Post‐fire salvage logging alters a key plant‐animal interaction for forest regeneration

J. Castro,C. Puerta-Piñero,A. Sánchez-Miranda,G. Moreno-Rueda,A. B. Leverkus

doi:10.1890/es12-00089.1

Abstract

Post‐fire salvage logging is widely implemented worldwide, but there is an increasing concern about its potential impact on the ecosystem. Moreover, there is scant information about the effect of salvage logging on ecosystem processes mediated by species interactions. We manipulated a burnt pine forest to experimentally analyze the effect of burnt‐wood management on the colonization of Holm oak (Quercus ilex) mediated by acorn dispersal by Eurasian jays (Garrulus glandarius). Three replicates of three treatments were established in an 18‐ha plot: salvage logging (SL), non‐intervention (NI), and partial cut plus lopping (PCL; felling and lopping most of the trees but leaving all the biomass in situ). We hypothesized that different burnt‐wood management could alter jays' landscape perception and thus the pattern of seed dispersal and seedling recruitment. We monitored jay abundance in each treatment for three winters and three breeding periods, and jay flights of potential acorn dispersal between nearby oak trees and the treatments. We also searched for oak seedlings recruited in the experimental plot for five years following the fire. Jays were recorded significantly more times (87%) in NI, and movements to this treatment during the acorn dispersal period were also more frequent (81% of the flights). Oak seedlings were also more abundant in NI (ca. 55%) than in SL or PCL (ca. 25% each), despite a strong effect of small remnants of live pines. The results show that the burnt forest, if unsalvaged, still provides a suitable habitat for jays, while salvage logging reduces the strength of this key plant‐animal interaction for oak natural regeneration. Non‐intervention policies after a forest fire therefore provide the opportunity for adaptive management that helps reduce restoration costs and increase the resilience of the system.

Highlights

After a forest fire it is customary that the local forest service removes the burnt logs from the site, a process that is referred to as salvage logging and that often involves the elimination of the remaining woody debris such as branches and snags by chopping, mastication, etc. (McIver and Starr 2000, Lindenmayer et al 2008)
The analysis of the effect of salvage logging on organisms has largely focused on its impact on diversity or on specific groups of species, whereas its effect on ecosystem processes has been focused on abiotic factors such as microclimate, hydrology, erosion, or nutrient cycling (Lindenmayer et al 2008, Maranon-Jimenez and Castro, in press)
The analysis of the different phases involved in Holm oak colonization of burnt areas supports a Number of flights

Summary

Introduction

After a forest fire it is customary that the local forest service (whether directly or through private counterparts) removes the burnt logs from the site, a process that is referred to as salvage logging and that often involves the elimination of the remaining woody debris such as branches and snags by chopping, mastication, etc. (McIver and Starr 2000, Lindenmayer et al 2008). Several reasons are invoked to support this practice, coming from economics (return of economic capital of wood), silvicultural (e.g., greater ease of future reforestation, reduction of fire and pest risk), visitor safety, or even aesthetics (McIver and Starr 2000, Lindenmayer et al 2008, Mavsar et al 2011) Many of these reasons are, controversial (e.g., Castro et al 2011), and an increasing number of studies are showing that salvage logging may have strong negative impacts on ecosystem processes, such as a reduction of the natural capacity for the regeneration of tree species (Donato et al 2006, Castro et al 2011), lesser diversity of plant and animal communities (McIver and Starr 2000, Castro et al 2010a), or increases in soil erosion and watershed runoff (Beschta et al 2004, Karr et al 2004, Lindenmayer et al 2008). The way in which post-fire management affects these interactions will determine the success or failure of other important ecosystem services such as ground cover, carbon fixation, or the scenic view of the landscape, among others (Millennium Ecosystem Assessment 2005, Lindenmayer et al 2008, Serrano-Ortiz et al 2011)

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