculicolawas pathogenic to broccolini plants. The broccolini isolates and P. syringae pv. maculicola isolates had the same pathogenicity results when crucifers and tomatoes were tested as hosts; broccoli and cauliflower (B. oleracea var. botrytis) were infected, and tomato results were variable. These tests suggest that the broccolini pathogen is the bacterial leaf spot pathogen, Pseudomonas syringae pv. maculicola, that occurs on broccoli and cauliflower transplants (1). To our knowledge, this is the first report of this pathogen causing a disease on commercially grown broccolini. Reference: (1) S. T. Koike et al. Plant Dis. 82:727, 1998.

Comunidades de insetos galhadores (Insecta) em diferentes fisionomias do cerrado em Minas Gerais, Brasil

Studies on the communities of galling insects and their host plants were performed in three cerrado physiognomies that occur in Minas Gerais: campo sujo, cerrado sensu strictu, and cerradao. Galls and host plants were collected along transects in a total of 3,000 herbs, 300 shrubs and 135 trees in each physiognomy. Ninety two species of galling insects (morphotypes) on 62 host plant species of 28 families were found. The highest galling insect richness was observed in the cerrado. Approximately 75.0% of galling insects belonged to the Cecidomyiidae (Diptera). The highest gall frequency was found on leaves (58.70%) of the host plants, and was glabrous (83.70%). Most gall shape were elliptic (30.43%). A low similarity in galling insect species was observed among the three sampled physiognomies - the highest similarity index was observed between cerrado and campo sujo (SΦrensen index = 0.20), indicating that the presence of rare species of galling insects might be common in these environments.

The structure of duplications on human acrocentric chromosome short arms derived by the analysis of 15p

We report the molecular analysis of a 130-kb DNA region containing a junction between beta and non-beta satellite DNA from chromosome 15p. The genomic region is characterized by beta satellite blocks intermingled with variants of the D4Z4 repeat, and duplicons from 4q24 and 4q35. Besides the p-arm of acrocentric chromosomes, the duplicons showed a wide genomespread involving pericentromeric, sub-telomeric, and interstitial regions. In this regard, the paralogous sequences were characterized by a high similarity index (96%), thus indicating a recent transposition during the evolution. The acrocentrics differedwith regard to the location of the 4q24 paralogous region, since it mapped on the p-arm of chromosomes 13-15 and 21, but only on 22q11.2. Conversely, the 4q35 duplication marked the p-arm of all the acrocentrics. In different individuals, the short arm of acrocentric chromosomes revealed a great variability of sequence representation and location at p11 and/or p13 for both the 4q24 and 4q35 duplications. The studied genomic region from chromosome 15p, of which a contig of approximately 200 kb has been derived, could lead to more detailed investigations into the sequence organization and possible biological function of chromosome regions that are located close to the rDNA array.

Effect of Intelligent Instruction on Students' Mental Models and Performance

The effects of two types of Intelligent Computer Aided Instruction (ICAI) and a non-intelligent tutoring system on the development of students' mental models and on performance was explored. One of the two ICAI systems provided both principle-based and task specific advice while the other provided task specific advice only. The non-intelligent CAI provided no advice. The problems presented to students increased in difficulty as the student progressed. It was hypothesized that the mental models of students who interacted with the ICAI that provided both principle-based and task specific advice would be most similar in structure to a “gold standard” model, and that these students would also exhibit the best performance. It was also hypothesized that students who were exposed to the ICAI that provided only task specific advice would perform better, and exhibit more accurate and detailed mental models than would students who interacted with the CAI that provided no advice. Study results indicated that students in both ICAI conditions achieved a higher similarity index, fewer errors, and faster task time, than did students in the no advice group. However, there was no significant difference between the two ICAIs for any of these measures. There was a significant interaction between version and problem difficulty for task time. As problem difficulty increased, task time increased for both of the two ICAI conditions, but not for the no-advice condition. These results are discussed in terms of their implications for the predictive validity of the Pathfinder measure, and in terms of the appropriate use and design of ICAI.

Effects of deforestation on seed banks in a tropical deciduous forest of western Mexico

Seed density and seed bank species composition were determined by germination trials on soils collected during the initial phase of deforestation in a Mexican tropical deciduous forest. The reference forest, pre-burn, 1-d post-burn, and 1-y post-burn soils contained 700, 1000, 70 and 3500 germinating seeds m−2, of 30, 30, 8 and 13 species, respectively. A total of 43 dicotyledonous species were identified. Percentages of herbs, vines, shrubs and small trees/shrubs were similar in reference forest, pre-burn, and 1-d post-burn soils; herbs were the most common growth form. Pasture conversion greatly altered seed bank species composition; 81% of the species that germinated from the seed bank before burning were absent from the seed bank 1 d after the fires. One-year post-burn soil was dominated by monocots; only 3% of the seedlings were herbs; no vines, small trees/shrubs or trees germinated. The reference forest and the pre-burn soils had 18 dicot species in common and the highest similarity index, 0.43; six of the shared species were herbs. One-day and 1-y post-burn soils had the lowest similarity index, 0.05. Burning the slashed forest and conversion to cattle pasture depleted the original seed bank, replacing it by one dominated by pasture grasses.

