Disturbance‐accelerated succession increases the production of a temperate forest

Abstract

Many secondary deciduous forests of eastern North America are approaching a transition in which mature early‐successional trees are declining, resulting in an uncertain future for this century‐long carbon (C) sink. We initiated the Forest Accelerated Succession Experiment (FASET) at the University of Michigan Biological Station to examine the patterns and mechanisms underlying forest C cycling following the stem girdling‐induced mortality of >6,700 early‐successional Populus spp. (aspen) and Betula papyrifera (paper birch). Meteorological flux tower‐based C cycling observations from the 33‐ha treatment forest have been paired with those from a nearby unmanipulated forest since 2008. Following over a decade of observations, we revisit our core hypothesis: that net ecosystem production (NEP) would increase following the transition to mid‐late‐successional species dominance due to increased canopy structural complexity. Supporting our hypothesis, NEP was stable, briefly declined, and then increased relative to the control in the decade following disturbance; however, increasing NEP was not associated with rising structural complexity but rather with a rapid 1‐yr recovery of total leaf area index as mid‐late‐successional Acer, Quercus, and Pinus assumed canopy dominance. The transition to mid‐late‐successional species dominance improved carbon‐use efficiency (CUE = NEP/gross primary production) as ecosystem respiration declined. Similar soil respiration rates in control and treatment forests, along with species differences in leaf physiology and the rising relative growth rates of mid‐late‐successional species in the treatment forest, suggest changes in aboveground plant respiration and growth were primarily responsible for increases in NEP. We conclude that deciduous forests transitioning from early to middle succession are capable of sustained or increased NEP, even when experiencing extensive tree mortality. This adds to mounting evidence that aging deciduous forests in the region will function as C sinks for decades to come.

Unraveling Forest Complexity: Resource Use Efficiency, Disturbance, and the Structure‐Function Relationship

“…More moderate disturbances such as thinning and selective harvest could be contributing to increased CSC within the study area, through assisting in the transition to uneven aged stands (Gough et al., 2021). This is observed at site SE6, which consists of a 19‐year‐old mixed aspen, white spruce, and balsam fir stand, a 22‐year‐old jack pine stand, a 75‐year‐old aspen stand, and a 92‐year‐old mixed upland hardwood stand (Figure 2).…”

Climate Drives Modeled Forest Carbon Cycling Resistance and Resilience in the Upper Great Lakes Region, USA

“…Many studies have investigated water, nutrients, and C cycling in post‐disturbance ecosystems (Amiro et al., 2010 ; Edburg et al., 2012 ; Gough et al., 2013 ; Matheny et al., 2014 ). However, the effects of interacting disturbances (Liang et al., 2016 ), disturbance severity (Stuart‐Haëntjens et al., 2015 ), disturbance‐climate interactions, and the longer‐term consequences of disturbances are difficult to study through observations and, therefore, less well understood (Gough, 2021 ).…”

Informing Nature‐based Climate Solutions for the United States with the best‐available science

“…Strategic deployment of new forest flux towers may be necessary, especially for NbCS focused on improved forest management, given that we still lack a clear picture for how carbon uptake varies as a function of forest age (Amiro et al, 2010; Curtis & Gough, 2018; Law et al, 2003; Novick et al, 2015). Moreover, with some exceptions (Gough et al, 2021), flux towers deployed over forests experiencing similar climate, but different management regimes, are largely absent from the networks. This knowledge gap is important to fill to constrain the potential of improved forest management as an NbCS.…”