Nutrient relations in coniferous forests

The environment controls physiological processes in plants and thus their growth. The question how forests will respond to global environmental changes is addressed with different approaches and using two coniferous tree species: Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) I have used the relationship (nitrogen productivity) between a plant's growth rate and the amount of nitrogen in the plant to analyse the growth response to temperature. Data on needle dry matter, production, and nitrogen content in needles from a wide range of climatic conditions were collected and needle nitrogen productivities were calculated. The result is that the nitrogen productivity (net carbon gain of a canopy) of conifers is not sensitive to temperature. Growth responses to temperature in conifers are therefore mediated by changes in nitrogen availability. I have used three Swedish forest experiments to study the long-term fate of N addition. The fertilisation increased tree biomass, more strongly for spruce than pine. Once fertilisation had ceased, the growth rates in all treatments in pine and spruce stands at Lisselbo and Stråsan converged towards similar levels. Chronic fertilisation with complete nutrient solution in pine stands at Jädraås resulted in long-term increase in production. Nitrogen budgets established 12 years (pine) and 7 years (spruce) after the last N addition show that the increases in N stocks in the pine stands were mainly in the soil. In contrast, in the spruce ecosystem trees accumulated most of the added N and the increase in the soil was restricted to the humus layer. In the pine ecosystem, large losses of added N (between 254 and 738 kg ha-1 out of 1040 kg ha-1 added as fertilizer) occurred, whereas in the spruce ecosystem more N was recovered than could be accounted for by inputs (between 250 and 591 kg ha-1). I have used humus and needle nutrients and site characteristic from 37 pine and 50 spruce stands from all over Sweden to analyze forest nutrient relations. Biologically controlled nutrients (C, N, P, S) are less variable and more correlated, but the biological control is not limited to only the covalently bound elements. Stoichiometric relations are not entirely rigid but are more constrained in needles than in humus. The use of nitrogen as a basis in stoichiometric relations may give stronger relations than the use of carbon

Relationships between tree and soil properties in Picea abies and Pinus sylvestris forests in Sweden

The exchange of elements between plants and the soil in which they are growing creates reciprocal control of their element composition. Within plants, the growth rate hypothesis from ecological stoichiometry implies a strong coupling between C, N, and P. No similar theory exists for predicting relationships between elements in the soil or relationships between plants and the soil. We used a data set of element concentrations in needles and humus of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) forests in Sweden to investigate the extent to which relationships between elements (C, N, P, S, K, Ca, Mg, Fe, Mn, Al) can be observed within and between plants and soils. We found element composition to be more strongly controlled in needles than in humus. Elements that are covalently bound were also more strongly controlled, with no apparent differences between macro- and micronutrients. With the exception of N/C, there were surprisingly few relationships between elements in needles and humus. We found no major differences between the two tree species studied, but investigations of additional forest types are needed for firm conclusions. More control over element composition was exercised with respect to N than C, particularly in needles, so it might be advantageous to express nutrient concentrations relative to N rather than on a dry weight or carbon basis. Variations in many ecosystem variables appeared to lack ecological significance and thus an important task is to identify the meaningful predictors

Markfaunans rumsliga spridning i betad och orörd stäpp i Chernozem-zonen i Ryssland

