農林水産研究情報センターで作成したPDFファイルを使用している。

<p>The main cause of environmental disturbance in the Fennoscandian boreal forests today is forestry. Natural disturbances are important to maintain diversity, but anthropogenic disturbance, such as forestry, differs in many ways from the natural ones. Forestry is a big industry in Sweden and only a small remnant of old-growth forest is left. Several studies have shown an initial decrease in e.g. dragonfly diversity a few years after logging, followed by an increase up to numbers comparable with the original species number. In this study I examined whether the new, quite diverse, species composition is similar to the one present before the logging or if some species are disappearing and are replaced with other, maybe opportunistic species. Other factors such as ongoing changes in climate also will be considered. A resampling of 34 (and an additional 4) lakes that also were sampled in 1996-97 was done during summer of 2006. Analyses of data from the two sampling occasions were done. I found that even if the diversity is just temporarily affected (or not affected at all), it is not always the same species involved. This means that the diversity in a single lake can appear to be high, but the total diversity in Sweden, or Scandinavia, is declining. I also found some interesting new species for the area, such as Nehalennia speciosa, Sympecma fusca and Aeshna mixta.</p>

The main cause of environmental disturbance in the Fennoscandian boreal forests today is forestry. Natural disturbances are important to maintain diversity, but anthropogenic disturbance, such as forestry, differs in many ways from the natural ones. Forestry is a big industry in Sweden and only a small remnant of old-growth forest is left. Several studies have shown an initial decrease in e.g. dragonfly diversity a few years after logging, followed by an increase up to numbers comparable with the original species number. In this study I examined whether the new, quite diverse, species composition is similar to the one present before the logging or if some species are disappearing and are replaced with other, maybe opportunistic species. Other factors such as ongoing changes in climate also will be considered. A resampling of 34 (and an additional 4) lakes that also were sampled in 1996-97 was done during summer of 2006. Analyses of data from the two sampling occasions were done. I found that even if the diversity is just temporarily affected (or not affected at all), it is not always the same species involved. This means that the diversity in a single lake can appear to be high, but the total diversity in Sweden, or Scandinavia, is declining. I also found some interesting new species for the area, such as Nehalennia speciosa, Sympecma fusca and Aeshna mixta.

Restoration of streams that were formerly channelized for timber-floating has become increasingly common. Generally, this restoration returns boulders from riparian zones to streams, leading to wider, more heterogeneous channels with slower flows. The primary goal is to enhance fish populations, but riparian vegetation is also expected to be favoured. However, increases in floristic diversity have not been observed and reasons for this slow response are still unknown. One possible explanation might be the lack of colonist pools. I therefore investigated how surrounding plant compositions influence riparian recovery. The vascular plant flora was identified in riparian sites and in adjacent upstream riparian and upland sites. Four reach types were included: unchannelized, channelized, restored and demonstration restored. Species richness and floristic similarities among types of sites and reaches were compared. Correlations with upland and upstream channel slopes were made and the importance of variation in seed floating ability was tested. The results show that unchannelized reaches were floristically similar to their adjacent upstream riparian and upland sites, whereas channelized reaches showed more different floras. Restoration created a somewhat more homogeneous flora among the three site types and demonstration restored reaches were most similar to upstream sites. Soil moisture conditions (i.e. wetland vs. forest) in the uplands had stronger impacts on species similarities than upland or upstream channel slopes. I conclude that adjacent sites are important for floristic recovery of riparian reaches and that demonstration restoration is most advantageous for riparian recovery. I recommend protection of upland sites from forestry to facilitate recovery. / Local- and landscape-scale effects on biodiversity after stream restoration

A study was initiated to adapt the REGEN regeneration prediction model to the Appalachians of Virginia and West Virginia. REGEN generates predictions via expert created REGEN knowledge bases (RKBs) that contain competitive rankings and stochastic parameters for selected species and size classes of advance reproduction. We developed RKBs for four site productivity classes (xeric, subxeric, submesic, mesic), and tested two (subxeric and submesic) using field collected inventory data in this study. To test the model we collected data from 48 paired sites which contained a mature stand and an adjacent regenerating stand (clearcut) of similar site productivity harvested within the past 20 years. Across all 48 sites, model predictions were within 5% of measured values on average, and explained 32% (R2 = 0.32) of the variation in species composition in regenerating stands. The species compositions of 41 of the paired stands on the Appalachian Plateau in West Virginia were further analyzed to compare species composition. Species composition was compared between the mature and regenerating stands in the subxeric and submesic site classes. A comparison of the upper canopy (dominant and codominant) species composition in regenerating stands to that of all stems ≥ 1.5 in dbh in the mature stands was conducted as well. Our results suggest that the future species composition of stands regenerating following clearcut harvests will likely differ from previous rotations with mesophytic, shade intolerant species being more numerous. Oaks will likely assume a smaller role as the clearcuts mature, particularly on the submesic sites. / Master of Science

