Biodiversity benefits of alley farming with old man saltbush in central western New South Wales

Abstract

Agricultural production systems that also provide opportunities to conserve biodiversity will be a crucial component of integrated and sustainable land use in mixed farming landscapes and should be considered and evaluated. Alley farming is an innovative farming system that aims to increase farm profitability while also enhancing environmental outcomes. Alley farming incorporates belts of woody perennial plants such as trees or shrubs, interspersed with alleys of conventionally rotated cropping and livestock grazing land. In the present study, we assessed the impacts on terrestrial biodiversity of alley farming with the native perennial chenopod shrub old man saltbush (Atriplex nummularia Lindl.) in central western New South Wales. Terrestrial biodiversity conservation status was assessed by site surveys conducted in spring 2005, 2006 and 2007 at 15 old man salt bush alley farming sites (OMSB), 15 conventionally managed sites and three native woodland remnants in and around the Condobolin Agricultural Research and Advisory Station in the central western plains of New South Wales. Biodiversity surveys included an assessment of ‘site condition’ – a metric of biodiversity conservation status at the site scale based on measurement of 10 habitat and vegetation condition attributes, compared against benchmark values for the appropriate native ecosystems with relatively little recent anthropogenic modification. Bird surveys were also conducted to assess the diversity and abundance of birds in OMSB, conventional and remnant woodland sites in four functional response groups. Site condition was significantly higher at remnant woodland sites than at conventional farming and OMSB alley farming sites. Remnant woodland sites had greater native overstorey cover and native ground cover of forbs, more trees with hollows, presence of at least some overstorey regeneration and the presence of fallen logs. Site condition was also significantly higher at OMSB sites than at conventional sites and increased significantly across 3 years. By the third year after establishment, OMSB sites had higher native plant species richness and native mid-storey cover than did conventionally farmed sites. These attributes increased markedly over time at the OMSB sites whereas they did not increase at conventional or remnant woodland sites. Native grasses and forbs established under and around the saltbush plants, indicating that OMSB alley plantings can provide habitat for a wide range of native plant species, enhancing biodiversity values of these areas through improved structure and composition. Improved habitat condition at the OMSB sites after 3 years did not lead to a significantly higher diversity or to a higher overall abundance of birds at the OMSB than at conventional sites. Furthermore, diversity and abundance of birds at both OMSB and conventional sites remained significantly below those of remnant woodland sites. Some decliner bird species were observed using OMSB sites, but not conventional sites. Old man saltbush alley farming can provide direct on-site benefits for native biodiversity by improving the structure, function and composition of vegetation at the site or paddock scale. If proposed as a replacement to conventional crop–pasture rotation, OMSB alley farming can enhance biodiversity conservation values, and where production benefits are likely, could play an important role in the integration of production and conservation as a synergistic ‘win–win’ system in mixed farming enterprises.

Post‐fire recovery of revegetated woodland communities in south‐eastern Australia

“…livestock grazing; Yates et al 2000). The higher overall percent native ground cover in remnants compared to revegetated sites reflects the habitat value of native vegetation remnants in agricultural landscapes (Cousins & Lindborg 2008;Seddon et al 2009). This is similar to results reported in Prober et al (2009), and highlights the resilience of native ground cover species.…”

“…This is similar to results reported in Prober et al (2009), and highlights the resilience of native ground cover species. The higher overall percent native ground cover in remnants compared to revegetated sites reflects the habitat value of native vegetation remnants in agricultural landscapes (Cousins & Lindborg 2008;Seddon et al 2009).…”

Comparing Regional Biodiversity Benefits of Investment Strategies for Land-Use Change

“…In these scenarios, alley farming was primarily implemented on the better cropping soils with high land‐use intensity and therefore very low current site condition values. Alley farming with old man saltbush can improve site condition by facilitating establishment of local perennial grasses and forbs and providing habitat for native fauna (Seddon et al ., 2009). Site condition improved in areas converted to alley farming under the farming system shift and salinity investment scenarios.…”

“…Site condition values were calculated for each combination of land‐use class, tree density and vegetation community. Data on site condition in the land‐use classes were obtained from 244 condition plots in remnant vegetation in the Little River catchment (Seddon et al ., 2002) and from 58 condition plots on seven farms in central western NSW (Seddon et al ., 2005; 2009). Where field data were not available for combinations of land use and vegetation community, estimates were made for each site condition variable using expert knowledge of relationships between land use and site condition in vegetation communities in the study area and similar areas in central west NSW (Seddon et al ., 2002; 2005; Zerger et al ., 2009).…”

Planted saltbush (Atriplex nummularia) and its value for birds in farming landscapes of the South Australian Murray Mallee

“…Exceptions are Norman et al. (2008) who examined plant and invertebrate assemblages in saltbush plantings on salt‐affected land in south‐western Western Australia and Seddon et al. (2009) who sampled bird species in planted saltbush alleys in western New South Wales.…”