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Riparian Ecosystems in Mexico: Current Status
and Future Direction 1
Miguel Caballero Deloya 2
An increasing population dependent on subsistence
agriculture threatens the future of Mexico's ext~nsive
riparian ecosystems. If these strategic ecosystems are to
survive to provide goods and services for future generations,
both the Meltican government and society :is a whole must be
involved in an effort to: (1) evaluate present conditions,
including causes of habitat destruction; and (2) generate
specific legislation to establish reforestation programs and
protective measure~.
INTRODUCTION
TYPES OF MEXICAN RIPARIAN
Mexico is a nation covered by numerous
mountain ranges. The most important are: Western
Sierra Madre, Eje Neovolcanico, Eastern Sierra
Madre, and Southern Sierra Madre. Many other
smaller mountain systems are scattered over the
Mexican geography. Several peaks have elevations
above 4,000 m (12,000 ft).
ECOSYST~MS
The remarkable variation in climate, altitude,
and soils, has provided for a notable diversity of
riparian habitats in Mexico. For the purposes of
this discussion, only three major types are
considered: arid-land, high-altitude, and
tropical riparian ecosystems.
Arid-Land Riparian Ecosystems
Such a wide orographic diversity has favored
the existence of abundant riparian ecosystems.
According to Tamayo (1962) there are 172 major
water courses in Mexico. Half of them (86) flow
to the Pacific Ocean. In all of them, an average
volume of 375 billion cubic meters of water flow
yearly. In addition to the Pacific Ocean, the two
other major drainage systems are the Atlantic
Ocean and the Interior 8asin.
From a broad perspective, Mexico is an arid
nation. The Mexican National Forest Inventory
provides an estimate of 67.44 million hectares of
arid and semi-arid lands in the country
(Subsecretaria Forestal. 1984. p. 13).
In arid regions, riparian ecosystems are
usually distinct from other habitats. Rivers and
water deposits are mostly seasonal, but water
availability in riparian ecosystems is higher. In
these conditions, vegetation is more abundant as a
response to more favorable growing conditions.
Shreve and Wiggens (1964) report for the Gulf of
California coastal lands, along the Baja
California Peninsula, a denser vegetation on the
water courses. Principal species include Prosopis
juliflora var. torreyana, Prosopis palmeri; Olneya
It is worth mentioning that the Mexican
nat ional tree, the "ahuehuet e" (Taxodium
mucronatum) is characteristically the most
widespread community component of riparian
habitats of subtropical and te1nperate climates.
Despite their abundance, riparian habitats
have received limited attention. Political,'
financial, and scientific efforts have been
directed to those ecosystems which exert the
greatest effect on rural community development,
those which impact most on agricultural and forage
production nationwide, or those which occupy the
greatest amount of land.
In the following pages, a brief discussion is
presented on the nature and characteristics of the
Mexican riparian habitats, the most important
problems they face, and what their perspectives
are for the coming years.
lpaper presented at the symposium, Riparian
Ecosystems and Their Management: Reconciling
Conflicting Uses, April 16-18, 1985, Tucson, •
Arizona.
2Director General, National Institute of
Forestry Investigations, Secretary of Agriculture
alld Water Resources, Mexico City, Mexico.
Fig. l.--Amacuzac river, in the dry lands of
Guerrero State.
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tesota; Cercidium floridum, Hymenoclea pentalepis,
and .!1aplopappus sonorensis, among others.
The high precipitation characteristic of
these regions is responsible for the existence of
several important rivers. Those rivers and their
tributaries concentrate large numbers of riparian
ecosystems. Tropical riparian systems contrast
with those of arid and high-altitude regions. The
majority of the rivers in tropical Mexico have a
continuous water flow throughout the year, even
though the amount of flow varies seasonally. This
characteristic, plus the fact the tropical
habitats occur at low elevations (usually below
500 m) create special conditions that determine
the amount and type of vegetation. Some of the
most widely distributed species in these types of
ecosystems are: Ficus spp. ("amates"),
Lonchocarpus hond~is ("gusano"), Inga spuria
("cuaj inicui 1"), Pachi ra aquat ica (" zapote-"-)-,-Pithecellobium arboreum ("coralillo"), Astianthus
viminalis, and Guadua aculiata.
Coyle and Roberts (1975) include the
following species as characteristic of riparian
habitats in Baja California: Anemopsis
californica, Arundo donax, Platanus racemosa,
Juncus sp., P~ £remOntii, Salix laevigata,
Salix chilensis, Typha sp., WashInitonia filifera,
and Washingtonia robUSt a.
In the Chihuahuan desert, Salix chilensis and
some species of the genus Populus are frequent
along permanent river courses. Along ephemeral
water courses, Schinus molle ("pirul"), Chilopsis
longipes ("mimbre"), Celtis pallida ("granjeno"),
Prosopis j ul i flora ("mezquit e") and Baccharis
glutinosa ("jarilla") are most representative.
