From a tree to a stand in Finnish boreal forests: biomass estimation and comparison of methods

There is an increasing need to compare the results obtained with different methods of estimation of tree biomass in order to reduce the uncertainty in the assessment of forest biomass carbon. In this study, tree biomass was investigated in a 30-year-old Scots pine (Pinus sylvestris) (Young-Stand) and a 130-year-old mixed Norway spruce (Picea abies)-Scots pine stand (Mature-Stand) located in southern Finland (61º50' N, 24º22' E). In particular, a comparison of the results of different estimation methods was conducted to assess the reliability and suitability of their applications. For the trees in Mature-Stand, annual stem biomass increment fluctuated following a sigmoid equation, and the fitting curves reached a maximum level (from about 1 kg/yr for understorey spruce to 7 kg/yr for dominant pine) when the trees were 100 years old. Tree biomass was estimated to be about 70 Mg/ha in Young-Stand and about 220 Mg/ha in Mature-Stand. In the region (58.00-62.13 ºN, 14-34 ºE, ≤ 300 m a.s.l.) surrounding the study stands, the tree biomass accumulation in Norway spruce and Scots pine stands followed a sigmoid equation with stand age, with a maximum of 230 Mg/ha at the age of 140 years. In Mature-Stand, lichen biomass on the trees was 1.63 Mg/ha with more than half of the biomass occurring on dead branches, and the standing crop of litter lichen on the ground was about 0.09 Mg/ha. There were substantial differences among the results estimated by different methods in the stands. These results imply that a possible estimation error should be taken into account when calculating tree biomass in a stand with an indirect approach.

Fuel conditions and fire behavior characteristics of managed Picea abies and Pinus sylvestris forests in Finland

The objectives of this study were to analyze the impact of structural stand characteristics on ignition potential, surface fuel moisture, and fire behavior in Pinus sylvestris L. and Picea abies (L.) Karst stands in Finland and to explain stand-specific fire danger using the Canadian Fire Weather Index System and the Finnish Fire Risk Index. Additionally, the study analyzes the relationship between observed fire activity and fire weather indices at different stages of growing season. Field experiments were carried out in Pinus sylvestris or Picea abies dominated stands during fire seasons 2001 and 2002. Observations on ignition potential, fuel moisture, and fire behavior were analyzed in relation to stand structure and the outputs of the Finnish and Canadian fire weather indices. Seasonal patterns of fire activity were examined based on national fire statistics 1996 2003, effective temperature sum, and the fire weather indices. Point fire ignition potential was highest in Pinus clear-cuts and lowest in closed Picea stands. Moss-dominated surface fuels were driest in clear-cut and sapling stage stands and presented the highest moisture content under closed Picea canopy. Pinus sylvestris stands carried fire under a wide range of fire weather conditions under which Picea abies stands failed to sustain fire. In the national fire records, the daily number of reported ignitions presented its highest value during late fire season whereas the daily area burned peaked most substantially during early season. The fire weather indices correlated significantly with ignition potential and fuel moisture but were unable to explain fire behavior in the experimental fires. During the initial and final stages of the growing season, fire activity was disconnected from weather-based fire danger ratings. Information on stand structure and season stage would benefit the assessment of fire danger in Finnish forest landscape for fire suppression and controlled burning purposes.

Use of biomass fuels in the brick-making industries of Sudan: Implications for deforestation and greenhouse gas emission

The study focuses on the potential roles of the brick making industries in Sudan in deforestation and greenhouse gas emission due to the consumption of biofuels. The results were based on the observation of 25 brick making industries from three administrative regions in Sudan namely, Khartoum, Kassala and Gezira. The methodological approach followed the procedures outlined by the Intergovernmental Panel on Climate Change (IPCC). For predicting a serious deforestation scenario, it was also assumed that all of wood use for this particular purpose is from unsustainable sources. The study revealed that the total annual quantity of fuelwood consumed by the surveyed brick making industries (25) was 2,381 t dm. Accordingly, the observed total potential deforested wood was 10,624 m3, in which the total deforested round wood was 3,664 m3 and deforested branches was 6,961 m3. The study observed that a total of 2,990 t biomass fuels (fuelwood and dung cake) consumed annually by the surveyed brick making industries for brick burning. Consequently, estimated total annual emissions of greenhouse gases were 4,832 t CO2, 21 t CH4, 184 t CO, 0.15 t N20, 5 t NOX and 3.5 t NO while the total carbon released in the atmosphere was 1,318 t. Altogether, the total annual greenhouse gases emissions from biomass fuels burning was 5,046 t; of which 4,104 t from fuelwood and 943 t from dung cake burning. According to the results, due to the consumption of fuelwood in the brick making industries (3,450 units) of Sudan, the amount of wood lost from the total growing stock of wood in forests and trees in Sudan annually would be 1,466,000 m3 encompassing 505,000 m3 round wood and 961,000 m3 branches annually. By considering all categories of biofuels (fuelwood and dung cake), it was estimated that, the total emissions from all the brick making industries of Sudan would be 663,000 t CO2, 2,900 t CH4, 25,300 t CO, 20 t N2O, 720 t NOX and 470 t NO per annum, while the total carbon released in the atmosphere would be 181,000 t annually.

