A Revegetation Guide for Temperate Grasslands: Restoring and Managing Native Ecosystems, Schemes and Mind Maps of History

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A Revegetation Guide

for

Temperate Grasslands

Who this guide is for

This introductory guide is for people wishing to learn about the basic principles and practices for revegetation of temperate grassland communities. This guide describes eight key steps that need to be followed to help ensure a successful revegetation project.

The importance of Temperate

Grasslands

The temperate grasslands of south eastern Australia have an irregular distribution from north of Adelaide in South Australia, east into inland Victoria, south into the midland plains of Tasmania and northwards through inland New South Wales and the Australian Capital Territory to the northern regions of New South Wales. By and large they encompass a zone of 500 mm average annual rainfall that can occur throughout the year.

Temperate grasslands are composed of four readily identifiable plant types:

1. Grasses with a C4 photosynthetic pathway (warm season active);
2. Grasses with the C photosynthetic pathway (cool season active);
   3. Native forb species (primarily perennial wildflowers); and;
   4. Non-indigenous grass and forb species (weeds).

Perennial tussock grasses produce most of the total plant biomass and ground cover. Of the native grasses , Austrostipa , Austrodanthonia, Poa and Themeda are the dominant genera. Annual and perennial forb species occupy the interstitial gaps amongst these grasses providing the bulk of plant diversity.

There is an urgent need to restore many patches of grassland as up to 99% of south eastern temperate grassland communities have been destroyed by prolonged and disruptive human impacts stemming from agricultural activity and urban development. Most remaining examples are found along roadsides and rail reserves, or as small patches on farmland (Photos 1a and 1b). The composition (density, stature and diversity) of remnant grassland communities is thought to be strongly correlated with the history of local disturbance events such as grazing, burning, slashing and drought.

Photo 1b.

Photo 1a.

Photo 1 (a-b). Highly diverse and colourful temperate grasslands were once widely distributed across southern Australia and Tasmania, but 99% have been destroyed or highly simplified. The few quality grasslands left are often found in (a) cemeteries or (b) along country roads.

2

A

REVEGETATION

GUIDE FOR

TEMPERATE

GRASSLANDS

STEP 3.

Secure a source of quality seed

Access to appropriate quantities of quality seed from a range of species is often the most limiting factor in achieving good restoration outcomes. For field-based collections, most guidelines advocate a ‘local is best’ approach. However, due to the small and fragmented nature of most remnant grasslands, recent research questions an overly strict adherence to this prinicple. The aim of grassland seed collection should be to:

• decrease the risk of establishing inbreeding populations;
• restore the geographic range of species; and
• increase access to greater seed quantities (especially for grasses).

Therefore, strict adherence to ‘local is best’ rather than a regionally focussed collection may be counter productive if local populations have been isolated by clearing, likely inbred and produce small quantities of seed.

Whether for nursery propagation, or use in direct seeding, seed collection zones should aim to match the environmental conditions of the revegetation site(s) particularly with respect to soil type and topography (e.g. slope). Ideally, collectors should aim to take seed over an entire growing season, from as many individuals as possible (e.g. 50 to 500). This figure will be much larger when mechanical harvest methods are ultilised. Where possible, collection should avoid conscious selection decisions (e.g. largest, most colourful) by working along transect lines to avoid closely

related plants. Together, these collection practices will aid in capturing a wide representation of the genetic characteristics exhibited across wild populations.

It may not be realistic to restore all species that occur in a collection zone to a new site. This may be because of limitations of seed, species range, or technical capacity (e.g. time, cost and skill). If the goal is restore some degree of biodiversity, restorationists should aim to select a mix of species that include representatives of the various ‘functional groups’ (plant types) that exist within grasslands. This may include groupings such as grasses (C3 and C4), annual and perennial species, legumes, plants that produce below ground structures (e.g. lilies) or those that exhibit key above-ground shapes such as groundcovers, or low or medium growing plants. In addition to utilising environmental resources in different and often complimentary ways, a diversity of these functional groups will provide a range of habitats for other life forms, such as insect pollinators, insectivorous and seed eating birds, and grassland reptiles. By successfully occupying a range of niches, a broad range of functional plant groups may also help resist the invasion of sites by weeds.

