Leaf litter is a major nutrient source for aquatic detrital food webs, fueling the microbes and macroinvertebrates that colonize it. Litter is especially important as a nutrient source for macroinvertebrates in headwater streams that tend to have lower primary production than higher-order stream systems. Understanding how litter decomposition and macroinvertebrates interact at large scales facilitates predictions about how stream ecosystems will change over space and time with regards to allochthonous nutrient inputs. We utilized a subset of the National Ecological Observatory Network's wadeable stream sites to deploy a litter pack study across the United States and Puerto Rico to determine the controlling factors for litter decomposition and associated macroinvertebrate assemblages, abundances, and species richness at a national scale. We found that litter species was the most important contributing factor to litter decomposition, and despite litter decomposition differences from stream to stream, the relative differences in decomposition rate between litter types was very similar. Stream identity, temperature, and flow also played roles in affecting decomposition patterns. In contrast to litter decomposition, litter species did not significantly contribute to variation in macroinvertebrate assemblages, abundance, or species richness, though environmental variables did impact abundance and species richness. These results suggest that there is functional redundancy in aquatic detritivore communities at large scales, and that the assemblages colonizing different species of leaf litter–despite being similar–might be functioning differently.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19032号 / 農博第2110号 / 新制||農||1031(附属図書館) / 学位論文||H27||N4914(農学部図書室) / 31983 / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 谷 誠, 教授 北山 兼弘, 教授 本田 与一 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

This study investigates the effects of forestry on leaf litter decomposition in small forest streams. Riparian forest, that is the land closest to the stream, maintain shading, water temperature and energy supply through litter fall. If the riparian zone is deforested, many riparian functions important for the integrity of the stream ecology, hydrology and biogeochemistry can be lost or modified. Leaf litter decomposition can be used as an integrated measure of the physical and biological changes following forestry perturbations.  This study was conducted in 11 northern and 12 southern Swedish streams to address; 1) How is leaf litter decomposition in small streams affected by forestry by measuring leaf litter decomposition in streams with different buffer widths, and; 2) How other environmental variables, such as  stream bottom substrate, canopy openness, water temperature and stream velocity affected leaf litter decomposition. Buffer width had no effect on decomposition. Temperature and proportion organic bottom substrate had respectively positive and negative trends with decomposition in the southern Swedish sites which suggests the importance of forestry targeting these riparian functions especially when managing small streams. At the northern sites, velocity showed a positive, and temperature a negative trend with leaf litter decomposition but none of these were significant. It is possible that the extraordinarily warm and dry weather before and during the study was conducted affected aquatic organisms to the degree that decomposition was inhibited, and most trends became too small to detect or that buffer width is less important in a warmer climate.

Forest plantations, widely grown for wood production, involve the selective promotion of single tree species, or replacement of natural species by exotic tree species. Slash pine (Pinus elliottii) has been chosen for reforestation of infertile sandy soils in southeast Queensland, Australia. These exotic pine plantations minimise soil and water losses, and are important scientific study sites. The soil environment of these plantations, though devoid of sufficient nutrients, oxygen and other factors, harbours innumerable bacteria that may play a crucial role in maintaining soil quality and ecosystem functions. These soil microorganisms also have the potential for use as sensitive biological indicators to reflect environmental changes. It is therefore essential to understand the interrelationships amongst bacterial communities and their environment by assessing their structural and functional diversity, and their responses to disturbances. The microbial community of an exotic pine plantation of subtropical Australia was analysed by both culture-dependent and culture-independent methods. In this study, a leaf litter-soil core sample (25 cm x 40 cm) was collected from a 22-year-old slash pine plantation in southeast Queensland, Australia in October, 2003. The core sample was divided into three fractions, namely, L layer leaf litter, F layer leaf litter, and forest soil 0-10 cm. In the culture-independent study, a modified DNA extraction and purification method was used to obtain highly purified high-molecular-weight DNA. This DNA was successfully used to amplify bacterial 16S rRNA genes with universal primers Fd1 and R6, to produce products of approximately 1500 bp. PCRamplified 16S rRNA genes were subsequently cloned and a total of 194 clones from leaf litter and soil were partially sequenced (about 510 bp). The 16S rRNA gene sequences were analysed and grouped into several phylogroups (the sequences with a similarity value ¡Ý 98 % were regarded as phylogenetically similar and grouped into one phylogroup). Sequencing representatives (¡Ö 1400 