Salvage-Logging after Windstorm Leads to Structural and Functional Homogenization of Understory Layer and Delayed Spruce Tree Recovery in Tatra Mts., Slovakia

Abstract

Stand-replacing disturbance and post-disturbance salvage-logging influence forest succession in different ways; however, limited knowledge regarding how salvage-logging affects vegetation patterns compared to natural development of forest ecosystems is still lacking. In this study, we described the diversity pattern of understory vegetation and tree regeneration in mountain spruce forest of Tatra Mountains, northern Slovakia, where a high severity windstorm affecting over 10,000 ha occurred in 2004. The area was consequently subjected to salvage-logging. We asked how the species composition, vegetation diversity, and its spatial heterogeneity were modified by severe salvage-logging. Vascular plants, deadwood coverage, and tree species densities were monitored on non-intervention (NI; n = 108) and salvage-logged (SL; n = 95) experimental plots (spatially nested design, sample plot area 3.14 m 2 ) six and seven years after disturbance, respectively. The NI sites were structurally more diverse with post-windstorms legacies such as deadwood and pit and mound topography being recorded. The NI plots contained more late-successional plant and moss species that are commonly found in the pre-disturbance forest. The NI plots were also more diverse in terms of alpha-and beta-diversity with abundant natural regeneration of Norway spruce (Picea abies (L.) Karst). The structure of SL site was more homogeneous and its species composition shifted towards being dominated by grasses, although the site accommodated a higher number of plant species due to newly established pioneer plant-and tree species. The retreat of late-successional species in favour of grasses can lead to structural and functional homogenization of habitat and to delayed succession towards establishment of spruce forest. We conclude that the removal of wind-disturbance legacies significantly diverts natural successional pathways. We recommend avoiding salvage-logging in protected areas since large-scale application of salvage-logging reduces beta-diversity of the landscape.

Evaluating Short-Term Impacts of Forest Management and Microsite Conditions on Understory Vegetation in Temperate Fir-Beech Forests: Floristic, Ecological, and Trait-Based Perspective

“…Changes in EIVs after the cutting treatments were most significant for light; plot-level EIV-L increased in both the 50% and 100% cutting. This is because of the increased richness and cover of early successional light-demanding species in management-created canopy gaps, a general pattern occurring in post-management conditions [68]. Mean EIV-F significantly decreased in canopy gaps (Figure 5d), indicating that some plant species that were more adapted to drier soil conditions colonized the gaps.…”

Short-Term Dynamics of Vegetation Diversity and Aboveground Biomass of Picea abies (L.) H. Karst. Forests after Heavy Windstorm Disturbance

“…Salvage logging certainly favored also high abundance of grasses. Several studies identified higher species richness and cover of graminoids at salvage-logged compared to non-intervention sites which likely triggered also different successional trajectories of post-disturbance herb layer vegetation [11,51,52]. Decline of grasses identified in our study possibly induces a compositional convergence of salvage-logged and non-intervention sites, however, our study did not examine successional processes following different management approaches, thus further research is needed to verify this assumption.…”

“…However, the period of four years our study is based on is likely too short to observe any significant changes. Perhaps, this might be related to lower levels of spatial heterogeneity [52] and also faster homogenization of young forest structure [53] at salvage-logged sites as this type of post-disturbance management was applied at our transects. Salvage logging certainly favored also high abundance of grasses.…”

Influence of different forest protection strategies on spruce tree mortality during a bark beetle outbreak

“…At the initial stage of an outbreak, sanitary management may prove effective. When a bark beetle outbreak reach an epidemic stage, the rate of sanitary cutting in the buffer zone may lead to large areas that have clear cuts and changed paths for forest succession in the buffer zone (Michalová et al 2017). In this case, decisionmaking bodies face a tough decision: either they should continue to use sanitary management in the buffer zone or they should look for other solutions, such as changes in the zonation of a protected area.…”

“…In the case of bark beetle epidemics in the core zone of a national park, these buffer zones can act as a bulwark against the spread of bark beetle infestations into managed forests. However, removal of wind-thrown trees can alter successional pathways compared to no-intervention areas (Michalová et al 2017;Thorn et al 2017); there is pressure from forest owners outside the park to stop or slow the spread of bark beetle outbreak leading to bark beetle suppression in the buffer zone. The highest intensity of sanitary management will usually focus on this area.…”