Piper aduncum, a tree species native to the Neotropics, has been introduced to other tropical regions and successfully invades secondary forest in fallow land after small scale slash-and-burn agriculture in Papua New Guinea (PNG). However, the effect of P. aduncum invasion on soil chemical properties as well as soil biota remains poorly understood. To fill this knowledge gap, we compared soil chemistry, soil microbiota and soil fauna between sites invaded by P. aduncum and sites with secondary native vegetation, where P. aduncum absent. Soils under P. aduncum had significantly lower P content at 0–5 cm depth, lower NO₃⁻ at 5–10 cm depth and lower N and C content at both depths compared to soil under secondary vegetation where P. aduncum absent. Sites invaded by P. aduncum also harbored lower microbial biomass measured by phospholipid fatty acid (PLFA) analysis, especially at 5–10 cm depth. The composition of microbial communities, based on PLFA and amplicon sequencing methods, also differed between soils invaded and uninvaded by P. aduncum, while soil macrofauna did not show any significant difference in the density of various faunal groups between invaded and uninvaded sites. Furthermore, we studied soil chemistry and foliar nitrogen in food gardens established after clearing of secondary vegetation in sites where P. aduncum had been experimentally excluded for five years. These gardens did not differ in soil chemistry compared to the control gardens where P. aduncum was not cleared. However, P. aduncum removal was associated with a higher N content in the leaves of sweet potatoes (Ipomoea batatas), but not bananas (Musa spp.). Our results suggest that P. aduncum has negative effect on soil microbiota and may slowdown nutrient turnover and availability as well as growth of plants on invaded soil. This finding requires further attention and may have practical implication for food gardening in tropical rainforests.

在巴布亚新几内亚 (PNG) 进行小规模刀耕火种农业后，新热带原产树种Piper aduncum已被引入其他热带地区并成功侵入休耕地的次生林。然而，P. aduncum入侵对土壤化学性质和土壤生物群的影响仍然知之甚少。为了填补这一知识空白，我们比较了P. aduncum入侵的地点和具有次生原生植被（没有P. aduncum 的地点）之间的土壤化学、土壤微生物群和土壤动物群。P. aduncum土壤在 0-5 cm 深度的 P 含量显着降低，NO ₃ ^-与没有P. aduncum的次生植被下的土壤相比，在 5-10 cm 深度和两个深度的 N 和 C 含量较低。由P. aduncum侵入的部位也具有通过磷脂脂肪酸（PLFA）分析测量的较低微生物量，特别是在 5-10 厘米深度处。基于 PLFA 和扩增子测序方法的微生物群落组成在P. aduncum入侵和未入侵的土壤之间也存在差异，而土壤大型动物群在入侵和未入侵地点之间的各种动物群密度方面没有显着差异。此外，我们研究了在P. aduncum清除次生植被后建立的食品园的土壤化学和叶面氮。已被实验性排除五年。与未清除P. aduncum的对照花园相比，这些花园在土壤化学方面没有差异。然而，去除P. aduncum与红薯 ( Ipomoea batatas ) 叶子中较高的 N 含量有关，但与香蕉 ( Musa spp.) 无关。我们的研究结果表明，P. aduncum对土壤微生物群有负面影响，可能会减缓营养物质的周转和可用性以及植物在入侵土壤上的生长。这一发现需要进一步关注，并且可能对热带雨林的食物园艺具有实际意义。