The Importance of Microtopography and Nurse Canopy for Successful Restoration Planting of the Slow-Growing Conifer Pilgerodendron uviferum

Jan Bannister,Rafael Coopman,Pablo Donoso,Jürgen Bauhus

doi:10.3390/f4010085

Jan Bannister, Rafael Coopman + Show 2 more

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https://doi.org/10.3390/f4010085

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Journal: Forests	Publication Date: Jan 16, 2013
Citations: 44	License type: CC BY 4.0

Affiliation: University of Freiburg, Austral University of Chile

Abstract

Recent studies have shown that, owing to a lack of seed trees, the natural rate of recovery of fire-disturbed bog forests previously dominated by the endemic and endangered conifer Pilgerodendron uviferum (D. Don) Florin is extremely slow. Hence, increasing the number of seed trees in the landscape through restoration planting could remove the principal biotic filter, limiting recovery of these forests. Here, we analyzed how the success of restoration plantings may be improved through the choice or manipulation of microsites in P. uviferum forests on Chiloé Island in North Patagonia. For this purpose, we manipulated microtopography in water-logged sites in bogs (mounds, flat terrain, mineral soil) and changed canopy conditions (gaps, semi-open, closed canopy) in upland sites with better drainage. In bogs, there was no significant effect of microtopography on growth and survival of P. uviferum plantings. However, fluorescence measurements indicated lower stress in seedlings established on mounds. Seedlings in upland areas established beneath a nurse canopy had lower mortality and higher relative shoot growth, foliar nutrients, photosynthetic light use efficiency and chlorophyll fluorescence values than those planted in the open. This indicates that seedlings of the slow growing P. uviferum can tolerate extremely wet conditions, yet suffer from stress when grown in the open. Here, the removal of canopy appeared to have also removed or reduced mycorrhizal networks for seedlings, leading to poorer nutrition and growth. Based on these results, recommendations for restoration plantings in highly degraded P. uviferum forests are presented.

Highlights

Successful restoration of degraded ecosystems often depends on the removal of the influences leading to degradation, but this will not always be sufficient to achieve the desired restoration [1].Generally, forest restoration has been divided into “passive” and “active” approaches, where the former comprises removal of environmental stressors and use of successional processes to restore ecosystems and the latter refers to artificial regeneration through planting or sowing, burning and/or thinning to achieve or promote the desired structure or development [2,3]
Recent studies have shown that the natural rate of recovery of fire-disturbed bog forests previously dominated by P. uviferum is limited by the low number of seed trees that survived disturbance or emerged post disturbance [6]
Mortality and survival of P. uviferum seedlings in bogs were highly variable within treatments, there was no significant effects of substrate type (Figure 3a)

Summary

Introduction

Successful restoration of degraded ecosystems often depends on the removal of the influences leading to degradation, but this will not always be sufficient to achieve the desired restoration [1].Generally, forest restoration has been divided into “passive” and “active” approaches, where the former comprises removal of environmental stressors and use of successional processes to restore ecosystems and the latter refers to artificial regeneration through planting or sowing, burning and/or thinning to achieve or promote the desired structure or development [2,3]. Pilgerodendron uviferum occurs in bog forests in high rainfall environments (2500–8000 mm per year) that cover almost 1 million ha from 40° S to 55° S and are often found on acidic and poorly-drained soils [5]. In the landscape of Chiloé and other areas of Patagonia, P. uviferum dominated forests are located in two topographical types: “bog areas” located in flat areas on raised peat bogs; and “upland areas” on hills shaped by till with better drainage [6]. Recent studies have shown that the natural rate of recovery of fire-disturbed bog forests previously dominated by P. uviferum is limited by the low number of seed trees that survived disturbance or emerged post disturbance [6]. The conservation status of the species considered by the IUCN is vulnerable [8], and it has been included in Appendix I of CITES [5]

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