High-Altitude Riparian Ecosystems
Some trees characteristic of temperate and
subt ropical regions frequent ly OCC'lr in tropical
riparian ecosystems. Examples are Salix
chinensis ("sauz"), Platanus chiapensrs("tatacui"), and Taxodium mucronatum
("ahuehuete"), which a("e present along the
riparian lands of the Nepac river, Chiapas.
These ecosystems occur along the mountain
ranges or in the high interior lands such as the
"altiplano" in central Mexico. They are usually
found at elevations higher than 6,500 ft. (2,000
m). Some of the common species in these
ecosystems are: Baccharis glutinosa, Salix
taxifolia, and Taxodium chilensis. Along the
river courses in the Chihuahuan Sierras, Acer
brachypterum and Platanus wrightii are conspicuous
components.
In subtropical and transitional riparian
ecosystems, the folLowing species are
characteristic: Populus spp., Alnus arbuta, and
Platanus spp. Among pine species, Pi~
chiapensis is perhaps the most ("epresentative in
east and southeast Mexico (Guerrero, Chiapas, and
Veracruz) .
Rzedowski (1978) reports the genuses
Platanus, Populus, Salix, Acer, Alnus, Carya, and
Fraxinus among others in the gallery forests of
this type up to an altitudinal limit of 9,186 ft.
(2,800 m).
IMPORTANCE 0.\<' RIPARIAN ECOSYSTEMS
The importance of MeKican ripa("ian ecosystems
can be analyzed from three perspectives:
provision of goods and services, preservation of
endemic vegetation and wildlife, and water
regulation and flood control.
Certain species typical of other types of
habitats (usually drier) are frequently found in
abundance in riparian habitats. That is the case
with Casuarina equisetifolia, Eucalyptus spp., and
different species of pines, in the Central High
Basin (Altiplano Central).
Provision of Goods and Services
Many high-altitude riparian ecosystems are
located within conifer forests. In the case of
conifer stands characterized by low precipitation,
firs tend to predominate over pines along the
water courses. A typical pine characteristic of
those ecosystems is Pinus ayacahuite, a species
with great demand for pulp production.
Tropical Riparian Ecosystems
Many ripa("ian ecosystems playa relevant role
for the subsistence of rural communities. In arid
lands, they provide productive sites in
non-irrigated lands for agricultural production.
In the dry lands of the States of Hidalgo,
Tlaxcala, and Puebla,, in central Mexico, numerous
small patches of cultivated Agaves and Opuntias
can be observed in lands adjacent to dry river
courses. Frequently, these lands offer the only
alternative for crop production. Where conditions
are more favoran le, apple and other fruit trees
are established.
Tropical regions are characteristically in
east and southeast Mexico. Most of them occur in
the States of Campeche and Quintana Roo in the
Yucatan Peninsula, and southeastern Chiapas, a
Guatemalan border State. Other tropical forests
can be found along the coastal plains of both the
Gulf of Mexico and the Pacific Ocean. The Mexican
National Forest Inventory has estimated an area of
13.2 million hectares covered by tropical forests.
Riparian sites are commonly appreciated for
their scenic and recreational value. "El
Contadot:''' national park in Texcoco, State of
Mexico, is a typical riparian ecosystem with
abundant beaut i ful "ahuehuetes" (Taxodium
mucronatum). The "Barranca de Cup at itzio" park in
Uruapan, Michoacan, is another example of the
beauty of a riparian ecosystem and its importance
to society from a rect:'eational point of view.
In the northern States of Chihuahua and
Durango, Picea chihuahuana behaves as a typical
riparian species along the mountain ranges.
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Riparian ecosystems also help support rural
communit ies by providing goods which are basically
consumed locally and occas ionally sold in regional
marl<.ets. Examples include fuelwood, wilrilife,
fruits, edihle plants, forage, and ornamental
plants.
In some regions, riparian habitats are being
rapidly transformed to establish new human
settlements. The rate of this transformation is
greatest in the Central Plateau, where the
demographic explosion is the highest in the
nation.
Preservation of Endemic Vegetation and wildlife
Because of their unique natural features,
riparian ecosystems have favored the existance of
endemic plants and animals. Due to the rate of
destruction of these habitats, and the na'rrowness
of their natural distribution, some species are
now endangered. This is the case of Acer
brachypterun in the States of Chihuahua and
'Sonora, Plcea chihuahuana in Chihuahua and
Durang(),~some species of Platanus in
trans it ional regions. In someregions, riparian
ecosystems play an important role for germplasm
preservation.
Fig. 2.--Contamination by garbage disposal on the
Oacapa river, Guerrero State.
Another form of riparian contamination occurs
mainly in the most populated region of the
count ry, the Cent ral Plateau, where many river
ditches--mainly near urban centers--are used as
garbage disposal areas. The Panuco and the Lerma
are probably the most contaminated rivers by this
and industrial wastes.
The eagle is an endangered species in most of
Mexico. One reason is the destruction of its
natural habitat. Another reason is the intense
hunting of the species by rural inhabitants.
