Aboveground Wood Production Is Sustained in the First Growing Season after Phloem-Disrupting Disturbance

Abstract

Carbon (C) cycling processes are particularly dynamic following disturbance, with initial responses often indicative of longer-term change. In northern Michigan, USA, we initiated the Forest Resilience Threshold Experiment (FoRTE) to identify the processes that sustain or lead to the decline of C cycling rates across multiple levels (0, 45, 65 and 85% targeted gross leaf area index loss) of disturbance severity and, in response, to separate disturbance types preferentially targeting large or small diameter trees. Simulating the effects of boring insects, we stem girdled > 3600 trees below diameter at breast height (DBH), immediately and permanently disrupting the phloem. Weekly DBH measurements of girdled and otherwise healthy trees (n > 700) revealed small but significant increases in daily aboveground wood net primary production (ANPPw) in the 65 and 85% disturbance severity treatments that emerged six weeks after girdling. However, we observed minimal change in end-of-season leaf area index and no significant differences in annual ANPPw among disturbance severities or between disturbance types, suggesting continued C fixation by girdled trees sustained stand-scale wood production in the first growing season after disturbance. We hypothesized higher disturbance severities would favor the growth of early successional species but observed no significant difference between early and middle to late successional species’ contributions to ANPPw across the disturbance severity gradient. We conclude that ANPPw stability immediately following phloem disruption is dependent on the continued, but inevitably temporary, growth of phloem-disrupted trees. Our findings provide insight into the tree-to-ecosystem mechanisms supporting stand-scale wood production stability in the first growing season following a phloem-disrupting disturbance.

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

“…Each severity treatment was applied within four different land ecosystems, representing a range in site productivity characteristic of the forests of the Upper Great Lakes Region (Atkins et al., 2020 ). Starting a year before the disturbance treatments were applied in 2018 C and nitrogen cycling, canopy structure, photosynthesis, biomass growth, and soil respiration were recorded (Grigri et al., 2020 ), documented, published, and distributed via the fortedata R package (Atkins et al., 2020 ).…”

“…Multi‐dimensional stability frameworks provide a basis for systematically decomposing and analyzing various features of disturbance response facilitating comparisons between different sources (i.e., studies, field or model observations) (Egli et al., 2019 ; Harrison, 1979 ; Mathes et al., 2021 ; Pimm, 1984 ). As part of FoRTE (Grigri et al., 2020 ; Gough, Bohrer & Curtis, 2021 ; Gough, Bohrer, Hardiman, et al., 2021 ), we have adopted the Hillebrand et al. ( 2018 ) multidimensional stability framework, described by Mathes et al.…”

Disturbance‐accelerated succession increases the production of a temperate forest

“…2012), girdled trees’ growth declined over a period of several years, slower than that following wind, fire, or felling, and may have been particularly gradual because of aspen’s large pool of non‐structural carbohydrates and intertwined clonal root system (Landhausser and Lieffers 2002, Grigri et al. 2020). Our targeted elimination of two tree genera is also representative of boring insect and pathogen host specificity (Lovett et al.…”

Structural complexity and primary production resistance are coupled in a temperate forest

“…Subcanopy, upper canopy, and total aboveground wood net primary production (ANPP w ) were calculated using protocols detailed by Grigri et al (2020) and Atkins et al (2021). Our approach used repeated measurements of DBH to infer the woody biomass increment from 1 year to the next.…”

“…Unlike severe disturbance, partial or moderate severity disturbances may cause patchy, species-specific tree mortality or eliminate entire plant functional groups and, consequently, dramatically reshape forest structure while producing gradients of disturbance severity across forest landscapes (Atkins et al, 2020). Yet, the degree to which these resulting changes in forest structure correspond with C cycling responses to partial disturbance, including net primary production (NPP), is unclear (Fahey et al, 2016;Gough et al, 2020;Grigri et al, 2020).…”