Frequently Asked Questions

Open trees and grasses
Tropical savannas can feature woodlands like these above ...

  Open-plain savannas

...or open plains like this

General questions | Climate | People of the tropical savannas | Land use in the tropical savannas |

General questions

What are tropical savannas?

Tropical savannas are landscapes of grass and scattered trees that occur throughout the world’s tropics. Tropical savannas can be almost treeless grasslands or denser woodlands – as long as the canopy cover of the trees is not so dense that it shades out the grass.

Note that some people use a narrower definition of tropical savannas, restricted to landscapes that are largely grassland with scattered trees or scrub. Landscapes with a continuous grass layer below and regular tree cover above, as seen in much of far northern Australia, would be called tropical woodland  rather than savanna under this defintion.

We use the broader definition of tropical savanna that includes both woodlands and grasslands because the ecosystem processes and management issues are similar across both landscapes in north Australia.

Where do you find them?

Tropical savannas are found in Africa, Australia, South America, India and South-East Asia – (see map). They cover a little less than a third of the world's land surface. In Australia, tropical savannas encompass around one quarter of Australia, stretching from the Indian Ocean in the west to the Pacific in the east. They border desert country to the south, rainforest on the east coast and are fringed by floodplains and peppered with monsoon forest patches in the north.

In Africa, tropical savannas form a broad semi-circle from the western Ivory Coast across to a southern border with northern Namibia. Approximately 45% of South America is savanna and exists as two large patches north and south of the equator. Approximately 10% of India and South-east Asia is considered savanna.


Encyclopaedia Britannica's map of the world's tropical savannas

How do Australian savannas differ from African ones?

Australia, unlike Africa, does not have large animals such as giraffe, zebra and wildebeest. In Australia, much of the plant material is eaten and re-cycled by insects such as termites! More than 40 thousand years ago, however, there were large grazing animals in Australian tropical savannas, such as giant wombats and kangaroos. Debate continues as to why these animals became extinct. Some argue that it was mainly because of climate change, others say that the ancestors of Australian Aborigines who arrived on the continent at least 40 thousand years ago, could have hunted them into extinction, and many say it was a combination of climate change and human action that removed many of the large animals from the Australian savannas.

Why are the tropical savannas important?

People consider tropical savannas to be important for a number of reasons. We list two of the most prominent reasons below, taking Australia’s tropical savannas as an example.

High in Biodiversity    Tropical savannas are a major reservoir of biodiversity – some areas of tropical savanna may have a similar biodiversity level to tropical rainforest. They are home to hundreds of species of native plants, mammals, birds, reptiles and amphibians and tens of thousands of different species of invertebrates. Many species in all these groups are found nowhere else in the world.

There are a few reasons for this. The tropics are generally found to have a higher biodiversity for any given area than regions in higher latitudes. This may relate to several factors, such as: (i) less frost; (ii) higher energy levels from the more intense sunshine reaching tropical ecosystems; (iii) the large areas of rainforest that are found in the tropics; (iv) tropical temperatures and humidity don't vary as much over time as they do in higher latitudes. Additionally, the tropics tend to be less intensively developed than the temperate areas of the world. This is particularly the case in Australia, and much of the natural habitat in northern Australia is relatively intact compared to that in southern Australia.

Rich in Culture   The tropical savannas are also important in cultural terms. The Australian tropical savannas for example, are home to a diverse and distinctive Aboriginal culture. Aboriginal communities manages a large fraction of the land area of the region. The didgeridu and the band Yothu Yindi come from the tropical savannas.

There is also a long history of pastoralism in northern Australia which has some of the largest cattle stations in the world.

Tourists and locals also value the tropical savannas for their wild and spectacular natural features. This part of Australia has world heritage areas like Kakadu National Park, Purnululu National Park.

Climate of the tropical savannas

What sort of climate do Australia’s tropical savannas have?

The tropical savannas of northern Australia have two starkly different seasons: the 'wet' and the 'dry'. The intensity and length of these seasons will vary depending on the latitude, topography and distance from the coast. These are European classifications – Aboriginal people will divide the year more finely with often six or more distinct seasons recognised.

The wet months, December to March, are hot and humid interspersed with torrential downpours and contrast with the dry months of May to August which have low humidity, little to no rain and cooler, wider-ranging temperatures. These two major seasons are separated by brief periods of variable conditions.

The Wet Season (December to March) At this time most of the tropical savannas, but particularly the northern sectors, are influenced by warm, moist, monsoonal north-westerlies. These winds, originating in equatorial regions, bring prolific rains to northern coastal areas. The annual average rainfall gradually diminishes, from more than 2000 mm to less than 600 mm, with distance inland and to the south. Rainfall also decreases from east to west, with areas of coastal Queensland (not savanna country but rainforest areas) receiving over 3000 mm of rainfall in some years!