The effects of environmental factors on biomass and microcystin production by the freshwater cyanobacterial genera Microcystis and Anabaena

Several cyanobacterial genera produce the hepatotoxins, microcystins. Microcystins are produced only in cells that have microcystin synthetase gene (mcy) clusters, which encode enzyme complexes involved in microcystin biosynthesis. Microcystin-producing and nonmicrocystin-producing genotypes of single cyanobacterial genus may occur simultaneously in situ. Previously, the effects of environmental factors on the growth and microcystin production of cyanobacteria have mainly been studied by means of isolated cyanobacteria cultures in the laboratory. Studies in the field have been difficult, owing to the lack of methods to identify and quantify the different genotypes. In this study, genus-specific microcystin synthetase E (mcyE) gene primers were designed and a method to identify and quantify the mcyE copy numbers was developed and used in situ. Microcystis and Anabaena mcyE genes were observed in two Finnish lakes. Microcystis appeared to be the most abundant microcystin producer in Lake Tuusulanjärvi and in one basin of Lake Hiidenvesi. Because the most potent microcystin-producing genus of a lake can be identified, it will be possible in the future to design genus-targeted strategies for lake restoration. Effects of P and N concentrations on the biomass of microcystin-producing and nonmicrocystin-producing Microcystis strains and an Anabaena strain were studied in cultures. P and N concentrations and their combined effect increased cyanobacterial biomass of all Microcystis strains. The biomass of microcystin-producing Microcystis was higher than that of nonmicrocystin-producing strains at high nutrient concentrations. The P concentration increased Anabaena biomass, but the effect of N concentration was statistically insignificant for growth yield, probably due to the ability of the genus to fix molecular N2. P and N concentrations and combined nutrients caused an increase in cellular microcystin concentrations of the Microcystis strain cultivated in chemostat cultures. Cyanobacteria are able to hydrolyse nutrients from organic matter through extracellular enzyme activities. Leucine aminopeptidase (LAP) activity was observed in an axenic N2-fixing Anabaena strain grown in batch cultures. The P concentration caused a statistically significant increase in LAP activity, whereas the effect of N concentration was insignificant. The highest LAP activities were observed in the most eutrophic basins of Lake Hiidenvesi. LAP activity probably originated mostly from attached heterotrophic bacteria and less from cyanobacteria.

Forest inventory-based large-scale forest biomass and carbon budget assessment: new enhanced methods and use of remote sensing for verification

In recent years, concern has arisen over the effects of increasing carbon dioxide (CO2) in the earth's atmosphere due to the burning of fossil fuels. One way to mitigate increase in atmospheric CO2 concentration and climate change is carbon sequestration to forest vegeta-tion through photosynthesis. Comparable regional scale estimates for the carbon balance of forests are therefore needed for scientific and political purposes. The aim of the present dissertation was to improve methods for quantifying and verifying inventory-based carbon pool estimates of the boreal forests in the mineral soils. Ongoing forest inventories provide a data based on statistically sounded sampling for estimating the level of carbon stocks and stock changes, but improved modelling tools and comparison of methods are still needed. In this dissertation, the entire inventory-based large-scale forest carbon stock assessment method was presented together with some separate methods for enhancing and comparing it. The enhancement methods presented here include ways to quantify the biomass of understorey vegetation as well as to estimate the litter production of needles and branches. In addition, the optical remote sensing method illustrated in this dis-sertation can be used to compare with independent data. The forest inventory-based large-scale carbon stock assessment method demonstrated here provided reliable carbon estimates when compared with independent data. Future ac-tivity to improve the accuracy of this method could consist of reducing the uncertainties regarding belowground biomass and litter production as well as the soil compartment. The methods developed will serve the needs for UNFCCC reporting and the reporting under the Kyoto Protocol. This method is principally intended for analysts or planners interested in quantifying carbon over extensive forest areas.

