Restoration potential of native forests after removal of conifer plantation: A perspective from Australia
Introduction
Forestry plantations are typically characterised by densely planted monocultures of introduced trees, often with very different trait sets than those represented in indigenous forests (Stephens and Wagner, 2007, FAO, 2010). Worldwide, up to 39% of plantations are composed of coniferous species that are often non-native (FAO, 2010, Gavran, 2013). With the continuing expansion of plantation estates and the global trend for a decline in area of natural forests, there is an increasing focus on the role of plantations in conserving biodiversity, and of approaches to returning native vegetation to sites after plantation crops have been harvested (Stephens and Wagner, 2007, Brockerhoff et al., 2008). For coniferous plantations, forest management practices aimed at improving biodiversity have focussed on the incorporation of broadleaved species to form mixed-species plantations (Heinrichs and Schmidt, 2009, Felton et al., 2010), and less frequently, the total replacement of non-native coniferous species with native broadleaved species (Ferracin et al., 2013, Spracklen et al., 2013). Despite the increased emphasis on returning native species to sites with coniferous plantations, relatively little is known about the restoration potential of clear-felled conifer plantations (Zerbe, 2002).
Clear-felling directly affects the diversity and composition of vegetation through removal and disturbance of extant vegetation and reproductive material, and indirectly through soil disturbance and changes to microclimate, light conditions, soil chemistry and hydrology (Vitousek et al., 1982, Marshall, 2000, Hope et al., 2003, Heinrichs and Schmidt, 2009). If left untouched after clear-felling, natural regeneration proceeds via extant vegetation, regeneration via suppressed rootstocks or clonal spread, germination of the soil seed bank or via seed rain and animal dispersal depending on the proximity and composition of surrounding vegetation (Halpern, 1989, Wunderle, 1997, Hérault et al., 2005). Associated changes in the composition of vegetation over time include an increase in species richness due to invasion of ruderal species (Prach and Pyšek, 1999, Heinrichs and Schmidt, 2009, Saure et al., 2013) followed by a reduction in shade intolerant and moisture-demanding species (Hannerz and Hånell, 1997, Heinrichs and Schmidt, 2009). In addition, the succession of plants after clear-felling is influenced by the severity and spatial and temporal variation of the disturbance caused during harvesting (Halpern, 1989).
The Australian softwood plantation estate, dominated by Pinus radiata, has remained relatively static at 1,000,000 ha since 2002 (Gavran, 2013). Plantations of P. radiata were most commonly established on cleared agricultural land. Between 2011 and 2012 there was a net decline of 1000 ha which is expected to increase over the next 5–10 years as plantations are harvested and not replanted. This is due to a number of reasons including reducing plantation area as a means to increase ground-water recharge, because they are considered commercially unviable, or due to incompatibility with biodiversity conservation values (Kasel and Bennett, 2007, Gavran, 2013). Decommissioned plantations have been converted to other land uses including native broadleaf vegetation (Kasel and Bennett, 2007). The conversion process typically involves the planting of overstorey species (Kasel, 2008) as a means of facilitating the return of understorey species by providing a ‘nurse-tree’ function (Lugo, 1988, Wilkins et al., 2003, Munro et al., 2009).
This study aims to identify general patterns in plant functional traits (sensu Violle et al., 2007) of species following harvesting of P. radiata plantation. Previous work in pine plantations also conducted in the same study location revealed that myrmecochorous trees, shrubs and herbs were largely excluded from the understorey while perennial herbs with intermediate specific leaf area (SLA) and clonal spread were tolerant of shaded conditions in pine plantations (Meers et al., 2010b). The soil seed bank of pine plantations was dominated by species with trait associations including therophyte and hemicryptophyte life forms with high SLA, wind-dispersed or small round seed and arbuscular or non-mycorrhizal associations (Meers et al., 2012). These patterns in plant functional traits suggest that the extant understorey vegetation and the soil seed bank have limited restoration potential in a post-harvesting landscape. Further, the reduction or destruction of vegetative propagules through harvesting disturbance may further increase the dependence on seed rain from surrounding vegetation (Martins and Engel, 2007).
