Is invasion of deforested Amazonia by the earthworm Pontoscolex corethrurus driven by soil texture and chemical properties?
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- 作者：Raphael Marichal ; Michel Grimaldi ; Jerome Mathieu ; George G. Brown ; Thierry Desjardins ; Mario Lopes da Silva Junior ; Catarina Praxedes ; Marlucia B. Martins ; Elena Velasquez ; Patrick Lavelle
- 关键词：Invasive species ; Invasion processes ; Amazon arc of deforestation
- 刊名：Pedobiologia
- 出版年：2012
- 出版时间：August, 2012
- 年：2012
- 卷：55
- 期：5
- 页码：233-240
- 全文大小：450 K
文摘
Pontoscolex corethurus (M¨¹ller, 1857) is the most common invasive earthworm in disturbed lands in the tropics. Conditions required for its successful colonization of new plots are still not understood since some areas can be invaded while others, sometimes in the vicinity, are not. We kept newly hatched P. corethrurus in a wide range of Amazonian soils where population densities had been previously evaluated. We identified soil conditions that best sustain survival, soil ingestion and growth of P. corethrurus in controlled laboratory conditions and checked if presence/absence in the field was consistent with laboratory observations. While pH and Ca influenced survival; Mg and C content were the greatest determinants for growth and C:P, Mg and clay contents determined soil ingestion rates. Soil ingestion and growth rate were correlated. There were no differences in earthworm soil ingestion rates between invaded and non-invaded soils. However, growth rate and survival were higher in soils from invaded sites than in soils from non invaded sites, indicating that soil quality may play a role in the invasion process. We identified two cases where P. corethrurus did not occur: (1) unfavourable soil texture and chemical properties, but also some areas with and (2) favourable soil texture and chemical properties but no invasion. Other parameters, like vegetation cover (grass or trees), soil structure and compaction, soil hydrologic processes or biotic resistance of native earthworm communities could potentially also be key elements for understanding why P. corethrurus populations occur in some sites and not in others.