Unplanned Wildland Conversion to Agricultural and
Forage Production
Population growth in ~exico is exerting
pressure on natural resource8. Lands for
agricultural and forage production are
increasingly demanded. As a consequence of this
pressure, the agricultural frontier is growing by
destruction of natural habitats, such as forest
and riparian lands. This uncontrolled land use
conversion is affecting the ecological equilibrium
of those sites affected. Silting of rivers and
wildlife mortality are some of the negative
results.
~reater
Water Regulation and Flood Control
Even though there is little information
available in Mexico, it is clearly recognized that
riparian ecosystems are important water flow
regulators. Evidently, riparian vegetation plays
an important role in this regulation, depending on
frequency, timing and i~tensity of flooding. Much
has to be learned however, about the nat ure of
these interactions.
Destruction of Endemic Biota
PROBLEMS AND LIMITATIONS
As previously mentioned, riparian ecosystems
in Hexico 'have been important providers of goods
and services, of high value to local commuities.
The increasing eKploitation of some of these
goods, most of them provided by endemic flara and
fauna, is causing severe damage to the biota.
Trees that supply fuelwood and wood for other
domesti~ uses, and species that provide forage
have been most affected.
Contamination
Riparian contamination occurs in two ways.
The first is the result of industrial.residual
discharge. This is the typical case with the
sugar industry, pulp and paper plants, refineries,
breweries, and textile, fertilizer, and chemical
plant8. In the States of Tabasco, Veracruz, and
Tamaulipas, contamination by oil extraction and
processing is becoming a major concern. In other
regions, contamination by organic effluents
(stools) has become a problem. Important rivers,
such as the Coat zacoalcos, 131 anco, Zahuapan,
Atoyac, term~, and Panuco, to cite a few, reflect
different degrees of pollution by the causes cited
above (Urroz, 1973).
By the same token, wildlife species
customarily consumed by humans reflect a dramatic
depletlon, as do those species that affect
domestic animals. In the first group, the
white-tailed deer and turkey are probably most
affected. The second group includes coyotes and
falcons among others.
In 1973, the sugar industry was the most
important organic contaminator of Mexican rivers.
This industry generated 34 percent of organic
pollutants found in the rivers that year. The
chemical industry followed in importance.
THE
FlJTURE
Present trends pose serious doubts and
concern about the future of Mexican riparian
ecosystems: Particularly in areas of denser
11
population, riparian destruction is ~ost evident.
Despite this fact, little information exists on
the proble~, and apparently no strategy at a
national level has been applied in Mexico to solve
it.
what actions and policies are taken by State
organizations, little will be gained to stop
natural resource destruction if the total Mexican
society is not involved in its conservation. Much
effort will have to be devoted by governmental
agencies in educating and creating consciousness
in the citizenship about the importance and vital
role of natural resources in their well being and
that of future generations.
If Mexican riparian ecosystems are to be
preserved for the enjoyment and ut i lizat ion of
future generations, then several urgent tasks
should be st arted. Some 0 f them are l,.isted be 1 mIT.
1) A national survey should be conducted to
evaluate present conditions of the most important
riparian ecosystems in the nation. Such an
evaluation should iclude not only the level of
hab~tat destruction, but information on agents
causing the damage.
LITERATURE CITED
Coyle, .I. and N.C. Roberts. 1975. A field guide
to the common and interesting plants of Baja
California. Nat. Pub. Company. La Jolla, Cal.
U.S.A. 206 pp.
2)
With the information gathered through the
survey, regional policies and actions should be
establ ished to preserve or restore endangered and
affected ecosystems. These include:
- Specific legislation
- Reforestation programs
- Protective measures (stabilization work,
erosion control, etc.)
Rzedowski, J. 1978. Vegetacion de Mexico.
Limusa, S.A. lao Ed. Mexico.
Edit.
Shreve, F. and T.L. Wiggins. 1964. Vegetation
and Flora of the Sonoran Desert. Vol.I. Stanford
University Press. Stanford, Cal. U.S.A.
Subsecretaria Forestal. 1984. Mexico Forestal.
Ci fras 1983. Sec ret aria de Agricult ura y Recursos
Hidraulicos. 59 pp. Mexico.
The challenge, however, is to control the
increasing demographic impact, which affects not
only riparian ecosystems, but all natural
resources. For this purpose, during the present
public administration the Secretary of Urban
Development and Ecology was created. This agency
has a highly important historical responsibility,
and will have to face some of the most complex
problems that affect the present Mexican society.
It should be recognized, however, that no matter
Tamayo, Jorge L. 1962. Geografia Gener.al de
Mexico. lnst. Mex. d~ Invest. Economicas. Tomo II.
2a. Ed. Mexico.
Urroz, E. 1973. Programa Nacional Contra la
Contaminacion del Agua. Proceedings of the First
National Meeting of Environmental Contamination
Prohlems. p. 51-54. Mexico.
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