Using repeated sampling of permanent monitoring plots, we examined the response of both individual traits and emergent groups (sensu Lavorel et al., 1997) as plant succession occurred following harvesting of P. radiata plantations. We addressed the following broad questions:
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Is there a shift in vegetation with time since harvesting and if so, does this shift trend toward the pre-plantation state (abandoned farmland), follow a trajectory towards the desired state (native forest), or towards some alternate state?
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What are the relationships among plant traits and environmental variables? In the scenario we used, environmental variables included location (e.g. distance to native forest, topography), land-use history (e.g. time since harvesting, time since revegetation), site factors (e.g. planted overstorey trees, litter cover) and edaphic conditions.
Section snippets
Study area
The Delatite Peninsula is located on the western slopes of the Great Dividing Range in Victoria, Australia (145°58′E, 37°8′S). The Peninsula was formed in 1956 by the construction of the Eildon Reservoir. The area has a steeply dissected topography with altitude ranging from 300 to 500 m above sea level. Annual rainfall is approximately 850 mm and falls mainly in winter and spring (Bureau of Meteorology, 1887–2011). Mean monthly maximum temperature ranges from 12.0 °C in July to 29.0 °C in
Change in environmental variables and vegetation with time
There was a significant decline in the cover of bare ground and litter in HPP between 2003 and 2011 while the cover of rocks, logs and branches remained unchanged (Table 1). The mean basal area of planted eucalypts in 2011 was 2.6 m2 ha−1 (range 0–11.2 m2 ha−1); a 400-fold increase from 2003 (Table 1). There was a significant increase in EC and a significant decrease in concentrations of NH4+–N, total N and total C in HPP between 2003 and 2011 (Table 1). The concentration of NO3−–N in 2003 was
Vegetation response to time since harvesting
Mean species richness of species in harvested pine plantation (HPP) declined with time since harvesting, consistent with other studies of conifer plantations that report greater species richness in recently (1–5 years) felled stands (Eycott et al., 2006, Heinrichs and Schmidt, 2009, Saure et al., 2013). The peak in species richness has been attributed to establishment of wind-dispersed species and annuals favoured by soil disturbance, increases in light availability and soil temperature and
Acknowledgements
This research was funded by the Department of Environment and Primary Industries (Victoria) and through an Australian Postgraduate Award (T Meers). Soils and plant material were collected under permit number 10502 issued by the Department of Environment and Primary Industries. We thank two reviewers for comments that improved the manuscript.
References (133)
- et al.
Influence of harvesting intensity on the floristic composition of natural Mediterranean maritime pine forest
Acta Oecologica
(2010) - et al.
Can plantations develop understory biological and physical attributes of naturally regenerated forests?
Biol. Conserv.
(2008) - et al.
Secondary succession after perturbations in a shrubland community
Acta Oecologica
(2002) - et al.
Patterns of plant trait-environment relationships along a forest succession chronosequence
Agric. Eco. Environ.
(2011) - et al.
Replacing coniferous monocultures with mixed-species production stands: an assessment of the potential benefits for the forest biodiversity in northern Europe
For. Ecol. Manag.
(2010) - et al.
Effects on the flora in Norway spruce forests following clearcutting and shelterwood cutting
For. Ecol. Manag.
(1997) - et al.
Short-term effects of selection and clear cutting on the shrub and herb layer vegetation during the conversion of even-aged Norway spruce stands into mixed stands
For. Ecol. Manag.
(2009) - et al.
An ecological comparison between ancient and other forest plant species in Europe, and the implications for forest conservation
Biol. Conserv.
(1999) - et al.
Responses of available soil nitrogen and litter decomposition to openings of different sizes in dry interior Douglas-fir forests in British Columbia
For. Ecol. Manag.
