title: Multiple successional pathways in human-modified tropical landscapes: new insights from forest succession, forest fragmentation and landscape ecology research.
abstract: Old-growth tropical forests are being extensively deforested and fragmented worldwide. Yet forest recovery through succession has led to an expansion of secondary forests in human-modified tropical landscapes (HMTLs). Secondary forests thus emerge as a potential repository for tropical biodiversity, and also as a source of essential ecosystem functions and services in HMTLs. Such critical roles are controversial, however, as they depend on successional, landscape and socio-economic dynamics, which can vary widely within and across landscapes and regions. Understanding the main drivers of successional pathways of disturbed tropical forests is critically needed for improving management, conservation, and restoration strategies. Here, we combine emerging knowledge from tropical forest succession, forest fragmentation and landscape ecology research to identify the main driving forces shaping successional pathways at different spatial scales. We also explore causal connections between land-use dynamics and the level of predictability of successional pathways, and examine potential implications of such connections to determine the importance of secondary forests for biodiversity conservation in HMTLs. We show that secondary succession (SS) in tropical landscapes is a multifactorial phenomenon affected by a myriad of forces operating at multiple spatio-temporal scales. SS is relatively fast and more predictable in recently modified landscapes and where well-preserved biodiversity-rich native forests are still present in the landscape. Yet the increasing variation in landscape spatial configuration and matrix heterogeneity in landscapes with intermediate levels of disturbance increases the uncertainty of successional pathways. In landscapes that have suffered extensive and intensive human disturbances, however, succession can be slow or arrested, with impoverished assemblages and reduced potential to deliver ecosystem functions and services. We conclude that: (i) succession must be examined using more comprehensive explanatory models, providing information about the forces affecting not only the presence but also the persistence of species and ecological groups, particularly of those taxa expected to be extirpated from HMTLs; (ii) SS research should integrate new aspects from forest fragmentation and landscape ecology research to address accurately the potential of secondary forests to serve as biodiversity repositories; and (iii) secondary forest stands, as a dynamic component of HMTLs, must be incorporated as key elements of conservation planning; i.e. secondary forest stands must be actively managed (e.g. using assisted forest restoration) according to conservation goals at broad spatial scales.
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Antigua Carretera a Patzcuaro 8701, Ex-hacienda de San Jose de la Huerta, Morelia 58190, Michoacán, Mexico.
authors.forename: Víctor
authors.initials: V
authors.lastname: Arroyo-Rodríguez
authors.affiliation: Departamento de Botânica, Universidade Federal de Pernambuco, Av. Professor Morais Rego, 1235 - Cidade Universitária, Recife, Pernambuco 50670-901, Brazil.
authors.forename: Felipe P L
authors.identifier: http://orcid.org/0000-0002-1271-3214
authors.initials: FP
authors.lastname: Melo
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Antigua Carretera a Patzcuaro 8701, Ex-hacienda de San Jose de la Huerta, Morelia 58190, Michoacán, Mexico.
authors.forename: Miguel
authors.initials: M
authors.lastname: Martínez-Ramos
authors.affiliation: Forest Ecology and Forest Management Group, Department of Environmental Sciences, Wageningen University, P. O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Frans
authors.initials: F
authors.lastname: Bongers
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road, Unit 3043, Storrs, CT 06269-3043, U.S.A.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Chazdon
authors.affiliation: Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, Circuito Exterior S/N, Coyoacan, Mexico City 04510, Mexico.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Meave
authors.affiliation: Fundación Cedrela, Bogotá 111311, Colombia.
authors.forename: Natalia
authors.initials: N
authors.lastname: Norden
authors.affiliation: Departamento de Sistemática e Ecologia, Universidade Federal da Paraiba, Campus I, Cidade Universitária, João Pessoa, Paraiba 58051-900, Brazil.
authors.forename: Bráulio A
authors.initials: BA
authors.lastname: Santos
authors.affiliation: Departamento de Botânica, Universidade Federal de Pernambuco, Av. Professor Morais Rego, 1235 - Cidade Universitária, Recife, Pernambuco 50670-901, Brazil.
authors.forename: Inara R
authors.initials: IR
authors.lastname: Leal
authors.affiliation: Departamento de Botânica, Universidade Federal de Pernambuco, Av. Professor Morais Rego, 1235 - Cidade Universitária, Recife, Pernambuco 50670-901, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Tabarelli
mesh_terms: D044822:Biodiversity; D003247:Conservation of Natural Resources; D004463:Ecology / Q000639:trends*; D017753:Ecosystem; D065928:Forests; D006801:Humans; D012106:Research / Q000639:trends; D014329:Tropical Climate
keywords: biodiversity conservation; ecosystem services; forest recovery; land-use transformation; landscape restoration; landscape structure