Securing wild seed has to be considered at least 1-2 years in advance to restoration. Seed of any particular species may only be able to be harvestable for short periods in its natural habitat. This in particular is the case during

extreme seasons. Advanced planning is needed to obtain the necessary permits to collect seed, organise with a landholder to remove livestock prior to seeding and obtain the necessary seed harvesting equipment. When purchasing seed for grassland revegetation, give suppliers at least 1 year advance notice. Like any crop, native seed quantity varies from year to year based on the season (temperatures, rainfall, winds).

Seed production

In many cases wild harvest will not supply the quantities of seed required. Indeed, care must be taken that repeated wild harvest des not have a negative impact on remnant communities. Seed from species that are rare (listed under State and Federal Acts) is generally unavailable for collection or from seed suppliers. Under both scenarios the establishment of seed production nurseries may be necessary. Seed production nurseries or areas are designed with the purpose of growing plant species as seed crops. Seed Production Areas (SPAs) can be as simple as a polystyrene ‘box’ system to more sophisticated containerised or in- ground plots (Photo 2abcd). Each approach comes with advantages and disadvantages in labour

“Collecting or buying

native seed is not the

same as buying a packet

of veggie seeds from the

shops”.

efficiencies, outputs and costs.

However, in general each system (or combination thereof) comprises seedlings grown at high densities (for suitable cross pollination or genetic factors) through to maturity and subsequent harvest. In recent years SPAs established in several south eastern States and regions have successfully grown seed from a range of grassland species in large quantities.

Seed Production Areas need to start with at least a small quantity of wild seed. This should be carefully collected to capture genetic quality and diverse traits within the defined collection zone. Similarly, in the SPAs, harvest protocols should aim to ensure these genetic features are preserved. In practice this means mixing and sub-sampling of wild seed-lots for propagation of seed crops, then an avoidance of selection bias when pricking-out (thinning) seedlings. Bias should also be avoided when harvesting seed from mature crops grown in SPAs.

Ideally SPA populations for each species should contain as many individuals as possible given space and resource factors. Aim for at least 100-1000 individuals per species. Another strategy to maintain genetic diversity in seed production is to introduce new seed from wild populations every 2- years.

The establishment of Seed Production Areas to support restoration projects has many positive features including reducing collection pressure on remnant wild populations, simplifying seed harvest and producing more reliable quantities of weed-free seed at times when field population may

be impacted by drought and/or other unfavourable events such as inadvertent burns, grazing, and predation. Through SPAs that include irrigation, it is possible to extend the period of seed-set for many grassland species through summer and into autumn when plants in wild populations have become dormant.

Seed testing

Regardless of the seed source (wild or from SPAs) restoration outcomes rely heavily on seed quality. For this reason, it is always preferable to obtain some indication of the quality characteristics of any seed- lots used. Purity testing is one relatively simple and cost effective method of assessment. Purity testing determines the percentage (by mass) of the seed that is pure filled seed of the species; the percentage (by mass) of impurities of other species seed (e.g. weeds); and the percentage (by mass) of inert matter (e.g. stems, seed appendages and seed coverings). If purity testing highlights particular issues, such as very low seed fill, other test methods such as cabinet germination or chemical viability tests can be conducted. However, both these involve longer time lines and increased costs. In summary, seed testing is important in understanding the quality of seed at the time of sowing (or propagating); allowing restorationists to more rigorously evaluate sowing outcomes.

Photo 2 (a-d). Except for a few common species of grass, Seed Production Areas (SPAs) will need to be established because harvesting large quantities of seed from the wild is unsustainable. SPAs can be as simple as growing a single species in a foam-box to small irrigated rows to large plots sown to a single species.

planting or to ‘clean-up’ restored sites where native plants have established as adults and native recruitment can be sacrificed for some period. Both approaches are commonly used in seed production systems where native species are grown as monocultures for seed crops.

Surface manipulation utilising standard agricultural techniques (plowing, chiselling, disking or harrowing) can be used to remove standing weeds prior to creating a friable seed or planting bed for restoration. However, soil disturbance and subsequent weed seed bank stimulation, means that chemical weeds controls are likely to be required in tandem with these actions. In most cases, site cultivation and weed control should begin up to 12 months prior to restoration activities. In many cases, adequate attention to pre- seeding or planting activities can minimise (but seldom negate) the requirement for post-restoration maintenance.