This study investigated the spatiotemporal distribution of abundances of the fish eggs and Engraulid eggs in relation to environmental factors along the coastal waters off southwestern Taiwan. Moreover, the key to fish eggs under an optical microscope in winter(January) was revised. Samplings were carried out on a bimonthly basis. In total, 38 tows were conducted from January to November 2003.The samplings of eggs were collected by horizontal hauls with NORPAC and cyclindricalconic net at the water surface along Jiading, Linyuan and Fangliao. Sea surface temperature, sea surface salinity, dissolve oxygen, chlorophyll a concentration and density were measured simultaneously with a seabird CTD. The spatiotemporal distribution of the total eggs abundances of two kinds of nets were very similar, and more the abundance of cyclindricalconic net than the NORPAC net. Therefore, the total eggs abundance and species of cyclindricalconic net were adopted to investigate the spatiotemporal distribution of the eggs along the coastal waters off southwestern Taiwan. The total abundances of fish eggs demonstrated significant seasonal variations highest in July and lowest in November. The geographical difference was also observed that the highest abundances were recorded at Jiading, and followed by Linyuan and Fangliao. Based on the results of correlation analyses, it was revealed that the spatiotemporal fluctuations in the total abundances of fish eggs were significant positive correlated to the monthly variation of precipitation. 2,110 fish eggs were obtained from six samples in January, 2003, including Ophichthidae, Clupeidae, Synodontidae, Scaridae, Callionymidae, Soleidae , Cynoglossidae and Engraulidae. The fish eggs that couldn¡¦t be identified were firstly sorted into 28 groups by the egg shape, size, and membrane pattern. Furthermore, they were stored into 64 species based on the presence or absence, and the pattern of pigmentation. The group BIII, Engraulids eggs and unknown dead eggs were the top three dominant species. Due to the different composition of the dominant species, there were significant differences in the spatial distribution. The species composition of dominant group were the Callionymids eggs and unknown dead eggs in Jiading. The species composition of dominance group were group BIII , Engraulids eggs and unknown dead eggs in Linyuan, and Fangliao. In 2003, Engraulids eggs were very abundant in the coastal waters off southwestern Taiwan, representing 14% of the total fish egg abundances. Two peaks of Engraulids eggs abundances were found. One in the July to September 2003, and other one in January 2003. Spatial distribution in the abundances were also observed that the highest abundances were recorded at Fangliao, and followed by Linyuan and Jiading. The mortality rate of the Engraulids eggs was the reverse trends and spatial distribution of the Engraulids eggs abundances. The abundances of eggs were increased when precipitation was high and abundance of Amphipoda was low. The shape of Engraulids eggs was displayed regional differences. Engraulids eggs in Jiading and Fangliao were elongated shape, and oval shape in Linyuan. Seasonal variation in the egg shape was observed and also segregated into two groups representing elongated eggs group in May, July and September and oval eggs group in January, March and November, respectively. Engraulids eggs longitudinal diameter was significantly positive correlated with the SST and monthly precipitation, and were negatively correlated with sea surface salinity, dissolve oxygen and density. Maybe the group BIII was Mugilids eggs. Their spawning ground occurred in Linyuan. Furthermore, the spawning ground of both Callionymids eggs and Synodontids eggs were at Linyuan and Fangliao. The main spawning grounds of Engraulids eggs were at Linyuan and Fangliao along the coastal waters off southwestern Taiwan. The peak spawning season were in summer and winter 2003. The spawning time of Engraulids eggs was approximately at 00:00 to 01:00. The spatiotemporal variations of Engraulids eggs size were influenced by the alternation of the spawning grounds of Engraulids fish along the coastal waters off southwestern Taiwan.