Långvarig boskapsdrift har visats ge tydliga förändringar av stäppväxtligheten samt vissa effekter på markens makrofauna. Syftet med detta arbete var att undersöka markfaunans rumsliga spridning i marken i naturreservatet i Kurskområdet, Ryssland. En parcell med orörd stäpp och en med betesmark (ko/ha) undersöktes. Prover insamlades med en jordborr (10 cm) till 15 – 20 cm djup. I varje parcell togs totalt 144 prover (6 rader om 24 prover). Proverna togs tättintill varandra. Markfaunan sorterades ut från varje jordprov för hand och analyserades tillsammans med provets vikt, stenighet, rötter och förna. Vår hypotes var att den rumsliga spridningen skulle vara mer homogen i en stäpp än i en betesmark där biocenosen är mer fragmenterad. Den orörda stäppen hade 2 gånger högre vikt av rötter och 20 gånger högre vikt av förna. Dessa skillnader medförde också skillnader i markfauna. Det totala antalet markdjur var högre i stäppen (349/m2) än i betesmarken (246/m2). I stäpp dominerade Staphylinidae (72 eks/m2), Scarabaeidae-larver(63) och Julidae (50). I betesmarken dominerade Curaelionidae-larver (40), Scarabaedae-larver (31), Elateridae larvi (39). Antalet Myriapoda var 60 gånger högre i obetad stäpp och saknades nästan i betesmarken. Vid jämförelsen av stäppytor och betesytor framgick att båda saknade daggmaskar, antagligen på grund av torkan. Markfaunas spridning var heterogenare i stäppen än i betesmarken. Heterogeniteten var hos somliga djurgrupper, t.ex. skalbaggslarver, som sped sig inom stäppytan på så sätt att de förekom med förhöjt antal samtidigt som de saknades på andra områden. I betesmarken spred sig larverna däremot jämnt. Den erhållna resultaten vederlägger hypotesen om en mer agreggerad fauna i en betesmark. Antal markdjur visade en positiv korrelation med förnans vikt, både i stäppen och i betesmarken, men korrelationskoefficienten var högre i stäppen. Förnan saknades nästan i betesmarken och där dominerade markdjur som spred sig mer homogent. Deras spridning var oberoende av förnans vikt

Securing a bioenergy future without imports

The UK has legally binding renewable energy and greenhouse gas targets. Energy from biomass is anticipated to make major contributions to these. However there are concerns about the availability and sustainability of biomass for the bioenergy sector. A Biomass Resource Model has been developed that reflects the key biomass supply-chain dynamics and interactions determining resource availability, taking into account climate, food, land and other constraints. The model has been applied to the UK, developing four biomass resource scenarios to analyse resource availability and energy generation potential within different contexts. The model shows that indigenous biomass resources and energy crops could service up to 44% of UK energy demand by 2050 without impacting food systems. The scenarios show, residues from agriculture, forestry and industry provide the most robust resource, potentially providing up to 6.5% of primary energy demand by 2050. Waste resources are found to potentially provide up to 15.4% and specifically grown biomass and energy crops up to 22% of demand. The UK is therefore projected to have significant indigenous biomass resources to meet its targets. However the dominant biomass resource opportunities identified in the paper are not consistent with current UK bioenergy strategies, risking biomass deficit despite resource abundance

Increasing biomass resource availability through supply chain analysis

Increased inclusion of biomass in energy strategies all over the world means that greater mobilisation of biomass resources will be required to meet demand. Strategies of many EU countries assume the future use of non-EU sourced biomass. An increasing number of studies call for the UK to consider alternative options, principally to better utilise indigenous resources. This research identifies the indigenous biomass resources that demonstrate the greatest promise for the UK bioenergy sector and evaluates the extent that different supply chain drivers influence resource availability. The analysis finds that the UK's resources with greatest primary bioenergy potential are household wastes (>115 TWh by 2050), energy crops (>100 TWh by 2050) and agricultural residues (>80 TWh by 2050). The availability of biomass waste resources was found to demonstrate great promise for the bioenergy sector, although are highly susceptible to influences, most notably by the focus of adopted waste management strategies. Biomass residue resources were found to be the resource category least susceptible to influence, with relatively high near-term availability that is forecast to increase – therefore representing a potentially robust resource for the bioenergy sector. The near-term availability of UK energy crops was found to be much less significant compared to other resource categories. Energy crops represent long-term potential for the bioenergy sector, although achieving higher limits of availability will be dependent on the successful management of key influencing drivers. The research highlights that the availability of indigenous resources is largely influenced by a few key drivers, this contradicting areas of consensus of current UK bioenergy policy

Temperature sensitivity of nitrogen productivity for Scots pine and Norway spruce