Soil scalping

An assessment of prevailing soil nutrient and weed bank characteristics at a restoration site may indicate that these factors are likely to overwhelmingly favour the growth of exotic species (weeds) and reduce the likelihood of restoration success. A number of studies of grassland restoration in the Northern Hemisphere, and more recently in Australia (the Grassy Groundcover Restoration Project), have shown that a technique described as ‘scalping’ can significantly enhance outcomes where high nutrient and weed loads prevail. Scalping, or topsoil removal, physically removes weed seed and bud material and reduces nutrient loads at the sowing

surface significantly limiting the competitive effect of weeds. The depth of scalping is site-specific and depends on how far nutrient loads and weed banks extend into the profile (both determined through the testing process). While some dismiss scalping as unmanageable at scale and uneconomic, it is relatively simple using readily available equipment such as road graders (Photo 3ab). Ideally, scalped topsoil can be spread at adjoining locations at low cost and utilised for agricultural purposes. Several research studies have shown that scalping can be far more successful that those initiated using chemical weed controls only (Photo 4ab).

Another technique that aims to reduce high soil nutrient loads is known as soil impoverishment or “reverse fertilisation”. This approach involves the removal of nutrients from soils, through the addition of soluble carbon. Additions of soluble carbon stimulates soil microbial growth, which in turn then accumulates available Nitrogen in their microbial biomass, making it unavailable for plant growth. Sources of suitable carbon sources include sucrose (sugar), straw, sawdust or grain hulls. While these methods have been shown as effective in reducing Nitrogen levels, they are not long lasting and additional carbon is required at regular intervals for any prolonged effect (thus increasing costs).

Photo 3a.

Photo 3b. Photo 3 (a-b). Removing weed and nutrient enriched topsoil (scalping) is a highly effective way to prepare soils for grassland restoration. Scalping can even be done at a large scale with road graders. These photos are of sites included in the Greening Australia and Melbourne University’s Grassy Groundcover Research Project.

Photo 4a.

Photo 4b. Photo 4 (a-b). (a) This photo was taken three years after seeding of a scalped site. Note the desirable gaps between the wildflowers and native grasses with no one species dominating and little weed competition. (b) A site which was not scalped prior to seeding with same the same seed mix as the photo above. On the right, note the lack of gaps between grass tussocks, no visible wildflower, nor native grasses, and high exotic grass biomass dominating.

For field plantings up to 3000 seedlings a day can be planted per planter using a ‘Pottiputki’ (a steel tube with a trigger release at the bottom; click here). The Pottiputki is pushed into the ground, the bottom of the tube is opened, and a plant passes down the tube into the ground so the root ball is below the mound surface. The ground is then compacted around the plant using the feet and the planter moves onto the next placement. For grassland restoration, normally seedlings are planted at densities of 4-12 plants per m 2. While plant densities in remnant communities commonly range between 60-120 plants per m 2 , planting at such densities for restoration is generally considered cost prohibitive. Ideally the upper soil horizon is moist at the time of planting. If this is not the case, then seedlings should be watered if possible, but this can be impractical for large plantings.

The best time for planting can vary from region to region and between seasons. In winter rainfall areas, planting may take place after an ‘autumn break’ (the onset of rains after the dry summer period). However, in times when the autumn break is unreliable or does not eventuate (e.g. during drought periods), early spring planting should be considered, when soil temperatures are rising and soils still retain moisture from winter rains. However, take care in frost prone areas or with frost- sensitive species.

STEP 6a.

Planting

Historically, conservation of remnant communities has been the focal objective the long-term protection of native grasslands. However, conservation on its own has not proved effective in halting the decline of these communities and restoration is now seen as an important component alongside conservation. To date, most grassland restoration projects have been conducted on relatively small scales (less than 1 ha) utilising container-grown stock or translocated plant material. Both have been popular with land managers and community groups, primarily because of the relative ease of planting material into the field and because of the instant visual effect. While these methods represent an effective use of a limited seed resource, reintroduction of nursery seedlings is labour intensive and quite expensive on a per hectare basis. Scientific reviews of many seedling plantings have also highlighted variable and sometimes quite low success under field conditions.

Direct seeding has the potential to deliver and establish many more plants (and species) than through planting seedlings. As the need and opportunity to restore grasslands has become more widely accepted, there has been a growing interest in adapting agricultural technologies to improve the efficiency and success with which seed can be introduced into restoration projects. Seeding techniques vary in nature, complexity and cost. Some examples of currently used

methods include hydro-seeding (for steep slopes and batters), seed-drilling and broadcast seeding.

