Browsing by discipline "Forest Ecology and Management"

Finnish energy production is producing around 1.5 million tons ashes annually. The aim is to utilize ashes instead of landfilling as well as to replace the use of exhaustible natural materials. Wood and peat ashes can be used, for example, in field and forest fertilization and land construction. In road construction and rehabilitation, ash can be used to replace expensive aggregates and achieve better load capacity features. This study was part of the Natural Resources Institute Finland’s (formerly the Finnish Forest Research Institute) project: "New technologies as assistance for the lower road network construction and maintenance". The purpose of this research was to investigate the leaching of heavy metals, nutrients and salts from ash treatments by collecting infiltrate waters with zero-tension lyzimeters, taking water samples from nearby ditch waters and clarify influencing factors. The plots were established in Jämsä on the old forest roads, which are rehabilitated with mixed wood and peat ash in the autumn 2011. The site consists of two forest roads, which had four types of ash treatments and control treatment. For each plot, six zero-tension lysimeters (0.1 m2) were installed every 20 meters, tree to the roads surface and tree to deeper levels. In addition to lysimeters, water samples were taken from nearby ditches. Water samples were collected during 2012 – 2014 once a month from May onwards for 6-8 months. The relations between the substances were tested for statistical correlations (Pearson) and the effects of treatments to leaching were tested with the Tukey HSD-test. Concentrations of 32 elements, ions and compounds were determined from lyzimeter and ditch water samples. Heavy metal concentrations were during the entire follow-up period mainly low. There were no elevated heavy metal concentrations in ditch waters either. The content of nutrients and salts in the water samples were higher from ash treatments than from control treatments. The content of nutrients and salts were also higher in ditch water samples compared to control ditch. Several soluble substances from the ashes had a statistically significant positive correlation (p <0.01) with each other. The results varied a lot progressively, between plots and between the lysimeters of the same plot. Significantly higher concentrations were measured from two lysimeters for number of elements compared to the other lysimeters in other plots (p <0.05). In most cases, the results were very mixed and there was no clear difference between the control and ash treatments. The study yielded valuable information about the leaching of substances from ash structures. A three-year follow-up period is short, for example, compared to the long-term forest fertilization experiments that can last for decades. The pH of the ash decreases in time and decrease in pH could increase solubility of heavy metals. The average concentrations of many elements in water samples from lysimeters and ditch waters were at the same level than in soil waters in forest. Although during the monitoring period, there were no increases in heavy metal concentrations in ditch waters, the accumulation of elements to nearby aquatic ecosystems is difficult to assess in the long-term if leaching behavior changes with time. Ash seems to be a promising material for road construction, as long as the ash quality is suitable to this particular purpose.

The biodegradation of wood by fungi in natural forest environment is of vital importance for carbon and nutrient replenishment. Additionally, the ecological functions, maintenance of biodiversity and fungal succession in forest ecosystems is partly dependent on the availability of utilizable organic substances. The fungal group of basidiomycetes are known to play important functional roles in these processes. There is however scarcity of information on how co-cultures of multiple fungi affect wood biomass decomposition as well as the consequent effect of interspecific interaction on niche colonization and substrate utilization. This study investigated and evaluated the role and efficiency of interspecific fungal interaction on biodegradation of Scots pine (Pinus sylvestris L), Norway spruce (Picea abies L. (H) Karst) and birch (Betula pubescens Ehrh) wood. Five fungal isolates were selected for the test in co-cultivation assay: Antrodia sinuosa P. Karst, Bjerkandera adusta (Willd.) P. Karst, Gloeophyllum sepiarium (Wulfen) P. Karst, Heterobasidion annosum (Fr.) Bref, and Phlebiopsis gigantea Jülich (Basidiomycota). The results revealed that antagonistic and competitive fungal interaction does not largely appear to speed up wood decay process. However, the rare combination of Phlebiopsis, Antrodia and Gloeophyllum had significant positive effect on degradation of spruce wood whereas Heterobasidion, Phlebiopsis, and Gloeophyllum had synergistic effect on pine wood decay. It is therefore likely that in nature, wood decay by fungi is mostly facilitated by parallel niche colonization and by fungal succession.

This study quantified above-ground biomass affected by selective logging in the tropical rainforest of South East Cameroon and also investigated the suitability of the density of logging roads, the density of log yards as well as variables from MODIS 250 m data (Red, NIR, MIR, NDVI, EVI) in explaining above-ground biomass logged. Above-ground biomass logged was quantified using allometric equations. The surface area of logging roads and log yards were quantified and used in the determination of above-ground biomass affected by these infrastructures based on a national reference baseline value for the forest zone of Cameroon. A comparative analysis revealed that 50% of potentially exploitable commercial tree species were effectively harvested with a harvesting intensity of 0.78 trees ha-1 representing an average above-ground biomass of 3.51 Mg ha-1. The results also indicated that 5.65 Mg ha-1 of above-ground biomass was affected by logging infrastructure .i.e. 62% as compared to 38% of above-ground biomass that was logged. Correlation and regression analysis showed that the density of the logging roads explained 66% of the variation in above-ground biomass logged and 73% of the variation in above-ground biomass logged was explained by the density of the logging roads and NDVI from MODIS data. The density of log yards and the variables from MODIS data were generally weak in explaining the variation in above-ground biomass logged.

