Salvage Logging Versus the Use of Burnt Wood as a Nurse Object to Promote Post‐Fire Tree Seedling Establishment

Abstract

Intense debate surrounds the effects of post-fire salvage logging (SL) versus nonintervention policies on forest regeneration, but scant support is available from experimental studies. We analyze the effect of three post-fire management treatments on the recruitment of a serotinous pine (Pinus pinaster) at a Mediterranean mountain. Treatments were applied 7 months after the fire and differ in the degree of intervention, ranging from "no intervention" (NI, all trees left standing) to "partial cut plus lopping" (PCL, felling most of the trees, cutting the main branches, and leaving all the biomass in situ without mastication), and "SL" (felling and piling the logs, and masticating the woody debris). Seedling survival after 3 years was the highest in PCL (47.3% versus 38.7% in SL). This was associated with the amelioration of microclimatic conditions under the scattered branches, which reduced radiation and soil temperature while increasing soil moisture. Seedling density after 2 years was approximately 5.5 times higher in PCL than in SL, as in SL a large fraction of seedlings was lost as a consequence of mechanized mastication. The NI treatment showed the lowest seedling survival (17.3%). Nevertheless, seedling density was similar to SL. Seedling growth scarcely differed among treatments. Our results show that branches left onsite acted as nurse objects that improved key microclimatic conditions for seedling recruitment. This creates a facilitative interaction ideal for seedling establishment in moisture-deficient ecosystems, as it provides the benefit of a shading overstory but without underground competition.

Post-Fire Seedling Recruitment and Morpho-Ecophysiological Responses to Induced Drought and Salvage Logging in Pinus halepensis Mill. Stands

“…The transpiration values were found lower in those individuals located in areas where dead wood was removed, which could be due to stomatal closure and a fall in photosynthetic activity (mainly for obligate seeders). Protection of dead standing trees for young seedlings implies lower surface solar radiation and temperature extremes, increased soil moisture and reduced water deficit (mainly for seeders) provided by standing dead trees and coarse woody debris [8,12]. In addition, intense drought periods reduce transpiration which promotes stomatal closure and those effects may be seasonally accumulative.…”

“…After wildfires, emergency actions and post-fire management are implemented to recover ecosystems and landscapes, and salvage logging is one of the commonest tools implemented in Spain [6], and also worldwide [7,8]. The goal of implementation comprises economic, silvicultural and aesthetic objectives, as well as related benefits for the ecosystem, such as improved seedling recruitment due to mechanical scarification and soil movements [9,10].…”

Deadwood Decay in a Burnt Mediterranean Pine Reforestation

“…Salvage logging is a common silvicultural practice after fires in Mediterranean pine reforestations, as well as other parts of the world [25,26,29]. The most obvious consequence of this approach is the subsequent large-scale absence of decomposing wood.…”

“…In this sense, extensive post-fire salvage logging-i.e., the removal of the logs, usually accompanied with the in situ elimination of the rest of coarse woody debris-is a widely implemented post-fire management action that seeks to recover part of the capital of the forest as well as to prepare the terrain for post-fire restoration [25,26]. However, post-fire salvage logging may impact ecosystem functioning and the capacity for natural regeneration through a variety of processes, such as reducing nutrient and moisture availability, decreasing the necessary substrate for saproxylic organisms, diminishing advance regeneration, or increasing soil erosion, among others [25,[28][29][30][31][32]. Understanding the rate of wood decomposition after a fire is thus of great relevance to properly balance the economic benefit of quick salvage operations against the potential benefits for conservation and natural regeneration of nonintervention approaches.…”

Modelling deadwood supply for biodiversity conservation: Considerations, challenges and recommendations

“…It provides habitat for a wide range of species, including many specialists (saproxylics) which require deadwood for at least part of their life cycle (Speight 1989, Siitonen 2001. Beyond this well-recognized value as habitat for forestdwelling organisms, deadwood has been shown to reduce soil erosion (Shakesby et al 1996, Thomas et al 2000, modify soil microclimate conditions (Castro et al 2011, Marañón-Jiménez et al 2013a, and contribute to carbon storage Castro 2012, Wiebe et al 2012) and nutrient cycling processes (Harmon et al 1986, Krankina et al 1999, Brais et al 2006, Marañón-Jiménez et al 2013b). Although it is not possible to harvest and manage forests in a way that maintains natural levels of deadwood everywhere, it is generally understood that retention and future recruitment (i.e., continued supply) of deadwood is an important element requiring careful consideration within the context of ecosystem management.…”