Bracken (Pteridium aquilinum) is an aggressive colonizer of disturbed and other successional habitats in temperate forests. However, little is known about how bracken colonization modifies soil microbial activity and nutrient cycling. We questioned whether bracken presence alters soil nutrient pools and soil microbial respiration throughout a growing season and whether this effect depends on the size of the bracken patch. To answer these questions, we sampled the soil in bracken patches of different sizes (large, medium and small) and in the surrounding pine forest (paired sampling design) in summer, autumn, winter and spring. We analyzed the samples to determine nutrient contents (C, N and P) and soil microbial respiration. Patch size did not influence soil microbial activity or nutrient pools. Bracken acted as nutrient sink for N pools through the growing season and as source or sink for C and P pools depending on season. Moreover, the effect on nutrient pools did not depend on bracken characteristics (area, density or height). Bracken presence enhanced soil microbial respiration proportionally to patch area. The control that bracken exerts over nutrient pools may determine the successful (or otherwise) establishment of other plant species. This contributes to making bracken a successful colonizer as no particular population threshold (area, density) has to be reached before nutrients becomes limiting to other plant species.

蕨菜（蕨））是温带森林中受干扰的和其他演替生境的侵略性定居者。但是，关于蕨菜定居如何改变土壤微生物活性和养分循环的了解甚少。我们质疑蕨菜的存在是否会改变整个生长季节的土壤养分池和土壤微生物的呼吸，以及这种影响是否取决于蕨菜斑块的大小。为了回答这些问题，我们在夏季，秋季，冬季和春季在不同大小（大，中，小）蕨菜地块和周围的松树林中采样了土壤（配对采样设计）。我们分析了样本以确定养分含量（C，N和P）和土壤微生物呼吸。斑块大小不影响土壤微生物活性或养分池。蕨菜在整个生长季节中充当N池的养分吸收器，并根据季节而成为C和P池的源或吸收器。此外，对养分库的影响并不取决于蕨菜的特性（面积，密度或高度）。蕨菜的存在与斑块面积成比例地增强了土壤微生物的呼吸作用。蕨菜对养分库施加的控制可以确定其他植物物种的成功建立（或以其他方式）。这有助于使蕨菜成为成功的定居者，因为在养分限制其他植物物种之前不必达到特定的种群阈值（面积，密度）。蕨菜的存在与斑块面积成比例地增强了土壤微生物的呼吸作用。蕨菜对养分库施加的控制可以确定其他植物物种的成功建立（或以其他方式）。这有助于使蕨菜成为成功的定居者，因为在养分限制其他植物物种之前不必达到特定的种群阈值（面积，密度）。蕨菜的存在与斑块面积成比例地增强了土壤微生物的呼吸作用。蕨菜对养分库施加的控制可以确定其他植物物种的成功建立（或以其他方式）。这有助于使蕨菜成为成功的定居者，因为在养分限制其他植物物种之前不必达到特定的种群阈值（面积，密度）。