Document ID: chunk:federal_register_of_legislation:F2023L01376:reg:3:p6
Version: federal_register_of_legislation:F2023L01376
Segment Type: reg
Provision Reference: reg 3 (pt 6/13)
Character Range: 100358–103412

known to be determined by climatic parameters, elevated temperatures in late autumn decreasing the probability of suitable conditions for flower bud initiation and/or decreased rainfall in summer affecting nut maturation, are likely to reduce the reproductive capacity of natural populations, especially those occupying the warmer drier end of climate gradients.
Climate change is also predicted to lead to a reduction in the extent of overlap of suitable environment among Macadamia species (Powell et al. 2014) thus potentially resulting in decreased hybridisation between Macadamia species. Research is required into the magnitude of change and the likely impacts on individual populations and species.
Finally, climate change may exacerbate other existing threats such as fire and weeds. For example, climate change may alter the distribution and abundance of some weeds, particularly exotic vines and pasture grasses at remnant edges, or result in vegetation changes within Macadamia habitat, leading to conditions more conducive to the spread of fire.
Loss of climatic habitat caused by anthropogenic emissions of greenhouse gases is a Listed Key Threatening Process under the Environment Protection and Biodiversity Conservation Act 1999 (Cth). Climate change is also identified as a Key Threatening Process under the Biodiversity Conservation Act 2016 (NSW).

Genetic pollution
DNA marker studies have confirmed hybrid genotypes (Peace 2005) of M. integrifolia and M. ternifolia, and M. integrifolia and M. tetraphylla hybrids occur in a 20 km overlap zone where both species co-occur within the same rainforest patch.
This natural predisposition for hybridisation has been found to be causing genetic 'pollution' of wild populations. A recent Honours level post graduate study identified gene flow between Macadamia nut cultivars (predominantly based on limited M. integrifolia germplasm) and nearby wild populations of M. tetraphylla (O'Connor 2013). There is a reasonable to high probability that the same phenomenon is occurring between cultivars and M. integrifolia and/or M. ternifolia. The study was, however, limited in scope and further research is required to identify thresholds of spatial proximity between cultivars and wild trees and to determine fitness (survival and reproductive potential) of hybrids among the affected wild populations. The major impact on wild Macadamia species is likely to be limited to the relatively few populations located in areas where Macadamia farms are a major agricultural activity such as the Alstonville Plateau in Northern NSW. In Queensland, the key Macadamia farming area is the Bundaberg region, which is well outside of the range of wild Macadamias. There are, however, numerous farms in south east Queensland and northern NSW within the range of M. integrifolia and/or M. ternifolia where gene flow between cultivars and wild Macadamia populations could potentially occur.

Public perception
Public perception that Macadamias are a plentiful species and therefore not threatened is an issue.