Environmental conditions control physiological processes in plants and thus their growth. The predicted global warming is expected to accelerate tree growth. However, the growth response is a complex function of several processes with both direct and indirect effects. To analyse this problem we have used needle nitrogen productivity, which is an aggregate parameter for production of new foliage. Data on needle dry matter, production, and nitrogen content in needles of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) from a wide range of climatic conditions were collected and needle nitrogen productivities, defined as dry matter production of needles per unit of nitrogen in the needle biomass, were calculated. Our results show that the nitrogen productivity for spruce is insensitive to temperature. However, for pine, temperature affects both the magnitude of nitrogen productivity at low needle biomass and the response to self-shading but the temperature response is small at the high end of needle biomass. For practical applications it may be sufficient to use a speciesspecific nitrogen productivity that is independent of temperature. Because temperature affects tree growth indirectly as well as through soil processes, the effects of temperature change on tree growth and ecosystem carbon storage should mainly be derived from effects on nitrogen availability through changes in nitrogen mineralization. In addition, this paper summarises data on dry matter, production and nitrogen content of needles of conifers along a temperature gradient

Temperature sensitivity of nitrogen productivity

Environmental conditions control physiological processes in plants and thus their growth. The predicted global warming is expected to accelerate tree growth. However, the growth response is a complex function of several processes. To circumvent this problem we have used the nitrogen productivity (dry matter production per unit of nitrogen in the plant), which is an aggregate parameter. Data on needle dry matter, production, and nitrogen content in needles of Scots pine (Pinus sylvestris) from a wide range of climatic conditions were collected from which needle nitrogen productivities were calculated. Our results show that nitrogen productivity is rather insensitive to temperature. As a consequence, the effects of temperature change on tree growth and ecosystem carbon storage should mainly be derived from effects on nitrogen availability through changes in nitrogen mineralisation

Global potential of sustainable biomass for energy

There is no doubt now that energy is fundamental to our development. Global energy trends such as higher energy demand and prices, big differences across regions, structural changes in an oil and gas industry increasingly dominated by national companies, the prospect of irreversible climate change, as well as demand for energy security all highlight the need for a rapid transition to a low-carbon, efficient and environmentally benign energy system. The search for energy alternatives involving locally available and renewable resources is one of the main concerns of governments, scientists and business people worldwide. As researchers tackle problems according to global trends, an overwhelming body of research focusing on bioenergy in relation to other types of renewable energy might illustrate the role bioenergy has as the most important renewable energy source for the near and medium-term future. Thus, analyzing the amount of existing research, we found that about 50% (4,911 records) of 9,724 renewable energy records available were bioenergy records. We also found that publications on each of the four main sources of biomass (agriculture, forest, waste and other) represent about one quarter of the 4,911 bioenergy records retrieved. Biomass – the fourth largest energy source after coal, oil and natural gas - is the largest and most important renewable energy option at present and can be used to produce different forms of energy. As a result, it is, together with the other renewable energy options, capable of providing all the energy services required in a modern society, both locally and in most parts of the world. Renewability and versatility are, among many other aspects, important advantages of biomass as an energy source. Moreover, compared to other renewables, biomass resources are common and widespread across the globe. The sustainability potential of global biomass for energy is widely recognized. For example, the annual global primary production of biomass is equivalent to the 4,500 EJ of solar energy captured each year. About 5% of this energy, or 225 EJ, should cover almost 50% of the world’s total primary energy demand at present. These 225 EJ are in line with other estimates which assume a sustainable annual bioenergy market of 270 EJ. However, the 50 EJ biomass contributed to global primary energy demand of 470 EJ in 2007, mainly in the form of traditional non-commercial biomass, is only 10% of the global primary energy demand. The potential for energy from biomass depends in part on land availability. Currently, the amount of land devoted to growing energy crops for biomass fuels is only 0.19% of the world’s total land area and only 0.5-1.7% of global agricultural land. Although the large potential of algae as a resource of biomass for energy is not taken into consideration in this report, there are results that demonstrate that algae can, in principle, be used as a renewable energy source. From all of these perspectives, the evidence gathered by the report leads to a simple conclusion: Biomass potential for energy production is promising. In most cases, shifting the energy mix from fossil fuels to renewables can now be done using existing technology. Investors in many cases have a reasonably short pay-back because of good availability of lowcost biomass fuels. The latter is of course dependant on local incentives, however. Overall, the future of bioenergy is also to a large extent determined by policy. Thus, an annual bioenergy supply covering global energy demand in 2050, superseding 1,000 EJ, should be possible with sufficient political support. Global production of biomass and biofuel is growing rapidly due to the increasing price of fossil fuels, growing environmental concerns, and considerations regarding the security and diversification of energy supply. There are many scenarios that predict a high potential for biomass in the future. There have also been many studies performed in recent decades to estimate the future demand and supply of bioenergy. Overall, the world’s bioenergy potential seems to be large enough to meet the global energy demand in 2050. The current stock of standing forest is a large reservoir of bioenergy and in line with the theoretical potential of biomass energy. However, most of the research studies on biomass potentials ignore existing studies on demand and supply of wood, despite the extensive literature and data on the subject. Taking into account data from a variety of international sources, rough estimates of the energy production potential of woody biomass from forestry show that, in theory, the demand for wood fuel and industrial roundwood in 2050 can be met, without further deforestation, although regional shortages may occur. However, the shift in the energy mix requires much more investment in infrastructure, equipment and in some cases R&D. Moreover, a prerequisite for achieving bioenergy’s substantially high potential in all regions is replacing current inefficient and low-intensive management systems with best practices and technologies

