Land Use, Land-Use Change and Forestry

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Figure 2-7: Range of temporal and spatial scales at which ecological processes occur, with related monitoring techniques. Forest inventories involve many of these methods and cover spatial scales from 1 to109 ha and temporal scales from 1 to 100 years.

2.4. Methods

2.4.1. Introduction

The amount of carbon held in the vegetation and soils of terrestrial ecosystems varies spatially and temporally as a result of natural processes and human activities. Sources and sinks of non-CO2 GHGs (methane and nitrous oxide) are also affected by changes in land use. The issue addressed here is whether there are methods of measuring stocks, losses, and accumulations of carbon, as well as changes in the flux of CO2 and non-CO2 GHGs, in ways that are compatible with the requirements of the Kyoto Protocol-in particular, whether the precision and costs of such methods will enable changes in carbon stocks and changes in the flux of GHGs to be determined satisfactorily over the commitment period 2008-2012.

Measuring carbon sequestration or release during the commitment period as a result of human-induced activities depends on two factors: first, the type of activities to be included-namely, activities considered in Articles 3.3 (ARD), 3.4 (other LULUCF activities), and 3.7 of the Protocol-or full carbon accounting; and second, the scale of interest (project or national level). Table 2-7 presents an analysis of the various methods in terms of scale of applicability, suitability for project-level versus national-level carbon monitoring, costs, accuracy, and so forth.

Methods exist for measuring the amount of carbon in all components of terrestrial ecosystems, as well as for measuring changes in this amount. The methods vary in complexity, precision, accuracy, and cost. Different methods are appropriate for different pools and components of terrestrial carbon and for different temporal and spatial scales (see Table 2-7 and Figure 2-7). Methods used to measure carbon, or a change in carbon, are different from those used to attribute cause to an observed change in carbon (e.g., direct human activity versus natural causes). This distinction is important because the Protocol is concerned with human-induced, rather than total, changes in carbon. Even the most direct measurements on small plots do not distinguish mechanisms or yield attribution. Attribution must be inferred from controlled experiments or from ecosystem process models that are based on the mechanism thought to be held responsible for the change (e.g., land-use change versus CO2 fertilization).

Table 2-7: Characteristics of methods for determining changes in carbon storage.

Scale of Applicability Time Span Parameter Assessed Suitable to Monitor ARD Activities Applicable when Alternative Definitions for ARD are Chosen Suitable to Monitor Soils and Additional Activities1 Suitable for Full Carbon Accounting

Sampling Density

Costs2 Accuracy3 Verifiability

Vegetation Inventory 0.01-109 ha 1-100 yr Aboveground stemwood volume and increment, harvesting and mortality; derived from whole-tree biomass Yes, but design of sampling must be adapted to cover Kyoto lands Yes, provided forest definitions used in inventories are adapted Mainly for specific additional measures that impact forest C stock, such as thinning, fertilization, etc. No-usually excludes soils Project basis: 400 plots on 5,000 ha; in national-scale inventories: 1 plot represents 1,000 ha US$ 0.05-0.6 ha-1 in national scale inventories; US$11-18 at project levels (10,000 ha) Area: s.e. = 0.4% Growing Stock: s.e. = 0.7% Increment: s.e. = 1.1% (Tomppo, 1996) Relatively easy

Soil Inventory 0.1-103 ha 10-1,000 yr SOC stock and changes over time Yes Yes Yes Assesses one compartment only Depending on soil heterogeneity ~300 sample points per 10,000 ha; one sample for every 10-cm depth US$ 3-20 per sample 2-3% error for analytical precision; total error much higher due to spatial heterogeneity and sampling error Relatively easy

Eddy Flux -20 ha Day - 10 yr Net Ecosystem Production For verification only For verification only For verification only No-excludes harvesting and decay of wood products Required sampling density to obtain a large area representative flux must still be determined US$ 100,000 per site initial costs; US$20,000 yr-1 running costs 10-20% Relatively easy through forest inventory and soil analyses

Flask Measurements -109 ha Decades Atmospheric CO2 concentration No No No No-excludes wood products Required sampling density to obtain a large area representative flux must still be determined Unknown Sample analysis is very accurate Verification of analysis is relatively easy

Satellite Remote Sensing 0.05-109 ha Day - decades Area (sometimes derived estimates of biomass and NPP) Yes Yes, provided spatial resolution is adequate Suitable for monitoring, e.g., fire management; in general, all area-related parameters of non-ARD No, mainly to assess areas ~80 sites in Northern Hemisphere Integral coverage through pixel size US$ 0.0002 ha-1 for the picture and same amount for labor to process it; aircraft-derived pictures more expensive Precise for area measurements (15%); for biomass, less precise Relatively easy with ground truth data

Ecosystem Modeling 0.1-1 ha Day - 100s of years NPP, NEP per compartment When validated with on-site data Yes, provided model can be parameterized with new forest data Yes, when management activities can be modeled Yes, if all components of C cycle are included in model Usually integral coverage Cheap once model is developed Uncertain; subject to many assumptions Difficult in long term

Biome Models Grid - 109 ha Day - 100s of years NPP, NEP per grid No No Often soils are included in these Yes, if all components of C cycle are included in model Usually integral coverage Cheap once model is developed Uncertain; subject to many assumptions Difficult

1 Additional activities could be low tillage, drainage of peatlands, reduced-impact logging, thinning, wood products recycling.
2 Costs cannot be scaled up to larger regions using these per hectare estimates. Average costs per hectare will vary more with heterogeneity than with absolute area.
3 In the absence of a reference, estimates of accuracy are based on expert judgment.

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