Observations of White-Tailed Deer and Cattle Diets in Mexico

Most rangelands in northern Nuevo Leon, Mexico, have been grazed intensely for more than 10 years simultaneously by cattle and white-tailed deer (Odocoileus virginianus texanus). There is a lack of information concerning diet selection of white-tailed deer and cattle in this region. We observed the dietary preferences of these ungulates in northeastern Nuevo Leon for a 6 month period. Two adjacent areas were subjected to rotational grazing (RG) and continuous cattle grazing (CG). Fecal analysis was used to determine dietary overlap of these 2 sympatric ruminants. Cattle diets averaged 70% grasses, 23% browse, and 4% forbs. Deer diets were 63% browse, 24% forbs and 12% grasses in both areas. The preferred species for cattle in both areas were grasses. Deer preferred fortes on the continuous grazed area and grasses on rotational grazed area. Zacate toboso [Hilaria mutica (Buckl.] Benth.) was the most preferred species by both ruminants in both management systems. Differences between cattle and deer diets were significant (P < 0.05). The similarity index was higher on the rotational grazed (23%) than on the continuous grazed area (15%) (P < 0.05). The higher similarity index in RG area may have been a result of the altered forage preferences of deer. Zacate toboso under RG could be an important feed resource in those areas where white-tailed deer and cattle graze in common.

Bacterial Leaf Spot of Cilantro in Florida.

In the 1995 to 1996 winter vegetable season, a leaf spot disease of cilantro (fresh coriander) (Coriandrum sativum L.) was widespread throughout commercial plantings in the Everglades Agricultural Area south and east of Lake Okeechobee. Symptoms first appeared as water-soaked spots ≤1 mm in diameter. These spots became dark brown to black and enlarged up to 2 mm in diameter. No chlorotic haloes developed around the lesions. The disorder was observed in numerous plantings of the cultivar Longstanding at four separate locations. Symptoms were apparent throughout each planting, with disease severity ranging from a few individual spots to numerous lesions covering nearly entire leaflets. Severe outbreaks were correlated with heavy precipitation events. In several instances, disease levels were great enough to render entire plantings totally unmarketable. A non-fluorescent bacterium was consistently isolated on King's medium B when a cooled inoculation needle was pushed through lesions. Six representative strains were chosen for further characterization. All strains were aerobic, gram-negative rods, and were oxidase and arginine dihydrolase negative. Levan was produced, but potato slices were not rotted. Tests for utilization of l-tartrate, l-lactate, and erythritol were negative. Biolog analysis identified all strains of the bacterium as Pseudomonas syringae. Highest similarity indices (0.52 to 0.81) were with P. syringae pv. pisi for four of the six strains. Suspensions of each strain were swab inoculated onto leaves of 4-week-old Longstanding cilantro seedlings in the greenhouse. Control plants were swabbed with sterile water only. Plants were covered with clear polyethylene bags for 72 h. Watersoaked spots were evident on test plants when bags were removed. Typical brown, greasy-looking leaf spots were seen by 6 days after inoculation. Control plants were symp-tomless. In a host-range study, cilantro and the following plants were mist-inoculated with a 107 CFU/ml suspension of each of the six test strains: carrot (Daucus carota L. 'Fancy Pack'), celery (Apium graveolens L. var. dulce (Mill.) Pers., 'June Belle'), garden pea (Pisum sativum L. 'Melting Sugar'), snap bean (Phaseolus vulgaris L. 'Pod Squad'), and onion (Allium cepa L. 'Evergreen Bunching'). Six days after inoculation, characteristic symptoms were evident on the cilantro. Four of the six strains produced a few (less than 10 per plant) bacterial leaf spot symptoms in carrot from which P. syringae was readily recovered. Some necrosis was observed on young, emerging leaves of snap bean. No symptoms were recorded for the other host species or the controls. This disease is similar to one reported on cilantro in California (1) and Germany (2).

