Mycorrhiza Fungal Diversity as
Impacted by the Loss of Endemic, Rainforest Plants in Madagascar.
1Cornell University, NY, USA.
2LDI International, Madagascar.
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We are evaluating the impact of slash and burn agriculture on vegetation succession and the diversity of arbuscular mycorrhizal fungi in the rainforest region of eastern Madagascar. High rates of deforestation and repeated burning are rapidly converting the rainforest that is characterized by very high endemic species diversity to scrub forest and degraded lands dominated by introduced weeds such as Lantana camara, Pteridium aquilinum and Imperata cyclindrica. We hypothesize that the loss of endemic plant species results in a corresponding and significant loss of mycorrhizal fungi. The Oxisols and Ultisols commonly found in this region are acid (pH 4.5 -5.5), have very low fertility and exchangeable P levels of <1 mg kg-1. Given the low levels of available P in local soils, mycorrhizal associations are likely to be vital for the successful regeneration of rainforest species on deforested land. This paper presents the first results of the mycorrhizal fungi encountered in the rainforest, and in secondary succession dominated by (a) Trema orientalis and Harungana madagascariensis, (b) Psiadia altissima, (c) Lantana camara and Rubus mollucana, and (d) Imperata cylindrica and Pteridium aquilinum. The sequence from forest to Imperata represents increasing levels of degradation and loss of native plant species.