The Mikea Forest Environment

Topics on this page
  • Seasons
  • Interannual variation in rainfall
  • Landscapes and plant inventories
Other pages

Seasons

Mikea recognize either three or four seasons:

Litsake, the rainy season (Dec-Feb), during which 90 to 95% of annual precipitation falls. This is the only time of the year that most plants have leaves. Insects are active, and so are the mammals and reptiles who eat them. Temperatures: daytime average 33o C (91o F); min 21oC (70o F); max 41o C (106o F).

Fararano, the early dry season (Mar-May). Trees drop their leaves. Plants flower. Some insects remain active, while the mammals and reptiles begin to estivate ("summer hibernate"). Not all Mikea recognize this as a distinct season. Temperatures same as Litsake.

Asotre, the middle dry season (Jun-Aug). Days are short and temperatures are cool. Insects and insectivorous animals estivate. Temperatures: average 26o C (79o F), min 7oC (45o F); max 36o C (97o F).

Faosa, the late dry season (Sep-Nov). Although mean temperature is similar to Litsake (33o C or 91o F), highs of 42o C (108o F) make this feel like the hottest time of the year. Nights may be cool (18o C or 65o F).

Temperature data were collected with a min / max thermometer in 1997-1999.


Interannual variation in rainfall

We measured rainfall from October 1997 through October 1999 using self-logging rain gauges. To the right are sample data from two sites. The range of interannual rainfall is high (104mm to 827mm). Villages on the eastern edge of the Mikea Forest received up to 1700mm rainfall in 1998-1999.

Interannual variation in rainfall has a major effect on the landscape. The series of photos below are of the same spot, the natural sinkhole well of Ambovosay, during 1996, 1999, 2000, and 2003. In 1996-1998, the water level was so low that we had
to lower a bucket on a stick a meter or so below the surface to access water. 1999 was an unusually rainy year. We were shocked to see the that the well had become a puddle. Heavy rain fell in 2000 also. The puddle had become a pond! By 2003 the pond had swolen to the size of a small lake. The oldest residents said that Ambovosay had been flooded during their grandparent's lifetime, but they had never seen it like this.
1996 1999 2000 2003



Landscapes and plant inventories
The Mikea Forest region consists of diverse landscapes. Click on part of the map to the left, or on the list below, or on the mini photo below, to access pictures, descriptions, and plant inventories for each landscape.

Note on plant inventories:

I am not a botanist; I have not collected botanical samples. My method was to collect Mikea and Masikoro vernacular names for plants, and then match these with published inventories, especially Sorg (1996) and LeBigre & Petignat (1998).


Bibliography

Decary, R. (1943). Le lac Ihotry. Bulletin de L'Academie Malgache, Nouvelle Séries 25:71-74.

Du Puy, D. J., and J. Moat (1996). A refined classification of the primary vegetation of Madagascar based on the underlying geology: Using GIS to map its distribution and to assess its conservation status. Biogéography de Madagascar 1996:205-218.

Fenn, M. D. (2003). The Spiny Forest Ecoregion. In S. M. Goodman and J. P. Benstead (eds), The Natural History of Madagascar (pp. 1525-1530). Chicago: University of Chicago Press.

Ganzhorn, J. U., S. Sommer, J.-P. Abraham, M. Ade, B. M. Raharivololona, E. R. Rakotovao, C. Rakotondrasoa, R. Randriamarosoa  (1996).  Mammals of the Kirindry Forest with special emphasis on Hypogromys antimena and the affects of logging on small mammal fauna.  Primate Report Special Issue 46-1. 

Goodman, S. M., and J. P. Benstead, eds (2003). The Natural History of Madagascar. Chicago: The University of Chicago Press.

Goodman, S. M., and B. D. Peterson, eds (1997). Natural Change and Human Impact in Madagascar. Washington: Smothsonian Institution Press.

Lebigre, J.-M., H. Petignat  (1998).  Répertoire des plantes du sud-ouest de Madagascar.  Feuillets de DyMSET No. 1.  Bordeaux: Université Michel de Montaigne.

Marchal, J. Y., G. Dandoy  (1972).  Contributions à l'Etude Géographique de l'Ouest Malgache.  Paris: ORSTOM.

Salomon, J. N.  (1978).  Fourres et forêts seches du sud-ouest malgache. Madagascar: Revue de Geographie, 32:19-39.

Seddon, N, J. Tobias, J. W. Yount, J. R. Ramanampamonjy, S. Butchart, and H. Randrianizahana (2000). Conservation issues and priorities in the Mikea Forest of south-west Madagascar. Oryx 34(4): 287-304.

Sorg, J.-P.  (1996).  Plant dictionary.  in Primate Report Special Issue 46-1.  Ganzhorn, J. U., J. P. Sorg, eds.


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