Seed Protein Pattern of Cowpea (Vigna unguiculata L.) and Its Distant Species

Seed protein was extracted from two varieties of cowpea (CO 2, CO 6) and eight distant species of Vigna and was analysed by SDS-PAGE. The relative migration (Rm) and Similarity Index (SI) were worked out. There was no difference in protein profiles of varieties CO 2, a vegetable type cowpea and CO 6, a grain type cowpea (SI = 100%). A high SI has been exhibited by V. glabrescens with V. radiata (62.5%) and V. umbellata (45.4%), the probable progenitors of the natural amphidiploid V. glabrescens. V. sublobata and V. trilobata trevealed greatest SI (90.9%) indicating a close evolutionary relationship, on the contrary, V. mungo and V. umbellata exhibited a zero value revealing a greater evolutionary distance. The electrophoretic variability study indicates difficulty in obtaining interspecific hybrids through conventional methods for cowpea improvement (SI < 26.67%).

OCCURRENCE OF NITROGEN-FIXING CYANOBACTERIA IN LOCAL RICE FIELDS OF ORISSA, INDIA

Cyanobacterial diversity occurring in some local rice fields of Orissa, India has been studied in two different seasons and influence of pH, organic carbon (%) and conductivity were correlated on their population. At different locations and seasons the pH of the soil varies from 6.30±0.20 to 6.66±0.305. Conductivity and organic carbon (%) varies from 0.6±0.10 to 0.76±0.152 and 0.56±0.045 to 0.70±0.025 respectively. Altogether 58 taxa belonging to 20 genera were obtained and characterized. Out of these 19 forms were heterocystous and 39 were non-heterocystous. Highest abundance of cyanobacteria was found in order Nostocales which was represented by 15 species. Among the species relative abundance of Oscillatoria chalybea (9.90%) was found to be highest followed by Phormidium purpurascens (8.49%), Cylindrospermum muscicola and Oscillatoria chlorina (8.01%). Highest Shannon's diversity index was recorded in sampling site 1, followed by site 2. Comparatively the diversity index was more during winter than in summer in all the study sites. Highest similarity index (0.174) was found in summer-summer isolates of site 1 and 3. Among the environmental variables (i.e., soil pH, organic carbon (%), conductivity) highly positive correlation was observed between cyanobacterial population and soil pH (r ≥ 9) in all the three sampling sites. The study indicates ubiquitous distribution of cyanobacteria in rice fields and could be exploited for biofertilizer in agriculture. Key words: Cyanobacteria; Rice fields; Abundance; Diversity index; Environmental variablesDOI: 10.3126/eco.v17i0.4120EcoprintAn International Journal of EcologyVol. 17, 2010Page: 77-85Uploaded date: 3 January, 2011

Vegetation structure, natural regeneration and management of Parroha community forest in Rupandehi district, Nepal

Understanding vegetation structure and regeneration in community forests in important for management planning. The present work was done during September to October 2005. The information on forest management practices was collected by Participatory Rural Appraisal (PRA) which included field observation, interviews and focus group discussion. A total of 125 plant species belonging to 55 families with 36 tree species, 50 shrubs and 39 herbs were recorded from the 0.7 ha sampling area. The total tree density and basal area at South-East (SE) facing slope was 595 pl/ha and 29.68 m²/ha, respectively, where Terminalia alata was the most dominant with highest importance value index (IVI). On the other hand, total tree density and basal area was 453 pl/ha and 41.78 m²/ha, respectively, at South-West (SW) facing slope, where Shorea robusta was the most dominant with the highest IVI. Total shrub/sapling density was 4708 pl/ha at SE slope and 4137 pl/ha at SW slope. Similarly, total herb/seedling density was 10.86 pl/m² at SE slope and 9.79 pl/m² at SW slope. The total number of tree species (S) in tree stage was higher at SE slope than at SW slope and the number of species in shrub layer was higher at SE slope than at SW slope. The two slopes had nearly equal number of species in herbaceous layer. Higher species diversity (H) of different lifeforms was found at SW slope. The SW slope had higher species evenness (J) and Simpson’s index of dominance (C) for all life forms than at SE slope. High similarity index for all tree, shrub/sapling and herb/seedling layers (63.63%, 84.61% and 77.10% respectively) were found between two sites. Alpha (α) diversity for shrub layer was higher at SE slope whereas beta (β) diversity for tree layer was higher at SW slope than at SE slope. Regeneration of Shorea robusta and Terminalia alata was continuous because density increased from tree, sapling to seedlings with a typical reverse J shaped size class diagram at both slope. But regeneration of S. robusta at SW slope was sporadic. The reccurence of forest fire during summer season has appeared as a major problem for the management of forest. The active participation of the local people in forest conservation activities can be effective for sustainable management of forest. Keywords: Community forestry; Vegetation; Regeneration; Size class diagram; Shorea robusta; Terminalia alata. DOI: http://dx.doi.org/10.3126/sw.v9i9.5523 SW 2011; 9(9): 70-81