nucleotides) from each phylogenetic group confirmed that five bacterial phyla were represented in the forest soil clone library. Phylum Acidobacterium was the most abundant phylogenetic group in terms of the number of clones and accounted for 42 % of all examined soil clones. The Verrucomicrobiales and Proteobacteria were the second and third most abundant phylogenetic groups found in the soil clone libraries, accounting for 12 % and 11 % of the soil clones, respectively. About 8 % of all examined soil clones were Planctomycetes and 27 % of soil clones were phylogenetically unidentified. The large amount of unclassified clone sequences could imply that novel groups of bacteria were present in the forest soil. When the two fractions of leaf litter clone libraries were compared, Firmicutes was the only phylum represented in the L layer leaf litter clone library. Similarly, Firmicutes dominated the F layer leaf litter (79 % of the library), was followed by Proteobacteria (21 %). For the culture-dependent study, a total of 21 isolates which were considered to represent 334 colonies from the leaf litter and forest soil were identified by 16S rRNA gene sequence analysis, indicating that L layer leaf litter and F layer leaf litter were dominated by Firmicutes (48 %) and Proteobacteria (69 %) respectively, and 91 % of the isolates from the forest soil were Firmicutes. Using culture-independent methods, Actinobacteria appeared to be absent from the L and F layer leaf litter and forest soil samples. The results implied that either the nucleic acids of Actinobacteria were difficult to extract or Actinobacteria were over represented in the culture-dependent examinations. Phylum Acidobacteria appeared to be numerically dominant and active members in most soils. However, only one named species had been isolated from an acid mine drainage site and reported by Kishimoto and Tano (1987). Analysis by culture-dependent methods revealed a different bacterial diversity, compared to the bacterial diversity from the 16S rRNA gene clone sequences. The most significant result was the observation that, as revealed by both culture-dependent and culture-independent methods, the bacterial diversity presented in the leaf litter was greatly different from the community of the soil. During the culture-dependent bacterial diversity study, four novel strains were isolated from the forest soil and leaf litter samples and complete characterisations of these novel strains were carried out. Reports on the descriptions of Bacillus decisifrondis strain E5HC-32T from forest soil and Frondicola australicus strain E1HC-02T from L layer leaf litter have been published (appendix). The information provided by assessing the microbial communities in different fractions of leaf litter and forest soil improves our understanding of the phylogenetic relationship between soil and leaf litter. It is suggested, in this study, to perform both culture-dependent and culture-independent methods to characterise the bacterial structure and diversity in forest litter and soil samples, particularly in response to different forest management practices and global change. This study also provides the basis for further functional studies of the forest soil and leaf litter of exotic pine plantation in subtropical Australia.

Forested riparian zones, which function as a buffer between agricultural fields and streams, filter out contaminants and sediment from the fields thereby improving water quality, cool the water with shade from trees, stabilize the stream bank and provide habitat for wildlife. However, in many agricultural areas, riparian vegetation has been removed for crop production or pasture purposes. Riparian restoration or rehabilitation is a way of restoring riparian ecosystem functions. This study examines the effect of riparian rehabilitation via tree planting along a first-order creek in Southern Ontario, 25 years after rehabilitation. Litter input, soil quality parameters and soil CO2 production rates were determined for the rehabilitated riparian zone, a grass-forb riparian zone and a natural forest riparian zone. Total litter input was 480, 580 and 295 g m-2 y-1 for the rehabilitated riparian zone, grass riparian zone and forest riparian zone, respectively. Soil bulk density was higher and hydraulic conductivity was lower for the rehabilitated riparian zone compared to the grass riparian zone and forest riparian zone. The concentration and soil stock of organic carbon and total nitrogen was lowest for the rehabilitated riparian zone compared to the grass riparian zone and forest riparian zone which were similar. The effect of riparian zone on soil CO2 production rates varied over the season. From spring to mid-summer, rates were 167, 224 and 104 mg C m-2 h-1 for the rehabilitated riparian zone, grass riparian zone and forest riparian zone, respectively. Soil CO2 production rates did not differ significantly (p < 0.05) between riparian zones for late summer and fall sampling dates. Soil CO2 production rates were significantly negatively correlated with soil C/N and positively correlated with soil pH and litter input. Soil CO2 production rates were positively correlated with soil temperature (r = 0.32) and negatively correlated with soil moisture (r = -0.48). Of the three riparian zones, the natural forest riparian zone exhibited the least amount of seasonal fluctuation for soil CO2 production rates, soil moisture and temperature. Results from this research indicated that more time is needed before soil quality and soil CO2 production rates of the rehabilitated riparian zone reach values similar to the natural forest riparian zone.

Forested riparian zones, which function as a buffer between agricultural fields and streams, filter out contaminants and sediment from the fields thereby improving water quality, cool the water with shade from trees, stabilize the stream bank and provide habitat for wildlife. However, in many agricultural areas, riparian vegetation has been removed for crop production or pasture purposes. Riparian restoration or rehabilitation is a way of restoring riparian ecosystem functions. This study examines the effect of riparian rehabilitation via tree planting along a first-order creek in Southern Ontario, 25 years after rehabilitation. Litter input, soil quality parameters and soil CO2 production rates were determined for the rehabilitated riparian zone, a grass-forb riparian zone and a natural forest riparian zone. Total litter input was 480, 580 and 295 g m-2 y-1 for the rehabilitated riparian zone, grass riparian zone and forest riparian zone, respectively. Soil bulk density was higher and hydraulic conductivity was lower for the rehabilitated riparian zone compared to the grass riparian zone and forest riparian zone. The concentration and soil stock of organic carbon and total nitrogen was lowest for the rehabilitated riparian zone compared to the grass riparian zone and forest riparian zone which were similar. The effect of riparian zone on soil CO2 production rates varied over the season. From spring to mid-summer, rates were 167, 224 and 104 mg C m-2 h-1 for the rehabilitated riparian zone, grass riparian zone and forest riparian zone, respectively. Soil CO2 production rates did not differ significantly (p < 0.05) between riparian zones for late summer and fall sampling dates. Soil CO2 production rates were significantly negatively correlated with soil C/N and positively correlated with soil pH and litter input. Soil CO2 production rates were positively correlated with soil temperature (r = 0.32) and negatively correlated with soil moisture (r = -0.48). Of the three riparian zones, the natural forest riparian zone exhibited the least amount of seasonal fluctuation for soil CO2 production rates, soil moisture and temperature. Results from this research indicated that more time is needed before soil quality and soil CO2 production rates of the rehabilitated riparian zone reach values similar to the natural forest riparian zone.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste estudo nós fornecemos os primeiros dados acerca dos parâmetros da comunidade de anuros de folhiço de uma floresta no estado do Paraná, sul do Brasil, incluindo informações sobre riqueza de espécies, densidades específicas e biomassa. Nosso estudo foi realizado na Reserva Natural Salto Morato entre julho de 2009 e abril de 2010. Para amostrar a comunidade de anuros de folhiço usamos 40 parcelas de 4 x 4 m em cada estação do ano (inverno, primavera, verão e outono), totalizando 2.560 m2 de chão de floresta amostrados. Nós amostramos um total de 96 anuros habitando o chão da floresta, pertencentes a sete espécies: Brachycephalus hermogenesi, Ischnocnema guentheri, Haddadus binotatus, Leptodactylus gr. marmoratus, Physalaemus spiniger, Proceratophrys boiei e Rhinella abei. A densidade total de anuros vivendo no chão da floresta foi de 3,73 ind/100m2, sendo I. guentheri (1,37 ind/100m2) a espécie mais numerosa e R. abei (0,19 ind/100m2), a mais rara. A estimativa da biomassa total na comunidade de anuros de folhiço foi de 3,290g. A temperatura foi um fator ambiental significativo para a abundância de anuros de folhiço, enquanto a umidade não foi importante na estruturação da comunidade na área estudada. A abundância, riqueza e densidade variaram consistentemente entre as quatro estações do ano amostradas, com os maiores valores ocorrendo nos meses mais quentes da primavera e verão. Esse estudo aumenta a distribuição geográfica de Brachycephalus hermogenesi. / In this study we provide the first data regarding community parameters of leaf-litter anurans inhabiting the floor of a forest in the State of Paraná, southern Brazil, including information on community species richness, composition, specific density and biomass. Our study was conducted at Reserva Natural Salto Morato between July 2009 and April 2010. To sample the leaf-litter frogs community used 40 plots of 4 x 4 m in each season (winter, spring, summer and autumn), totaling 2.560 m2 of forest floor sampled. We sampled a total of 96 frogs inhabiting the forest floor, belonging to seven species: Brachycephalus hermogenesi, Ischnocnema guentheri, Haddadus binotatus, Leptodactylus gr. marmoratus, Physalaemus spiniger, Proceratophrys boiei and Rhinella abei. The overall frog density in the forest floor was 3.73 ind/100m2, being I guentheri (1.37 ind/100m2) the most numerous species and R. abei (0.19 ind/100m2), the rarest. The estimated overall frog mass in the community was 3.290g. The temperature was a significant environmental factor for the abundance of leaf-litter frogs, while the humidity was not important in structuring the community in the area. The abundance, richness and density varied consistently among the four seasons sampling, with the highest values occurring in the spring and summer seasons. This study adds to the geographic distribution of Brachycephalus hermogenesi.