Height Growth of Korean Pine Seedlings Planted under Strip-Cut Larch Plantations in Northeast China

Toshiaki Owari,Mingfang Yin,Shinichi Tatsumi,Liangzhi Ning

doi:10.1155/2015/178681

Abstract

To develop two-storied forest management of larch plantations in Northeast China, this study examined the height growth of Korean pine (Pinus koraiensisSieb. et Zucc.) seedlings planted under strip-cut larch canopies. We measured the height growth of the underplanted seedlings 4 years after planting. The larch canopies were of varying stand age (12, 17, and 37 years) and strip-cut width (4.5, 6.0, and 7.5 m). We measured the seedling height growth in an open site (i.e., a site with no canopy). Underplanted seedlings had a smaller height growth (12.1–20.1 cm year−1) than the seedlings planted in the open site (23.7 cm year−1). The seedlings underplanted in the wider strip-cuts tended to have greater height growth than the seedlings underplanted in the narrowest strip-cuts. A generalized linear mixed model analysis predicted the greatest seedling height growth in the open site. A 36–47% reduction in annual height growth was predicted for the narrowest strip-cuts (4.5 m) versus the open site, while a 13–36% reduction in annual height growth was predicted for the wider strip-cuts (6.0–7.5 m) versus the open site. To maintain adequate height growth, forest managers are recommended to create wider strip-cuts (i.e., ≥6.0 m) for the purpose of underplanting Korean pine seedlings in larch plantations.

Highlights

Larches (Larix spp.) are important fast-growing and highyield tree species in Northeast China, and government policy has keenly promoted larch plantations in the region [1]
Two-storied forest management in which overstory larch trees are strip-cut and Korean pine (Pinus koraiensis Sieb. et Zucc.) seedlings are underplanted has been deemed a viable option in Northeast China [6, 10]
Our generalized linear mixed model (GLMM) analysis successfully derived a statistical model that allows the assessment of annual height growth of Korean pine seedlings at the early stages of growing

Summary

Introduction

Larches (Larix spp.) are important fast-growing and highyield tree species in Northeast China, and government policy has keenly promoted larch plantations in the region [1]. To enhance ecosystem functioning while maintaining the economic benefits of larch plantations, a pressing need exists to develop alternative forest management regimes in Northeast China [5, 6]. Forest management whereby even-aged plantation monocultures are transformed to two-storied mixed-species stands has been practiced in many forests around the world [7,8,9]. Underplanting is combined with the partial cutting of the existing stand to promote the development of complex stand structure with multiple canopy layers and various tree sizes [9]. Two-storied forest management in which overstory larch trees are strip-cut and Korean pine Korean pine has great economic value, because it produces high-quality timber and commercial seeds for eating and medical use [13, 14]

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Conclusion