Certification criteria for sustainable biomass for energy

Rising energy prices, geopolitics as well as concerns over increasing oil prices, national security, and the impacts of greenhouse gas emissions on global climate change are driving large-scale efforts to implement bioenergy alternatives. Biomass fuels offer many new opportunities, but if not managed carefully, they may also carry significant risks. Biomass in this context is non-fossil material of biological origin from forest, energy crops, agriculture and different kind of wastes. Markets for energy generated from biomass are expanding at a fast pace. Sustainable use of biomass as an energy source requires comprehensive management of natural, social and economic resources. Establishing certification schemes is a possible strategy to ensure that bioenergy is produced in a sustainable manner. At this time, a clear certification of traded biomass is needed. Different types of certification systems, international standards and initiatives relevant to biomass production already exist. However, an analysis of the experience gained with these systems, reveal that they are not effective to monitor and manage all effects of biomass production for energy. There is no international consensus on universal sustainability requirements and the inclusion or exclusion of certain exemplary criteria is one of the difficulties of setting up a certification scheme. The role of certification efforts in this report is to participate in creation of a global market for sustainable biomass fuels and in extension sustainable bioenergy. In attempt to support the development of an implementable international certification scheme for sustainable biomass production, the existing Forest Certification Schemes were evaluated against environmental sustainability through 15 indicators and against social and economic sustainability through 19 indicators identified from literature. The set of principles and criteria suggested is the final result of sampling, evaluation, filtering and completion following a review of literature, analysis of the activity and experience in forestry as well as in the other sectors. PRINCIPLE 1: Biomass shall be produced in an environmentally responsible way. Principle 1 is covered by the following criteria: the use of chemicals; forest/land management planning; forest/land monitoring; maintenance of biological diversity; protection of areas of high ecological value; protection of the soil and prevention of erosion; protection or enhancement of water quality and regeneration following harvesting. PRINCIPLE 2: Sustainable management of social capital. Principle 2 is covered by the following criteria: recognition and respect for the customary and traditional rights of indigenous/local people; protecting the health and safety of employees; provision of information to increase public awareness of forest management planning, forest operations and/or forest outcomes; protection of areas of particular historic, cultural or spiritual value and the rights of children. PRINCIPLE 3: Biomass production shall be economically viable. Principle 3 is covered by the criterion: maintenance or enhancement of the economic viability of operations. The proposed system has a hierarchical structure in which the overall task of avoiding unsustainable biomass is translated into three principles. Each of the principles is designed to ensure that biomass is produced in accordance with sustainability requirements. The goal of the principles is to promote environmentally responsible, socially beneficial and economically viable management of the biomass-for-energy production systems, by establishing a worldwide standard of recognized and respected Principles of Biomass Certification System. Each principle is in the next hierarchical level guaranteed by a number of workable sustainability criteria