VEGETATION ATTRIBUTES OF FOUR INTEGRATED PEST MANAGEMENT (IPM) SITES ON THE VICTORIAN VOLCANIC PLAIN

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1 VEGETATION ATTRIBUTES OF FOUR INTEGRATED PEST MANAGEMENT (IPM) SITES ON THE VICTORIAN VOLCANIC PLAIN Report prepared for Cam Nicholson, Southern Farming Systems, Newtown Victoria 322 February 27 Vivienne Turner, Jaimie Mavromihalis and Heidi Zimmer Arthur Rylah Institute, Department of Sustainability and Environment, 123 Brown St Heidelberg, Victoria, 384. Objective To assess vegetation attributes (species richness, % cover, life form composition, sward heterogeneity) of the four IPM sites on the VVP. Methods Hypothesis Vegetation complexity is correlated with invertebrate complexity. Rationale Vegetation complexity is expressed via plant species and life-form richness and cover as well as sward heterogeneity. Higher numbers of species and life forms and greater diversity in sward heights may be expected to provide a larger number of places (habitats, niches) for invertebrates to dwell. A corresponding complexity and diversity in invertebrate community structure may be expected. Floristic Composition Five, 5 cm x 5 cm quadrats were used to sample the vegetation associated with past IPM invertebrate sampling sites. In each quadrat the cover of all vascular plant species as well as that of bare ground was measured using a modified Braun-blanquet scale. Samples were taken in spring (period of peak biomass) before the pastures were re-grazed. The cover estimates below were generated using data collected in the 5 quadrats. Post sampling, the data were categorised according to various vegetation and site functional attributes (Table 1). Table 1. Vegetation and site functional attribute groups UK Exotic annual grass Exotic annual forb Exotic perennial grass Exotic perennial forb Native perennial forb Native perennial grass Bare ground Unknown Figure 1: Rising plate meter 1

2 Sward height heterogeneity Sward height heterogeneity was measured using a rising plate meter (Figure 1) (Stewart et al. 21). Measurements were taken every 5 cm along transects of an appropriate length to adequately sample the variation associated with the sites sampled for invertebrates. Results Figure 2: Mt Hesse Mount Hesse: Exotic annual pasture The dominance of exotic annual forbs and exotic annual grasses (Figure 2) is primarily driven by Trifolium subterraneum and Bromus hordaeaceus (Table 2). Mean % Cover Sedge Litter U/K Functional Group (refer to Table 1) Table 2: Mt Hesse Individual Species Abundance Latin Name Common Name % Cover Grasses *Bromus hordaeaceus subsp. hordaeaceus Soft Brome 21. *Phalaris aquatica Toowoomba Canary-grass 11. *Lolium perenne Perennial Rye-grass 3.4 *Aira cupaniana Quicksilver Grass 5.6 *Vulpia bromoides Squirrel-tail Fescue 2.6 *Briza minor Lesser Quaking-grass 2.2 Austrodanthonia caespitosa Common Wallaby-grass 1. Themeda triandra Kangaroo Grass.2 Forbs *Trifolium subterraneum Sub Clover 33. *Trifolium dubium Suckling Clover 13. *Cerastium glomeratum Common mouse-ear Chickweed 1.6 Eryngium ovinum Blue Devil 1.4 Unknown forb Caryophyllaceae Family 1. Oxalis perennans Grassland Wood-sorrel.8 *Parentucellia latifolia Common Bartsia.2 Other Carex sp. Sedge.6 Bareground 1.6 Litter 8. 2

3 Figure 3: Leighview Leighview: Exotic perennial pasture Phalaris aquatica is the single and dominant exotic perennial grass species (Figure 3). Several species contribute to a high cover of exotic annual grasses. This site has the highest % bare ground well as a lot of litter (Table 3). Mean % Cover Sedge Litter Functional Group (refer to Table 1) Table 3: Leighview Individual Species Abundance Latin Name Common Name % Cover Grasses *Phalaris aquatica Toowoomba Canary-grass 28. *Briza minor Lesser Quaking-grass 7.2 *Vulpia bromoides Squirrel-tail Fescue 4.2 Poa sp. Tussock-grass 3.2 *Bromus hordeaceus subsp. hordeaceus Soft Brome 3. *Aira caryophyllea Silvery Hair-grass 1.2 *Avena fatua Wild Oat.2 Forbs Lobelia pratioides Poison Lobelia 1. *Cirsium vulgare Spear-thistle.2 *Hypochoeris radicata Cat's Ear.2 Other Juncus sp. Rush.6 Bareground 23. Litter 3. 3

