Comparing the success of active and passive restoration in a tropical cloud forest landscape: A multi-taxa fauna approach

Abstract

Tropical forest restoration initiatives are becoming more frequent worldwide in an effort to mitigate biodiversity loss and ecosystems degradation. However, there is little consensus on whether an active or a passive restoration strategy is more successful for recovering biodiversity because few studies make adequate comparisons. Furthermore, studies on animal responses to restoration are scarce compared to those on plants, and those that assess faunal recovery often focus on a single taxon, limiting the generalization of results. We assessed the success of active (native mixed-species plantations) and passive (natural regeneration) tropical cloud forest restoration strategies based on the responses of three animal taxa: amphibians, ants, and dung beetles. We compared community attributes of these three taxa in a 23-year-old active restoration forest, a 23-year-old passive restoration forest, a cattle pasture, and a mature forest, with emphasis on forest-specialist species. We also evaluated the relationship between faunal recovery and environmental variables. For all taxa, we found that recovery of species richness and composition were similar in active and passive restoration sites. However, recovery of forest specialists was enhanced through active restoration. For both forests under restoration, similarity in species composition of all faunal groups was 60–70% with respect to the reference ecosystem due to a replacement of generalist species by forest-specialist species. The recovery of faunal communities was mainly associated with canopy and leaf litter covers. We recommend implementing active restoration using mixed plantations of native tree species and, whenever possible, selecting sites close to mature forest to accelerate the recovery of tropical cloud forest biodiversity. As active restoration is more expensive than passive restoration, both strategies might be used in a complementary manner at the landscape level to compensate for high implementation costs.

Combating Desertification through Enhancement of Woody Floral Diversity in the Drylands of Kenya: Analysis, Milestones, and Strategies

“…There is little consensus on whether active or passive restoration strategies are more successful for recovering biodiversity because few studies make adequate comparisons [41]. In some studies, recovery of species' richness and composition is similar in active-and passive-restoration sites, while in others, recovery of forest specialists is enhanced through active restoration [40,41].…”

“…There is little consensus on whether active or passive restoration strategies are more successful for recovering biodiversity because few studies make adequate comparisons [41]. In some studies, recovery of species' richness and composition is similar in active-and passive-restoration sites, while in others, recovery of forest specialists is enhanced through active restoration [40,41]. While both restoration strategies may lead to different vegetation structures, they may support similar biomass of foliage-dwelling arthropods and be similarly used by foraging insectivorous birds [40].…”

“…Effective restoration and rehabilitation of degraded drylands require a combination of policies and technologies and the close involvement of local communities. There are two categories of landscape-restoration methods that are commonly applied in the drylands: active restoration and passive restoration [40,41].…”

Acceleration of Forest Structural Development for Large Trees and Mammals: Restoration in Decades or Centuries?

“…This question is particularly germane as we enter 2021-2030 which the United Nations General Assembly has declared as the "Decade on Ecosystem Restoration" [31]. There is much controversy over the relative successes of "active" vs. "passive" restoration, but few studies have focused on animals and their responses to forest recovery [32].…”

Rewilding and restoring nature in a changing world

“…For example, Broughton et al [4] found that secondary woodlands in England that were adjacent to ancient woodlands recovered naturally over a period of a few decades. Díaz-García et al [10] compared recovery of amphibians, ants, and dung beetles in naturally regenerating and actively planted tropical forests in Mexico; they found that passive and active restoration approaches were similarly effective in restoring species richness of all guilds, but that forest specialists were enhanced through active planting. In contrast, other studies show that intensive anthropogenic interventions such as transplanting corals (Ferse et al [11]), or controlling invasive species and reintroducing fauna (Roberts et al [12]) are necessary to facilitate recovery.…”