(2003) - et al.
Land-use history, forest conversion, and soil organic carbon in pine plantations and native forests of south eastern Australia
Geoderma
(2007)
Restoration of plant biodiversity beneath tropical tree plantations in northern Australia
For. Ecol. Manag.
Impacts of forest harvesting on biological processes in northern forest soils
For. Ecol. Manag.
Soil seed banks in tropical forest fragments with different disturbance histories in southeastern Brazil
Ecol. Eng.
Conversion of native forest to exotic Pinus radiata plantation: response of understorey plant composition using a plant functional trait approach
For. Ecol. Manag.
Deforestation strongly affects soil seed banks in eucalypt forests: generalisations in functional traits and implications for restoration
For. Ecol. Manag.
Dynamics of understorey herbaceous plant diversity following shrub clearing of cork oak forests: a five-year study
For. Ecol. Manag.
Soil functional responses to excess nitrogen inputs at a global scale
Ambio
The mineral nutrition of wild plants revisited: a re-evaluation of processes and patterns
Adv. Ecol. Res.
Dispersal distance as a benefit of myrmecochory
Oecologia
Permutation tests for univariate or multivariate analysis of variance and regression
Can. J. Fish. Aquatic Sci.
Rates of seed removal by ants at heath and woodland sites in south-eastern Australia
Aust. J. Ecol.
Myrmecochory in Australia’s seasonal tropics: effects of disturbance on distance dispersal
Aust. J. Ecol.
PERMANOVA+ for PRIMER: Guide to Software and Statistical Methods
Navigating the multiple meanings of β diversity: a roadmap for the practicing ecologist
Ecol. Lett.
Predicting patterns of post-fire germination in 35 eastern Australian Fabaceae
Aust. J. Ecol.
Use of ordination and other multivariate descriptive methods to study succession
Vegetatio
Ecological aspects of seed germination
The process of germination in Australian species
Aust. J. Bot.
Tolerance of thermal shock in seeds
Aust. J. Bot.
Partialling out the spatial component of ecological variation
Ecology
An ordination of the upland forest communities of southern Wisconsin
Ecol. Monogr.
Plantation forests and biodiversity: oxymoron or opportunity?
Biodiversity Conserv.
Migration of vascular plants to secondary woodlands in southern Sweden
J. Ecol.
Model Selection and Inference: A Practical Information-Theoretic Approach
A review of some aspects of the germination of Acacias
Proc. Royal Soc. Vic.
Fallow Deer: Their History, Distribution and Biology
Convergence during secondary forest succession
J. Ecol.
Non-parametric multivariate analyses of changes in community structure
Aust. J. Ecol.
Change in Marine Communities: An Approach to Statistical Analysis and Interpretation
A handbook of protocols for standardised and easy measurement of plant functional traits worldwide
Aust. J. Bot.
Endozoochorous seed dispersal by cattle and horse in a spatially heterogenous landscape
Plant Ecol.
An experimental assessment of seed adhesivity on animal furs
Seed Sci. Res.
Early stages of succession following the complete felling and burning of Eucalyptus regnans forest in the Florentine Valley, Tasmania
Aust. J. Bot.
Beolite’s Country, Devil’s River
Non-indigenous grasses impede woody succession
Plant Ecol.
Eucalypt Planting
Native Forest Silviculture Guideline No. 9
The importance of ecological research for ecosystem management: the case of browsing by swamp wallabies (Wallabia bicolor) in commercially harvested native forests
Ecol. Manag. Restor.
Plant functional traits, ecosystem structure and land-use history along a climatic gradient in central-western Argentina
J. Veg. Sci.
The plant traits that drive ecosystems: evidence from three continents
J. Veg. Sci.
Plant responses to livestock grazing frequency in an Australian temperate grassland
Ecography
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Current address: Faculty of Agriculture and Environment, University of Sydney, Eveleigh, New South Wales 2015, Australia.
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Current address: School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia.