The framework species method: harnessing natural regeneration to restore tropical forest ecosystems

Abstract

As interest in restoring tropical forests surges, so does the need for effective methods to ensure success. The framework species method (FSM) restores forest ecosystems by densely planting open sites, close to natural forest, with woody species, indigenous to the reference ecosystem and selected for their ability to accelerate ecological succession. Criteria for selecting framework species include: (i) representative of the reference forest ecosystem, (ii) tolerant of open conditions, (iii) ability to suppress weeds, (iv) attractiveness to seed-dispersing animals and (v) easily propagated. The method is effective where forest remnants and viable populations of seed dispersers remain. The origins and elements of the FSM are discussed. We review its adoption in 12 countries. Adherence to original principles was mostly high, but some misuse of the term was evident. The need for clearer definitions was identified. We place the FSM on a scale of restoration methods, matched with degradation levels and compare its establishment costs with those of other methods. Obstacles to its wider adoption, both technical and socio-economic, are discussed, along with how these might be overcome. Finally, the FSM is more clearly defined to facilitate its use in contributing towards the goals of the UN Decade on Restoration. This article is part of the theme issue ‘Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration’.

A practice-led assessment of landscape restoration potential in a biodiversity hotspot

“…Research shows that the land area affected by wildfires decreases dramatically where canopy cover exceeds 40 ± 10% [52] Firebreak cutting≥ 40 (≥ 30 to ≥ 50)AnyAny Grass cutting≥ 40 (≥ 30 to ≥ 50)AnyAnyForest/savanna/agro-ecological mosaic Framework planting≥ 65 and < 95 (≥ 50 and < 90; ≥ 80 and < 100)Any≥ 200 (≥ 100 to ≥ 300) intactBased on AGB estimates for sites known by the authors to have significantly reduced ecosystem function in the study region, areas with ≥65 ± 15% AGB deficit were assumed to require planting to restore. Framework species planting [53] was planned in areas > 100–300 m from nearby intact forest (< 40–80% deficit) and savanna/agro-ecological mosaic (< 40–50% deficit), where seed dispersal was assumed to be restricted [16,17,54]. Severely degraded sites with ≥ 95 ± 5% AGB deficit were assumed to require soil improvement ([55] and [56]) followed by planting pioneer, nitrogen-fixing plants to be replaced with native trees over time [19] Soil improvement and nurse planting≥ 95 (≥ 90 to ≥ 100)AnyAny…”

“…shows that the land area affected by wildfires decreases dramatically where canopy cover exceeds 40 ± 10% [52] Firebreak cutting ≥65 ± 15% AGB deficit were assumed to require planting to restore. Framework species planting [53] was planned in areas > 100-300 m from nearby intact forest (< 40-80% deficit) and savanna/ agro-ecological mosaic (< 40-50% deficit), where seed dispersal was assumed to be restricted [16,17,54]. Severely degraded sites with ≥ 95 ± 5% AGB deficit were assumed to require soil improvement ( [55] and [56]) followed by planting pioneer, nitrogen-fixing plants to be replaced with native trees over time [19] Soil improvement and nurse planting produced in ArcGIS Pro version 2.7.1 [58].…”

Fifteen essential science advances needed for effective restoration of the world's forest landscapes

“…This is despite degraded soils presenting the greatest ecological challenge for forest restoration, requiring the highest cost and level of management input [ 95 ]. In this theme issue, a review of tree-planting approaches indicates that the plant–soil interface should be considered when selecting species for planting; survival may be enhanced by species with key functional traits [ 96 ]. For example, and also in this theme issue, Werden et al .…”

“…And yet, even relatively established procedures for species selection do not include steps to help reconcile these contrasts, e.g. through engagement with all local stakeholders [ 96 ]. To feed into this, more research is needed on species–site matching, considering social and biophysical factors, across a broader range of sites and on planting procedures for ecosystem functioning and restoration outcomes.…”

“…In this theme issue, a critique of the widely employed Framework Species Approach shows that procedures for selecting species are inconsistent and ill-defined [ 96 ]. Accordingly, new data in the theme issue show that plantings are often species-poor [ 69 ], which may be partly due to limited infrastructure to access local seed sources or limited knowledge of nursery practices for a broad set of species.…”