求翻译：4.1土壤pH 值都随土层深度增加而减少，腐殖质、淀积层变化一致，均是柴桦兴安落叶松林最小，溪旁兴安落叶松林最大，除溪旁兴安落叶松林PH在中性范围，其它都显酸性, pH值在3.98~7.15之间。是什么意思？

4.1 soil pH values decrease with increased soil depth, humus, deposition layer changes are fruticosa pall of Larix gmelini minimum, Larix gmelinii forest next to the river's largest, with the exception of larch forest in neutral PH range next to the River, others are acidic, pH value between 3.98~7.15.