The southern savannas, situated below the range of regular monsoon winds, are influenced more directly by rain-bearing 'pseudo' or 'quasi-monsoons'. The pseudo-monsoon winds bring a moist, westerly flow in from the Indian Ocean while the trade winds of the quasi-monsoon originate in the Pacific Ocean to the east.  As their names imply, these winds do not bring the reliable rainfall of the true monsoons, but are more variable.

Throughout the wet, temperatures near the coast hover around the low 30s (oC) with warmer conditions inland where occasional days in excess of 50oC have been recorded. Temperatures at this time of year may be moderated by the passage of storms or persistent cloud cover. However, 'climate discomfort' days are numerous as it’s often humid as well as hot.

The change from wet to dry (late March to April) It is noted for its hot periods with increased hours of sunshine, calm or variable winds, fewer and less intense storms and reduced humidity. Towards the end of this period temperatures drop as the north-west monsoon winds are replaced by the south-east trade winds. The dry season arrives earlier in the southern regions.

The Dry Season (May to August) With dry south-east winds (moister on the east coast), cooler temperatures, greater temperature variation during the day, clear skies and low humidity. Light rains may fall, particularly in the south-east portions, during the early months but can occur in any month. Occasionally cold air from the south penetrates well into the tropics and night-time temperatures may drop enough for frosts to form in some inland regions in the east and west. However, the savannas are mostly frost free. As the dry progresses through August and September the temperatures begin to rise as the sun moves more directly overhead and the south-easterly winds begin to subside.

The change from dry  to  wet (September to November) At the transitional pre-monsoon period, the monsoon trough moves south over the savannas again. It is a time of calm and variable winds. The intermittent westerly winds bring increased humidity and scattered thunderstorms develop. Temperatures increase and so hot and humid days become more intense and numerous – hence this time of year is called the “build-up”. When the monsoons fully develop again it comes as a relief to many people, and the new wet season has arrived.

How does this climate compare to those of other tropical savannas?

When compared with the climate of the largest tropical savannas – those of western and eastern Africa – Australia’s climate is distinguished by a couple of features.

Firstly, in the wetter northern region of Australia’s savannas the climate is remarkable for the stark division between the wet and dry seasons: in the wet up to 2400 mm of rain can fall and there is always a wet season; yet in the dry there is regularly none or almost no rain for two or three months. In the wetter parts of Africa the rainfall is more variable.

Secondly in the drier, southern parts of the Australian savannas, there is not such a regular division between the seasons. The climate of this region is influenced by the El Nino/Southern Oscillation phenomenon with some years having much less rain than others. In some years there can be rain in the dry season. In other years there can be very little rain in the wet season.

People of the tropical savannas

Who lives in Australia’s tropical savannas?

Not many people. Australia's tropical savannas are relatively sparsely populated compared to other areas in Africa or Asia. With 15.4% of Australia's area, the northern and eastern tropical savanna zones contain only 0.8% of Australia's population. There is also a uniquely high proportion of Aboriginal and Torres Strait Islander peoples among the inhabitants of the tropical north, amounting to around a quarter of the population.

Despite the low overall numbers of people, there is still great variation in the population density within Australia’s tropical savannas. In the west – in the Kimberley and the more remote regions of the Northern Territory, the population is very sparse with a relatively high percentage of Aboriginal people and cattle station and mining workers. Most of the people in the western part of the savannas, however, live in major centres like Darwin, Broome and Katherine where major employers are in government service, the tourist industry and the defense forces. Moving east to Queensland the density of people and cattle stations increases, although they are still pretty sparse in the gulf and Cape York. The highest densities occur on the east coast where Townsville is the major centre and the largest town in the tropical savannas.

How long have people been living in Australia’s tropical savannas?

There is still some speculation around the date of human occupation of Australia, however, it is becoming more widely accepted that Aboriginal occupation goes back 40,000 years and may go back as far as 60,000 years ago. This would make the Aboriginal culture of the tropical savannas one of the oldest on Earth.

Land use in the tropical savannas

What are the main ways people make a living in Australia’s tropical savannas?

The main areas of employment can be summarised as: the Grazing Industry, management of National Parks, Tourism, the Australian Defense Force, the Mining industry, Aboriginal land use and the Horticulture industry. There are also urban centres which require infrastructure, goods and services and therefore generate employment in areas such as local and state government, hospitals, schools, and hospitality.

Until a few decades ago, cattle grazing was the main economic base of the tropical savannas, accompanied by lesser, but more intensive uses such as mining, agriculture or urban development. More recently however, mining and tourism have become the dominant economic industries, although their use of land area remains relatively small. In terms of sheer numbers most people in the tropical savannas live in the major towns where provision of government and other services, tourism and defense are the major occupations. 

Across the vast landscapes that make up the rangelands of the tropical savannas, there has been a rise in resource values and land-use options other than traditional cattle grazing. These include managing for biodiversity, and an increase in land ownership by Aboriginal people. Many Aboriginal groups, however, still want to carry on cattle grazing on land they have acquired. The areas of recreation and tourism have been on the rise over the past few decades, and tourism has now reached the point of yielding a higher regional income than the cattle industry.

The map below shows the major land uses in the tropical savannas.