Soil respiration is a process in which soil organic carbon is released in the atmosphere as carbon dioxide. In boreal forests, soil carbon storage is particularly high relative to the carbon storage of aboveground biomass. Due to the large size of the forest areas of the biome, boreal forests’ soil organic carbon storage is globally is significant. The cool climate drives the formation of soil carbon storage in boreal regions. With climate change, the growing conditions can become drier and warmer than they have been in the past, which can accelerate the carbon release from soil to the atmosphere, thereby further warming the climate. Soil respiration is divided into two distinct processes: heterotrophic respiration where carbon dioxide is released from decomposi-tion of dead organic matter, and autotrophic cellular respiration of plant roots and root associated fungi. Increase in heterotrophic respiration in relation to litter formation rate implies a decrease in the carbon stock of the soil, whereas increase in autotrophic respiration implies an acceleration in the activity of the photosynthesizing biomass and, at the same time, an increase in the amount of carbon stored in the root system. The effect of drought on the activity of both components has been studied extensive-ly, and it appears that autotrophic terrestrial respiration responds to drought more slowly and less strongly in the boreal forest ecosystem. Atmospheric carbon dioxide contains two stable carbon isotopes, carbon-12 and carbon-13, of which C3 plants prefer lighter carbon-12 in photosynthesis. The relationship between these carbon isotopes is expressed with δ13C-value, and the discrimina-tion of carbon-13 in photosynthesis reflected in the cellular respiration of the autotrophic organisms. As a result, the δ13C-value of autotrophic respiration has been found to be lower than the δ13C value of heterotrophic respiration, as carbon-13 is discriminated less in the heterotrophic respiration. However, it has been found that during a drought period there is less discrimination of car-bon-13 in plants’ carbon assimilation, as the photosynthesizing plant may not be as selective for the carbon as when it is not exposed to drought. Thus, there is a difference in the δ13C-value of the soil respiration components, but it becomes smaller as the components experience drought. The purpose of this study was to determine whether the respiration rate of the components vary in different ways as they experi-ence drought by examining whether autotrophic respiration decreases more slowly than heterotrophic. In addition, it was sought to determine whether the components could be distinguished by their δ13C-value, so the study examined the development of the components’ δ13C-valu during drought. The measurements were done in two different experiment sites. The first one was an artificial drought experiment with pine saplings (Pinus sylvestris) in a greenhouse, where carbon dioxide flux and its δ13C-flux was measured from pine roots and their soil by incubation method. Second one was in a Pirkanmaa pine forest where carbon dioxide flux and its δ13C-flux were measured with incubation method and chamber measuring method. After the sampling, the development of the phenomenon was examined together with moisture- and temperature conditions at the time of the measure-ment. In this study, soil respiration’s autotrophic component changed more slowly in relation to drought than the heterotrophic compo-nent. In addition, in the pine forest, the δ13C-value of autotrophic respiration was below the heterotrophic δ13C-value, as the theory suggests. However, there was no clear development in relation to drought with the components’ δ13C-value. In the green-house experiment, no clearly distinguishable development was observed between the development of the components, and the δ13C-value of soil respiration was rather similar between the components. In both experiment sites, there appeared to be sources of error as environmental conditions improved unexpectedly in both the greenhouse and in the forest. Furthermore, it can be stated that the less destructive chamber measuring protocol seems to produce more reliable data.

