Biodiversity

Wednesday, March 14, 2007

IMPORTANT FACTS ABOUT RESTIONACEAE

The family Restionaceae is part of an important and defining element in Fynbos i.e. restiods, the other two elements include: ericoid and proteoid. This family dominates in the Western Cape, 341 of the 350 species are found in this region and in the Cape Floral Region it dominates in the South Western Mountains (207), Northern Mountains (139) and in the Cape Peninsula (107). The bedrock on which they occur include: Table Mountain Sandstone, acid coastal and shale.

Their main plant form is tufted but other plant forms are also observed such as: clumped, mat forming and tangled. Most Restionaceae species have a compact base type without rhizomes or stolons (211), although rhizomes (100) and stolons (77) are present in some species. Majority of these plants reach 1 m in height. Fire plays an important role in Fynbos and plants that belong to this biome are readily exposed to this harsh yet essential disturbance. These plants have therefore adapted to fire by either resprouting or reseeding after fires. Dispersal methods include winged seeds,dispersal by wind, or some seeds contain elaiosomes (a lipid) that attract ants.

This family also has some economic uses; some species are used for thatching, horticulture and grazing. Fortunately most of this family is not threatened although some species are classified as rare and a minority (8) is classified as endangered.

RESTIONACEAE

Extracted from Delta data base

The family Restionaceae is a fundamental family within the Cape Fynbos. Members of the family are usually characterized as a reed-like shrub, growing mainly on table mountain sandstones and acid coastal sand. Out of the 350 species in the family, 23 species occur on nutrient rich granites, 21 species are found on shale, 15 species occur on limestone and 8 taxa occur on alkaline sands. These shrubs are predominantly about 1 m in length; however species such as Cannomois grandis may reach lengths up to 5 m. The predominant growth form is tufted, while 22 % are clumped, others are mat forming or tangled and a mere 3 % form isolated shoots. Most species acquire nutrients from low nutrient soils via horizontal rhizomes which are 2- 12 mm in diameter. Some species have stolons or compact root systems without rhizomes or stolons. Members of Restionaceae differ from other Fynbos families in that the leaves are completely reduced to a leaf sheath surrounding the stem. Hence the stem is photosynthetic.

Restionaceae is mainly distributed in the Western Cape, Northern Cape, Eastern Cape of South Africa, as well as parts of Malawi. Main dispersal mechanisms include nuts containing the ovary with seeds. These nuts are normally brown, black or tan and are elliptic in cross section.

These plants are not suitable for grazing; however some may be used for thatching or in horticulture. Compared to other families, 6 % of Restionaceae species are vulnerable, 2.3 % are endangered and 15 % are rare. Willdenowia affinis is the only species that I could find that have gone extinct within Restionaceae.

Fire plays a major role in Fynbos growth and management; hence members of this family generally show fire resistance by being either re-sprouters or re-seeders. In addition, some members of Restionaceae make use of fire smoke as cue for seed germination. Seeds can subsequently fully exploit nutrients re-generated by a passing fire. The intensity, frequency and duration of fire play a pivotal role in Fynbos management.

CHAPTER 2 PART A IS NOW UP

The first section of Chapter 2: Exploring Biodiversity is now up. The attached notes will still need some work, but the PowerPoint is complete but does not have Sound.

This explores the Deutrostomes and includes all the groups except the Chordates which will make up the second part.

Cheers

Rich