Carbon Management: Forest Conservation and Management

Grace Ding[1] [2]* and Nguyen Thuy[1]

Introduction

The construction industry is dramatically growing and developing worldwide (Joseph and Tretsiakova- McNally, 2010). Construction activities are supporting the large upstream and downstream supply chains, including the building material products, such as tiles, wood, steel, cement, bricks and glass (Australian Industry Group, 2015). Simultaneously, the construction industry also contributes to the environmental impacts comprising of high energy usage, over-consumption of water and natural resources, and generation of waste to the surrounding environment. Each year, the construction industry in the world depletes approximately 25% of the global wood harvest, and is responsible for the use of 40% of stone, sand and gr avel, and 16% of water usage (Joseph and Tretsiakova-McNally, 2010).

United Nations Environment Programme-Sustainable Building and Climate Initiative (UNEP- SBCI)’s report estimated that the building sector contributes up to 30% of annual global greenhouse gas (GHG) emissions and consumes up to 40% of all energy, both in developed and developing countries (UNEP-SBCI, 2009). Natural resources, such as iron ore, limestone, bauxite, coal, natural gas and petroleum, which are used to produce heavy building materials (such as concrete, steel and aluminium), are non-renewable resources. Australia and Brazil are the two leading countries of iron ore production for steelmaking and the production has decreased from 900 million metric tonnes in 2014 to 400 million metric tonnes in 2018 (US Geological Survey, 2018). The world’s accessible iron ore reserves have now considerably declined approximately 44% from 150 billion metric tonnes in 2009 to 84 billion metric tonnes in 2018 (Crawford. 2011; US Geological Survey, 2018). Subsequently, with the average annual extraction rate of 4.9%, global iron ore reserves will be enough for only around 20 years.

The use of traditional heavy materials will not just depleting the non-renewable natural resources but also high in carbon dioxide (CO,) intensity, which is considered to be one of the most significant contributing factors to climate change. Therefore, the selection of renewable building materials with low CO, emissions plays a crucial role in mitigating the environmental burdens and resource scarcity. The use of timber to substitute heay materials in construction has now attracted escalating attention around the world.

Carbon emission is considered the main contributor to global climate change and it is closely related to the energy consumption of various activities in the economy. Anthropogenic emissions come from two principal sources, namely, the combustion of fossil fuels, and conversion of land use and cultivation of soil (Lai, 2008). Ол ег the years, governments and organisations have developed policies, regulations and standards to reduce carbon emissions. The global forest is considered as an important way to mitigate climate change by absorbing and storing carbon from the atmosphere (Carroll, 2012; Mitchard, 2018). It is estimated that forests absorb approximately 10-15% of the global CO, emissions (Sample et ah,

2015). However, recent research studies indicate that the carbon sink of forests is declining as a result of deforestation and forest degr adation (Sample et ah, 2015). Therefore, forest conservation and management potentially play an important role in carbon management in reducing atmospheric CO, concentration.

Timber is one of the most environmentally friendly and renewable building materials because the production of timber requires less energy and emits less CO, than other materials (Skullestad et ah, 2016). Timber has been used for residential construction for centuries. More than 90% of residential housings in Australia use timber for the construction of wall and roof frames (FWPA, 2005). Chen (2012) states that the embodied energy used to construct a five-storey reinforced concrete (RC) building was higher than that of an equivalent engineered timber building by about 22%. Furthermore, building with timber saves almost 45 tonnes (out of 80 tonnes) of CO, per dwelling, which can be a significant difference compared with using traditional heavy materials at a global scale (Waugh Thistleton Architects, 2018). Wood waste, such as sawdust and offcuts produced during timber processing and timber components at the end of the building's lifespan, are potential bioenergy resources that could replace fossil fuels in the production of electricity. According to NAFI (2007), renewable energy produced using wood waste instead of coal-fired electricity generation reduces CO, emissions by 95-99% for each megawatt-hour (MWh).

This chapter begins with a review of the importance of forests, followed by the policies, initiatives and regulations concerning forest conservation and management at both national and international levels. This chapter examines the technological advancement of timber and engineered timber products as they replace traditional heavy material for constructions. Finally, the chapter discusses the challenges that timber and timber products may encounter in order to be in competition with the traditional materials.

The Importance of Forests in the Mitigation of Climate Change

Forests play an important role in the mitigation of climate change by absorbing CO, in the atmosphere. However, the land use conversion and fossil fuel combustion to support human activities har e severely altered the global carbon cycle, leading to the continued increase of the CO, concentration in the atmosphere (Lai, 2008). Mitchard (2018) states that between 1960 and 2015, approximately 20% of anthropogenic carbon emissions were due to the change of land use of the tropical forests. Mitchard (2018) continues to state that the tropical forests are likely to become a source of carbon emissions owing to the continued vanishing of forests and the diminishing capacity of the remaining forests to assimilate the increasing CO, concentration in the atmosphere.

F orests cover about one-third of the earth’s land and the combined temperate and boreal forests make up of approximately 49% of the total (Carroll, 2012; Knauf et ah, 2015). Forests help in lessening climate change through their inherent ability to sequestrate and store CO, from the atmosphere to both above- and below-ground biomass through the processes of photosynthesis and tree growth. The problem of climate change is closely related to the increasing atmospheric concentrations of CO,. Approximately a quarter of the anthropogenic CO, emissions are from the destruction of the forest ecosystem, farming activities and soil degr adation, and the concentration will continue to rise if no immediate action is taken (FAO, 2018).

