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Submitted December 2016; accepted May 2017
The invasive technique of increment coring may be unavoidable in forest ecology research requiring data on wood traits. Despite this, no study has examined the effects of increment coring on tropical forest trees. We cored 35 trees of 11 species from nine families, with wood densities ranging from 0.30 to 0.69 g cm-3, at two sites in Singapore. Tree survival, borehole closure and external signs of damage resulting directly from the coring were monitored for 1 year. Tree radial growth was estimated from changes in diameter at breast height. Of the cored trees, only one died after 1 year. Twenty-five out of the 35 trees had at least one closed borehole, and the median time to closure was 10 months. The species of tree cored was the only significant predictor of borehole closure. We observed three main categories of external damage: discoloured bark, surface wounds and the presence of fungal fruiting bodies or insects within the boreholes. Changes in the trunk diameter were not significantly different between cored and uncored trees. Our results suggest that increment coring in the tropics does not negatively impact the survival and growth of some species of tropical forest trees within the first year after coring.
Keywords: Plant disease risk, wounding, trunk wound response, tree radial growth
INTRODUCTION
Increment coring is an invasive process which involves the use of an increment borer to extract cylindrical wood samples from living trees, inevitably causing some injury to the trees. It has conventionally been practised in forestry for decay detection to examine tree growth (Meyer & Hayward 1936), wood density and anatomy (Lawton 1984, Francis 1994), as well as for dendrochronology (Eckstein & Dujesiefken 1999). Outside of these traditional areas of study, tree coring has in recent years become necessary also in theoretical and applied environmental research areas that are rapidly growing in popularity such as the estimation of wood density or wood specific gravity for the study of tree functional traits (e.g. Chave et al. 2009, Schüller et al. 2013), the assessment of forest carbon stock (e.g. Martin & Thomas 2011), and the approximation of sapwood area (e.g. Parolin et al. 2008, Pfautsch et al. 2012) in the study of plant water use...