Plants that produce specialised cluster roots, which mobilise large quantities of poorly available nutrients such as phosphorus (P), can provide a benefit to neighbouring plants that produce roots in the cluster rhizosphere, as demonstrated previously in pot studies. To be effective, such roots must be present within the short time of peak cluster activity. We tested if this requirement is met, and quantified potential P benefits, in a hyperdiverse Mediterranean woodland of southwest Australia where cluster-rooted species are prominent. Using minirhizotrons, we monitored root dynamics during the wet season in the natural habitat. We found non-cluster roots intermingling with all 57 of the observed cluster roots of the studied tree species, Banksia attenuata. Almost all (95%) of these cases were observed in a high-moisture treatment simulating the 45-year average, but not present when we intercepted some of the rainfall. We estimate that cluster-root activity can increase P availability to intermingling roots to a theoretical maximum of 80% of total P in the studied soil. Due to their high P-remobilisation efficiency (89%), which results from P rapidly being relocated from cluster roots within the plant, senesced Banksia cluster roots are a negligible P source for other roots. We conclude that, rather than serving as a P source, it is the cluster-root activity, particularly the exudation of carboxylates, that may improve the coexistence of interacting species that are capable of root intermingling, thus potentially promoting species diversity in nutrient-poor habitats, and that this mechanism will be less effective in a drying climate.

如先前的盆栽研究所示，产生专门簇状根的植物可动员大量缺乏营养的养分，例如磷（P），可为在簇状根际中产生根的邻近植物带来好处。为了有效发挥作用，此类根必须在峰值簇活动的短时间内出现。我们测试了在澳大利亚西南部的一个以物种为根的物种最为突出的地中海多样化林地中是否满足了这一要求并量化了潜在的P效益。我们使用小型根尖管，在自然栖息地的雨季期间监测了根系动态。我们发现非丛集根与研究的树种班克西亚树的全部57个丛集根混合。几乎所有这些案例（95％）都在模拟45年平均值的高湿度治疗中观察到，但在我们截获一些降雨时却没有出现。我们估计簇根活动可以增加磷的有效性，使根系混杂到研究土壤中总磷的理论最大值的80％。由于磷的高迁移率（89％），这是由于磷迅速从植物内的簇生根中重新定位而引起的，Banksia感冒。群集根是其他根的可忽略的P源。我们得出的结论是，簇根活动（特别是羧酸盐的渗出）而不是用作磷源，可以改善能够根混合的相互作用物种的共存，从而潜在地促进营养贫乏的物种多样性栖息地，并且这种机制在干旱气候下效果会更差。