Executive
Summary -
Mosses, Liverworts, and Hornworts: Status Survey and Conservation
Action Plan for Bryophytes
Mosses, liverworts, and
hornworts belong to a division of the Plant Kingdom known
as Bryophyta - the bryophytes. Morphologically, bryophytes
are usually small organisms, typically green, and lacking
some of the complex structures found in vascular plants.
They do not produce flowers or seeds, and the majority
have no internal mechanism for transporting water or nutrients.
Although they have no roots they do have root-like structures
for anchoring and water absorption.Bryophytes
range from a few millimetres to half a metre in height;
mosses may be erect, lateral, or multiple-branched in
structure. They are found on soil, rocks, and trees throughout
the world, from coastal Antarctica to the tundra of the
Northern Hemisphere, and from the Australian deserts to
the Amazon rainforests. Although small in stature, they
are an essential part of the earth's biodiversity and
play a significant role in diverse terrestrial and aquatic
ecosystems; some species even dominate pond and river
habitats.Bryophytes assist
in the stabilisation of soil crust by colonising bare
ground and rocks, and are essential in nutrient recycling,
biomass production, and carbon fixing. In general, they
are very efficient at regulating water flow by means of
an effective water-retention mechanism. They also have
an economic value, whether it is as peat for fuel, horticulture,
oil absorption, or as sources for a wide variety of chemical
compounds. Bryophytes have long been used for medicinal
purposes and their value as pollution indicators is also
well known. They are also a food source for animals in
cold environments.
However, the worldwide reduction, fragmentation, and degradation
of habitats important for bryophytes has led to a loss
of species richness and genetic diversity. Threats to
bryophytes include deforestation, forest cultivation,
land reclamation, urbanisation, road and dam construction,
mining, wetland drainage, and over-grazing. Invasive,
introduced vascular plant species can also devastate native
bryophyte floras.Bryophytes
are threatened partly because of their morphology and
reproduction rates. They are fragile organisms, sensitive
to drought, and have a relatively low growth rate and
therefore desiccate quickly during periods of dry weather.
They are highly vulnerable to disturbance and also extremely
sensitive to pollution as they lack a cuticule (a layer
on the outer cell surface that protects the tissue from,
for example, harmful chemicals). Bryophytes are also threatened
because of their lack of "image" within the
sphere of nature conservation. They are not large, charismatic
species, and this, coupled with a lack of understanding
of how they contribute towards ecosystem functioning,
often results in their being overlooked by the general
public and conservation groups. Unfortunately many areas
where species diversity is extremely high are highly threatened
by habitat destruction, for example the lowland regions
of East and Southeast Asia.This
Action Plan reviews the status of bryophytes worldwide
and provides examples of habitats currently rich in bryophytes.
It is aimed at individuals who work in the field of, and
have an interest in, nature conservation and wish to take
steps to conserve bryophytes. It is also aimed at governmental
and non-governmental organisations, politicians, and the
general public. These individuals and organisations have
the ability to implement the recommendations and general
initiatives forwarded within this plan. The United Nations
Convention on Biological Diversity (CBD) may be a legislative
option for effective bryophyte conservation in some countries.
One hundred and seventy-seven countries have now ratified
this convention, and bryophytes should be included in
the National Biodiversity Strategy and Action Plan of
each country.This Action
Plan suggests a number of more general initiatives, including:
* increasing inventories in the tropics to determine bryophyte
richness in different regions and habitat types and to
determine which species are locally common, rare, or threatened;
* establishing protected areas or national systems of
protected areas where endangered bryophytes occur;
* incorporating bryophyte conservation in development
and industrial activities;
* comparing bryophyte floras of undisturbed and disturbed
habitats to determine the impact of disturbance, and to
identify those species unable to survive in disturbed
areas. Without reliable information on the habitat requirements
of species, including information on the quality of the
habitats, it is impossible to determine appropriate conservation
actions;
* studying the taxonomy and distribution of individual
species to determine how species can be identified, to
determine their ranges, and to help identify those that
are narrowly endemic (i.e., occur only within a small
region);
* training local people to become specialists. Because
of the speed at which natural environments are disappearing
worldwide, this initiative is extremely urgent and should
be implemented immediately; and
* creating user-friendly regional identification guides.Examples
of priority projects for bryophyte conservation and a
list of the most endangered bryophyte species throughout
the world can be found in the appendices of this Action
Plan. The 2000 IUCN World Red List of Bryophytes can be
found at the following Internet site: <www.dha.slu.se/guest/WorldBryo.htm>.