Tractor-mounted seed-drills have been shown as effective in seeding herbaceous species into cultivated soil profiles. However, while direct drilling offers excellent seed to soil contact, the drilling equipment can be problematic. Those species with fuzzy, hairy and long awned seed (e.g. Asteraceous and Poaceous species) often become entwined and tangled, preventing individual seeds dropping from hoppers into seed drills. This problem can be lessened by adding a bulking agent such as coarse vermiculite to the sowing-mix to facilitate its free flow, or by cleaning to ‘pure seed’.

Agricultural fertiliser spreaders have been used to deliver seed onto cultivated seed beds. However, delivery is often unreliable (particularly under windy conditions) and this machinery present difficulties with calibrating the seeding rate.

The Victorian-based Grassy Ground Cover Project (GGRP) run by Greening Australia in partnership with the University of Melbourne, investigated the use and modification of machinery used in the landscaping and turf businesses. There is a commercially available machine developed to aerate and de- compact soils in urban parks and sporting grounds (AERA- vator®), which has also proved ideal for seed bed preparation in agricultural sites (the width of the machine is 1.5 m).A traditional tube-feed seed-hopper mounted on the machine was modified to

STEP 6b.

Seeding

shed their seed which in most lowland grasslands and grassy woodlands occurs spring to mid- summer. Therefore, late summer to autumn is often considered an appropriate time to burn for biomass reduction. However, restorationists should always adhere to local fire regulations, restrictions and requirements for permits. Use the skills and knowledge of local fire brigades to help undertake burns safely and effectively (Photo 7).

Photo 7. Members of the Snake Valley Fire Brigade assist in reducing biomass loads at a Grassy Groundcover Research Project site near Chepstowe in south west Victoria by conducting an autumn burn. Controlled burns such as this help to maintain open spaces between grass tussocks (Photo 4a) so a brilliant diversity of wildflowers can persist.

Managing biomass - grazing

Livestock grazing has been shown to be effective in maintaining species diversity within semi-natural grasslands in northern Europe, however, the effects of grazing on the maintenance of species diversity within restored and remnant grassland communities in south eastern Australia is still under investigation. Negative effects of grazing by livestock can include defoliation and litter reduction, trampling, soil compaction, possible importation of seed (both natives and weeds), localised

STEP 7.

Maintenance for diversity

deposition and return to the soil of dung and urine, and modification of seed and fruit dispersal.

Local studies have shown that cattle graze tall native perennial grasses (such as Themeda and Dichanthium ) in preference to smaller tussock grasses (like Austrodanthonia and Austrostipa ). Sheep are more selective of palatable species and graze closer to the ground. ‘Crash’ or ‘Pulse’ grazing, involving high stocking rates in defined areas for limited time periods (few hours or days), may reduce selective grazing impacts while effectively removing biomass. Grazing as a tool for grassland management requires fencing (fixed, movable or electric) and good stock management skills. Deferred and rotational grazing are alternative approaches where stock have access to vegetation from late summer to mid-winter when most species have finished flowering or rapid growth. Again, the objective for such grazing is to maintain or enhance grassland biodiversity (plants and animals) by reducing herbage biomass and maintaining gaps between perennial tussock grasses.

Restored sites should be managed to preserve and develop the diversity of the original sowing and restrict weeds. This can include a range of management actions, both chemical and physical. Biomass build-up (dead and alive) is a significant factor in lowering diversity in complex grasslands where native grasses dominate. Diverse grasslands need small patches of open ground for the germination of many wildflowers (Photo 4a). Targeted fires, short-term intense grazing, or mowing followed by removal of slash can be use to reduce the smothering effect of biomass build-up.

Managing biomass - fire

Several studies have shown that most mature grassland plants are relatively robust and insensitive to the effects of fire season. The effect on long-term seed regeneration of differing fire seasons may however be an important determinant in the evaluation of appropriate timing of these events. It is generally accepted that restored (or remnant) communities should not be burnt until species have finished flowering and

Native species like kangaroo grass can become dominant just like exotic pasture species such as phalaris if not managed.

Photo 4a. This photo shows desirable gaps between the wildflowers and native grasses with no one species dominating and little weed competition.

Managing biomass - mowing

Biomass reduction on public road reserves or lands is often carried out by mowing. This is a valuable tool to control the structure and composition of grassland vegetation due to the ready access to machinery and relatively low cost. Ideally, slashing is followed by raking and baling to remove biomass (Photo 8).

Photo 8. Another way to control the biomass of dominant native grasses is to mow and bale. This reduces the build up of native grass biomass allowing sub-dominant wildflowers to access sunlight, moisture and soil nutrients.