No description available.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The diversity of microorganisms and the influence of their enzymatic activities in soil are critical to the maintenance of good soil health. Changes in these parameters may be the earliest predictors of soil quality changes, potentially indicating anthropogenic influences. The goal of this study was to investigate the soil microbial diversity and function of grasslands along an urbanization gradient. Soil samples were collected in the Potchefstroom municipal area, South Africa, at specific sites. Sampling sites were described as urban, suburban and rural - according to the V-I-S (Vegetation-Impervious surface-Soil) model of Ridd (1995). Soil samples were collected over a warmer, wet season (May) and a colder, dry season (August) over two years (2007 and 2008). Collected soil samples were characterised using certain physical and chemical parameters. Plant species composition and abundance were determined at each site, along with basic site data (soil compaction, percentage ground cover, percentage bare ground, percentage organic material present). The Shannon-Weaver diversity index was used to calculate biodiversity values for all the investigated sites regarding collected plant species composition. The microbial component of the soil was quantified and characterized using culture-dependent and culture-independent techniques. Culture-dependent techniques included the investigation of the aerobic heterotrophic bacteria and fungi. Organisms were plated out on different media, and the bacterial component was broadly grouped using morphology. Dominant organisms were identified by sequencing of PCR amplified 16S ribosomal DNA fragments. Shannon-Weaver index for bacterial diversity was determined for each of the sites. Denaturing gradient gel electrophoresis (DGGE) profiling of selected bacterial communities were also conducted. Microbial community function was determined using enzyme assays of five major groups of enzymes, namely (i) dehydrogenase; (ii) β-glucosidase; (iii) acid phosphatase, (iv) alkaline phosphatase and (v) urease. Plant species results were then brought into context with microbiological diversity and functionality results using multivariate statistics. Physical and chemical parameters of the collected soil samples revealed patterns present along the urbanization gradient. The pH values were mostly higher in the sub-urban and urban sites than in the rural sites. Electrical conductivity values were generally highest in the sub-urban sites. Plant species composition revealed trends along the urbanization gradient. Ordinations clearly grouped the plant species into rural, sub-urban and urban groups regarding plant species composition. Rural sites had the highest number of plant species. Shannon-Weaver values regarding the plant diversity supported the plant species composition data indicating higher plant diversity in the rural areas, followed by the sub-urban and the urban areas. Plant structural data indicated that forbs were most numerous in the rural sites, and less so in the urban sites. Higher average aerobic heterotrophic bacterial levels were present in the urban soil samples. The bacterial levels were lower in the sub-urban and rural soil samples. Subsequent identification of the dominant bacteria in the soil samples revealed organisms of the genus Bacillus dominated the aerobic heterotrophic bacterial communities in the soil samples. Bacillus species dominated the soil samples along the urbanization gradient. Shannon-Weaver indices based on culture-dependent methods indicated that urban sites had the highest biodiversity. These results could have been exaggerated, because of an overestimation of the number of bacterial morphotypes present in samples. Fungal levels were higher in the soil from samples collected at the rural samples sites. The culture-independent method (DGGE) was not optimized and inconclusive results were obtained. Enzyme assays revealed that potential dehydrogenase, β-glucosidase and urease activity followed a trend along the urbanization gradient, with urban samples registering the highest values and rural sites the lowest. Enzymes involved in carbohydrate catabolism (β-glucosidase and dehydrogenase) registered significantly higher potential activity in urban sites than the sub-urban and rural sites. The results could indicate that urban sites have the potential to lose carbon at higher rates than the rural sites. This aspect may need further investigation. Higher potential urease activity could indicate higher N-cycling in the urban soil environment. Ordination results for soil-, plant- and microbial diversity as well as microbial functionality indicated certain trends along the urbanization gradient. Plant species composition and structure data indicated that urbanization has a definite effect on the plant communities in the urban ecosystem. Results regarding aerobic heterotrophic bacteria populations and potential enzyme activity of the dehydrogenase, β-glucosidase (both active in the carbon cycle) and urease (active in the nitrogen cycle) illustrated clear trends along the urbanization gradient. In conclusion, results indicated that urbanization has an effect on plant species composition, and the population and function of aerobic heterotrophic bacteria and the fungal population. Furthermore, this study demonstrated the potential of using microbial diversity and activity as tools to investigate carbon utilization and storage along an urban-rural gradient. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2011