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.
Highlights
Riparian forests are dynamic and heterogeneous ecosystems that concentrate high species diversity at both local and regional scales [1,2]
Deforestation and degradation of riparian forests result in severe loss of biodiversity and ecosystem functions [2,6,7]
The vegetation development of restoration areas should lead them to a growing similarity with reference forest sites [12,13]
Summary
Riparian forests are dynamic and heterogeneous ecosystems that concentrate high species diversity at both local and regional scales [1,2]. These forests shelter specialized species that live in riparian areas, and species of adjacent habitats, being important corridors for the dispersal of animals and plants at the landscape level [3,4,5]. The importance of riparian forest restoration to recover ecosystem functions and services, and for the conservation of biodiversity, is recognized by worldwide public policies [2,8,9,10,11]. The trajectory of forest development may vary among restoration sites independently of time since restoration was Diversity 2018, 10, 90; doi:10.3390/d10030090 www.mdpi.com/journal/diversity
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