Herbage left on site can return unwanted nutrients and smother vegetation or restrict seedling recruitment. Mowing to remove excessive grass canopy in late winter can benefit the growth of early flowering forbs, while a late summer-autumn slashing and raking can provide canopy gaps for the recruitment of autumn germinating forb species. However, some drawbacks of mowing include the possible introduction of weed seeds brought in on equipment, soil compaction, and physical damage to plant structure by the tires of mowing equipment.

Most grassland restoration projects that plan to establish complex communities up to 3 ha in size or larger should plan for a minimum five-year cycle for maximum success. This period allows for 1-2 years of site preparation, seed collection and seed production before seeding or planting, then at least two years of monitoring and maintenance. Following seeding or planting, sites will be vulnerable to weeds, grazing and insect pests. This will require close monitoring to ensure management actions are taken when and where required. However, monitoring should start at the beginning of a project. Monitoring should record what is done at each step of any restoration project (Figure 1). Successful restoration projects show that effective monitoring benefits from setting clear

STEP 8.

Monitor to learn and improve

objectives and goals and these can be easily forgotten a few years later. Too often monitoring starts at the wrong end of this sequence.

There is a common desire to monitor restoration outcomes. However, it is also prudent to first monitor (record) the Objectives and Strategies of a restoration project, followed by a record of the Actions to be implemented, then the Results of those actions (e.g. dead or alive plants). The Table below provides a suggested list of fields (bits of data) that should be collected to monitor all aspects of a grassland restoration project.

A REVEGETATION GUIDE FOR TEMPERATE GRASSLANDS I^13

Further Reading

Australian National Botanic Gardens (2012) Growing Native Plants on the Web.

Broadhurst, L. (2007) Managing genetic diversity in remnant vegetation. Technical Note 01/2007.

Broadhurst, L. M., A. Lowe, D. J. Coates, S. A. Cunningham, and M. McDonald. 2008. Seed supply for broadscale restoration: maximizing evolutionary potential. Evolutionary Applications 1:587-597.

Coor, K. 2003. Revegetation Techniques: A Guide For Establishing Native Vegetation In Victoria. Greening Australia Victoria.

Cole, I. A., I. Dawson, W. Mortlock, and S. Winder. 2007. Guideline 9: Using native grass seed in revegetation. FloraBank. Available from URL

Cole, I. A. and W. H. Johnston. 2006. Seed production of Australian native grass cultivars: an overview of current information and future research needs. Australian Journal of Experimental Agriculture 46:361-373.

Foster, P. R. Reseigh, J. Myers, J. P.

2009. An introduction to the nutritional composition of Australian Native Grasses: forage and seed. Rural Solutions, Adelaide.

Gibson-Roy, P. G., Moore, G., Delpratt, J. and Jess Gardner, J. (2010) Expanding horizons for herbaceous ecosystem restoration: the Grassy Groundcover Restoration Project. Ecological Management and Restoration 11: 176-186.

Grassy Groundcover Gazette. 2006-

10. Greening Australia. Available from URL

Hall, M., J. Delpratt, and P. Gibson- Roy. 2006. Viability testing of Victorian Western Plains grasses. Australasian Plant Conservation 15:23-25.

McDougall, K. L. and J. Morgan.

2005. Establishment of native grassland vegetation at Organ Pipes National Park near Melbourne, Victoria: Vegetation changes from 1989 to 2003. Ecological Management and Restoration 6: 34-

Mortlock, W. 2007. Basic germination and viability tests for native plant seed. Guideline 8. FloraBank.

Prober, S. M. and K. R. Thiele. 2005. Restoring Australia’s temperate grasslands and grassy woodlands: integrating function and diversity. Ecological Management & Restoration 6:16-27.

Smallbone, L., S. M. Prober, and I. D. Lunt. 2007. Restoration treatments enhance early establishment of native forbs in a degraded grassy woodland. Australian Journal of Botany 55:818-830.

Further Assistance

For further assistance or advice we suggest you try contacting:

Greening Australia ph 1300 886 589 or find us on the web page

Your Regional NRM (catchment) Organisation

Acknowledgments

Funds for the preparation and publication of this guide were provide by the Australian Government through the Biodiversity Fund. The guide was compiled by Dr Paul Gibson-Roy and he provided the photographs. Editorial services were provided by Dr David Freudenberger and Dr Jason Cummings. Graphic design was provided by Landcare Australia Ltd.

Disclaimer

The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those of the Australian Government or the Minister for Sustainability, Environment, Water, Population and Communities.