The importance of seed trees in the dioecious coniferPilgerodendron uviferumfor passive restoration of fire disturbed southern bog forests

Abstract

Biological legacies are important for ecosystem recovery following disturbance as demonstrated by studies in the northern hemisphere. Southern bog forests dominated by the conifer Pilgerodendron uviferum in Northern Patagonia are a typical case of an ecosystem with low resilience to disturbance by fire, which kills most trees and seeds, on which the species depends for regeneration. In this study, we hypothesize that the natural recovery of P. uviferum populations in burned areas is limited by seed availability and this limitation may be exacerbated by the dioecy of the species. Using a multi-scaled approach, we quantified the seed dissemination potential from P. uviferum seed trees, assessed the suitability of substrates for the germination of seedlings, and finally analysed the spatial distribution of seed trees of the species at the landscape level. Our results indicate that 70 years after a fire on Chiloé Island (43°S), natural regeneration from seed trees can assist the recovery of P. uviferum populations following large-scale fire disturbance, but their effect is limited at a landscape level owing to a low number of reproductive female trees (0.3 trees ha −1 ) and limited seed dispersal (<20 m). In this context, a mixed passive-active restoration approach that takes into account the spatial pattern and sex of seed trees could be the most effective and efficient option to restore not only P. uviferum forests in North Patagonia, but also other heavily disturbed forests with few remnant seed trees, in particular of dioecious species.

Shrub influences on seedling performance when restoring the slow‐growing conifer Pilgerodendron uviferum in southern bog forests

“…Moist substrates comprising Sphagnum or mineral soil are the best substrates for the germination of P. uviferum seedlings. In contrast, dry conditions in the same substrates decreased seed germination by more than a third (Bannister et al ). Chiloé Island is located in the northern part of the distribution of P. uviferum .…”

“…After centuries of deforestation by anthropogenic fires and logging (Holz & Veblen ; Bannister et al ), Chiloé Island (North Patagonia, Chile) has seen dramatic changes from landscapes dominated by old‐growth North Patagonian evergreen forests to extensive areas of land dominated by shrubs (Bannister & Donoso ; Bannister et al ). Due to the poor drainage of the post‐glacial soils in which North Patagonian forests develop, the removal and subsequent absence of trees has had dramatic and long‐lasting effects on the water balance of these areas (Díaz et al ).…”

Browsing evidence of the native and near-threatened Pudu puda deer in restoration plantings on Chiloé Island, Chile

“…Due to forest fragmentation, degradation and heavy deforestation, restoration of native temperate forests constitutes a major challenge in Chile, especially in Chiloé Island, were currently several restoration experiments exist (Bannister et al 2016). In this island, evergreen North-Patagonian forests and Pilgerodendron uviferum (D. Don) Florin dominated bog forests are priority forests for conservation and restoration (Bannister et al 2014. While higher browsing in open FIGURE 1: Pudu puda in burned Pilgerodendron uviferum forests of Lago Chaiguata, Chiloé Island (a) and Browsing of Pudu puda inside a restoration planting (b).…”

Seed production, seed dispersal and seedling establishment of two afromontane tree species in and around a church forest: implications for forest restoration

“…Assisted natural regeneration and natural regeneration rank highest on the restoration ladder (sensu Chazdon 2008) with the highest ranks in biodiversity and ecosystem services at the lowest associated cost. These approaches, however, have the highest requirements in terms of spatial distribution of residual vegetation or biological legacies (Bannister et al 2014). In order to achieve cost-efficient and timely restoration, a combination of mixed passive and active restoration strategies are favored in certain situations (Bannister et al 2014).…”