Native bird breeding in a chronosequence of revegetated sites

Abstract

Restoration of degraded landscapes through replantings of native vegetation has been proceeding in response to habitat loss and fragmentation and plummeting biodiversity. Little is known about whether the investments in ecological restoration have resulted in biodiversity benefits. We evaluated the potential of restored sites to support populations by assessing bird breeding activity. We surveyed 21 revegetated sites of various ages (9-111 years) in the box-ironbark region of Victoria, Australia. Sites differed in landscape context, patch features and in-site characteristics. The latter, including whether sites were grazed, amounts of fallen timber and numbers of remnant trees, were most important in affecting overall bird breeding activity. Patch-configuration (e.g., shape, area) was of secondary importance. Landscape context appeared to have little effect on bird breeding except for one species. While these results suggest that in-site habitat structure is the predominant driver, we caution against dismissing the importance of patch characteristics and landscape context for two reasons. First, the available sites covered a relatively small range of areas (<54 ha), and we could not provide a broad range of landscape-contextual contrasts given that we could only use existing plantings. Second, much of the breeding activity was by bird species known to be tolerant of smaller woodland areas or of the open countryside. We show that there is very little breeding activity in replantings by species that have declined dramatically in rank abundance between large 'reference' areas and fragmented landscapes. It seems likely that most replantings provide habitat configurations unsuited for dealing with declines of species most vulnerable to habitat loss and fragmentation.

Not All Kinds of Revegetation Are Created Equal: Revegetation Type Influences Bird Assemblages in Threatened Australian Woodland Ecosystems

“…Many past studies have examined the biodiversity values of particular kinds of temperate vegetation such as old growth woodland [11], regrowth [17] or plantings [19], [20]–[22]. However, to the best of our collective knowledge, and to the knowledge of a range of colleagues whom we contacted about this paper (see Acknowledgments), no-one in Australia has completed a comparative study of the bird biota of different growth types of temperate woodland, including different kinds of passively regenerated regrowth as well as plantings.…”

“…[17], and (2) seedling regrowth which develops after a reduction in grazing pressure by domestic livestock [18] or after some kinds of disturbance like ploughing after droughts. In addition, throughout threatened Australian temperate woodlands, there are extensive efforts to replant native vegetation [19]–[22]. A key question is: Are there differences in the richness and composition of biotic communities in different kinds of regrowth and how does this compare to old growth and plantings?…”

Balancing the environmental benefits of reforestation in agricultural regions

“…Previous work on reforestation has focused on specific disciplines and structural or functional effects (e.g. changes to water yields or bird assemblages, Jackson et al, 2005;Selwood et al, 2009). With the expected increase in reforestation, there is increasing exploration of the trade-off between carbon sequestration and biodiversity potential (Hall et al, 2012;Bryan et al, in preparation).…”

“…Sergio and Bogliani, 2000). In a long chronosequence (9-111 years) of tree plantings in south-eastern Australia, breeding activity was dominated by opencountry species, with breeding by declining woodland species only evident in plantings >100 years (Selwood et al, 2009). There is a need for comparisons of a range of taxa among tree plantings, agricultural land and remnant forests to determine the degree to which reforestation induces breeding because we currently have little idea of whether plantings are 'sinks' rather than 'sources' for declining species.…”

Towards modelling persistence of woodland birds: the role of genetics

“…Long-term monitoring has identified significant collapses in woodland bird populations in southern and eastern Australia, including of recently common species Szabo et al 2011;Watson 2011). The capacity to improve the situation depends on understanding the interaction of the natural history of species with habitat features, subsequent demographic outcomes, and critical ecological processes within a system (Kavanagh et al 2007;Bowen et al 2009;Selwood et al 2009;Ford 2011). In one example, key drivers of extinctionproneness for some woodland birds differed among species: low dispersal ability was important for Brown Treecreepers (Climacteris picumnus), whereas nest predation leading to low recruitment was critical for Hooded Robins (Melanodryas cucullata) (Ford et al 2009).…”