Marojejy National Park - Topography and Habitat

Topography and Habitat

Marojejy National Park covers 55,500 ha (214 sq mi) and protects almost the entire massif, which ranges in elevation from 75 to 2,132 m (246 to 6,995 ft) at the summit. The massif is part of a mountain chain that stretches from Tsaratanana in the northwest to the Masoala Peninsula in the south. The crests of the massif form an east–west line with a series of distinct peaks along its irregular structure, which consists of parallel or divergent crest lines broken apart by steep and irregular slopes. Rising 2,000 m (6,600 ft) over as little as 8 km (5.0 mi), the Marojejy Massif has some of the most precipitous terrain in Madagascar. As a result of this sharp rise in elevation and rugged topography, it has a variety of microclimates and a visible change in habitat, making it one of the few places in the world where cloud-covered rainforest rapidly transitions to high mountain shrubland over a distance that can be covered on foot. Also due to the rugged topography, the vegetative mosaic varies between the crests and slopes of the massif, even at the same elevations. For example, crests and adjoining slopes often have less than 20% of their flowering plant species in common.

Temperatures in the region are fairly constant, with both the daily temperature range and the seasonal range varying only slightly. February is the hottest month, averaging 25 °C (77 °F), while August is the coolest, averaging 19 °C (66 °F). Climbing the peaks, temperature decreases by 1 °C per 200 m of increased altitude (1 °F per 360 ft), and temperatures on the summit decline to 1.5 °C (34.7 °F) in July. The relative humidity for the region hovers around 87% throughout most of the year, although it rises to 97% between March and April. Rain falls every month on the southern side of the mountain, with the region receiving at least 2,300 mm (91 in) of rain annually, making it one of the wettest areas in Madagascar. The northern side of the mountain is more tropical, with a 6-month dry season, and receives about 1,500 mm (59 in) of rain per year. The general region receives the most rainfall during the warm season, from November through April, when heavy rain and occasional cyclones are delivered from the northwest by monsoons. During the cooler season, between May and October, lighter rains are delivered by winds from the southeast.

Both temperature and rainfall vary significantly by location within the park. Lower temperatures are found at higher elevations, and the eastern slopes of the massif receive the most of the rainfall, since the western slopes lie in the rain shadow of the mountain and consequently experience a prolonged dry period. The tops of the ridges experience strong winds and offer poor soil conditions. The effect can be seen in the plant life and their growth rates. The wide range in elevations and the rugged topography also play a crucial role in creation of the varied habitats distributed across the mountain slopes by affecting air temperature, fluctuations in temperature, and humidity levels. The interplay between these factors impacts the growth and development of plants, which form the foundation of the ecosystem. The result is an extremely varied and unevenly distributed forest that covers 90% of the park.

The mountains of both Marojejy and nearby Anjanaharibe-Sud Special Reserve feed several drainage basins, including the Lokoho River, which is sourced from the western and southern slopes of Marojejy, and the Androranga River, which originates from the northern slopes of Marojejy. Both rivers travel towards Sambava and drain into the Indian Ocean. Marojejy is connected to the Anjanaharibe-Sud Special Reserve by the Betaolana corridor, a narrow mid-elevation strip of forest extending west and slightly south.