Sensitivity of seedling growth to phosphorus supply in six tree species of the Australian Great Western Woodlands

Abstract

Many Australian native plants from regions with ancient, highly weathered soils have specialised adaptations for acquiring phosphorus (P) and can exhibit negative effects of excess P supply on growth and survival. Despite this, fertiliser (including P) is routinely applied in post-mining and other restoration schemes. In this study we investigated the effect of a range of applied P on the growth and tissue P concentrations for six woody species from the Great Western Woodlands (GWW) of Western Australia – a region that it not only biodiverse, but that has experienced significant levels of mining related activities. Our data from a pot-based experiment show that all six species exhibited greater growth with increased P application up to 15 mg kg sand–1. However, at P concentrations in excess of 15 mg kg–1, dry mass accumulation did not increase further for three of the species tested. For the other three species, dry mass accumulation declined as the P concentration increased above 15 mg kg–1. For all of the study species, root and shoot P concentrations increased as the concentration of applied P increased. The internal shoot P concentration, at which dry matter accumulation either plateaued or started to decline, was in the range 1.95 to 3.2 mg P g–1 dry matter. This was ~2–4 times the concentration found in natural vegetation. These data suggest that in a restoration context, there is a potential risk that, excess P application may decrease plant growth rates for some species. Consequently, the addition of fertiliser to restored sites may have unpredictable impacts on the plant community by directly reducing the growth of some species but increasing the growth of others. We suggest that careful consideration should be given to designing appropriate fertiliser regimes for land restoration schemes in ancient P deplete landscapes to avoid the risk that fertiliser addition has the unwanted outcome of decreasing growth and survival of the target native species and increasing the abundance of unwanted weeds or aggressive pioneer species.

The where, when and what of phosphorus fertilisation for seedling establishment in a biodiverse jarrah forest restoration after bauxite mining in Western Australia

“…While the negative effect of applied fertiliser on abundance / growth of these taxa may be mediated by direct negative effects of P (e.g. Lambers et al, 2002;Williams et al, 2019), it is also likely that these slowgrowing species are susceptible to competition from highly P responsive species such as A. celastrifolia. Indeed, negative competitive effects of vigorous legume growth, in response to applied P, on slow-growing understorey species have been reported elsewhere (e.g.…”

Too much of a good thing: phosphorus over-fertilisation in rehabilitated landscapes of high biodiversity value

“…These data suggest a potential risk that-in a rehabilitation contextexcess applied P may decrease growth rates for some plant species. Therefore, fertiliser addition has the potential to have unpredictable impacts on competitive dynamics and affect developing plant communities (Williams et al 2019).…”

Phosphorus uptake and toxicity is delimited by mycorrhizal symbiosis in P-sensitive Eucalyptus marginata but not in P-tolerant Acacia celastrifolia

“…Similar contrasting patterns in response to increasing P-supply have been observed previously for a range of Australian species from severely nutrient-impoverished environments (Grundon, 1972; Groves & Keraitis 1976; Handreck, 1997; Pang et al . 2010; de Campos et al ., 2013, Williams et al ., 2019). For E .…”

“…Species adapted to naturally low soil P concentrations may display symptoms of P-toxicity when supplied with P concentrations above those that they experience naturally in soil (Handreck, 1991; Lambers et al ., 2002; Shane et al ., 2004a; Standish et al ., 2007; Pang et al ., 2010; de Campos et al ., 2013; Williams et al ., 2019), due potentially to the loss of low affinity transporter systems (Huang et al ., 2011). P-sensitive species occur in a range of families, including the Fabaceae, Haemodoraceae, Myrtaceae, Proteaceae and Rutaceae.…”

“…Symptoms of P-sensitivity are highly species-specific and occur at shoot P-concentrations less than 1 mg g −1 dry mass (DM) to more than 40 mg P g −1 DM (Shane et al ., 2004b and references therein). Symptoms of P toxicity include a reduction in growth with increasing external P (e.g., Standish et al ., 2007; Williams et al ., 2019) and visible symptoms including early leaf senescence and necrotic and chlorotic regions on leaves (e.g., Handreck, 1991; Lambers et al ., 2002; Shane et al ., 2004ab; Kariman et al ., 2014a; Ye et al ., 2021).…”