Synergies between biodiversity and timber management

This Special Issue of the International Journal of Biodiversity Science, Ecosystem Services & Management (IJBESM) examines possibilities for positive synergy between managing timber species (especially those of high value) and biodiversity. Management for the production of high-value timber species and to conserve biodiversity can conflict with each other. But the demand for high-value timbers and increasing urgency to conserve biodiversity prompt the goal to integrate these management objectives. This Special Issue is based on a technical session at the IUFRO 2014 World Congress that explored potentially positive interactions between high-value timber management and biodiversity. The papers cover a wide geographic range: from temperate forests in Europe (Löf et al. 2016; Merganic et al. 2016), Canada (Hébert et al. 2016), and Japan (Owari et al. 2016), to tropical forests in Cameroon (Doucet et al. 2016) and Ghana (Onyakwelu & Olabiwonnu 2016; Stephens et al. 2016).

Globally, forested lands experience increasing pressure for timber production and provision of ecosystem services, are being converted for agriculture to feed an increasing human population, and will be altered by climate change. These convergences make it ever more critical that synergies in benefits are accounted for and that management strategies be developed to meet multiple ends. Of over 76,000 species assessed and published on the IUCN Red List, more than 22,000 are threatened with extinction (IUCN 2016). Of over 9500 tree species assessed and published on the IUCN Red List, more than 6400 are threatened (Global Trees 2016). At the same time, by 2015, global natural forest area had decreased by 240 Mha since 1990 (Keenan et al. 2015), 26% of remaining forests was managed for multiple purposes (including production) (Köhl et al. 2015), and 278 Mha were in plantations (7.5% of forested area) (Keenan et al. 2015). While strict reserves are certainly needed for biodiversity conservation, and some land will be dedicated solely to timber production, neither form of land use will completely fulfill those goals at the global scale. A solution is to manage some lands for both purposes.

Positive interactions between biodiversity and timber management include biodiversity helping to protect high-value species from pests and pathogens, biodiversity as an indicator for intact ecosystems that can sustain production of high-value species, use of high-value species in restoration and plantations to help to reestablish or conserve biodiversity, enrichment planting of high-value species to help to maintain forests and their biodiversity by increasing forest value, and high-value species themselves as biodiversity in need of conservation. The papers in this Special Issue illustrate examples of joint management for timber production and biodiversity in seminatural forests, plantation management of single overstory species that conserves biodiversity in other strata, and the possibility for biodiversity to enhance timber quality.

Studies by Löf et al. (2016), Owari et al. (2016), and Doucet et al. (2016) show how management can help meet the joint goals of timber production and biodiversity conservation. Löf et al. (2016) examined how different management regimes affect high-value timber production, biodiversity, and cultural services in Swedish oak forests. Their analysis suggests that active management can provide an acceptable balance of all three outputs in forest stands. Owari et al. (2016) present a single-tree management system for extremely high-value trees in Japanese forests, an approach that also maintains large trees and their ecosystem function, even after death. For example, Betula maximowicziana can be worth more than 4500 USD m^–3, and the value increases after death, due to the change of the wood to a color preferred by buyers. Doucet et al. (2016) describe a test of a strategy for enrichment planting, which employs simple mixtures of 23 native species in secondary forest in Cameroon as a method for restoring high-value trees, including many of conservation concern, such as Entandrophragma utile. Due to the removal by logging of seed sources and the need for canopy openness for early growth, many of these species require special attention to regeneration for recovery.

The impact of timber management on biodiversity, especially how biodiversity recovers after plantation establishment, is examined by Stephens et al. (2016), Onyakwelu and Olabiwonnu (2016), and Hébert et al. (2016). Stephens et al. (2016) show that the understory ant community recovered 80% of natural forest species only 2 years after the establishment of small plantations of mixtures of native species in Ghana. They concluded that modest changes in management, such as incorporation of more species in plantations, can help to reclaim significant levels of biodiversity. In Ghana, Onyakwelu and Olabiwonnu (2016) found that overstory tree diversity was lower in a Gmelina plantation than in natural forest, as expected, but the diversity of saplings and seedlings was similar between the plantation and natural forest. In addition, the saplings and seedlings in the plantation included high-value species. The study by Onyekwelu and Olabiwonnu emphasizes that understory diversity should be considered in biodiversity comparisons between plantations and natural forest. Similarly, Hébert et al. (2016) describe understory recovery in Populus plantations in temperate forest in Quebec. They found that 12 years after severe substrate modification by scraping and furrowing the planting surface to break up the soil, understory biodiversity was approaching that of a comparable natural forest. Of course, recovery of biodiversity in these studies depended on the availability of sources for recolonizing the sites.

Positive relationships between biodiversity and timber quality are captured by Merganic et al. (2016) and Owari et al. (2016). Merganic et al. (2016) found that, depending on the stage of stand development, forest biodiversity, structural diversity, and spatial heterogeneity can be positively related to timber quality in the Czech Republic. However, these relationships must be considered in the context of other factors that also impact timber quality. Owari et al. (2016) showed that, at the stand level, the number of superior-quality trees among extremely high-value species in Japan was positively associated with overall diversity in tree species.

Economic considerations also affect management that combines both timber production and biodiversity conservation. Löf et al. (2016) assessed economic returns for management focused on production in oak forests, but concluded that more information is needed for a complete economic analysis of management that incorporates both production and biodiversity. Owari et al. (2016) point out that the single-tree management model may only be cost-effective for extremely high-value species. Doucet et al. (2016) found that the cost of restoration planting challenges profitability even for fast-growing species so that regeneration planting requires both incentives and a regulatory structure that promotes attention to regeneration. Although investment in incentives, regulations, and oversight are required, can we afford to do less?

We hope that these interesting papers stimulate more research into how a biodiverse environment can positively impact timber management and, conversely, how timber management, especially of high-value species, can help conserve biodiversity, for the end result of maintaining both resources.

Disclosure statement

No potential conflict of interest was reported by the authors.