Deforestation and forest degradation caused by tree harvesting and disintegrating contribute to approximately 17% of global carbon emissions (UNREDD, 2015). Levashova (2011) states that illegal logging is one of the primary causes for the degradation of forest resources and more than 20% of timber entering the EU market comes from illegal sources. Therefore, the prevention of further deforestation and forest degradation plays a significant role in addressing the issue of global climate change.

The endurance of the forest ecosystem is vital in lowering CO, concentrations as it has the ability to store and sequestrate carbon from the atmosphere (Mackey et al.. 2008: Lai, 2010; UN Climate Summit, 2017). It can improve the global carbon cycle by storing carbon above ground through trees and plants and below ground in soils (Stupak et ah. 2011; Carroll, 2012). Therefore, managing forests sustainably is all about the maximising carbon sequestration, minimising carbon release, maintaining biodiversity, protecting water systems and providing environmental goods and sendees.

Carbon sequestration of forests is one of the essential ecosystem sendees and is defined as the net rate of carbon uptake by an ecosystem per annum (Yan, 2018). Carbon sequestration is the natural process of CO, being extracted from the atmosphere and stored in plants and soil for an extended period of time. Carbon sequestration in renewable products, including wood, bamboo or agricultural products, can be either at the product level or global level. The product level (biogenic CO,) is related to the carbon stored in wood dining the growth of a tree (van der Lugt et ah, 2012). At the global system scale, CO, is captured in the forests, ocean and the soil. It is estimated that the amount of CO, emissions each year that are a result of burning fossil fuels and deforestation in tropical and sub-tropical forests is about 6.4 Gt and 1.93 Gt, respectively, whereas carbon sequestration each year due to reforestation on the Northern Hemisphere is only about 0.85 Gt (Vogtlander et ah, 2014). Therefore, if there is no change in the area of forests and no change in using wood products, there will be no change for carbon sequestration.

The forest carbon cycle is where live forests sequestrate carbon from the atmosphere through the natural process of photosynthesis, the harvested forest, however, will need reforestation in order to continue with the process of carbon sequestration. Above ground, carbon is absorbed for growth and stored, while below ground, carbon is absorbed and stored in tree roots and soil. The harvested forest will turn into harvested wood and bioenergy. Managing young forests can maximise carbon uptake while conserving old forests and prolonging rotations lead to greater carbon storage in the below-ground soil pool (Carroll, 2012). Yan (2018) conducts research to assess carbon sequestration between living and harvested forest. Research results reveal that the impact of harvested forest on carbon sequestration can be improved by increasing growth rate, extending harvest period, and reducing harvest intensity.

Carbon can also be sequestered in wood products as long as they continue to be in use and will only be released when they are burned or decomposed at the end of the useful life. Approximately two million tonnes of timber and timber products are disposed of in landfills each year at the end of the useful life of wood products (Ximenes et al., 2013). Several studies have investigated the fate of carbon stored in wood products in landfills. In an early study by Micales and Skog (1997), the amount of methane and CO, generated from timber products in landfills was approximately 3% into the atmosphere. Ximenes et al. (2008) examine the decomposition of wood products in landfills in Australia. Research results reveal that after 46 years in the landfills, the loss of carbon was 8.7% for hardwood and 9.1% for softwood. Ximenes et al. (2013) calculate the amount of captured carbon in wood products in landfills based on the results of the bioreactor experiments. They concluded that particleboard and medium-density fibreboard (MDF) reactors stopped producing gas after two months, but no gas was produced in high-pressure laminate (HPL). In anaerobic reactors, in the laboratory under optimal decay conditions, the proportions of carbon loss were 1.65%, 0.65% and 0%, respectively, for particleboard, MDF and HPL, and carbon can be retained in storage indefinitely.

The use of traditional heavy materials in buildings is well recognised as environmentally and timber is proposed to be a suitable substituting material for the construction of buildings. While the interest in using timber in construction leads to more plantations and more carbon sequestered in harvested wood products, the negative or positive impact of the using wood in construction on the impact on the carbon cycle, emissions and sequestration will depend on the type of wood. For instance, the demand for tropical hardwood is more than the supply from plantations (35%-40% of FSC wood is from plantations). Consequently, the increasing demand for tropical hardwood may escalate deforestation if not managed sustainably and, thus, may disrupt the carbon sequestration cycle. On the contrary, the use of plantation wood may encourage afforestation and reforestation, resulting in an expansion of the carbon sequestration pool (Vogtlander et al., 2014). As a result, the use of timber products from well-managed forests will enhance the world's carbon sequestration and storage capacity.

  • [1] Faculty of Design, Architecture and Building, University of Technology Sydney, Building 5C, 1 Quay Street, Haymarket,NSW 2000.
  • [2] Faculty of Engineering and Information Technology, University of Technology Sydney, Building 11,81 Broadway, Ultimo,NSW 2007. Email: This email address is being protected from spam bots, you need Javascript enabled to view it * Corresponding author: This email address is being protected from spam bots, you need Javascript enabled to view it
  • [3] Faculty of Design, Architecture and Building, University of Technology Sydney, Building 5C, 1 Quay Street, Haymarket,NSW 2000.
 
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