Tree and bird functional groups as indicators of recovery of regenerating subtropical coastal dune forests

Rolo, Víctor; Olivier, Pieter I.; Aarde, Rudi J. van

doi:10.1111/rec.12501

Cited by 15 publications

(13 citation statements)

References 56 publications

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“…These species occur exclusively or preferentially in the forest interior, suggesting that their performance is directly related to tree size and density [4]. However, studies evaluating the responses of bird assemblages to forest restoration generally compare areas in restored vs remnant reference forests [28,29], classify areas in age classes [26,30], or use time since restoration as a continuous predictor variable [31,32]. Although these studies recognize the importance of vegetation structure on bird assemblages, few studies explicitly used the development of forest structure as a predictor variable.…”

Section: Introductionmentioning

confidence: 99%

Bird Functional Traits Respond to Forest Structure in Riparian Areas Undergoing Active Restoration

2018

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Abstract:Monitoring wildlife responses is essential to assess restoration projects. Birds are widely used as bioindicators of ecosystem restoration, but most studies use only taxonomic descriptors to compare categories of reference and restoring sites. Here, we used forest structure as a continuous predictor variable to evaluate avifaunal taxonomic and functional indicators in riparian forest reference and restoration sites on southeastern Brazil. Reference sites were riparian forest remnants, and restoration sites were pasture before seedling reintroduction. Forest structure variables (mean tree height, canopy depth, mean diameter at breast height, basal area, tree layering, tree density, and grass cover) were reduced into two axes using a Principal Component Analysis (PCA), Forest Axis 1 (tree biomass vs. grass cover) and Forest Axis 2 (canopy depth vs. tree density). Bird species were classified in relation to five functional categories (i.e., diet, foraging stratum, nest height, cavity dependence for nesting, and forest dependence). Forest Axis 1 influenced the functional diversity of bird assemblages and the relative abundance within levels of each functional category (except for nest height). The relative abundance of all functional categories combined was also affected by Forest Axis 2. Therefore, forest structure affected the predominant functional traits of bird species in riparian sites under restoration. Sites with higher tree biomass were the richest, with canopy birds that were insectivores and frugivores of high forest dependence, whereas more open sites were associated with birds of low forest dependence and ground-foraging insectivores. Forest structures of similar-aged sites were strongly variable, due to natural and anthropic disturbances, so restoration age was a poor indicator of forest development. These unpredictable disturbances can change the development of sites under restoration, so that forest structure can be a better descriptor of the trajectory of these ecosystems.

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Section: Introductionmentioning

confidence: 99%

Bird Functional Traits Respond to Forest Structure in Riparian Areas Undergoing Active Restoration

2018

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“…One group benefiting from the presence of large trees are large frugivores, which are of major importance for long‐distance dispersal and can contribute to restore degraded forest (Galetti et al., ). In the studied rehabilitating forest, previous research has shown a decline in large frugivore abundance as the forest ages (Rolo, Olivier, & van Aarde, ). This evidence is in accordance with the significantly lower presence of tall trees in the rehabilitating forest as compared to the reference forest.…”

Section: Discussionmentioning

confidence: 88%

Determinants of canopy gap characteristics in rehabilitating coastal dune forests

Rolo

Olivier

Aarde

2018

Applied Vegetation Science

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Questions:What drives canopy gap formation in regenerating coastal dune forest?Does canopy gap size frequency distribution differ between new and old-growth forests? Can canopy gaps divert regenerating trajectories?Location: Rehabilitating coastal dune forest, KwaZulu-Natal, South Africa. Methods:We mapped canopy gaps in regenerating dune forest patches of varying age, which develop after seeding of the pioneer Vachellia kosiensis, and a reference forest by means of unsupervised classification of multi-spectral satellite images. We tested if gap formation can be explained by abiotic (exposure to winds) and/or biotic (tree density at early stages) variables. We calculated the scaling exponent of a power-law model to quantify if gap size frequency differed between new and oldgrowth forests. Finally, we measured canopy openness, tree height and number of stems to validate canopy gap classification and assess the consequences of canopy gaps on regenerating trajectories.Results: Exposure to winds and tree density at early stages were both significant predictors of gap presence. Gaps were more likely to be present along dune ridges and areas with low tree density than valleys and areas with high tree density at early stages. Large gaps were common in both new and old-growth forests. The scaling exponent was positively related to regeneration age, indicating a reduction in gap size as the forest aged. Areas with open canopies had shorter individual trees that were more likely to be multi-stemmed than areas with closed canopies. Conclusion: Canopy gaps are an important component of new and old-growth coastal dune forests dynamics. Although gaps are filled during forest development, changesin individual life-history strategies and morphology may alter regeneration trajectories. However, because their effect is partly controlled by the exposure to wind and tree density at early stages, it can also be manipulated by management to ensure nucleation, which could accelerate forest recovery. K E Y W O R D Scanopy openness, hierarchical Bayesian models, multi-stemming, random forest classification, size frequency distribution, SPOT6

