Managing Mixed Stands: Reassessing a Forgotten Stand Type in the Southeastern United States

Abstract

Forestry in the Southeastern United States has long focused on converting natural stands into pine plantations or managing exclusively for hardwoods. Little consideration has been given to managing stands containing pine and hardwood mixtures, as these stands were considered inferior in terms of productivity and/or quality. Recent declines in small-diameter softwood markets and logging workforce have, however, begun to stress the traditional pine production model in some locations, raising interest in management alternatives. Here, we provide biological, economic, and sociocultural rationale for pine-hardwood mixtures as an alternative strategy for landowners with multiple management objectives. To support this idea, an illustration compares a mixed-species plantation to pine and hardwood monocultures under a variety of simulated scenarios to demonstrate growth potential and economic and biological resilience. Moreover, to identify scenarios where managing pine-hardwood mixtures would be most appropriate, and to help conceptualize landowner interest in mixed stands, we present a guide combining biological, economic, and sociocultural factors that we anticipate influencing the adoption of mixed-stand management. The aim of this conceptual paper is not to suggest that mixed-species stand management should become the dominant management paradigm; rather, we seek to encourage researchers and land managers to consider it as part of the broader silvicultural toolbox.

Optimal forest management of pure and mixed forest plantations in the southeastern United States

“…For the three applied interest rates of 3%, 6% and 9%, mixtures with 25% and 50% hardwoods produced higher LEVs than pure loblolly stands. These results contradict the results obtained by Willis et al (2019). For an 8% interest rate and a 30-year rotation length, they found higher LEVs for pure pine stands than for pinesweetgum mixtures.…”

“…As it is self-calibrating, the FVS growth models match the measured growth rates of a particular location consistent with the source of the input data. The FVS is, therefore, capable of adapting to local conditions (Crookston and Dixon, 2005) and has been widely employed in forest growth simulations (Susaeta et al 2021;Willis et al 2019).…”

“…Fortunately, we do not have to start from scratch. Willis et al (2019) assessed the management of mixed stands containing pine and hardwood mixtures in the southeastern United States (US). They calculated land expectation values for pure sweetgum stands, pure pine stands and pine and sweetgum mixtures, with and without high mortality rates caused by insect outbreaks, nding that pure pine stands have the highest land expectation values but the mixed stands showed lower losses in the event of signi cant insect outbreaks.…”

Mixedwood management positively affects forest health during insect infestations in eastern North America1

“…However, many of the forests in the mid-Atlantic and northeastern US impacted by gypsy moth infestations are intermediate aged, following recovery from extensive logging, agricultural use and abandonment, and in some areas, severe wildfires, and thus do not encompass the full range of age classes (Pan et al 2011;Duveneck et al 2017;Stambaugh et al 2018). As these forests age, simulating natural successional processes (or delaying them) through silvicultural management to create more resistant and resilient mixedwood forests is possible (Webster et al 2018;Willis et al 2019;Kenefic et al 2021). Treatments combining multi-aged mixedwood management in the prescription could be particularly successful (Castagneyrol et al 2020).…”

“…Global prices for pulpwood are relatively low, with abundant supply from international sources (e.g., Australia, Brazil, Chile). This has driven a recent reevaluation of short-rotation pine production in the southeastern and mid-Atlantic US for some landowners, with longer-rotation mixedwood forest management as an option (Willis et al 2019).…”