This title can be completed in many different ways and for most of them it would hold true. To the readers of this blog the statement is familiar from the world of quarries.
But the authors of a Science Advances magazine article Crouzeilles et al. (2017) have just published the result of a meta-study on tropical forest restoration including 133 published works.
Ecological restoration success is higher for natural regeneration than for active restoration in tropical forests (DOI: 10.1126/sciadv.1701345).
The authors ask the question is planting the best approach to achieve ecological restoration success (the return to a reference condition, that is, old-growth forest) when compared to natural regeneration in tropical forests?
Their meta-analysis of 133 studies demonstrated that natural regeneration surpasses active restoration in achieving tropical forest restoration success for all three biodiversity groups (plants, birds, and invertebrates) and five measures of vegetation structure (cover, density, litter, biomass, and height) tested.
Their finding challenges the widely held notion that natural forest regeneration has limited conservation value and that active restoration should be the default ecological restoration strategy. The authors explain the prevailing opinion that active restoration achieves greater restoration success than natural regeneration with flawed study design that lacked controls for biotic and abiotic factors. Given the cost-effectiveness of natural regeneration , the author argue that these methods should be given higher priority when policies and plans for forest restoration are made.