The introductory chapters to the book provide a detailed account of how changes in the grasslands inhabited by grass aloes have affected the plants. There are also discussions about the processes which are integral to the lives of grass aloes, particularly periodic grass fires.
The mountain grassland habitat of Aloe albida, Aloe chortolirioides
and the newly described Aloe craibii. The photograph was taken in
the late winter south east of Barberton in Mpumalanga. This area
is typical grass aloe habitat.
The contents of most of these introductory chapters are summarised below:
Aloe boylei habitat east of Carolina in Mpumalanga. Encroaching
exotic pine forests are visible in the distance. The whole of the
habitat in the foreground has now been afforested with exotic pines.
MINING, INDUSTRIALISATION, URBAN EXPANSION AND INFORMAL SETTLEMENTS.
Some land use patterns such as deep level gold mining in Western Gauteng
inadvertently work towards the preservation of grasslands. They keep
processes such as natural burning cycles intact and prevent urban expansion
and the development of informal settlements. Open cast mining, in contrast,
destroys large surface areas of grassland.
Aloe kniphofiodes in flower after the felling of an exotic pine
forest. The plants had been dormant in the forest under a layer of
pine needles for about 20 years. The area has since been replanted
with pines and it will be interesting to see if the plants survive
a second round of exotic afforestation.
Informal settlements on the outskirts of towns are in the process of destroying many significant colonies of grass aloes such as the rare Aloe inconspicua in KwaZulu Natal.
These types of processes are discussed in this chapter with reference to several examples.
ROAD AND RAILWAY LINE RESERVES.
The fenced off areas beside road and railway lines are significant sanctuaries
for a number of grass aloe species throughout the grasslands of eastern
South Africa. These micro-habitats, although artificially created,
are a significant source of seeds. Once the seeds are dispersed and
germinate they replenish adjacent grassland with young plants. This
is an important factor for the regeneration of formerly over- grazed
grassland. Various species would disappear from these areas were it
not for the seed bank provided by road and railway line reserves.
Aloe craibii photographed in late winter at the type locality.
The grassland and dormant dried grass aloe leaves readily burn during
the dry winter months. Fires are essential ecological processes in
grass aloe autecology.
FIRE AND BURNING, THE ESSENTIAL ELEMENTS IN THE LIFE CYCLE OF GRASS
ALOES.
Grass fires used to be less frequent in earlier centuries. They were
initiated by lightning strikes, on the whole, at the beginning of the
rainy season in September and October. These fires were ideal in that
they cleared the habitat of moribund grass and other vegetation just
before grass aloe species initiated their growth cycles.
Fires are more frequent nowadays and may occur at any time during the dry winter months from May until late spring, October. Plants are as a result, left exposed to harsh conditions for many months before they start to grow.
Roads, exotic forestry, urbanization and other factors introduced into the environment have resulted in fragmented burning of the grassland. In consequence some grasslands burn too frequently and others not enough. These factors are bringing about the decline of most grass aloe species but benefit a limited number of others.
Fires cycles are discussed in detail in this chapter.
EXOTIC TIMBER AFFORESTATION AND THE SPREAD OF EXOTICS IN GRASSLAND.
The majority of grass aloe species occur in regions with extensive timber
plantations. These have destroyed a great deal of grass aloe habitat
and altered natural processes in the areas that remain, in the vicinity
of the plantations. The processes that have been particularly affected
are fire cycles and the pollination biology of various grass aloe species.
A detailed account of these processes is provided in this chapter followed up by discussions of how specific species have been affected. The chapters about specific grass aloe species deal with this subject with reference to the affected grass aloe species.
The spread of invasive alien vegetation is another serious problem for the long term survival of grass aloes particularly the rare species such as Aloe modesta. In conjunction with exotic afforestation the habitat available for many grass aloes is continually shrinking.
Aloe chortolirioides in flower at the end of winter in its grassland
habitat near Barberton. The plants came into flower after a late
winter grass fire. The habitat in the vicinity is heavily afforested
with exotics. A eucalyptus plantation is visible in the background
of the photograph.
GRASS ALOE TAXONOMY AND THE SOCIOLOGY OF KNOWLEDGE.
There have been two accounts of grass aloe taxonomy included within revisions
of the Genus Aloe. The one used in this book is that proposed by Gilbert
Reynolds (1969:101-153.) This system of classification is closely related
to the field characteristics of grass aloes in their grassland habitats.
The use of such a taxonomic system is necessary for a book that focuses
on the autecological processes that affect grass aloe populations.
This chapter relates grass aloe classifications to the Sociology of Knowledge, particularly the use of the concepts of genus and species. The internal consistency of taxonomic models which deal with grass aloe classifications are discussed with reference to specific examples.
GRASS ALOE HABITATS.
The chapter examines the range of habitat niches frequented by the different
species of grass aloes. Some species make use of a range of niches
in their habitat whilst others are restricted to rocky areas or open
grassland.
Areas that have been afforested with timber or invaded by exotics reduce the range of possible habitat niches for most grass aloe species. Some robust grass aloes have, however, responded favourably to certain kinds of habitat alteration. These processes are discussed in detail in the chapter.
GRASSLAND FREQUENTED BY CHORTOLIRION ANGOLENSE.
The present concept of Chortolirion angolense accounts for it
as a very widespread species in the grasslands of South Africa. Much
of the habitat frequented by the plants is still in relatively pristine
condition and grassfires occur closely resembling these in former times.
The plants are found in moist and drier grasslands. The land usage in much of the present habitat is stock farming. Plants tend to become more abundant in grasslands on the outskirts of towns, where there is usually an absence of livestock since trampling of plants and seedlings is virtually eliminated.
THE CULTIVATION AND PROPAGATION OF GRASS ALOES.
This chapter, at the end of the book provides a detailed account of the
cultivation of grass aloes. Several species grow easily in cultivation
and flower regularly. Others are difficult to cultivate except under
specialised conditions. These conditions need to imitate as closely
as possible the natural grassland environments in which the plants
occur. A number of species do not flower regularly or at all unless
their dead leaves are burnt during the winter dormancy period.
Grass aloes are mostly readily germinated from seeds. Care needs to be taken to prevent "damp off" fungi from killing off newly germinated seedlings during moist or warm weather. Several species are particularly prone to "damping off".
Some grass aloes thrive best in conserved areas of natural grassland, where homeowners have these on their property. An account is provided of the methods that can be used for creating suburban grassland reserves.
Aloe hlangapies in a road reserve east of Piet Retief in Mpumalanga.
Road reserves play an important role in preserving several grass
aloe species in areas heavily forested with exotics
DETAILS ABOUT THE PUBLICATION OF THE BOOK.
Details about the publication of the book may be obtained directly from
Umdaus Press. It is now expected that the book will be published towards
the middle of 2005. The brochures about the book, including order forms
for the sponsor's copies, collector's copies and standard editions,
should be printed in the first few months of 2005.
Parties interested in the book should contact Umdaus Press at
| Postal address: | P.O. Box 11059 |
| Hatfield 0028 | |
| Pretoria | |
| South Africa | |
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| Email: | umdaus@succulents.net |
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REFERENCE. |
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