4 Mt Gow: Exotic perennial pasture Figure 4: Mt Gow This is pre-dominantly an exotic pasture with some native species present (Figure 4). Phalaris aquatica is again dominant, and has produced this exotic perennial pasture. This site has the highest litter cover (Table 4). Mean % Cover Sedge Litter U/K Functional Groups (refer to Table 1) Table 4: Mt Gow Individual Species Abundance Latin Name Common Name % Cover Grasses *Phalaris aquatica Toowoomba Canary-grass 52. *Vulpia bromoides Squirrel-tail Fescue 8. *Bromus hordeaceus subsp. hordeaceus Soft Brome 3.8 Austrostipa bigeniculata Kneed Spear-grass 2. Austrodanthonia pilosa var. pilosa Velvet Wallaby-grass 1.6 *Lolium perenne Perennial Rye-grass 1. *Aira sp. Hair-grass.4 Forbs *Trifolium sp. Clover 1.8 Herb sp. (Unknown) 1. *Trifolium subterraneum Sub Clover.4 Rumex brownii Dock.2 Other *Romulea rosea Onion Weed 1.6 Juncus sp. Rush.4 Litter 5. Bareground 4.2 4

5 Warrambeen: Native Perennial Grassland The site is a diverse native grassland, largely weed free, with scattered rocks throughout (Figure 5). Themeda triandra, and to a lesser extent Poa labillardierei, are the dominant native perennial grasses (Table 5). Mean % Cover Figure 5: Warrambeen (Site 2) Sedge Litter Functional Group (refer to Table 1) Table 5: Warrambeen Individual Species Abundance Latin Name Common Name % Cover Grasses Themeda triandra Kangaroo Grass 46. Poa labillardierei var. (Volcanic Plains) Common Tussock-grass 12.8 *Briza maxima Large Quaking-grass 3. *Vulpia bromoides Squirrel-tail Fescue 2.6 Austrodanthonia (likely bipartitia) Leafy Wallaby-grass 1.6 *Aira caryophyllea Silvery Hair-grass 1. *Bromus hordeaceus subsp. hordeaceus Soft Brome.2 Dichelachne crinita Long-hair Plume-grass.2 *Hordeum sp. Barley-grass.2 Forbs *Plantago bellardii Silky Plantain 2.2 Leptorhynchos squamatus Scaly Buttons 2. *Trifolium dubium Suckling Clover 1.8 *Hypochoeris radicata Cat's Ear 1.2 Hypoxis glabella Tiny Star 1. Asperula conferta Common Woodruff.8 *Centaurium erythraea Pink Stars.2 Cullen parvum Small Scurf-pea.2 Oxalis perennans Grassland Wood-sorrel.2 Solenogyne dominii Smooth Solenogyne.2 *Trifolium subterraneum Subterranean Clover.2 *Trifolium sp. Clover.2 *Trifolium arvense var. arvense Hare's foot clover.2 Wahlenbergia sp. Bluebell.2 Other Carex sp. Sedge.4 Schoenus apogon Common-bog sedge.4 Bareground 11.8 Litter 18. 5

6 Sward height heterogeneity Mean sward height varies little among the sites. In contrast, variability in sward height (or sward heterogeneity) was much higher at Warambeen and Leighview, when compared with Mt Hesse and Mt Gow. Figure 6: All Sites: Average Sward Height Height (cm) Mt Hesse Leighview Mt Gow Warambeen Figure 7: All Sites: Sward Height Variance Height (cm) Mt Hesse Leighview Mt Gow Warambeen Discussion Table 6: Summary attributes of all sites. Site Classification No. Native Spp. No. Exotic Spp. Mean Sward Height (cm) Sward Height Heterogeneity (variance)(cm) Mt Hesse Exotic Annual 5/9* Pasture Leighview Exotic Perennial Pasture Mt Gow Exotic Perennial Pasture Warambeen Native Perennial Grassland (*Mt Hesse species count including species recorded in pasture cage.) 6

7 Native grassland and native pasture is not synonymous. Native pastures are generally speciespoor; they contain few inter-tussock forbs. Native pastures are usually dominated by only a few species of native perennial grass and may have been substantially modified (Carter et al. 22). Warambeen was rich in native forbs far beyond the other sites and has more abundant native perennial grasses, resulting in a high level sward height variance; it was the only true native grassland. The other three sites were lower in native species diversity. Leighview had the greatest sward heterogeneity. Sward height heterogeneity appears to have a positive relationship to bare ground e.g., Leighview had the highest sward height heterogeneity and the highest % bare ground. There is no apparent relationship between sward height heterogeneity variance and litter cover: low sward variance occurs alongside high litter cover (i.e., Mt Gow) and low litter cover (i.e., Mt Hesse). However, litter cover does have a positive relationship with cover of perennial grasses. The four sites differed in their plant species composition and sward height heterogeneity. Warrambeen had the highest native species diversity alongside a high level of sward height heterogeneity. However, Leighview, a pasture dominated by exotic species, had the greatest sward heterogeneity. References: Carter, O., Murphy, A. M., and Cheal D. C. (23) Natural Temperate Grassland Pub. Environment Australia, Biodiversity Unit, Biodiversity Series. Online at < Stewart, K. E. J., Bourn, N. A. D. and Thomas, J. A. (21) An evaluation of three quick methods commonly used to assess sward height in ecology. Journal of Applied Ecology 38, Appendix: Photos of sites: (Top to bottom) Mt Hesse, Leighview, Mt Gow and Warrambeen. 7

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