Effect of River Ecological Restoration on Biofilm Microbial Community Composition

Abstract: Across the world, there are increasing attempts to restore good ecological condition to 16 degraded rivers through habitat restoration. Microbial communities developing as biofilms play an 17 important role in river ecosystem functioning by driving organic matter decomposition and 18 ecosystem respiration. However, little is known about the structure and function of microbial 19 communities in riverine systems, and how these change when habitat restoration is implemented. 20 Here, we compared the biofilm bacterial community composition using 16S rRNA genes targeted 21 high-throughput Illumina Miseq sequencing in three river types, degraded urban rivers, urban 22 rivers undergoing habitat restoration and forested rivers (our reference conditions). We aimed to 23 determine: (i) the biofilm bacterial community composition affected by habitat restoration (ii) the 24 difference in bacterial diversity in restored rivers, and (iii) correlations between environmental 25 variables and bacterial community composition. The results showed that both water quality and 26 biofilm bacterial community structure were changed by habitat restoration. In rivers where habitat 27 has been restored, there has been an increase in dissolved oxygen, a reduction in organic pollutants, 28 a reduction in bacterial diversity and a related developing pattern of microbial communities, which 29 is moving towards that of the reference conditions (forested rivers). River habitat management 30 stimulated the processing of organic pollutants through the variation in microbial community 31 composition, however, a big difference in bacterial structure still existed between the restored rivers 32 and the reference forest rivers. Thus, habitat restoration is an efficient way of modifying the biofilm 33 microbial community composition for sustainable freshwater management. It will, however, take a 34 much longer time for degraded rivers to attain the similar ecosystem quality as the “pristine” forest 35 sites than the seven years of restoration studied here

Floristic Composition and Phytomass in the Drawdown Zone of the Soyangho Reservoir, Korea

The Soyangho Reservoir in Korea has a large drawdown zone, with an annual maximum water level fluctuation of 37 m due to dam operations to maintain a stable water supply and control flooding, especially during the monsoon period. The floristic composition, distribution and biomass of the major plant communities in the drawdown zone of the Soyangho Reservoir were assessed in order to understand their responses to the wide water level fluctuation. Species richness of vascular plants was low, and species composition was dominated by herbaceous annuals. Principal co-ordinates analysis using both flora and environmental data identified slope angle and the distance from the dam as important factors determining floristic composition. The species richness was low in the steep drawdown zone close to the dam, where much of the soil surface was almost devoid of vegetation. In shallower slopes, distant from the dam plant communities composed of mainly annuals were found. The large fluctuation in water level exposed soil where these annuals could establish. An overall biomass of 122 t (metric tons) Dry Matter was estimated for the reservoir, containing ca 3.6 t N (nitrogen) and ca 0.3 t P (phosphorus); the role of the vegetation of the drawdown zone in carbon sequestration and water pollution are briefly discussed

Measured estimates of semi-natural terrestrial NPP in Great Britain: comparison with modelled values, and dependence on atmospheric nitrogen deposition

Plant growth in nitrogen (N)-limited, unfertilised terrestrial ecosystems should respond to additional N inputs from atmospheric deposition (Ndep). We investigated this for sites in Great Britain (GB) by compiling 796 estimates of net primary productivity (NPP) from measured biomass production over the period 1932-2014, although the great majority were for 1995 onwards. The sites were largely vegetated with shrubs, grass and bracken, and had a wide range of Ndep (0.5 – 3.3. gN m-2 a-1 in 2000). The measured NPP estimates were compared with calculated values from the biogeochemical ecosystem model N14CP, which predicts that NPP depends strongly upon Ndep. The measured and modelled average total NPP values (gC m-2 a-1) from all data were 387 (standard deviation, SD = 193) and 377 (SD = 72) respectively. Measured and modelled averages for vegetation classes followed the sequence: broadleaved trees ~ needle-leaved trees > herbs (rough grassland + bracken) ~ shrubs. After averaging measured values for sites in individual model grid cells (5 km x 5 km) with 10 or more replicates, the measured and modelled NPP values were correlated (n=26, r2=0.22, p=0.011), with a slope close to unity. Significant linear relationships were found between measured ln NPP and cumulative Ndep for both herbs (n=298, p=0.021) and shrubs (n=473, p=0.006), with slopes comparable to those predicted with the model. The results suggest that semi-natural NPP in GB depends positively upon Ndep, in a manner that agrees quantitatively with N14CP predictions. Calculations with the model, using modelled temporal variation in Ndep, indicate that fertilisation by Ndep caused average increases in semi-natural NPP over the period 1800 to 2010 of 30% for shrubs, 71% for herbs, and 91% for broadleaved trees. Combined with previous published results for forests, our findings suggest a general and widespread vegetation response to fertilisation by Ndep

