Scattered paddock trees are a familiar feature across rural Australia. These trees are important for maintaining agricultural productivity and are critically important for the conservation of wildlife. However, due to old age, stress from agricultural production, fire, and a lack of continuous replacement of old trees, we are rapidly losing these iconic trees.
If current trends continue, it is possible that in as little as 40 years all scattered paddock trees across most of the south-west slopes of NSW will be gone.
By keeping scattered paddock trees in good condition, and ensuring that trees are recruited to replace lost trees, we can retain this valuable resource for the next generation of landholders as well as help to conserve our native wildlife.
Scattered paddock trees, particularly in pastoral areas, are valuable assets that boost farm productivity and profitability.
The most recognised and understood value of trees on farms is shade for livestock, and providing shelter from the wind. Shade/shelter is necessary to reduce the amount of heat and cold stress experienced by livestock. This allows livestock to dedicate less energy to self-maintenance, which can result in improved farm productivity.
Energy expended by livestock to maintain a regular body temperature diverts valuable energy away from desired production gains, such as live weight gain, milk production or wool growth.
- Dairy cows have been shown to produce 17% more milk in paddocks with trees that provide shelter.
- Less energy is required to maintain optimal body temperature in livestock, which can improve weight gain and lower livestock nutrient requirements. For example, sheltered off-shears wethers require approximately one third the amount of supplementary feed to maintain bodyweight compared to those that have no shelter.
Production gains from shelter provided by paddock trees is not limited to livestock. Benefits to other parts of your farm include:
- Improving soil structure and quality as wind and water erosion is reduced. Soil fertility also improves as leaf litter and animal droppings decompose, returning nutrients to the soil.
- Salinity management as trees can reduce waterlogging and dryland salinity problems.
- Scattered paddock trees have been shown to increase water infiltration in soils, helping retain moisture in the landscape.
- The shelter provided by paddock trees has been shown to increase pasture growth and reduce desiccation in hot and dry periods.
- Paddock trees are associated with an increase in the abundance and diversity of insect pollinators and natural pest control agents. Native bats, lizards, and birds will prey on common farm pests, and many of these species use scattered paddock trees for roosting and foraging. The presence of these animals on farms can significantly reduce the number of insect pests.
Scattered paddock trees can represent the last remaining remnants and individuals of previously widespread vegetation communities, such as box gum grassy woodlands. Furthermore, due to their age (these trees are often hundreds of years old), they have disproportionally positive benefits for wildlife, as features such as tree hollows can take over a century to form.
Not only do scattered paddock trees allow many species to persist in agricultural landscapes, they also influence biodiversity across the wider landscape. Scattered paddock trees are typically the oldest living features in the landscape, and provide essential and often critical wildlife resources, that are preferred by many species, including threatened species such as the Superb Parrot and Squirrel Glider.
Features of scattered paddock trees that are important to wildlife include:
- Tree hollows and large canopies. These resources/features are critical for the persistence of some wildlife and are difficult to replace as they can take many centuries to develop.
- Connecting habitat and native vegetation patches and plantings by providing ‘stepping-stones’ for wildlife to move across the landscape. This increased connectivity positively influences biodiversity within the broader landscape.
- Cracks and crevices in paddock trees provide habitat for small mammals and reptiles.
- Paddock trees will often flower more heavily than other trees, providing important resources for wildlife, such as honeyeaters. In addition, a variety of tree species across the landscape ensures that species such as honeyeaters, sugar gliders and other animals that depend on nectar and pollen have a continuous supply of nectar.
- Provide a source of natural regeneration for the next generation of paddock trees and a source of seeds for collection, storing and propagation.
- The presence of paddock trees will have a positive influence on the biodiversity of other vegetation on farms such as remnant patches or tree plantings, whether they are within the other vegetation or located in the surrounding area.
There is no single cause of the demise of scattered paddock trees. Factors that have brought about their decline include: increased stress caused by agricultural practices (e.g. spray drift, stock camps and stubble burns), changes in hydrology, drought, insect attack, clearing, and natural death due to old age.
As these veteran trees vanish from the landscape, there are no trees to replace them. Regrowth – a source of future paddock trees – has been suppressed over the last century by livestock grazing, clearing practices, fire and other land management activities.
There are many actions farmers can take to turn this situation around and arrest the decline to ensure there is a succession of trees to replace lost trees. These solutions will vary across different landscapes and for different production systems.
Identify the main threats and manage for them
Identifying the main threats to scattered paddock trees on your property and managing these where possible is a good place to start.
