Long-term effects of biological sprout control of unwanted hardwoods on conifer sites

Leena Hamberg,Tiina Laine,Jarkko Hantula,Timo Saksa

doi:10.1016/j.foreco.2021.119288

Leena Hamberg, Tiina Laine + Show 2 more

Open Access

https://doi.org/10.1016/j.foreco.2021.119288

Copy DOI

Abstract

Long-term investigations revealing the effects of a decay fungus, Chondrostereum purpureum (Pers. Ex Fr.) Pouzar on competition between deciduous and conifer tree species in young forests are missing. Therefore, the effects of three different sprout control treatments were tested in young Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) stands by evaluating sprouting ability of deciduous tree stumps, and competition level around cultivated conifers five years after the treatments. Sprouting control was performed (i) by cutting only (control), and ii) by applying low-concentration (dilution 1:400) or iii) high-concentration (dilution 1:100) C. purpureum preparates (mycelial solutions) on stumps immediately after cutting. Deciduous saplings were cut, and fungal inoculum was applied by spreading it onto freshly cut stump surfaces. Following high-concentration fungal treatment, the number of young deciduous trees cut in the treatment was by 25% lower compared to control; moreover, the number of sprouts per stump was also significantly negatively affected by the fungal treatment. As a result, the number of cases when competing deciduous trees occurred within a 1 m sample plot around the investigated conifers was 40% lower following high-concentration fungal treatment than in the control, resulting in better height and diameter development of conifers. Thus, additional sprout control is not necessarily needed after the high-concentration fungal treatment.

Highlights

In young conifer stands, self-regenerating deciduous tree saplings cause problems for cultivated conifers by competing for resources and causing physical damage (Jobidon, 2000; Huuskonen and Hynynen, 2006; Saksa and Miina, 2007; Fahlvik et al, 2011; Huuskonen et al, 2020)
The number of young deciduous trees cut in 2014 was ca. by 25% lower in high-concentration fungal treatment sample plots (4.6 in Norway spruce and 2.4 in Scots pine sample plots) than in control treatment (6.1 and 3.2, respectively, GLMM, p < 0.001)
No significant difference was found between the low-concentration fungal treatment (5.6 and 3.0 young deciduous trees cut in 2014 in the Norway spruce and Scots pine sample plots, respec tively) and control (p = 0.239)

Summary

Introduction

Self-regenerating deciduous tree saplings cause problems for cultivated conifers by competing for resources and causing physical damage (whipping) (Jobidon, 2000; Huuskonen and Hynynen, 2006; Saksa and Miina, 2007; Fahlvik et al, 2011; Huuskonen et al, 2020). The biggest problems caused by self-regenerating deciduous saplings include reduction in height and diameter development of young cultivated conifers such as Norway spruce (Picea abies (L.) H. Deciduous trees are being cut with a clearing saw but excessive re-sprouting usually causes a need for subse quent sprout control operations (Uotila et al, 2010, 2012; Thiffault and Roy, 2011; Uotila and Saksa, 2014).

Methods

Results

Discussion

Conclusion