Model parameterization to simulate and compare the PAR absorption potential of two competing plant species

Mountain pastures dominated by the pasture grass Setaria sphacelata in the Andes of southern Ecuador are heavily infested by southern bracken (Pteridium arachnoideum), a major problem for pasture management. Field observations suggest that bracken might outcompete the grass due to its competitive strength with regard to the absorption of photosynthetically active radiation (PAR). To understand the PAR absorption potential of both species, the aims of the current paper are to (1) parameterize a radiation scheme of a two-big-leaf model by deriving structural (LAI, leaf angle parameter) and optical (leaf albedo, transmittance) plant traits for average individuals from field surveys, (2) to initialize the properly parameterized radiation scheme with realistic global irradiation conditions of the Rio San Francisco Valley in the Andes of southern Ecuador, and (3) to compare the PAR absorption capabilities of both species under typical local weather conditions. Field data show that bracken reveals a slightly higher average leaf area index (LAI) and more horizontally oriented leaves in comparison to Setaria. Spectrometer measurements reveal that bracken and Setaria are characterized by a similar average leaf absorptance. Simulations with the average diurnal course of incoming solar radiation (1998–2005) and the mean leaf–sun geometry reveal that PAR absorption is fairly equal for both species. However, the comparison of typical clear and overcast days show that two parameters, (1) the relation of incoming diffuse and direct irradiance, and (2) the leaf–sun geometry play a major role for PAR absorption in the two-big-leaf approach: Under cloudy sky conditions (mainly diffuse irradiance), PAR absorption is slightly higher for Setaria while under clear sky conditions (mainly direct irradiance), the average bracken individual is characterized by a higher PAR absorption potential. (∼74 MJ m−2 year−1). The latter situation which occurs if the maximum daily irradiance exceeds 615 W m−2 is mainly due to the nearly orthogonal incidence of the direct solar beam onto the horizontally oriented frond area which implies a high amount of direct PAR absorption during the noon maximum of direct irradiance. Such situations of solar irradiance favoring a higher PAR absorptance of bracken occur in ∼36% of the observation period (1998–2005). By considering the annual course of PAR irradiance in the San Francisco Valley, the clear advantage of bracken on clear days (36% of all days) is completely compensated by the slight but more frequent advantage of Setaria under overcast conditions (64% of all days). This means that neither bracken nor Setaria show a distinct advantage in PAR absorption capability under the current climatic conditions of the study area

Self-Guided Psychological Treatment for Depressive Symptoms: A Meta-Analysis

Background: A number of trials have examined the effects of self-guided psychological intervention, without any contact between the participants and a therapist or coach. The results and sizes of these trials have been mixed. This is the first quantitative meta-analysis, aimed at organizing and evaluating the literature, and estimating effect size. Method: We conducted systematic literature searches in PubMed, PsycINFO and Embase up to January 2010, and identified additional studies through earlier meta-analyses, and the references of included studies. We identified seven randomized controlled trials that met our inclusion criteria, with a total of 1,362 respondents. The overall quality of the studies was high. A post-hoc power calculation showed that the studies had sufficient statistical power to detect an effect size of d = 0.19. Results: The overall mean effect size indicating the difference between self-guided psychological treatment and control groups at post-test was d = 0.28 (pless than0.001), which corresponds to a NNT of 6.41. At 4 to 12 months follow-up the effect size was d = 0.23. There was no indication for significant publication bias. Conclusions: We found evidence that self-guided psychological treatment has a small but significant effect on participants with increased levels of depressive symptomatology.Original Publication:Pim Cuijpers, Tara Donker, Robert Johansson, David C. Mohr, Annemieke van Straten and Gerhard Andersson, Self-Guided Psychological Treatment for Depressive Symptoms: A Meta-Analysis, 2011, PLoS ONE, (6), 6.http://dx.doi.org/10.1371/journal.pone.0021274Copyright: Public Library of Science (PLoS)http://www.plos.org