Elsevier

Biological Conservation

Volume 141, Issue 1, January 2008, Pages 174-186
Biological Conservation

Time lags in provision of habitat resources through revegetation

https://doi.org/10.1016/j.biocon.2007.09.010Get rights and content

Abstract

Broadscale land use changes are occurring rapidly in rural landscapes worldwide, within which revegetation with native plant species to increase the area of suitable habitat is a key activity. Current models for planning revegetation are based solely on the spatial arrangement of new and remnant vegetation. Making wise decisions about revegetation requires projective models of ecological responses to revegetation, but there are few appropriate data. Substantial time lags are expected in the availability of many habitat resources because different resources are realised at different stages of vegetation maturation. Here we present results of surveys of 72 revegetation sites established over a range from 5 to more than 130 yr from the slopes and plains of central Victoria, Australia. We surveyed vegetation provision of habitat resources essential for many birds and arboreal and scansorial mammals (e.g. canopy, large boughs, tree hollows and fallen timber). Predictive models were developed for habitat resource provision as functions of time since planting, planting density and other covariates. Different habitat resources developed at different rates. While dense canopy and various forms of bark resources developed in about 10 yr, large boughs, tree hollows and fallen timber loads required at least 100 yr to develop. The development of these key habitat resources was delayed in revegetated sites with high stem densities. Habitat resources that are essential for many birds and arboreal and scansorial mammals have long time lags that models for planning offsets or landscape reconstruction should account for. Management has substantial effects: planting at high densities greatly reduces tree girth growth rates and delays the occurrence of large boughs, tree hollows and fallen timber by decades.

Introduction

In many regions including Europe, North America and parts of Australia, de-intensification of land use and rehabilitation of agricultural lands is occurring with allocation of much human, biological and economic resources (Madsen, 2002, Stanturf and Madsen, 2002, Vallejo et al., 2006). Most effort has been directed towards restoration and afforestation using woody vegetation. While passive restoration (management to encourage recruitment from persistent mature individuals or from seed banks) is often desirable, active replanting with seed or seedlings is frequently required (Honnay et al., 2002, Vallejo et al., 2006, Vesk and Dorrough, 2006). In Australia, recent years have seen significant replanting of native trees and shrubs in rural landscapes (National Heritage Trust, 2005). In 2006, the community-based organization Greening Australia planted 2.6 million seedlings and direct seeded 1776 km of rows of native species (Greening Australia, 2007). While most revegetation is multifunctional in purpose, and control of soil salinity and provision of shelter for stock have been primary aims for much Australian revegetation, a key goal has been the conservation of native biodiversity. However, little is known about the ecological benefits of revegetation (Vesk and Mac Nally, 2006), information that is crucial for effective revegetation planning. Frequently, monitoring focuses on implementation, with tenuous links to ecological outcomes (Lake, 2001, Freudenberger et al., 2004, Vesk and Mac Nally, 2006). More useful are monitoring of fauna occupancy and abundance or using space-for-time substitutions of sites revegetated at differing but relatively short time frames (5–25 yr) (Biddiscombe, 1985, Ryan, 1999, Fisher, 2001, Martin et al., 2004, Cunningham et al., 2007, Kavanagh et al., 2007, Loyn et al., 2007). Both approaches fail to provide robust predictions of the long-term responses (50–200 yr) because most revegetation activities are recent.

