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Global environmental problems such as climate change, tropical deforestation, loss of biodiversity and desertification are receiving serious attention of all stakeholders including scientists, citizens and policymakers. Interestingly, all these environmental issues are linked to land-use systems. Climate change and its manifestations, particularly rising temperatures, changing precipitation patterns and sea level rise (IPCC 2007a), are of global environmental concern and have the potential to impact most natural ecosystems (such as forests, grasslands and wetlands) and socioeconomic systems (such as food production, fisheries and coastal settlements) in all countries. Under extreme conditions, the impacts are likely to be catastrophic to human survival and may lead to irreversible loss of natural ecosystems. Climate change in the long term is projected to adversely affect supply of fresh water, production of food and forest products and ultimately economic development of both industrialized and developing countries (IPCC 2007b).

The carbon cycle is one of the biogeochemical cycles and describes the movement of carbon, in its many forms, within the biosphere, atmosphere, oceans and geosphere. The global carbon cycle involves the earth’s atmosphere, oceans, vegetation and soils of the terrestrial ecosystem and fossil fuels. Carbon in the form of inorganic and organic compounds, notably carbon dioxide (CO ), is cycled between different components of a system. For example, green plants absorb CO from the atmosphere during photosynthesis, also called primary production, and release CO back into the atmosphere during respiration. Another channel of exchange of CO is between the oceans and the atmosphere: CO dissolved in the oceans is used by marine biota in photosynthesis.

Two important anthropogenic processes that contribute CO to the atmosphere are burning of fossil fuels and changes in land use. Fossil fuels, namely coal, oil and natural gas, are burnt in industries, power plants and automobiles. Land use is a broad term, which encompasses a host of essentially human-induced activities including conversion of natural ecosystems such as forests and grasslands to managed systems such as cropland, grazing land and settlements. Land conversion and other human activities such as extraction and burning of biomass and livestock grazing lead to soil degradation and emission of carbon contained in biomass and in soil to the atmosphere: CO emissions from the biosphere to the atmosphere result mainly from burning and decomposition of organic matter.

Chapter 1 briefly describes the rationale and need for carbon inventory methods and guidelines and touches upon different programmes, activities and projects requiring carbon inventory. A carbon inventory involves estimation of changes in the stocks of carbon (in biomass and in soil) or its emissions and removal, normally expressed in tonnes of carbon per hectare, for a given land-use system, and time at a project level or national level. Carbon inventory is required for estimating: (i) the contribution of a country to global greenhouse gas (GHG) emission; (ii) carbon mitigation potential of a given project or activity; (iii) production of commercial timber or fuelwood from a plantation forestry project; and (iv) the impact of land reclamation projects on soil fertility.

Global carbon cycle involves exchange of CO between the atmosphere and the biosphere, apart from oceans. Plants fix CO from the atmosphere during photosynthesis to produce organic matter, which is stored in above- and below-ground parts. Bulk of the biomass in above- and below-ground plant parts is eventually transferred to the dead organic matter pool or it is oxidized or burnt. Dead organic matter, which consists of deadwood (standing as well as fallen) and litter, is either decomposed or oxidized, or stored for longer periods above or below the ground as detritus. CO fixed by plants ends up in soil as organic matter or in finer forms as humus through the process of decomposition. Thus, CO removed from the atmosphere is stored as dead and living biomass or soil carbon in the biosphere.

A carbon inventory is required for projects involving carbon mitigation, traditional forestry and roundwood production as well as for other land-based development (noncarbon) projects. This chapter focuses on the carbon inventory process at different phases of a project cycle. A typical project cycle comprises conceptualization, consultation, proposal preparation, appraisal, approval, implementation, monitoring and evaluation. Project proposals are written to seek support for investment capital or grant, technology transfer, capacity development or for conducting research. Most land-based projects involve appraisal, monitoring and evaluation of environmental, financial, social, institutional and legal aspects at multiple stages of the project cycle. The focus of this handbook is on environmental aspects, particularly assessment of carbon emissions, removals or carbon stock changes due to project activities that require a carbon inventory. Even projects not directly related to carbon mitigation require assessment of production of roundwood or grass, rates of growth of organic matter in soil and stock changes. Such agencies as the World Bank, Asian Development Bank, UN organizations, Clean Development Mechanism (CDM) Executive Board, bilateral funding agencies and national institutions have their own guidelines for developing project proposals, appraisal, monitoring and evaluation. However, the basic components of any project cycle involving carbon mitigation, roundwood production or land reclamation would involve multiple stages as illustrated in Fig. 5.1.

All land-based projects require carbon inventory. Carbon inventory for land use, land-use change and forestry (LULUCF) projects for climate change mitigation is contentious because of both methodological issues and uncertainty in the data required to estimate gains in carbon stocks. LULUCF projects include carbon mitigation activities in three categories, namely forestry, cropland and grassland. The complexity of methods for estimation and projection of carbon stock changes leads to several methodological issues, which are important to consider at different phases of a project cycle. Examples of methodological issues are non-permanence, leakage and additionality of carbon gains. Some of these issues are also relevant to non-climate mitigation, land-based conservation and development projects. Issues such as non-permanence are unique to land-based mitigation projects. The following methodological issues are addressed in this chapter:

● ?Baseline

● ?Additionality or incrementality

● ?Permanence

● ?Leakage

● ?Project boundary

● ?Scale of projects

The main goal of carbon inventory for carbon mitigation projects is to estimate the incremental or additional biomass and soil carbon stocks gained because of project activities. Estimation of incremental or additional carbon benefit or stock gain requires monitoring of carbon stocks of a given area and over a given period under the “without-project” or “baseline scenario” as well as changes in stocks for the project area over the same period as a result of implementation of project activities under the “project scenario”. Carbon inventory methods are required in a project cycle during project proposal development, post-project implementation and monitoring phases. This chapter describes the broad approaches, methods and steps for estimating carbon stock changes at two levels:

● ?Under baseline and project scenarios

● ?At project development and monitoring phases of the project cycle These approaches and methods are also applicable to non-carbon land-based projects, such as roundwood production. Detailed methodologies for measurement, calculation, projection and monitoring of different carbon pools are described in the later chapters.

Estimating the area and delineating the boundary of a land-use category for greenhouse gas inventory and of area dedicated for a proposed project is the first basic step in preparing a carbon inventory. Methods ranging from field measurements, such as a physical land survey, to more complex methods involving the use of a satellite available for estimating land area and marking its boundary are presented in this chapter. The need for stratification of land area to increase the accuracy will be highlighted (methods for stratification are described in Chapter 10). These methods could be used in preparing greenhouse gas inventories of different land-use categories for use in carbon mitigation or roundwood production projects.

In this chapter, the generic approach to estimating carbon through “Gain– Loss” or “Stock-Difference” method is presented (IPCC 2003, 2006) along with an overview of the various methods for estimating different carbon pools.