328
S.E. Ibarra-Obando et al.
Historically, subsistence plant agriculture was based on "dry land farming" or made limited use of water from "arroyos". Today, such practice
remains widespread and appears to have little impact on the environment,
although native vegetation may temporarily be displaced, as some of the
native grasses and other desert scrub vegetation are slow to return. Modern
horticulture based on irrigation, with most products being exported to the
U.S.A., is an example of widespread natural resource utilization in Baja
California (4,000ha in 1960 to 240,000ha in 1996; SPP 1981; INEGI 1991b,
1997).Apart from over-exploitation of groundwater, the use of agrochemical nutrients, herbicides, and pesticides potentially contaminates the
groundwater and soil. However, one of the most detrimental effects of
modern horticulture has been on the desert landscape. The coastal scrub
between 31°30'N and 30°19'N has almost disappeared. As a consequence,
some endemic plants and animals, like the Baja California legless lizard
(Aniella geronomensis), the California meadow wole (Microtus californicus
equivocus), and the kangaroo rat (Dipodomys gravipes) have also disappeared. Loss of habitat has reduced the distribution range of some species
and population size of others, including the wren cactus ( Campylorhynchus
brunneicapillus bryanti), the California gnatcatcher (Polioptila californica
atwoodi), and the ornate shrew (Sore ornatus; E. Mellink, pers. comm. ).
Fisheries of a variety of species have been present in Baja California for
a long time. However, only coastal ocean fisheries, mainly of sardines, tuna,
sharks, chub mackerel, Gulf coney, skipjack tuna, Pacific bonito, spotted
sand bass and squids, are economically important. A few species (i.e. abalone, lobster, clams and crabs) are both "coastal" and commercially significant and especially abalone and lobster appear to be overfished. The
formation of natural salt deposits in evaporation pans of some lagoons
(i.e., La Salina, Laguna Guerrero Negro, Laguna San Ignacio) has been
exploited for commercial salt production without harm to the environment (Fig. 21.1). Laguna Guerrero Negro has the largest salt pan in the
world and thousands of migratory birds are present in ponds and whales
enter the lagoon. However, the expansion of salt flats in Laguna San Ignacio Lagoon has raised international concern about a possible loss of gray
whales nursery grounds.
S.E. Ibarra-Obando et al.
Historically, subsistence plant agriculture was based on "dry land farming" or made limited use of water from "arroyos". Today, such practice
remains widespread and appears to have little impact on the environment,
although native vegetation may temporarily be displaced, as some of the
native grasses and other desert scrub vegetation are slow to return. Modern
horticulture based on irrigation, with most products being exported to the
U.S.A., is an example of widespread natural resource utilization in Baja
California (4,000ha in 1960 to 240,000ha in 1996; SPP 1981; INEGI 1991b,
1997).Apart from over-exploitation of groundwater, the use of agrochemical nutrients, herbicides, and pesticides potentially contaminates the
groundwater and soil. However, one of the most detrimental effects of
modern horticulture has been on the desert landscape. The coastal scrub
between 31°30'N and 30°19'N has almost disappeared. As a consequence,
some endemic plants and animals, like the Baja California legless lizard
(Aniella geronomensis), the California meadow wole (Microtus californicus
equivocus), and the kangaroo rat (Dipodomys gravipes) have also disappeared. Loss of habitat has reduced the distribution range of some species
and population size of others, including the wren cactus ( Campylorhynchus
brunneicapillus bryanti), the California gnatcatcher (Polioptila californica
atwoodi), and the ornate shrew (Sore ornatus; E. Mellink, pers. comm. ).
Fisheries of a variety of species have been present in Baja California for
a long time. However, only coastal ocean fisheries, mainly of sardines, tuna,
sharks, chub mackerel, Gulf coney, skipjack tuna, Pacific bonito, spotted
sand bass and squids, are economically important. A few species (i.e. abalone, lobster, clams and crabs) are both "coastal" and commercially significant and especially abalone and lobster appear to be overfished. The
formation of natural salt deposits in evaporation pans of some lagoons
(i.e., La Salina, Laguna Guerrero Negro, Laguna San Ignacio) has been
exploited for commercial salt production without harm to the environment (Fig. 21.1). Laguna Guerrero Negro has the largest salt pan in the
world and thousands of migratory birds are present in ponds and whales
enter the lagoon. However, the expansion of salt flats in Laguna San Ignacio Lagoon has raised international concern about a possible loss of gray
whales nursery grounds.