Liu Jinliang, Zhou Mengsi, Li Xue, Li Tianxiang, Jiang Haoyue, Zhao Luping, Chen Shuman, Tian Jingying, Han Wenjuan
College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China.
Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, Wenzhou University, Wenzhou 325035, China.
Plants (Basel). 2023 Aug 15;12(16):2946. doi: 10.3390/plants12162946.
Global changes in nutrient deposition rates and habitat fragmentation are likely to have profound effects on plant communities, particularly in the nutrient-limited systems of the tropics and subtropics. However, it remains unclear how increased phosphorus (P) supply affects seedling growth in P-deficient subtropical fragmented forests. To explore this, we applied P to 11 islands in a subtropical Chinese archipelago and examined the results in combination with a contemporary greenhouse experiment to test the influence of P addition on seedling growth and survival. We measured the growth (i.e., base area) and mortality rate of seedlings for one arbuscular mycorrhizal (AM) and one ectomycorrhizal (EcM) tree species separately and calculated their relative growth rate and mortality when compared with P addition and control treatment on each island. We also measured three functional traits and the biomass of seedlings in the greenhouse experiment. Results showed that P addition significantly increased the mortality of AM and EcM seedlings and reduced the growth rate of EcM seedlings. The relative growth rate of AM seedlings, but not EcM seedlings, significantly decreased as the island area decreased, suggesting that P addition could promote the relative growth rate of AM seedlings on larger islands. The greenhouse experiment showed that P addition could reduce the specific root length of AM and EcM seedlings and reduce the aboveground and total biomass of seedlings, indicating that P addition may affect the resource acquisition of seedlings, thereby affecting their survival and growth. Our study reveals the synergistic influence of habitat fragmentation and P deposition, which may affect the regeneration of forest communities and biodiversity maintenance in fragmented habitats.
全球养分沉降速率和栖息地破碎化的变化可能会对植物群落产生深远影响，尤其是在热带和亚热带养分有限的系统中。然而，目前尚不清楚增加磷（P）供应如何影响亚热带缺磷破碎森林中的幼苗生长。为了探究这一问题，我们在中国亚热带群岛的11个岛屿上施加了磷，并结合一项当代温室实验来检验施磷对幼苗生长和存活的影响。我们分别测量了一种丛枝菌根（AM）树种和一种外生菌根（EcM）树种幼苗的生长（即基部面积）和死亡率，并计算了与每个岛屿上的施磷和对照处理相比时它们的相对生长速率和死亡率。我们还在温室实验中测量了幼苗的三个功能性状和生物量。结果表明，施磷显著增加了AM和EcM幼苗的死亡率，并降低了EcM幼苗的生长速率。随着岛屿面积的减小，AM幼苗的相对生长速率显著下降，但EcM幼苗没有，这表明施磷可以促进较大岛屿上AM幼苗的相对生长速率。温室实验表明，施磷会降低AM和EcM幼苗的比根长，并降低幼苗的地上生物量和总生物量，这表明施磷可能会影响幼苗的资源获取，从而影响它们的存活和生长。我们的研究揭示了栖息地破碎化和磷沉降的协同影响，这可能会影响森林群落的更新和破碎栖息地中生物多样性的维持。
