Avolio Meghan L, Koerner Sally E
Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA.
Department of Biology, University of North Carolina, Greensboro, Greensboro, NC, USA.
Oecologia. 2024 Dec 20;207(1):14. doi: 10.1007/s00442-024-05648-2.
Nitrogen deposition continues to change grassland plant community composition particularly in more mesic systems; however, whether these altered plant communities will respond differently to other global change factors remains to be seen. Here, we explore how nutrient-altered tallgrass prairie responds to drought. Seven years of nutrient treatments (control, nitrogen (N), phosphorus (P), and N + P) resulted in significantly different plant communities. Within this experimental context we imposed a 3-year drought followed by 3 years of recovery from drought. The response of plant functional types depended on the nutrient treatment. During recovery years, C grasses recovered in the first year in all treatments but the N + P treatment, where instead annual grasses increased. These differential responses during recovery resulted in greater shifts in community composition in the N + P treatment compared with the controls. Despite the effects on community composition, we found no interaction between nutrient treatment and drought treatment on species richness or evenness and standing biomass during drought or recovery. We found drought induced shifts in plant functional groups led to the composition of previously droughted N + P plot becoming more dominated by annual grasses during the recovery years, likely creating a lasting legacy of drought.
氮沉降持续改变着草原植物群落的组成，尤其是在较为湿润的生态系统中；然而，这些改变后的植物群落对其他全球变化因素的反应是否会有所不同仍有待观察。在此，我们探究了养分改变后的高草草原对干旱的响应。七年的养分处理（对照、氮（N）、磷（P）以及氮+磷）导致了显著不同的植物群落。在此实验背景下，我们施加了为期3年的干旱，随后是3年的干旱恢复期。植物功能类型的响应取决于养分处理。在恢复期的第一年，除了氮+磷处理外，所有处理中的C4草本植物都有所恢复，而在氮+磷处理中，一年生草本植物增加。与对照相比，恢复期的这些差异响应导致氮+磷处理中群落组成的变化更大。尽管对群落组成有影响，但我们发现在干旱期或恢复期，养分处理和干旱处理之间对物种丰富度、均匀度和现存生物量没有交互作用。我们发现干旱引起的植物功能群变化导致，在恢复期，先前经历干旱的氮+磷地块的组成更多地由一年生草本植物主导，这可能造成了干旱的持久遗留影响。