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste estudo nós fornecemos os primeiros dados acerca dos parâmetros da comunidade de anuros de folhiço de uma floresta no estado do Paraná, sul do Brasil, incluindo informações sobre riqueza de espécies, densidades específicas e biomassa. Nosso estudo foi realizado na Reserva Natural Salto Morato entre julho de 2009 e abril de 2010. Para amostrar a comunidade de anuros de folhiço usamos 40 parcelas de 4 x 4 m em cada estação do ano (inverno, primavera, verão e outono), totalizando 2.560 m2 de chão de floresta amostrados. Nós amostramos um total de 96 anuros habitando o chão da floresta, pertencentes a sete espécies: Brachycephalus hermogenesi, Ischnocnema guentheri, Haddadus binotatus, Leptodactylus gr. marmoratus, Physalaemus spiniger, Proceratophrys boiei e Rhinella abei. A densidade total de anuros vivendo no chão da floresta foi de 3,73 ind/100m2, sendo I. guentheri (1,37 ind/100m2) a espécie mais numerosa e R. abei (0,19 ind/100m2), a mais rara. A estimativa da biomassa total na comunidade de anuros de folhiço foi de 3,290g. A temperatura foi um fator ambiental significativo para a abundância de anuros de folhiço, enquanto a umidade não foi importante na estruturação da comunidade na área estudada. A abundância, riqueza e densidade variaram consistentemente entre as quatro estações do ano amostradas, com os maiores valores ocorrendo nos meses mais quentes da primavera e verão. Esse estudo aumenta a distribuição geográfica de Brachycephalus hermogenesi. / In this study we provide the first data regarding community parameters of leaf-litter anurans inhabiting the floor of a forest in the State of Paraná, southern Brazil, including information on community species richness, composition, specific density and biomass. Our study was conducted at Reserva Natural Salto Morato between July 2009 and April 2010. To sample the leaf-litter frogs community used 40 plots of 4 x 4 m in each season (winter, spring, summer and autumn), totaling 2.560 m2 of forest floor sampled. We sampled a total of 96 frogs inhabiting the forest floor, belonging to seven species: Brachycephalus hermogenesi, Ischnocnema guentheri, Haddadus binotatus, Leptodactylus gr. marmoratus, Physalaemus spiniger, Proceratophrys boiei and Rhinella abei. The overall frog density in the forest floor was 3.73 ind/100m2, being I guentheri (1.37 ind/100m2) the most numerous species and R. abei (0.19 ind/100m2), the rarest. The estimated overall frog mass in the community was 3.290g. The temperature was a significant environmental factor for the abundance of leaf-litter frogs, while the humidity was not important in structuring the community in the area. The abundance, richness and density varied consistently among the four seasons sampling, with the highest values occurring in the spring and summer seasons. This study adds to the geographic distribution of Brachycephalus hermogenesi.

The decomposition of dead plant biomass substantially contributes to the carbon cycle and therefore is one of the key processes in temperate forests. While the role of fungi in litter and deadwood decomposition was repeatedly addressed, there are just a few surveys of bacteria associated with decomposing plant biomass. The development of bacterial community within leaf litter is likely driven by the changes in litter chemistry and by the availability of nutrients in the litter. Fungal activity greatly contributes to changing properties of substrate and thus influences bacterial community. Availability of nutrients is changing during biomass decomposition from easily accessible substrates toward more recalcitrant ones (e.g. lignin). The colonization of deadwood by bacteria is influenced by various factors such as microclimate conditions, tree species and volume. The aim of this thesis was to describe bacterial community dynamics during the first two years of decomposition of leaf litter and deadwood. In the leaf litter experiment, bacterial community was analysed in the live, senescent and decomposing leaves of Quercus petraea. This experiment was performed in the Xaverovsky Haj Natural Reserve, Czech Republic. Deadwood experiment was focused on the composition of bacterial community in the initial...