Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden

Abstract

Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Piceaabies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinussylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.

Adaptation to Climate Change in Swedish Forestry

“…Despite such benefits, several obstacles to uptake appear to remain, including concerns regarding browsing pressure, increased management complexity, and continued uncertainty regarding economic and production outcomes. [43] In addition, one effect of the increased use of mixed forests that was not considered in the 2007 report is the potential benefits derived from the increased natural biological control of insect pests. The primary mechanism relies on an associated increase and more stable abundances of generalist natural enemies and the relative dilution of individual tree species hosts ( [44,45]).…”

Accumulation of soil organic C and N in planted forests fostered by tree species mixture

“…Thereby, plantations play an important role in soil carbon sequestration and mitigating the global atmospheric carbon budget (Cunningham et al, 2015). However, considering the problems caused by pure plantations (Peng et al, 2008), nowadays planting mixed forest with different species in one stand is becoming more and more popular in worldwide plantation management (Felton et al, 2016;Oxbrough et al, 2012) for the potential positive effects (Knoke et al, 2007). Mixed forests, compared with monocultures, are generally characterized by the sustainability to resist disturbance, potential for higher yield and better ecological services (Grime, 1998;Knoke et al, 2007).…”

Vegetation and Soil Carbon Pools of Mixed Plantation of Acacia nilotica and Dalbergia sissoo under Social Forestry Scheme in Kurukshetra, India

“…Tree plantations play an important role both in vegetation and soil and carbon sequestration. Considering the problems prevalent in pure plantations, planting mixed forest with different species in one stand is becoming more and more popular in worldwide plantation management programmes [36,37] There are many benefits attributed to planting a mixed plantation which includes more efficient nutrient use, conservation of site quality and biodiversity, enhanced yields over time, reduced risk of catastrophic damage from pests and disease outbreaks. Thus, the present study also emphasizes the promotion of tree plantation with mixed species for various land uses such as barren land, wasteland, agricultural lands, drylands, fallow lands and private lands etc.…”