Bird functional diversity in restored and secondary forests of the Colombian Andes

Abstract

Forest plantations may have detrimental effects on biodiversity. However, these plantations are widely used to restore degraded habitats, yet their contribution to restoring functional diversity remains largely unknown. We assessed vegetation structure, resource availability, and bird abundance, as well as bird morphological, behavioral, life history, and functional diversity in 35-year-old monospecific protected Andean alder (Alnus acuminata) forest plantations in the Central Andes range at elevations between 2,400 and 2,800 m, to determine if plantation structure and resource availability favor bird functional diversity. We compared our findings to a 35-to 45-year-old secondary forest that had naturally regenerated. We found similarities in bird functional diversity but different functional composition between the Andean alder plantation and secondary forest. The bird life history, behavioral, and morphological traits from the secondary forest were more heterogeneous than those from the plantation. In addition, standing dead trees in the Andean alder plantation promoted bird functional diversity and the presence of birds in the plantation interior. Overall, vegetation structure and understory resource availability of Andean alder plantations appear sufficient to enable bird functional diversity partially resembling that of secondary forests in the region.

Bird Functional Diversity in Agroecosystems and Secondary Forests of the Tropical Andes

“…According to our functional diversity metrics, agroecosystems have larger functional diversity values (in terms of RaoQ and functional richness) than secondary forests. This result agrees with the results of Morelli, Benedetti, Perna and Santolini [60], but contrasts with many other studies [6,31,[61][62][63][64]. Such differences may be due to community characteristics (e.g., species richness and abundance) or to environmental filters related to vegetation structure and landscape heterogeneity.…”

“…We deployed mist-nets at each habitat type [38,39]. We have chosen this approach because it allows us to register bird species that are usually difficult to detect using other methods (e.g., point-counts) and also allows us to capture the individuals to obtain morphological measurements [31,40,41]. The method used was previously validated in the study area by Castaño-Villa et al [29].…”

“…Thus, habitat disturbance along the Colombian Andes has changed bird species richness and abundance, with noticeable impacts on highly specialized groups, such as the understory insectivore birds [29,30]. Differences in habitat structure and vegetation composition impose environmental filters that favor some species over others, leading to dissimilar communities [30,31]. A recent study on this area has compared bird functional diversity between secondary and restored native forests [31], but to the best of our knowledge it has not been assessed on birds from productive lands.…”

“…Differences in habitat structure and vegetation composition impose environmental filters that favor some species over others, leading to dissimilar communities [30,31]. A recent study on this area has compared bird functional diversity between secondary and restored native forests [31], but to the best of our knowledge it has not been assessed on birds from productive lands. In this regard, coffee, cocoa, and citrus crops occupy a large altitudinal range in some areas, such as the Caldas region, harboring 923 bird species [32].…”

“…In this context, we assessed the effects of agroecosystems on bird functional diversity and bird functional trait composition, aiming to: (1) compare the functional diversity of traits between agroecosystems and native forests using four functional diversity metrics, and (2) determine which functional traits explain the functional diversity differences between agroecosystems and native forests. As agroecosystems have a lower structural complexity than native forests and because functional diversity responds to vegetation structure [31,34], we hypothesize that birds in agroecosystems would have a lower functional diversity with a reduced set of dominant traits determined by environmental filters.…”