The Process of Succession
Ecosystems undergo ecological succession, which refers to the natural process of change over time brought about by progressive replacement of one plant (or animal) community with another in response to changes in environmental conditions. This process starts off with the pioneer community and eventually leads to the development of a stable mature community, referred to as the climax community. The process of succession can halt in a pre-climax stage when some factor is limiting, such as when the organism needed to bring about the necessary changes that lead to the creation of the following community, is absent. Limiting factors may also be abiotic (non-living), such as lack of water.
Succession can be of two types. Primary succession begins with the colonisation, by pioneer species (such as mosses and lichens) of barren substrate (rock, sand or soil), which has never supported any vegetation. On the other hand, secondary succession occurs in areas where natural vegetation has been disturbed or destroyed. The latter type is generally less species rich.
Natural habitats in the Maltese Islands appear in different stages of ecological succession. In certain localities it is easy to differentiate between the different stages, though in other cases, the habitats occur as a mosaic of the different stages of ecological succession. There are four principle stages of ecological succession in the Maltese Islands. These are, steppe (Maltese: Steppa); garrigue (Maltese: Xagħri); maquis (Maltese: Makkja) and woodland (Maltese: Masġar). Succession is most commonly secondary.
Olive trees were introduced to our Islands in antiquity due to their economic importance. Formerly, the Olive tree was extensively cultivated, namely to supply food (olives) and for oil production, as indicated by the place names Żebbuġ and Żejtun.
Some Olive trees found in Malta are very old – even 600 to 1,000 years old!
The Olive tree is an evergreen tree which is short and squat, having a broad crown, which rarely reaches 8 to 15m in height. Its trunk is usually gnarled and twisted. Its linear dark green leaves are leathery and whitish underneath, owing to a dense covering of short hairs which help reduce water loss. Its creamy white flowers are small and found in branched inflorescences.
In Malta we find a wild race of Olive tree which is very rare in Malta. This tree differs slightly from the cultivated species as it has smaller leaves and fruits.
The Olive tree has become naturalised and today is considered to be part of the Maltese landscape. It is protected through national legislation and permits are required from the relevant authorities to prune, fell or uproot such trees. MEPA is also helping to protect communities based on Olive trees through the designation of Special Areas of Conservation, such as Buskett.