Canopy gaps and their characteristic features (e.g. area and shape) influence the availability of nutrients, moisture and light in a forest ecosystem, and consequently affect the regeneration process and species composition in the forest. Most of the earlier research on canopy gap used field measurement and conventional remote sensing to quantify gap and these methods have limitations and accuracy problems. However, the development in Light Detecting and Ranging (LiDAR) technology has been effective in overcoming limitations and challenges associated with conventional remote sensing. The ability of LiDAR to represent the three-dimensional structure of the canopies and the sub-canopy resulting in high-resolution topographic maps, highly accurate estimated of vegetation height, cover and canopy structure makes it suitable technology for gap studies. LiDAR-based digital surface model (DSM) and digital elevation model (DEM) were used to quantify the canopy gaps over 5124ha of University of Tokyo Chichibu Forests (UTCF) consisting of three forest-types; primary, secondary and plantation forest. Disturbance driven canopy gaps might have spatial and characteristic variation due to differences in disturbance history, nature, frequency and intensity in different forest and land-types. Quantifying gap characteristics and studying variation and size distribution in different forest types and topography help to understand the different gap dynamics and their ecological perspectives. In this study, a gap was defined as an opening with a maximum height of 2m and minimum area threshold of 10m2. The minimum area threshold, which represents the gap area created by the death of at least a single tree, was determined through a random sampling of 100 tree crowns at UTCF using high resolution aerial photographs. Gap size distribution was analyzed in different forest types and land types. Spatial autocorrelation of gap occurrence was studied using semivariance analysis and distance to the nearest gap (DNG), which is the distance to the nearest gap for an individual gap. Canopy gap size frequency distribution in different forest-types was investigated using power-law. The negative exponent (α), which is also the scaling component of the power-law distribution, was compared between forest-types. Altogether, 6179 gaps with area 10-11603 m2 were found. Gap size distribution in UTCF showed skewness with a high frequency of smaller gaps and a few large gaps. Half of the gaps were smaller than 19 m2 and less than one percent of gaps (0.73 %) were larger than 400 m2. Primary forest contained high gap density (1.85 gaps per ha), shortest mean-DNG (22m) and second-largest gap-area fraction (0.72 %) after plantation forest area (0.76 %). Secondary forest had the lowest gap density (1.03 gaps per hectare) but had the larger mean gap-area (43 m2) than in primary forest (39 m2). The Kolmogorov–Smirnov test showed differences (p<0.05) in gap size distribution between primary and secondary forest. However, the gap size distribution in primary forest show similarity (p=0.59) with plantation forest area. In primary and plantation forest there was a high frequency of small gaps and few very large gaps (2000-10500 m2), whereas very large gaps (>2400 m2) were absent in the secondary forest. Gap size frequency distribution followed a power-law distribution only in plantation forest area (p>0.1, α =2.27). The scaling parameter in the primary and secondary forest was 2.56 (p=0.01) and 2.20 (p=0.02), respectively. Gap distribution showed some spatial autocorrelation in primary and secondary forest at least with distance up to 1300m. Most of the gaps in the primary forest were concentrated in the valley and middle slope, whereas the upper and middle slope had fewest gaps.

Forest biomass is considered as one of the most important alternative energy sources across the globe. Growing attention has been given to the studies concerning biomass and related bioenergy and biofuel, and their potential for future development. This study takes higher education as unique aspect, focusing on the awareness of Chinese university students of Forest Based Bioenergy (FBB) development and how education background / awareness may influence the FBB development in China. Since FBB is relatively a new concept in China, its development and further utilization are believed to largely relay on the matters of education, social trend and awareness. Students in higher education are considered as a special group: they may be educated related to FBB and will become the future consumers and even decision-makers. This make awareness, attitude and opinions about FBB from the students` point of view significant. A literature review was made for the background study and quantitative research, plus surveys and interviews were conducted as data collection methods. Objectives of the thesis are to study the awareness of and attitudes towards FBB among Chinese university students and if those opinions were influenced by their studies. Results indicate that education strongly affects students´ attitudes. FBB development is seen as a positive signal and students are likely to support FBB development. FBB is believed as a new trend of renewable energy development. However, FBB in China will not see a rapid booming in the near future and it has only limited impact towards the traditional fossil fuel domination, but due to its characteristics, governmental recognition and growing awareness, it certainly shall be seen as strong supporter of China´s sustainable development. It also has to be holistically utilized considering environmental, social and economic aspects, to reach its full potential and to support China´s target of sustainable energy development.

The objective of this thesis was to compare the effects of thermal modification under saturated steam and flowing steam on the Scots Pine and the Silver Birch, respectively. One method used in this article complied with the basic principles of traditional ThermoWood process. Treatment temperatures were chosen to be 180℃ and 200℃which are widely used in this method. Super-heated steam and flow-through system were applied in this system. Another one followed the principles as Wood Treatment technology (WTT) developed in Denmark. For this treatment, lower temperatures of 125℃ and 145℃ were applied. The treatment was conducted in a closed system with saturated steam. According to my results, modification under 125℃ saturated steam was ineffective for both Scots Pine and Silver Birch. 200℃ flowing steam is most suitable for the Silver Birch modification. While for the Scots Pine, I would recommend 145℃ saturated steam modification, because under this condition, there is a moderate bending and impact strength reduction but effective anti-swelling efficiency (ASE) improvement. The effects of thermal modification are better on the Silver Birch than the Scots Pine. Modification equipment and chosen of modified specimens need to be considered carefully as they influence the wood properties a lot. In general, mass loss as an indicator value to compare different thermal modification methods is not directly recommended.

