Natural regeneration and biodiversity: a global meta‐analysis and implications for spatial planning

Abstract

Natural regeneration offers a cheaper alternative to active reforestation and has the potential to become the predominant way of restoring degraded tropical landscapes at large-scale. We conducted a meta-analysis for tropical regions and quantified the relationships between both ecological and socioeconomic factors and biodiversity responses in naturally regenerating areas. Biogeographic realms, past disturbance, and the human development index (HDI) were used as explanatory variables for biodiversity responses. In addition, we present a case study of large-scale natural regeneration in the Brazilian Atlantic Forest and identify areas where different forms of restoration would be most suitable. Using our dataset for tropical regions, we showed that natural regeneration was predominantly reported within: the Neotropical realm; areas that were intensively disturbed; and countries with medium HDI. We also found that biodiversity in regenerating forests was more similar to the values found in old growth forests in: countries with either low, high, or very high HDI; less biodiverse realms; and areas of less intensive past disturbance. Our case study from Brazil showed that the level of forest gain resulting from environmental legislation, in particular the Brazilian Forest Code, has been reduced, but remains substantial. Complementary market incentives and financial mechanisms to promote large-scale natural regeneration in human-modified agricultural landscapes are also needed. Our analysis provides insights into the factors that promote or limit the recovery of biodiversity in naturally regenerating areas, and aids to identify areas with higher potential for natural regeneration.Abstract in Portuguese is available with online material.

Effectiveness of passive restoration on density and diversity of regenerating tree species in mixed Dipterocarp forests of Nepal

“…We assessed seedling and sapling development under natural regeneration conditions, as ecologists have raised concerns about biodiversity, stability, and sustainability of plantations (Jordan & Farnworth ; Loo et al ) and natural regeneration was determined to be more successful than active restoration in tropical forests (Latawiec et al ; Crouzeilles et al ). Moreover, in the current scenario of downward trending in acreage of natural forest areas across the globe (Keenan et al ), forest regeneration success should be evaluated on the basis of what actually happens under natural forest conditions (Baatuuwie et al ).…”

Planting accelerates restoration of tropical forest but assembly mechanisms appear insensitive to initial composition

“…Minimal restoration intervention includes actions to remove chronic disturbance so natural succession may take place; this is also referred to as “passive” restoration (Zahawi, Reid, & Holl, ) or unassisted forest regeneration (Chazdon & Guariguata, ); whereas maximal intervention (Guzmán‐Luna & Martínez‐Garza, ), also called assisted succession (Chazdon & Guariguata, ), involves restoration plantings. Minimal intervention is suggested for landscapes with existing seed sources and resulting communities should ultimately resemble the original communities (Latawiec et al., ); this approach is cheaper and is therefore easier to implement at larger scales (Chazdon & Guariguata, ), although some hidden costs have been identified (Zahawi et al., ). On the other hand, even when restoration plantings are expensive, they may decrease species loss (Martínez‐Garza & Howe, ) by favouring the establishment of vulnerable tree species (de la Peña‐Domene, Minor, & Howe, ).…”

Look down—there is a gap—the need to include soil data in Atlantic Forest restoration

“…Deforested and fragmented landscapes compromise the provision of ecosystem services such as biodiversity conservation, water quality and quantity regulation, carbon storage, and soil protection (Gama‐Rodrigues et al ; Ditt et al ). In response to land degradation and the need to recover services that ecosystems provide, such as biodiversity (Latawiec et al ; Crouzeilles et al ), carbon (Porter et al ), or water (Ferraz et al ), restoration has gained increased interest and has been promoted globally and locally (Aronson et al ). For instance, the Bonn Challenge sets a goal to restore worldwide 150 million hectares of disturbed ecosystems and the 20x20 Initiative aims to bring 20 million hectares into restoration, both by 2020.…”