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“…Among wildlife taxa, birds are conspicuous early responders to forest restoration (Dunn 2004, MacGregor-Fors et al 2010, Rolo et al 2017). Because of their diverse life history strategies including wide variation in diet, specialized foraging strategies, and microniche preferences, birds can act as an indicator taxon for recovering ecological complexity during forest restoration (Da Silva and Vickery 2002).…”

Section: Introductionmentioning

confidence: 99%

“…The return of forest-associated birds to forest restorations is a metric of restoration progress (Twedt et al 2002, Nichols and Nichols 2003, Rolo et al 2017. Increasing compositional overlap with forest bird communities at less disturbed reference sites indicates progress toward biodiversity conservation goals (Catterall et al 2012, Rolo et al 2017. In restorations intended as wildlife corridors between forest fragments, forest-associated birds demonstrate restorations are functioning as planned (Jansen 2005).…”

Section: Introductionmentioning

confidence: 99%

Recovery of bird activity and species richness in an early-stage tropical forest restoration

Roels¹,

Hannay²,

Lindell³

2019

ACE

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Bird habitat creation is often a goal of tropical forest restoration because bird-driven ecosystem services can accelerate forest recovery. However, resident tropical bird responses are not well characterized in the earliest years following restoration action. During a five-year study of the bird community in an experimental tropical forest restoration, we examined temporal trends in bird activity and diversity and the effects of habitat variables on the distribution of bird species within the site. Our site consisted of 16 replicate plots with 1, 2, 4, or 8 native tree species planted into former heavily-grazed pasture. Four years after tree planting, we observed a 3-fold increase in bird activity and 11-fold increase in species richness compared to preplanting. We also found changes in proportions of habitat guilds, with marked declines in open country birds and increases in birds associated with brushy, early secondary growth, and forest edge habitats. Number of bird species observed differed strongly between plots four years postplanting. Using a multispecies occurrence model under a Bayesian framework, we considered possible reasons for these differences related to plot content and context. Content features within plots ("content"), including number of tree species planted, canopy cover, tree species identity, and presence of legacy trees, did not explain differences in number of bird species observed, potentially because of small plot size relative to bird mobility. Neighborhood features ("context") of each plot did explain differences; more bird species were detected in plots with more adjacent woodland and farther from actively grazed pasture. Our results demonstrate that planting native tree species in highly degraded sites can generate rapid, positive responses from tropical bird communities. These responses are likely mediated by surrounding habitat matrix, which influences rates of bird community recovery. Considering site context can improve predictions of fine-scale distribution of bird activity and diversity within restoration sites. Rétablissement de l'activité et de la richesse aviaire au cours des premiers stades de régénération d'une forêt tropicale RÉSUMÉ. La création d'habitat pour les oiseaux est souvent envisagée dans le cas de restauration de forêts tropicales parce que les services écosystémiques découlant de la présence des oiseaux peuvent accélérer le rétablissement forestier. Toutefois, le comportement des oiseaux tropicaux résidents n'est pas bien connu au cours des premières années suivant les activités de restauration. Pendant cinq années, nous avons examiné les tendances temporelles de l'activité et de la diversité des oiseaux et l'effet des variables d'habitat sur la répartition des espèces d'oiseaux dans un site d'étude au coeur d'une forêt tropicale faisant l'objet d'une restauration expérimentale. Notre site d'étude était composé de 16 parcelles répétées comportant 1, 2, 4 ou 8 espèces d'arbres indigènes plantés dans d'anciens pâturages extrêmement broutés. Quatre ans après la ...

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Tree and bird functional groups as indicators of recovery of regenerating subtropical coastal dune forests

Cited by 15 publications

References 56 publications

Bird Functional Traits Respond to Forest Structure in Riparian Areas Undergoing Active Restoration

Bird Functional Traits Respond to Forest Structure in Riparian Areas Undergoing Active Restoration

Determinants of canopy gap characteristics in rehabilitating coastal dune forests

Recovery of bird activity and species richness in an early-stage tropical forest restoration

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