The physiological effects of drought on trees has been studied excessively but many of them remain unclear. In this thesis I studied tree sugar dynamics under drying-wetting cycle as well as the role of soil hydraulic conductivity on how trees experience drought. I experimented with five Norway spruce seedlings in October and November 2016. The seedlings were in water after which they were put in to PEG solution of -0.5 MPa for 24 h and then transferred back to water. Sugar samples were taken from liquids, needles and roots once for every phase. Osmolality samples were taken from current year needles and water potential samples were taken from current year needles and roots every half an hour during day time. Continuous gas exchange measurements were done with Walz GFS-3000. There was no change in osmolality and no significant change in photosynthesis or transpiration rate. For sugar concentrations there was significant increase of non-structural carbohydrates in needles and significant decrease in roots. There was no change in sugar concentration in liquid. Overall impression was that trees did not suffer much from the PEG treatment. The results supported my hypothesis that changes in soil hydraulic conductivity are more important to effects of drought than changes in soil water potential.

The main aim of this thesis was to study the ecosystem services provided by large-scale industrial eucalypt plantations of UPM in Paysandú region, Uruguay. In the landscape, natural pastures and forests are combined with rows of planted trees. The second aim was to study how various stakeholder groups use ecosystem services from the plantation landscape, and to what extent the rights and expectations related to their use vary among these groups. The third aim was to study the best ways to combine the production of ecosystem services with large-scale industrial tree plantations in the study area. The data used in this study consisted of 55 semi-structured interviews, which were recorded in Uruguay during summer of 2015. Among the persons interviewed, 15 people were classified as key-informants with a broad view on plantation industry in the study area. They were from educational institutions, companies, ministries and from non-governmental organizations. Based on results of the key-informants interviews, a total of 40 persons were selected for stakeholder interviews. They represented four groups; 1) cattle ranchers, 2) honey producers, 3) tree growers and 4) general public from the surrounding communities. With stakeholder interviews, the aim was to collect quantitative data with structured questionnaires. The key-informants and stakeholders were asked about the same issues, but the key-informant interviews had open questions for collecting both qualitative and quantitative data. The results of this study show that industrial tree plantation landscapes provide a plenitude of ecosystem services. However, the perceived changes in the landscape during the past ten years were in some cases more negative than positive. According to the key-informants, the most important ecosystem services provided included industrial wood, animal shelter, fodder and foods. This indicates that local livelihoods can be combined with industrial plantations and the stakeholders benefit from them in many ways. The cattle ranchers obtained mainly animal shelter and fodder. For them, also the regulation of natural hazards was important. The honey producers valued foods, pollination and biodiversity services. The tree growers valued industrial wood and, similarly as the cattle ranchers, animal shelter and fodder. For the general community, educational information was the most important service. Food, honey and mushrooms, and fuel wood were also highly valued ecosystem services. Industrial tree plantations create a wealth of ecosystem services, often with low or no cost. UPM Uruguay considers local stakeholders and their livelihoods in many ways. According to the company, the best ways to integrate industrial tree plantations and ecosystem services are already used in many parts, although there was no data disclosed about all of them. However, it seems that UPM is well aware of the local conditions. In the future, there is a need to study the monetary value and benefit sharing of ecosystem services e.g. through payments of ecosystem services schemes.

Biochar is a product from the pyrolysis of plant derived-biomass and it is intended to be applied to soil given its potential of carbon sequestration and soil fertility improvement. Some studies also suggest that increasing application rate of biochar has a positive feedback on biological nitrogen fixation (BNF) and on soil microbial biomass. However, these effects are not well known for boreal forests. The purpose of this study was to evaluate the effects of different biochar application rates: 0 t ha-1, 5 t ha-1 and 10 t ha-1 on BNF, on microbial biomass carbon and nitrogen (MBC and MBN), and on moss biomass. The field experiment was established in Juupajoki, Southern Finland in young Scots pine stands. The stands were amended with biochar one year before the measurements took place. BNF was determined using acetylene reduction assay (ARA), and microbial biomass was estimated using chloroform fumigation-direct extraction (CFDE). The microbial biomass samples were incubated at the temperatures: 10 °C, 15 °C and 20 °C. Biochar amendment raised soil pH, whereas no differences were verified for BNF, MBC, MBN, nor for moss biomass. There was, however, variation in the response of N fixation to incubation temperature, and variation in the response of MBC and MBN to the time of measurement. Observed changes in pH are often likely to justify variations in the rates of BNF and MB, however in this study they were not shown to be of significance. It is possible, however that biochar will have a positive effect on soil vegetation as it is incorporated into the soil in the long-term. Although this study focuses on BNF and MB, the findings may well have a bearing on the use of biochar as a tool for C sequestration, since amendment with biochar was demonstrated as neither beneficial nor harmful to the soil biota.