Trade-Offs among Release Treatments in Jack Pine Plantations: Twenty-Five Year Responses

Holly D Deighton,Eric B Searle,Mathew Leitch,Nelson Thiffault,Jennifer Dacosta,Mahadev Sharma,Frederick Wayne Bell

doi:10.3390/f12030370

Abstract

We assessed 27 indicators of plant diversity, stand yield and individual crop tree responses 25 years post-treatment to determine long-term trade-offs among conifer release treatments in boreal and sub-boreal forests. This research addresses the lack of longer-term data needed by forest managers to implement more integrated vegetation management programs, supporting more informed decisions about release treatment choice. Four treatments (untreated control, motor-manual brushsaw, single aerial spray, and complete competition removal) were established at two jack pine (Pinus banksiana Lamb.) sites in Ontario, Canada. Our results suggest that plant diversity and productivity in boreal jack pine forests are significantly influenced by vegetation management treatments. Overall, release treatments did not cause a loss of diversity but benefitted stand-scale yield and individual crop tree growth, with maximum benefits occurring in more intensive release treatments. However, none of the treatments maximized all 27 indicators studied; thus, forest managers are faced with trade-offs when choosing treatments. Research on longer term effects, ideally through at least one rotation, is essential to fully understand outcomes of different vegetation management on forest diversity, stand yield, and individual crop tree responses.

Highlights

International agreements such as the Paris Climate Agreement, the UN SustainableDevelopment Goals and the Montréal Process are providing opportunities and setting challenges for forest managers worldwide
A field study was established in jack pine plantations in 1993 and 1994 on two sites to examine the effect of three release treatments and a control on individual crop tree growth, stand-scale growth and yield and plant diversity (Table 1)
Our results suggest that release treatments did not reduce plant diversity but benefitted stand yield and individual crop tree growth, with maximum benefits occurring in more intensive treatments

Summary

Introduction

International agreements such as the Paris Climate Agreement, the UN SustainableDevelopment Goals and the Montréal Process are providing opportunities and setting challenges for forest managers worldwide. Forests can provide an array of ecosystem services while helping to offset greenhouse gas emissions but are affected by natural and anthropogenic disturbances and climate change. These disturbances can interact with climate change to modify forest composition and productivity, affecting the capacity of forests to sustain services such as supplying wood assortments, maintaining biodiversity, and sequestering carbon [1]. While natural regeneration plays a substantial role in forest renewal—for example, about 44% of the area harvested in the past 20 years in Canada regenerated naturally [2]—the use of plantation forestry to regenerate specific species compositions offers added advantages for supporting sustainable forest management. Planted forests cover ~291 million ha worldwide, representing 7% of the world forests [3] and are expected to dominate future industrial wood supply [4]

Objectives

Methods

Results

Discussion

Conclusion