Assessing site form as an indicator of site quality in even-aged Pinus radiata D. Don stands in north-western Spain

Juan Alberto Molina-Valero,Fernando Castedo-Dorado,Ulises Diéguez-Aranda,Juan Gabriel Álvarez-González,César Pérez-Cruzado

doi:10.1007/s13595-019-0904-1

Juan Alberto Molina-Valero, Fernando Castedo-Dorado + Show 3 more

Open Access

https://doi.org/10.1007/s13595-019-0904-1

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Abstract

Key messageSite form and site index have shown similar precision for estimating site quality in even-agedPinus radiataD. Don stands in north-western Spain. Additionally, SF presents the advantage that it does not require stand age information and can therefore be used in a wider set of situations in the forestry practice.ContextEstimation of site quality is essential for characterizing, monitoring and predicting forest resources. Site index (i.e. the dominant height of the stand at a reference age) is ordinarily used to estimate site quality; however, this index is only useful for even-aged stands of known age. By contrast, SF is age-independent as it uses the dominant height of the stand at a reference dominant diameter.AimsThe aim of this study was to compare the performance of SF and SI for site quality estimation in even-aged P. radiata stands.MethodsDynamic equations derived with the Generalized Algebraic Difference Approach (GADA) from the Hossfeld IV base model were fitted to predict site quality with both SI and SF. SF predictions were compared with SI regarding variability within the same plot and consistency in site quality predictions, using the observed maximum mean annual volume increment (MAI) as a direct measure of site quality.ResultsBoth approaches showed good performance in model fitting and provided similar goodness-of-fit statistics and variability in the predictions. However, SI performed slightly stronger when related to MAI.ConclusionSF performed adequately in estimating site quality for even-aged P. radiata stands, with results comparable to those obtained using traditional SI.

Highlights

Assessing and monitoring forest resources require a reliable and efficient estimation of site quality, which is essential for predicting growth and yield of plant biomass under different management regimes for both even-aged (Skovsgaard and Vanclay 2008) and unevenaged stands (Peng 2000)
Site index (SI) performed slightly stronger when related to mean annual volume increment (MAI). & Conclusion & Site form (SF) performed adequately in estimating site quality for even-aged P. radiata stands, with results comparable to those obtained using traditional SI
The plots were established throughout the area of distribution of the species in north-western Spain (Fig. 1), a region mainly located in the Atlantic Biogeographical Region (European Environment Agency 2006), where mesophytic deciduous broadleaved and mixed coniferous-broadleaved forests correspond to the natural vegetation (Bohn et al 2000)

Summary

Introduction

Assessing and monitoring forest resources require a reliable and efficient estimation of site quality, which is essential for predicting growth and yield of plant biomass under different management regimes for both even-aged (Skovsgaard and Vanclay 2008) and unevenaged stands (Peng 2000). Site index (SI), defined as the average height of the dominant trees of the stand at a given reference age, is one of the most commonly used indicator of site quality for even-aged stands Age-independent methods have been developed to overcome the latter problem, enabling modelling of the dominant height growth and estimation of site index in the absence of age data It will be desirable to assess more age-independent methods, as this work aims

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