ABSTRACT Despite near-extinction in the nineteenth century, after efficient restoration measures the population of Eurasian beaver (Castor fiber L.) in Latvia currently is viable and growing. While the ecological effect of the species on water quality and biodiversity is generally positive, the high number of animals in production forests often creates challenges for management. Drainage ditches are among the most favoured habitats of beavers resulting in flooded stands, reduced tree growth and economical losses. The aim of the study was to evaluate the chemical properties of water in forest drainage ditches, affected by beaver activity, and their changes after the dam removal. Chemical composition of surface water in ditches was analysed in sampling points above dam, below dam and in the ditch itself after removal of the dam; results compared to pristine beaver site nearby on a small stream. Results did not show significant differences between concentrations above and below dams. After removal of the dams, significant increase in DOC, N-NO3 -, N-NH4 + and TSS concentrations and significant decrease in TP concentrations were observed in some of the sites. Observed concentrations of all measured parameters were significantly lower in pristine beaver site than in beaver sites on drainage ditches.

中文翻译：

---

海狸坝拆除对泥炭地森林排水沟水化学性质的影响

摘要 尽管在 19 世纪濒临灭绝，但在采取有效的恢复措施后，拉脱维亚的欧亚海狸（Castor fiber L.）种群目前仍可生存且仍在增长。虽然该物种对水质和生物多样性的生态影响通常是积极的，但生产林中的大量动物往往给管理带来挑战。排水沟是海狸最喜欢的栖息地之一，导致水淹林分、树木生长减少和经济损失。该研究的目的是评估森林排水沟中受海狸活动影响的水的化学性质，以及大坝拆除后的变化。对坝上、坝下采样点及拆坝后沟渠内的沟渠地表水化学成分进行分析；结果与附近一条小溪上的原始海狸遗址相比。结果并未显示大坝上方和下方的浓度之间存在显着差异。拆除大坝后，在一些地点观察到 DOC、N-NO3 -、N-NH4 + 和 TSS 浓度显着增加，TP 浓度显着下降。在原始海狸遗址中，所有测量参数的观察浓度显着低于排水沟上的海狸遗址。