Influence of Different Tillage Systems and Weed Treatments in the Establishment Year on the Final Biomass Production of Short Rotation Coppice Poplar

Jonathan Sheppard,Frieder Seidl,Christopher Morhart,Heinrich Spiecker

doi:10.3390/f4040849

Jonathan Sheppard, Frieder Seidl

Open Access

https://doi.org/10.3390/f4040849

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Abstract

In this study the influence of three different tillage systems in combination with eight varying weed treatments applied within the establishment year and its effect on the final above ground leafless biomass production (after the third growing season) of short rotation coppice poplar is presented. The three tillage systems included variants with ploughing and harrowing, variants with cultivation and ley cropping and variants without tillage. Weed treatments included the application of different herbicides, but also more environmentally sound variants such as mulching and the use of mulch materials to avoid the use of herbicides. To estimate the influence on final biomass production, regression analysis was undertaken using DBH as the predictor variable. Based on 1056 DBH measurements the biomass production of the different variants was compared. The interactions of tillage system and weed treatment on biomass yield were found to be statistically significant. Between tillage systems the ploughing variant displayed a better overall performance than the cultivation with ley crop variant and the variant without any tillage. Differing weed treatments reveal greater success for the whole area application of herbicides than band application, both being better than the use of mulch materials. These results suggest that the right tillage system in combination with effective chemical weed control is the key to the successful establishment of Short rotation coppice (SRC) poplar plantation following the principles of an integrated weed management approach. Furthermore, ecological variants such as ploughing in combination with the use of mulch materials and mechanical vegetation control between the rows could be a solution to reduce dependence on chemical control. However, this comes at the expense of a considerable loss in yield.

Highlights

The increasing demand for wood for energetic purposes in the last decades has raised attention in plantations stocked with fast growing trees such as poplar (Populus spp.) and willow (Salix spp.).Short rotation coppice (SRC) plantations providing high wood yields are a strong focus of research with an aim to improve planting material as well as plantation design and management
It has been shown that the tillage systems and weed control treatments utilised within this study have an effect on biomass production over the whole rotation
Within the 24 tillage and weed treatment combinations investigated within this study a number of conclusions can be drawn with respect to total above ground dry leafless biomass production for the hybrid poplar clone “AF2”

Summary

Introduction

The increasing demand for wood for energetic purposes in the last decades has raised attention in plantations stocked with fast growing trees such as poplar (Populus spp.) and willow (Salix spp.).Short rotation coppice (SRC) plantations providing high wood yields are a strong focus of research with an aim to improve planting material as well as plantation design and management. The control of weed species to ensure a maximal yield is an important element of SRC management, since the occurrence of weeds can present a significant suppression of crop growth coupled with an increased rate of mortality. It has previously been estimated that during the establishment year vigorous weeds were found to reduce SRC growth by 50% to 95% [2]. It has been suggested that the competitiveness of a weed species is closely linked to both the crop’s growth strategy and morphology allowing it to effectively compete with the crop, primarily for available nutrient, water and secondarily light [5]. Most research and guidance emphasises the importance of weed control due to the low competitive ability of SRC poplar and willow during the early stages of growth [7]. SRC poplar is known to be most sensitive in regards to weed competition during the establishment phase, but such sensitivity differs considerably between hybrid varieties [8]

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