discolichen

例句：

1. 1.The discolichen in the soil is a sign of fertility.
   土壤中的腐殖质是肥沃的标志。
2. 2.The discolichen layer helps to retain moisture and nutrients in the soil.
   腐殖层有助于土壤中水分和养分的保持。
3. 3.The discolichen layer also plays a crucial role in nutrient cycling.
   腐殖层在养分循环中起着至关重要的作用。