Incorporate scattered paddock trees in farm planning
Incorporation of scattered paddock trees in farm planning is a great way to identify management options that suit your property. Going through this process can often identify some obvious and easily achieved options, such as identifying scattered trees that could be protected (e.g. by incorporating them into tree plantings) or paddocks where you might wish to increase scattered paddock trees, creating a wooded pasture for extra livestock shelter and wildlife.
Avoid herbicide spray drifting on to scattered trees
While most trees recover from many herbicides, the initial stress caused by herbicides weakens trees making them more vulnerable to insect attack, disease and wind damage.
Reduce stocking rates or remove stock pressure directly under trees
Stock camps can cause major stress on scattered paddock trees, through physical damage to the root zone and to the trunk of the tree, and increased nutrient loads within the soil. By reducing or removing stock pressure directly under trees (at least within the drip line, which is the diameter of the trees canopy) can help trees recover, prolong their life and encourage natural regeneration. Shade and shelter benefits can still be gained by excluding livestock access directly below a tree’s dripline.
Spelling paddocks on a regular basis (e.g. periods of grazing with recovery times of 3, 6 or 12 months) or by setting a paddock aside for a longer period (2-3 years) can promote regeneration of trees and allow existing scattered paddock trees time to recover. Note that results can vary due to climatic conditions during this period and factors associated with nutrient loads and grass cover.
Increase the number and age range of trees
Having a range of ages of paddock trees recruiting will help to offset the loss of old scattered paddock trees. While the impact of livestock on paddock trees is rarely equally dispersed, having more trees can spread their impact. This recruitment to offset the function is a long term investment, as many characteristics of old trees may take centuries to form, e.g. tree hollows.
Protect scattered paddock trees from fire
Avoid exposing scattered paddock trees to fire, whether wildfire, burn off, or stubble fires. Old trees are particularly vulnerable.
Fertilize away from scattered paddock trees
Avoid applying fertilizer in the root zone of trees.
Protect existing trees and recruitment trees (consider a whole of paddock restoration)
Physically protecting trees by fencing individuals or clumps of paddock trees can prolong the life span of trees and allows for natural regeneration to occur relatively quickly and effectively. The fence needs to be wider than the canopy as the most robust seedlings are found outside the canopy area.
Tree guarding individual recruitment or planted trees is often a preferred option by many farmers, as they can be selective of where trees go and paddocks can be managed as business as usual. However, for the long-term viability of this asset, consideration needs to be given to the stresses that will be put on these new trees by existing paddock management and/or stock.
If planting new trees, plant more then you need to allow for losses.
Whole of paddock restoration is a practice developed by Greening Australia where a paddock or part of a paddock (>10 ha) is set aside in order to recruit scattered trees on properties. This is an ideal way to recreate and restore scattered paddock trees / wooded pasture at a larger scale, improving shelter and other productivity values, and also generating positive outcomes for biodiversity. This method involves direct seeding or planting patches of trees and shrubs, while allowing >50 m wide areas between for pasture. On average, within 2 years short spells of grazing can be tolerated and after five years the paddock can be return to business as usual.
- Sources and further reading
Fischer J, Stott J, Zerger A, Warren G, Sherren K & Forrester R. 2009. Reversing a tree regeneration crisis in an endangered ecoregion. Proceedings of the National Academy of Sciences of the USA, 106 (25): 10386-10391.
Fischer J, Stott J & Law BS. 2010. The disproportionate value of paddock trees. Biological Conservation, 143 (6): 1564-1567.
Gibbons P & Boak M. 2002. The value of paddock trees for regional conservation in an agricultural landscape. Ecological Management & Restoration, 3(3): 205-210.
Gibbons P, Lindenmayer DB, Fischer J, Manning AD, Weinberg A, Seddon J, Ryan P & Barrett G. 2008. The future of scattered trees in agricultural landscapes. Conservation Biology, 22 (5): 1309-1319.
Manning AD, Fischer J & Lindenmayer DB. 2005. Scattered trees are keystone structures: Implications for conservation. Biological Conservation, 132 (2006): 311-321.
Manning AD, Gibbons P, Fischer J, Oliver DL & Lindenmayer DB. 2013. Hollow futures? Tree decline, lag effects and hollow-dependent species. Animal Conservation, 16 (4): 395-403.
NSW Government Local Land Services. 2014. Scattered Paddock Trees. Factsheet. December 2014. Available from: https://centralwest.lls.nsw.gov.au/__data/assets/pdf_file/0009/537597/Scattered-paddock-trees-web.pdf
Reid N & Landsberg J. 2000. Tree decline in agricultural landscapes: what we stand to lose. In: Hobbs RJ & Yates CJ (eds). Temperate Eucalypt Woodlands in Australia: Biology, Conservation, Management and Restoration. Surrey Beatty & Sons, Chipping Norton, NSW. Pp. 127-166.
- Useful links