Natural forest regeneration and ecological restoration in human‐modified tropical landscapes

Abstract

In human-modified tropical landscapes (HMLs) the conservation of biodiversity, functions and services of forest ecosystems depends on persistence of old growth forest remnants, forest regeneration in abandoned agricultural fields, and restoration of degraded lands. Understanding the impacts of agricultural land uses (ALUs) on forest regeneration is critical for biodiversity conservation in HMLs. Here, we develop a conceptual framework that considers the availability of propagules and the environment prevailing after field abandonment as two major determinants of forest regeneration in HMLs. The framework proposes that regeneration potential decreases with size, duration and severity of agricultural disturbance, reducing propagule availability and creating ill-suited environmental conditions for regeneration. We used studies from Southern Mexico to assess this framework. First, we identify regeneration bottlenecks that trees face during transit from seed to follow-up life stages, using demographic analysis of dominant pioneer species in recently abandoned fields. Then, we explore effects of ALUs on forest regeneration at the field and landscape scales, addressing major legacies. Finally, we integrate agricultural disturbance with landscape composition to predict attributes of successful second growth forests in HMLs, and provide indicators useful to select tree native species for active restoration. An indicator of disturbance inflicted by ALUs, based on farmers' information, predicted better regeneration potential than measurements of soil and microclimate conditions at time of abandonment. Cover of cattle pastures in the landscape was a stronger indicator of forest regenerating attributes than cover of old growth forest remnants. To conclude, we offer recommendations to promote forest regeneration and biodiversity conservation in HMLs.Abstract in Spanish is available with online material.

International principles and standards for the practice of ecological restoration. Second edition

“…By understanding how recovery processes operate in cases of natural disturbances, strategies for the restoration of human‐caused degradation can be developed (Cairns Jr et al ; Chazdon ). Correctly assessing the capacity of individual species to regenerate at a specific site facilitates selection of appropriate approaches and treatments, thus enabling efficient use of financial resources and other restoration inputs (McDonald ; Martínez‐Ramos et al ).…”

Active rehabilitation of Amazonian sand mines converges soils, plant communities and environmental status to their predisturbance levels

“…The conservation of the unique biodiversity of this forest, one of the largest challenges of the present century (Glamann, Hanspach, Abson, Collier, & Fischer, ; Rands et al, ), depends on the protection of old‐growth forests within large conservation units. Additionally, the rehabilitation of degraded areas including minelands is expected to contribute to the maintenance of biodiversity and ecosystem services (Chazdon et al, ; Martínez‐Ramos et al, ; Poorter et al, ). As rehabilitation paths depend on many factors, continuous monitoring of these sites is required to provide assessments of the quality of rehabilitating areas for environmental agencies and to identify deviations from desired trajectories and project failures when they arise (Favas, Martino, & Prasad, ; Matthews & Spyreas, ).…”

Intensive silviculture enhances biomass accumulation and tree diversity recovery in tropical forest restoration

“…Intensive silviculture may, however, hamper natural forest regeneration and ecological succession if planted trees rapidly dominate the system and use most of the environmental resources available at the site. Natural regeneration of spontaneously regenerating plants is considered a key ecological process for tropical forest restoration success (Suganuma and Durigan 2015, Viani et al 2015, Wheeler et al 2016, and impeding it has serious negative consequences for the ecological sustainability of restored forests (Parrotta et al 1997, Mart ınez-Ramos et al 2016, C esar et al 2018.…”