Restoration over time: is it possible to restore trees and non‐trees in high‐diversity forests?

Abstract

Questions Do different growth forms have distinct temporal patterns of recovery of their structure, diversity, and composition in restored Atlantic Rain forest? Are tree and non‐tree assemblages structured by the same factors? Location Atlantic Rain Forest, restored by planting an assemblage of high‐diversity tree species, Brazil. Methods We measured plant colonization of restoration sites of different ages to evaluate restoration success in terms of species diversity, colonization by non‐tree species and structure measures among stands. We used Procrustes analysis to test whether the same conditions that influence tree composition influence non‐tree composition (congruence between non‐trees and trees present on the same sites). Results Many structural aspects of recovering forests, e.g. tree basal area, canopy cover, height, tree richness, and non‐tree floristic composition resembled a mature forest within five decades. Although tree species diversity increased according to restoration age of sites, planted sites did not recover the richness of all growth forms even after five decades of restoration, and particularly lacked climbers and epiphytes. We detected significant similarity between corresponding points (tree and non‐tree composition) from separate ordinations only in the reference forest. Therefore, naturally assembled communities are more concordant than those originating from active restoration. Conclusion Non‐tree assemblages respond to different factors than the tree assemblages in restoration sites. Hence, non‐tree recovery may not result as a natural consequence of tree recovery, and specific restoration strategies for non‐tree species must be applied. Tree richness recovered after two decades. Only half of the non‐tree species richness was recovered in old restoration sites, but their composition similarity reached expected levels of reference values. Further studies will investigate if low richness of non‐tree species is a consequence of low input of allochthonous propagules (landscape filter) or whether they are arriving but not establishing (environmental filter). Enrichment planting of non‐tree species may be required if the problem is propagule input. We recommend enrichment planting should be implemented within 10 yrs after initial restoration planting because of the need for trees as supporting structures. However, if propagules are arriving but not establishing, the solution is to detect which environmental filters are important and to manipulate them through forest management.

Colonization of woody seedlings in the understory of actively and passively restored tropical moist forests

“…As restoration sites mature, microsite limitations may be modulated, which facilitates more seedling colonization in older than younger sites (Bertacchi et al 2016), implying that microsites are a stronger limiting factor to seedling colonization in younger than older sites. The progressive increase of diversity and richness with age shown by this study, and other ecosystem components such as trees (Garcia et al 2016), arthropods (Nyafwono et al 2014) reported in previous studies highlight the biodiversity benefits of continued management of restored forests.…”

Assessment of the nursery species pool for restoring landscapes in southeastern Brazil

“…Furthermore, the restoration species pool constituted a narrow spectrum of growth forms that lack or underrepresent lianas, epiphytes, and herbs. Likewise, other studies regarding plant nursery diversity in tropical regions (specifically in Panama, Philippines, and Mexico) (Román et al 2012;Gregorio et al 2017;Ramírez-Soto et al 2018) confirmed the bias toward tree species, despite the relevant role these growth forms play in ecological restoration (Campbell et al 2015;Garcia et al 2016;Mayfield 2016). This fact reinforces the practical gaps related to the restoration of nonforest ecosystems in the tropics, where restoration demand is increasing and propagation knowledge is lacking (Overbeck et al 2013;Veldman et al 2015).…”

Comparing the recovery of richness, structure, and biomass in naturally regrowing and planted reforestation

“…Eucalyptus species), or reflect biases in tubestock availability. Biased patterns of growth‐form recovery have been commonly observed in active restoration of other vegetation types (Munro et al ; Nichols et al ; Garcia et al ). Our results suggest that, when mature, vegetation structure in plantings may be less complex than remnant stands, which has been shown to reduce the maximum carbon that can be stored as woody biomass (Ford & Keeton ).…”