Glasshouse vs field experiments: do they yield ecologically similar results for assessing N impacts on peat mosses?

• Peat bogs have accumulated more atmospheric carbon (C) than any other terrestrial ecosystem today. Most of this C is associated with peat moss (Sphagnum) litter. Atmospheric nitrogen (N) deposition can decrease Sphagnum production, compromising the C sequestration capacity of peat bogs. The mechanisms underlying the reduced production are uncertain, necessitating multifactorial experiments. • We investigated whether glasshouse experiments are reliable proxies for field experiments for assessing interactions between N deposition and environment as controls on Sphagnum N concentration and production. We performed a meta-analysis over 115 glasshouse experiments and 107 field experiments. • We found that glasshouse and field experiments gave similar qualitative and quantitative estimates of changes in Sphagnum N concentration in response to N application. However, glasshouse-based estimates of changes in production--even qualitative assessments-- diverged from field experiments owing to a stronger N effect on production response in absence of vascular plants in the glasshouse, and a weaker N effect on production response in presence of vascular plants compared to field experiments. • Thus, although we need glasshouse experiments to study how interacting environmental factors affect the response of Sphagnum to increased N deposition, we need field experiments to properly quantify these effects.

Climatic modifiers of the response to nitrogen deposition in peat-forming Sphagnum mosses: a meta-analysis.

Peatlands in the northern hemisphere have accumulated more atmospheric carbon (C) during the Holocene than any other terrestrial ecosystem, making peatlands long-term C sinks of global importance. Projected increases in nitrogen (N) deposition and temperature make future accumulation rates uncertain. Here, we assessed the impact of N deposition on peatland C sequestration potential by investigating the effects of experimental N addition on Sphagnum moss. We employed meta-regressions to the results of 107 field experiments, accounting for sampling dependence in the data. We found that high N loading (comprising N application rate, experiment duration, background N deposition) depressed Sphagnum production relative to untreated controls. The interactive effects of presence of competitive vascular plants and high tissue N concentrations indicated intensified biotic interactions and altered nutrient stochiometry as mechanisms underlying the detrimental N effects. Importantly, a higher summer temperature (mean for July) and increased annual precipitation intensified the negative effects of N. The temperature effect was comparable to an experimental application of almost 4 g N m(-2) yr(-1) for each 1°C increase. Our results indicate that current rates of N deposition in a warmer environment will strongly inhibit C sequestration by Sphagnum-dominated vegetation.

Monitoring of heavy metal deposition in Northern Italy by moss analysis.

A survey of heavy metal deposition in the mountainous territories of Northern Italy was carried out in 1995-96. Moss samples (mainly Hylocomium splendens) were collected in a dense network of sites (about 3.2 sites/1000 km(2)) and the data of metal concentrations in moss tissues were statistically correlated with environmental and climatic factors, as well as with bulk deposition of elements and elemental concentrations in the soil. Three main geographic patterns of metal concentration in mosses could be defined: (1) Fe, Ni, and Cr, all derived both by soil particulates and anthropogenic emissions connected with ferrous metal manufacturing, were mostly concentrated in Northwestern Italy; (2) Cu and Zn, as typical multi-source elements, showed rather high concentrations with little ranges of variation over the whole area and small peaks reflecting local source points; (3) Cd and Pb reflected long-distance transport and showed highest concentrations in the regions with highest precipitation, especially in the Eastern Alps.

[Prevalence of intestinal parasitosis in schoolchildren]. / Prevalência de parasitose intestinal em escolares da primeira série de uma escola pública.

OBJECTIVE: Aiming to identify the prevalence and the social risk factors of the intestinal parasitosis in first grade school children of Campinas, State of São Paulo, Brazil. METHODS: Cross-sectional descriptive and analytical study based in personal and social data obtained by interview and feces analysis of 146 children to investigate Ancylostomatidae, Ascaris lumbricoides, Endolimax nana, Entamoeba coli, Entamoeba histolytica, Enterobius vermicularis, Giardia lamblia, Hymenolepis nana, Iodamoeba bütschlii, Schistosoma mansoni, Strongyloides stercoralis, Taenia sp and Trichuris trichiura. RESULTS: The prevalence of Ascaris lumbricoides was 12.3% and of Giardia lamblia was 8.2%. The prevalence of intestinal parasitosis, in general, was 30.8%. The social risk factors for intestinal parasitosis were low maternal (OR=2.3) and paternal education (OR=3.9), small house (OR=3.0), large household (OR=2.7) and proletarian group (p=0.02). After adjusting for social variables, intestinal parasitosis was predicted by paternal education (p=0.003). CONCLUSIONS: The role of health education is important for disease prevention and the school is a natural place to reach the community living next to it.