There is scope for exploring development of revegetation over longer timeframes. Historical plantations date back to the late 1800s in Victoria (Bannear, 1997), albeit not intended specifically for biodiversity benefits. One approach is survey fauna in these plantations to assess the ecological outcomes of current revegetation efforts. However, this assumes that such plantations are a good proxy for current revegetation such that faunal responses would be expected to be similar between the historic and current revegetation at equivalent ages. There are reasons why this may not be valid. Some of the ways in which historical plantations differ from contemporary ones include: intention (shelter, woodlots); landscape context (isolated versus adjacent to remnants); tree species (many early plantings were Eucalyptus cladocalyx, which has a highly restricted natural range); planting designs (stem densities, understorey, spatial configuration). For these reasons, historical plantations may make for poor habitat that is unlikely to support populations of fauna. Many plantings, both historical and contemporary, are small, isolated from remnant native vegetation and have high perimeter to area ratios (Freudenberger et al., 2004, Radford and Bennett, 2007), properties commonly associated with low probabilities of occupancy (Mac Nally et al., 2000b, Westphal et al., 2003a), population persistence (Fahrig and Merriam, 1994, Mac Nally, 2007b), and dominance by aggressive, territorial species (e.g. noisy miners, Manorina melanocephala) (Clarke and Oldland, 2007, Maron, 2007).

An alternative is to focus on change in vegetation structure, with the eventual aim of modelling habitat resources, independent of spatial configuration of the planting and the surrounding landscape (Dennis et al., 2003). Many fauna are known to have strong associations with habitat resources such as boughs or hollows for nesting (Sedgwick and Knopf, 1986, Gibbons and Lindenmayer, 2002), flowers for nectar provision (Mac Nally and McGoldrick, 1997, Wilson and Bennett, 1999), and fallen timber for both foraging and shelter (Mac Nally, 2006, Mac Nally and Horrocks, 2007a). There is extensive literature on provision of timber resources in relation to time and silvicultural practices in managed forests (Smith et al., 1997). However, there has been limited research on the habitat resources provided for fauna by revegetation (Hobbs et al., 2003) and none has examined how these resources may change as vegetation matures. Knowledge about the provision of habitat resources over time can be incorporated into habitat suitability models for the purpose of projecting suitability beyond the ages of empirical datasets of faunal occupancy in revegetation (Mac Nally, 2007a). Here, we present results of a survey of habitat resources within revegetated areas of known age ranging from about 5–130 yr. We have three main aims: to demonstrate the timelags in the process of habitat restoration; to assess the effects of management, namely planting density, on this process; and to assess the functionality of the replanted habitat.

Section snippets

Study location and site selection

Surveys were conducted on the inland slopes and adjacent plains of the Great Dividing Range in south-eastern Australia from October 2005 to August 2006. The area lies within the 300–700 mm annual rainfall zone (Fig. 1). All sites were on sedimentary soils. Sites affected by past mining disturbance were avoided. Sites <1 ha and shelter-belt style plantings (linear strips) were excluded.

Site selection was based primarily on replanting age. We aimed to sample representatively with respect to age of

Results

Planting tubestock has been the most common method of active revegetation and direct seeding also has long been employed (Fig. 2). Sites ranged in size from 0.3 to 235 ha (median 2.9 ha, mean 13.8 ha).

Discussion

Our data extends to much older sites than any other published study of revegetation in Australia. The three major contributions are: (1) documentation of the time course of provision of habitat resources necessary for faunal (specifically birds and mammals) occupation of these sites; (2) analysis of the effect of management, through planting density, on this time course; and (3) analysis of the functionality of planted sites in terms of recruitment and life form diversity.

Acknowledgements

Sites were located following extensive consultation with the North-Central, Goulburn-Broken, North-East and Mallee Catchment Management Authorities, the Victorian Departments of Sustainability and Environment, Primary Industries and Education, Parks Victoria, the University of Melbourne School of Forestry, Trust for Nature, Landcare, Greening Australia, farm forestry organizations, and a number of private landholders. Thanks to the many landholders who allowed access to their properties and

References (74)

  • S. McIntyre et al.

    A conceptual model of land use effects on the structure and function of herbaceous vegetation

    Agriculture, Ecosystems & Environment

    (2007)
  • R. Reid

    Diameter-basal area ratio as a practical stand density measure for pruned plantations

    Forest Ecology and Management

    (2006)
  • P.A. Vesk et al.