Biomassan energia-arvon nostaminen sekundäärilämmöllä kuivaamalla

Viime aikoina ilmastonmuutos, fossiilisten polttoaineiden väheneminen ja niiden hinnan nousu ovat lisänneet merkittävästi maailmanlaajuista kiinnostusta uusiutuviin energiavaroihin. Suomessa uusiutuvien energialähteiden käytössä on jo pitkään panostettu metsäteollisuuden sivutuotevirtana tuottamaan puuperäiseen biomassaan, jota metsäteollisuus käyttää energiantuotantoonsa. Metsäteollisuuden jätevesien käsittelyssä syntyy erilaisia lietteitä, jotka joko uusiokäytetään tai hävitetään polttamalla tai sijoittamalla kaatopaikalle. Erityisesti biolietteiden uusiokäyttö on hankalaa ja kaatopaikkasijoitus tulevaisuudessa mahdotonta tai ainakin kustannuksiltaan kohtuutonta. Käytännössä liete hävitetään polttamalla ja kuivaamalla siitä tulee polttoaine. Lietteiden energiakäyttö on järkevin tapa hävittää jäteliete. Lietteiden korkean vesipitoisuuden vuoksi ne tulee kuitenkin kuivata ennen polttoa. Lietteen kuivaaminen sekundäärienergiavirralla eli metsäteollisuusprosesseissa sivutuotteena muodostuvalla ns. hukkalämmöllä lisää lietteen poltosta saatavaa energiamäärää ja korvaa fossiilisten polttoaineiden käyttöä. Tutkimuksen tavoitteena oli selvittää lietteen kuivaukseen optimaalisin kuoren ja lietteen seossuhde eri kuivausparametrejä vaihdellen. Kokeellinen työ aloitettiin rakentamalla energiatekniikan koehalliin laboratoriokokoluokan kiintopetikuivuri, jossa kuivumista tutkittiin puhaltamalla polttoainepedin läpi lämmitettyä ilmaa. Kuivattavina polttoaineina olivat kuoren ja lietteen seos tai pelkkä kuori ja liete erilaisilla massoilla ja erilaisilla prosenttisilla suhteilla ja erilaisissa lämpötiloissa. Kuivumiskäyrien määritys perustui massanmuutokseen. Koelaitteessa olivat anturit lämpötilan mittausta varten, jotta lämpötila saatiin säädettyä ja seurattua kokeen edellyttämällä tavalla. Lämpötilat ja painonmuutokset tallentuivat koetta tehdessä tietokoneelle. Kuivauskokeet osoittivat, että liete-kuori seos kuivuu hyvin kiintopedissä kun lietteen massaosuus seoksessa on korkeintaan 50 %. Lietteen massaosuuden ollessa tätä suurempi kuivaaminen ei enää ole tehokasta, mikä johtuu luultavasti ilman suuresta kanavoitumisesta kuivauspedissä. Kuorta kuivatessa lämpötilan nosto 50 °C:stä 70 °C:een oli huomattavasti tehokkaampaa kuin 70 °C:stä 90 °C:een, ajallisesti ero oli noin kaksinkertainen.

Integrated climatic impacts of forestry and fibre-based packaging

The purpose of this study was to examine the integrated climatic impacts of forestry and the use fibre-based packaging materials. The responsible use of forest resources plays an integral role in mitigating climate change. Forests offer three generic mitigation strategies; conservation, sequestration and substitution. By conserving carbon reservoirs, increasing the carbon sequestration in the forest or substituting fossil fuel intensive materials and energy, it is possible to lower the amount of carbon in the atmosphere through the use of forest resources. The Finnish forest industry consumed some 78 million m3 of wood in 2009, while total of 2.4 million tons of different packaging materials were consumed that same year in Finland. Nearly half of the domestically consumed packaging materials were wood-based. Globally the world packaging material market is valued worth annually some €400 billion, of which the fibre-based packaging materials account for 40 %. The methodology and the theoretical framework of this study are based on a stand-level, steady-state analysis of forestry and wood yields. The forest stand data used for this study were obtained from Metla, and consisted of 14 forest stands located in Southern and Central Finland. The forest growth and wood yields were first optimized with the help of Stand Management Assistant software, and then simulated in Motti for forest carbon pools. The basic idea was to examine the climatic impacts of fibre-based packaging material production and consumption through different forest management and end-use scenarios. Economically optimal forest management practices were chosen as the baseline (1) for the study. In the alternative scenarios, the amount of fibre-based packaging material on the market decreased from the baseline. The reduced pulpwood demand (RPD) scenario (2) follows economically optimal management practices under reduced pulpwood price conditions, while the sawlog scenario (3) also changed the product mix from packaging to sawnwood products. The energy scenario (4) examines the impacts of pulpwood demand shift from packaging to energy use. The final scenario follows the silvicultural guidelines developed by the Forestry Development Centre Tapio (5). The baseline forest and forest product carbon pools and the avoided emissions from wood use were compared to those under alternative forest management regimes and end-use scenarios. The comparison of the climatic impacts between scenarios gave an insight into the sustainability of fibre-based packaging materials, and the impacts of decreased material supply and substitution. The results show that the use of wood for fibre-based packaging purposes is favorable, when considering climate change mitigation aspects of forestry and wood use. Fibre-based packaging materials efficiently displace fossil carbon emissions by substituting more energy intensive materials, and they delay biogenic carbon re-emissions to the atmosphere for several months up to years. The RPD and the sawlog scenarios both fared well in the scenario comparison. These scenarios produced relatively more sawnwood, which can displace high amounts of emissions and has high carbon storing potential due to the long lifecycle. The results indicate the possibility that win-win scenarios exist by shifting production from pulpwood to sawlogs; on some of the stands in the RPD and sawlog scenarios, both carbon pools and avoided emissions increased from the baseline simultaneously. On the opposite, the shift from packaging material to energy use caused the carbon pools and the avoided emissions to diminish from the baseline. Hence the use of virgin fibres for energy purposes, rather than forest industry feedstock biomass, should be critically judged if optional to each other. Managing the stands according to the silvicultural guidelines developed by the Forestry Development Centre Tapio provided the least climatic benefits, showing considerably lower carbon pools and avoided emissions. This seems interesting and worth noting, as the guidelines are the current basis for the forest management practices in Finland.