Although carbon (C) gas exchange during the summer largely determines the annual C balance of mires, the wintertime fluxes cannot be ignored. Decomposition continues as long as the soil is not frozen and a proportion of the gases produced during summer are also released during winter. We measured carbon dioxide (CO2) and methane (CH4) fluxes along a successional mire sequence during two winters following growing seasons with divergent weather conditions. We studied the successional trends in wintertime C release in boreal mires, and quantified the contribution of wintertime C fluxes to annual fluxes. Wintertime CO2 and CH4 fluxes from the successional mire sequence were related to the flux rates during the previous summer. Average winter CO2 release along the successional sequence varied between 19.5 and 44.9 g CO2-C m–2 winter–1(6-months), and accounted for 8–14% of the annual CO2 release. There was no clear successional trend in CO2 fluxes. Average winter CH4 release along the successional sequence varied between 0.20 and 7.29 CH4-C g m–2 winter–1(6-months).The winter CH4 fluxes accounted for up to 38% of the annual CH4 emissions. Occasional CH4 uptake was detected at the younger successional stages during winter following the dry summer, while after the wet summer all sites emitted CH4. In general, most of the winter C losses were composed of CO2.
Avainsanat: sukkessio, suon kehitys, primaarisoistuminen, hiilidioksidi, metaani, lumikerros, Siikajoki, maankohoamisrannikko
Keywords: mire succession, mire development, primary paludification, carbon dioxide, methane, snow pack, land uplift coast, Siikajoki
Mirva Leppälä, Finnish Forest Research Institute, FIN-91500 Muhos, Finland. Current address: Metsähallitus, Natural Heritage Services Ostrobothnia, BOX 81, FI-90101 Oulu, Finland, email: mirva.leppala@metsa.fi
Anna Laine, University of Oulu, Department of Biology, FIN-90014 University of Oulu, Finland, email: anna.laine@oulu.fi
Eeva-Stiina Tuittila, Peatland Ecology Group, Department of Forest Sciences, P.O. BOX 27, FIN-00014 University of Helsinki, Finland, email: eevastiina.tuittila@helsinki.fi
Tutkimuksen tavoitteena oli selvittää turpeen ja nykypuuston kaliumvarojen määrä sekä arvioida kaliumvarojen riittävyys puuston kasvulle päätehakkuuvaiheessa ja toisen puusukupolven aikana vanhoilla varputurvekankaan (Vatkg) ojitusalueilla Lounais-Suomessa. Tarkoituksena oli arvioida, voiko osalla karuista varputurvekankaista kalium loppua jo ennen päätehakkuuvaihetta tai viimeistään toisen puusukupolven aikana. Puustoon oli mittaushetkellä sitoutunut kaliumia keskimäärin 62 % (23–106 %) turpeen kaliumvarastoon verrattuna. Jos kiertoajan kokonaistuotokseksi arvioidaan 200 m3 ha–1, eikä turpeen tiivistymisen tai laskeuman mahdollista vaikutusta kaliummäärien muutoksiin huomioida, oli pintaturpeessa keskimäärin 67 % (34–96 %) siitä kaliummäärästä, jonka puusto tarvitsee tuon kokonaistuotoksen maanpäällisen biomassan saavuttamiseksi. Kaliumin riittävyys nykypuuston koko kiertoajalle sekä seuraavan puusukupolven tarpeisiin riippuu paljolti siitä, pystyvätkö ilmasta tuleva kalium ja turpeen tiivistyessä konsentroituva kalium kompensoimaan hakkuun ja huuhtoutumisen aiheuttamat menetykset. Tarkastelu osoittaa, että myös karuilla rämeillä käytettävissä olevan kaliumin määrä saattaa rajoittaa puuston kehitystä. Vähiten kaliumia sisältävien turpeiden kasvupaikoilla ongelmia voi ilmetä jo ensiharvennuksen jälkeen, eikä kalium ehkä riitä edes tavoiteltuun 200 m3 ha–1 kokonaistuotokseen. Kaliumin riittävyyden ongelma lienee pahin niillä varputurvekankailla, jotka ovat lähtöisin runsaasti nevapintaa sisältäneistä lyhytkorsirämeistä (LkR).
Avainsanat: turvemaa, kuivatus, ravinnepuutos, pääravinne, kaliumin riittävyys
Keywords: peatland, drainage, nutrient deficiency, macronutrient, potassium sufficiency
Markku Saarinen, Metsäntutkimuslaitos, Länsi-Suomen alueyksikkö, Kaironiementie 15, FI-39700 Parkano, email: markku.saarinen@metla.fi.
Timo Silver, Metsäkeskus Lounais-Suomi, Kuralankatu 2, FI-20540 Turku, email: timo.silver@metsakeskus.fi
Rosetta branch is one of the two main branches in Nile delta and El-Rahawy drain is one of this main sources, which outlet on the branch. It is subjected to many sources of pollutions from municipalities, agriculture and industry, but only little information is available on the quality of river water. The aim of this study was to analyze the river water quality in Rosetta branch at the outlet of El-Rahawy drain, Nile delta. Water samples were collected seasonally from El-Rahawy and Rosetta branch and the following physicochemical parameters were analyzed: hydrogen ion concentration (pH), total dissolved solids (TDS), electrical conductivity (EC), dissolved oxygen (DO), ammonia (NH3), total alkalinity (CO3+HCO3); biochemical oxygen demand (BOD) and chemical oxygen demand (COD). The results were compared with the water quality standards of Egypt (Law 48/1982), FAO and Canadian Water Quality standards (CWQGs). Statistical studies were carried out by calculating correlation coefficients between different parameters. The large transports of NH3, and TDS with low COD, BOD and DO values along El-Rahawy drain were seriously deteriorating the water quality in the downstream of Rosetta branch, especially during the low flow condition in winter.
Key words: river water, stream flow, water pollution, El-Rahawy drain.
Avainsanat: jokivesi, virtaama, kuormitus, El-Rahawy.
Mohamed M. El Bouraie, Eman A. Motawea, Mohamed M. Yehia, Central Laboratory for Environmental Quality Monitoring (CLEQM), National Water Research Center (NWRC), Cairo, Egypt, email: mido.chemie@gmail.com
Gehad G. Mohamed, Department of Chemistry, Cairo University (CU), Giza, Egypt
As part of an investigation of the long-term effects of ditch-draining on peat deposits, we cored peat samples altogether from 51 peatland sites that had been earlier inventoried by volumetric coring by the Geological Survey of Finland (GTK) during the 1980s. In most cases, it proved possible to match the old and new profiles cored of the same site, especially concerning their lower parts, in which typically no big changes seem to have taken place. However, comparison of the results revealed a recurring, albeit not systematic bias: the dry bulk density values of the GTK data tended to be somewhat smaller than our corresponding results. In cases where peat compression can be ruled out, a plausible explanation is that the piston corer did not function properly. This paper describes a test series in which we compared the GTK piston corer, a 1-m box corer and a Russian peat corer in quantitative sampling of peat strata. The piston corer proved to have a slight tendency to underperform, particularly with peats rich in sedge, cottongrass or wood remains. Implications of the variable sampler performance on quantitative peat inventories are discussed.
Key words: corer performance, peat coring, peat samplers, volumetric sampling
Avainsanat: turvekaira, turvetutkimus, volumetrinen näytteenotto
Aki Pitkänen, Heikki Simola, Deparment of Biology, University of Eastern Finland, P.O.Box 111, FI-80101 Joensuu, Finland, email: aki.pitkanen@uef.fi
Jukka Turunen, Geological Survey of Finland, Neulaniementie 5, FI-70210 Kuopio, Finland