The Application of Stem Analysis Methods to Estimate Carbon Sequestration in Arboreal Shrubs from a Single Measurement of Field Plots

Peter Beets,Mark Kimberley,Graeme Oliver,Stephen Pearce

doi:10.3390/f5050919

Abstract

Repeated measurements of plots are usually made to directly determine carbon stock changes over time. However, it is sometimes only practical or feasible to inventory plots at the end of a period of interest, and stock changes need to be predicted retrospectively from supplementary information on growth rate. This situation applied to the natural stratum of post-1989 forest in New Zealand, for which carbon sequestration over Commitment Period 1 (2008–2012) of the Kyoto Protocol needed to be estimated from inventory data acquired in 2012. A pilot study was undertaken to test and refine methods that could be applied in the national inventory, utilizing plots that had been installed in eligible post-1989 natural forest in 2008. The plots had actual measurements and shrub biomass sampling to directly estimate carbon stocks in 2008. These plots were re-measured and sampled in 2012, and basal disc samples from plants growing adjacent to each plot collected to provide data to model stem annual increment in diameter and height of shrubs growing on the plot. We present the results of this test of methods, and discuss refinements to field procedures and calculation methods to be applied in the national inventory of this stratum of post-1989 forest in 2012.

Highlights

The Ministry for the Environment has implemented a carbon inventory and analysis system (LUCAS) that is used for reporting on New Zealand’s commitments under the United NationsFramework Convention on Climate Change (UNFCCC) and the Kyoto Protocol [1]
Carbon stocks in post-1989 natural forest would be estimated directly from stem basal diameter and height of shrubs in inventory plots measured in 2012, and carbon stocks in would need to be estimated indirectly from diameter increment and age of a representative sample of shrubs harvested outside each plot
This paper presents the results of the pilot study, and discusses refinements to field procedures and calculation methods to be applied in the national inventory of post-1989 natural forest in 2012

Summary

Introduction

The Ministry for the Environment has implemented a carbon inventory and analysis system (LUCAS) that is used for reporting on New Zealand’s commitments under the United NationsFramework Convention on Climate Change (UNFCCC) and the Kyoto Protocol [1]. In New Zealand, the carbon stock in the naturally regenerating stratum of pre-1990 natural forest is estimated from measurements of orthogonal widths and height of crowns of discrete shrubs or from canopy height and cover if the canopy is closed [3]. As neither of these approaches can be adapted to estimate stock changes from a single measurement, methods based on stem diameter and height [4,5] were considered, because these measurements in conjunction with diameter increment data from stem analysis, can be used to estimate stock changes over defined time intervals [6,7]. Questions that need to be addressed include: (1) will the analysis of basal disc samples from shrubs growing adjacent to the plot provide accurate estimates of diameter increment of shrubs growing within the plot; and likewise (2) will shrub age information from basal disc samples provide accurate estimates of height increment using height/age functions?

Methods

Results

Discussion

Conclusion