Chile: Research provides
data on the role of native forests in the production of water
An article published in the
newspaper “La Tercera”(1) and taken up on the Mapuche
IMC blog (2) reveals the results of research carried out by scientists
from Valdivia’s Austral University that link the presence
of native forests with greater water production.
According to this study, a
major part of South American temperate forests are found within
the Valdivian Rainforest Ecoregion (35–488S) in Chile and
adjacent areas of Argentina, which has been classified among
those with the highest conservation priority worldwide.
The study points out that most
of the native forests in Chile are privately owned (71% of the
total). The remaining is in national parks and reserves. Privately
owned forests have been generally valued and used for firewood
and timber production (mainly within unsustainable logging schemes)
or as land for the expansion of other productive activities:
agriculture, pastureland and fast-growing commercial tree plantations
of exotic species (Pinus radiata and Eucalyptus spp). Rapid conversion
to forest [sic] plantations between 1975 and 2000 resulted in
deforestation rates of 4.5% per year within an area.
The research states that the
poor conservation status of native forests may be explained by
the forest policy followed since 1974 in Chile. This policy has
not provided economic incentives for the sustainable management
and conservation of native forests, in contrast to the use of
public funds to support the establishment of plantations. This,
along with the liberalization of exports and privatization of
state-owned plantations and pulp mills, explain the fast growth
of the forestry industry based on plantations, often regarded
as an economically successful model in other Latin American countries
and elsewhere (Lara and Veblen, 1993; Sedjo et al., 1999; Lara
et al., 2006).
While tree plantations increase,
native forests are degraded or destroyed. According to information
provided in the article in ‘La Tercera’:
“in the Araucanía region, an average of 2,845 hectares
per year is lost through forest fires, flooding from dams, illegal
logging and forest degradation. The scenario has improved, as according
to FAO, before 2000 the average annual loss was 20 thousand hectares.
Other estimates: between the V and XII regions the loss has amounted
to 100,000 hectares since 1995. And a study by the universities
of Concepción, Austral (Chile) and Alcalá, (Spain)
states that 82,131 hectares of native vegetation was lost in the
V, Metropolitan and VI regions between 1975 and 2008 – the
equivalent of 42.5% of the original total.”
Academics have responded to
the loss of native forest by trying to show its importance as
an ecosystem, together with the benefits it provides, either
directly or indirectly, to society. Among these benefits, is
the provision of water, both in quantity and in quality.
The research carried out by
the Austral University “took daily measurements, during
four years in six basins ranging from 140 to 1,462 hectares in
the Coastal Cordillera, in the Valdivia area. The percentage
of native forest cover was considered for each basin as well
as the runoff rate – that is the relationship between stream-flow
and annual precipitation. And the conclusion was that stream-flow
and production of water are correlated with the percentage of
native forests covering the basins. In figures: an increase of
10% in the native forest cover in the basins would produce an
increase of 14.1% in the summer stream-flow.”
"The native forest reduces
the speed of runoff, enabling the water table to recharge and
the water to flow slowly towards rivers and streams maintaining
summer stream-flows, as compared to farm land and tree plantations,” explained
Antonio Lara, Dean of the Austral University and member of the
research team. The forest regulates water flow and provides a
balance.
Furthermore, the study refers
to research showing that the conversion of native forests to
fast-growing plantations decreases streamflow especially in summer.
In addition, studies of the water balance of young plantations
of E. globulus and P. radiata in south-central Chile have revealed
an increased depletion of the soil moisture reserves with stand
ageing, as well as an increase in the canopy interception and
evapotranspiration. Furthermore, conversion to plantations has
led to a decrease in water quality due to increased sediment
loads associated to clearcuts in plantations managed under 12-year
rotations for Eucalyptus spp. and 20 years for Pinus radiata.
As pointed out in the article
in ‘La Tercera’ academic results confirm what the
Mapuche movement and socio-environmental organizations have been
stating for a long time: monoculture tree plantations impact
on soils and water reserves.
Today more than ever forests
must be cared for. They are the basis of biodiversity and life
support, not only for the communities who directly depend on
them for sustenance but, in the long run, for humanity as a whole.
(1) “Estudio relaciona
presencia de bosque nativo con mayor producción de agua”, http://www.mapuexpress.net/images/publications/18_12_2009_23_3_41_1.jpg
(2) http://aureliennewenmapuche.blogspot.com/2009/12/estudios-relacionan-presencia-de-bosque.html
