Data from: The role of topography and plant functional traits in determining tropical reforestation success

1.Early establishment and sapling growth is a key phase in ensuring cost-effective reforestation success in relation to biodiversity outcomes. Therefore species selection must consider the interaction between plant functional traits and the often-challenging and heterogeneous biophysical environment of degraded landscapes.

2.In this study, we examine how microtopography (slope) results in spatial heterogeneity of soil nutrients, especially phosphorus (P) in a degraded tropical pasture landscape in Queensland, Australia. We then explore how this small-scale heterogeneity influences the growth of two native tree species, Cardwellia (C.) sublimis (Proteaceae) and Flindersia (F.) brayleyana (Rutaceae), which differ in key nutrient-acquisition strategies.

3.The proteaceous C. sublimis was found to be buffered from possible P limitation in degraded soils due to its effective P acquisition by cluster roots. In contrast to C. sublimis, which showed no difference in growth after 5 years across a range of soil conditions, F. brayleyana was found to be highly responsive to soil conditions with increased growth in low-slope, higher P availability areas. The ability of F. brayleyana to take advantage of high soil P levels, including the development of leaves with higher P concentrations, resulted in an apparent switch in competitive fitness between these two species across a landscape gradient.

4.Synthesis and applications. In a detailed study of a landscape reforestation experiment in North Queensland, Australia, we demonstrate that site edaphic factors can vary within tens of meters due to topographic relief, and that species respond differently to these conditions. We therefore show the need to consider both the spatial heterogeneity of edaphic factors and the belowground functional traits of potential reforestation species when planning reforestation programs.

1. 幼苗早期定植与生长是实现兼具成本效益与生物多样性成效的造林成功的关键阶段。因此，物种遴选需考量植物功能性状（plant functional traits）与退化景观中普遍存在的严苛且异质化生物物理环境之间的交互关系。
2. 本研究以澳大利亚昆士兰州一处退化热带牧场景观为研究对象，首先探究微地形（microtopography，即坡度）如何驱动土壤养分，尤其是磷（phosphorus，P）的空间异质性；随后解析这种小尺度异质性对两种本土乔木生长的影响——这两种乔木分别为山龙眼科的Cardwellia sublimis（C. sublimis）与芸香科的Flindersia brayleyana（F. brayleyana），二者在关键养分获取策略上存在显著差异。
3. 研究发现，山龙眼科的C. sublimis可通过簇根（cluster roots）高效获取磷，从而规避退化土壤中可能存在的磷限制风险。与在5年观测周期内、不同土壤条件下生长无显著差异的C. sublimis不同，F. brayleyana对土壤条件响应极强：在坡度较低、磷有效性更高的区域，其生长量显著提升。F. brayleyana能够利用土壤高磷水平——包括形成磷浓度更高的叶片——这一特性使得二者在景观梯度上的竞争适合度（competitive fitness）发生了明显转换。
4. 综合与应用。本研究通过对澳大利亚昆士兰州北部一处景观尺度造林试验的详细分析表明：受地形起伏影响，样地土壤因子（edaphic factors）在数十米范围内即可出现显著变异，且不同物种对该类环境条件的响应存在差异。因此，在规划造林项目时，需同时考量土壤因子的空间异质性与潜在造林物种的地下功能性状（belowground functional traits）。