    The clock is ticking – revegetation and habitat for birds and arboreal mammals in rural landscapes of southern Australia

    Agriculture, Ecosystems & Environment

    (2006)
  • Bannear, D., 1997. Study of Historic Forest Activity Sites in the Box-Ironbark and Midland Areas of Victoria: Report to...
  • Bennett, A.F., Kimber, S., Ryan, P., 2000. Revegetation and Wildlife: A Guide to Enhancing Revegetation Habitats for...
  • A.F. Bennett et al.

    Tree hollows as a resource for wildlife in remnant woodlands: spatial and temporal patterns across the northern plains of Victoria, Australia

    Pacific Conservation Biology

    (1994)
  • E.F. Biddiscombe

    Bird populations of farm plantations in the Hotham River valley

    W. A. Western Australian Naturalist

    (1985)
  • D.J. Bruggeman et al.

    Landscape equivalency analysis: methodology for estimating spatially explicit biodiversity credits

    Environmental Management

    (2005)
  • M.F. Clarke et al.

    Penetration of remnant edges by noisy miners (Manorina melanocephala) and implications for habitat restoration

    Wildlife Research

    (2007)
  • Corr, K., 2003. Revegetation Techniques: A Guide for Establishing Native Vegetation in Victoria. Greening Australia...
  • Crainiceanu, C.M., Ruppert, D., Wand, M.P., 2005. Bayesian analysis for penalized spline regression using WinBUGS....
  • R.B. Cunningham et al.

    Reptile and arboreal marsupial response to replanted vegetation in agricultural landscapes

    Ecological Applications

    (2007)
  • R.L.H. Dennis et al.

    Towards a functional resource-based concept for habitat: a butterfly biology viewpoint

    Oikos

    (2003)
  • Driscoll, D., Milkovits, G., Freudenberger, D., 2000. Impact and Use of Firewood in Australia, CSIRO Sustainable...
  • L. Fahrig et al.

    Conservation of fragmented populations

    Conservation Biology

    (1994)
  • A.M. Fisher

    Avifauna changes along a Eucalyptus regeneration gradient

    Emu

    (2001)
  • Florence, R.G., 1996. Ecology and Silviculture of Eucalypt Forests. CSIRO Publishing,...
  • H. Ford et al.

    Foraging and aggressive behaviour of the Regent Honeyeater Xanthomyza phrygia in northern New South Wales

    Emu

    (1993)
  • D. Freudenberger et al.

    Predicting the biodiversity benefits of the Saltshaker Project, Boorowa, NSW

    Ecological Management and Restoration

    (2004)
  • A. Gelman

    Prior distributions for variance parameters in hierarchical models

    Bayesian Analysis

    (2006)
  • A. Gelman et al.

    Posterior predictive assessment of model fitness via realized discrepancies

    Statistica Sinica

    (1996)
  • Gibbons, P., Lindenmayer, D.B., 2002. Tree Hollows and Wildlife Conservation in Australia. CSIRO Publishing,...
  • Greening Australia, 2007. On Ground Action. <http://live.greeningaustralia.org.au/GA/NAT/OnGroundAction/> (accessed...
  • D.J. Harper et al.

    No net loss of fish habitat: a review and analysis of habitat compensation in Canada

    Environmental Management

    (2005)
  • R. Hobbs et al.

    Faunal use of bluegum (Eucalyptus globulus) plantations in southwestern Australia

    Agroforestry Systems

    (2003)
  • O. Honnay et al.

    Ecological perspectives for the restoration of plant communities in European temperate forests

    Biodiversity and Conservation

    (2002)
  • R.P. Kavanagh et al.

    Eucalypt plantings on farms benefit woodland birds in south-eastern Australia

    Austral Ecology

    (2007)
  • Cited by (204)

    View all citing articles on Scopus
    1

    Present address: CSIRO Sustainable Ecosystems, Canberra, ACT, Australia.

    View full text