Casuarina equisetifolia

Cultivation Details

Casuarina equisetifolia is adaptable to a wide range of conditions, being found from the semi-arid to subhumid tropics and subtropics, usually near sea level but succeeding under cultivation at heights up to 1,400 metres^{[1, 2]}. It grows best in areas where the mean annual temperature is in the range 10 - 35°c and prefers a mean annual rainfall in the range 700 - 2,000mm, though it tolerates 200 - 3,500mm^{[1, 2]}. In most areas where it grows there is a distinct dry period of 4 - 6 months, although this seasonality decreases towards the equator in Southeast Asia and in the southern parts of its range in Australia^[1]. Requires a sunny position and a well-drained soil^{[1, 3]}. Prefers alkaline to neutral soils^[2]. Prefers a pH in the range 5 - 6.5, but tolerates 4 - 8.5^[4]. Plants are very resistant to salt spray and can also tolerate occasional inundation by sea water at extremely high tides^[1]. Young plants are susceptible to drought until their roots reach the groundwater table, which may take up to 2 - 3 years after planting^[1], but then they become very drought resistant^[3]. Casuarina equisetifolia is a fast growing species with prolific seeding ability which is able to take advantage of disturbed sites for colonization. Where it establishes it may form dense, low biodiversity stands with negative impacts on native flora, fauna, soil character and dynamics. It is reported to be invasive in a number of countries and is a particular problem in Florida and South Africa, and is said to be invasive in many other countries including Brazil and the Caribbean^[5]. This species can flower and produce fruit all year round^[6]. Common ru has a life span of 40 - 50 years and displays fast early growth. Under favourable conditions, early growth rates are about 2 metres per year. On favourable sites, it can yield an annual increment of 15 cubic metres per hectare of wood in 10 years^[1]. In South China, where an estimated 1 million hectares in shelterbelts along the coastal dunes have been established since 1954, heights of 7 - 8 metres and diameters of 5 - 7 cm are achieved in about 4 years^[1]. The rotation period ranges from 4 - 5 years for fuel wood and 10 - 15 years for poles^[1]. Common ru can be the only woody species growing over a ground cover of dune grasses and salt-tolerant broadleaved herbs; it can also be part of a richer association of trees and shrubs collectively termed the Indo-Pacific strand flora^[1]. The tree is not fire resistant and protection is necessary^[1]. The plant coppices only to a limited extent and best results are obtained when cut young^[1]. Timely thinning is essential as Casuarina species trees demand light^[1]. Young trees are susceptible to competition from weeds, especially grasses^[1]. Although the tree is evergreen, it usually sheds a large amount of twigs throughout the year^[7]. In Asia, leaf litter from plantations is often removed for use as fuel and this draws heavily upon soil phosphorus and potassium reserves. This can result in reduced yield in the subsequent rotation^[1]. In cultivation, this species hybridizes with Casuarina glauca and Casuarina junghuhniana^[1]. Root nodules containing the actinorhizal symbiont Frankia enable Casuarina equisetifolia to fix atmospheric nitrogen. These root nodules can be prolific^[1]. The tree possesses proteoid roots and forms associations with vesicular arbuscular mycorrhizae^[1]. This species can be monoecious or dioecious. Dioecious plants will require both male and female forms to be grown if fruit and seed are required^{[1, 2, 7]}.