Propagation of exotic plant species is found in many regions of Madagascar Island. This work aims to describe the impacts of the propagation of Grevillea banksii on soil microbial activities and on the regeneration of...Propagation of exotic plant species is found in many regions of Madagascar Island. This work aims to describe the impacts of the propagation of Grevillea banksii on soil microbial activities and on the regeneration of two native tree species （Intsia bij＇uga and Dalbergia trichocarpa） in the eastern part of Madagascar. The study was conducted within Ianjomara forest where some types of the vegetation are observed such as an area characterized by grassland （P 1）, by homogeneous population of G. banksii （P2） and by a natural forest composed mainly of L bijuga or D. trichocarpa （P3 and P4）. Structure of mycorrhizal fungi communities and associated microorganisms were described on soils from each study plot. The development of I. b^juga and 1）. trichocarpa, was evaluated 4 months after planting on P1, P2, P3, P4 soils formerly colonized by G. banksii. According to the nutrients availability on each soil type, the development of G. banksii was accompanied or not by a high formation of cluster roots. The authors＇ results also show that soil occupied by G. banksii decreased the global microbial and phosphatase activities of soil especially on soil within a high density of cluster roots. Moderately mycotrophic, G. banksii disturbs the structure and the dynamics of symbiotic microflora such as endomycorrhizal fungi （MA） and rhizobia associated with the two native tree species. The findings illustrate the negative impact of G. banksii propagation on the regeneration and the conservation of native tree species in Madagascarian forest.展开更多
文摘Propagation of exotic plant species is found in many regions of Madagascar Island. This work aims to describe the impacts of the propagation of Grevillea banksii on soil microbial activities and on the regeneration of two native tree species （Intsia bij＇uga and Dalbergia trichocarpa） in the eastern part of Madagascar. The study was conducted within Ianjomara forest where some types of the vegetation are observed such as an area characterized by grassland （P 1）, by homogeneous population of G. banksii （P2） and by a natural forest composed mainly of L bijuga or D. trichocarpa （P3 and P4）. Structure of mycorrhizal fungi communities and associated microorganisms were described on soils from each study plot. The development of I. b^juga and 1）. trichocarpa, was evaluated 4 months after planting on P1, P2, P3, P4 soils formerly colonized by G. banksii. According to the nutrients availability on each soil type, the development of G. banksii was accompanied or not by a high formation of cluster roots. The authors＇ results also show that soil occupied by G. banksii decreased the global microbial and phosphatase activities of soil especially on soil within a high density of cluster roots. Moderately mycotrophic, G. banksii disturbs the structure and the dynamics of symbiotic microflora such as endomycorrhizal fungi （MA） and rhizobia associated with the two native tree species. The findings illustrate the negative impact of G. banksii propagation on the regeneration and the conservation of native tree species in Madagascarian forest.
