Variations in Oak Litter Quality Along an Urban-Rural Gradient and Effect on Leaf Litter Decomposition

尽管纽约的空气污染和土壤重金属含量高于农村地区，但沿着城乡梯度分布的栎林的凋落物分解速度在城市地区惊人地快。为了确定树叶质量的差异是否会导致城市垃圾更快的腐烂速度，卡列罗博士将对沿着梯度收集并在实验室培养的新落叶进行分解实验。由于温度、湿度和微生物接种量将被标准化，因此该实验将直接测定城市中活橡树叶的质量是否发生了足够的变化，从而导致树叶掉落后更快地腐烂。在4个月的时间间隔内，将测量实验室孵化的产仔的干重损失。真菌和细菌定植凋落物的生长和呼吸活动也将在腐烂过程中进行测量，以确定对叶片质量可能差异的反应。了解城市和农村森林中不同凋落物腐烂率背后的机制很重要，因为分解率调节着这些生态系统内的养分流动，并影响植物的养分可利用性。可供进行这项研究的设施是一流的。*＊*

Although air pollution and soil heavy metals are higher in New York than in rural sites, litter decomposition rates in oak forests located along an urban-rural gradient were surprisingly faster in urban sites. To determine whether differences in leaf quality contribute to faster decay rates of urban litter, Dr. Carriero will conduct a decomposition experiment on newly fallen oak leaves collected along the gradient and incubated in the laboratory. Since temperature, moisture, and microbial inoculum will be standardized, the experiment will directly assay whether the quality of living oak leaves has been changed enough in cities to result in more rapid decay after leaf fall. Dry weight loss of laboratory-incubated litter will be measured at intervals over a 4-month period. Growth and respiratory activity of fungi and bacteria colonizing litter will also be measured as decay progresses to determine responses to possible differences in leaf quality. An understanding of mechanisms behind the different litter decay rates in urban and rural forests is important since decomposition rates regulate nutrient flows within these ecosystems and influences nutrient availability to plants. The facilities available for conducting this research are first-rate. ***