for ruminants. Crop residues remaining in the fields generally decay rapidly and
contribute to the redistribution of C and matter flows in cultivated tropical mountainous watersheds (Schmitter et al. 2011), or in Chieng Koi’s case, are deposited in
the reservoir (Weiss et al. 2008).
Within the perennial land use systems studied, ABG C stocks varied by an order
of magnitude, which clearly shows the potential for (and variation in) C sequestration in agroforestry systems, depending on the specifics in terms of stands, species
and management practices. CDM projects may provide new income opportunities
for local farmers, and Nguyen et al. (2010b) indicated that shifting from an
extensively managed mango plantation to a teak plantation regime may lead to
additional income opportunities for local farmers, but needs to operate within a
framework that links individual HHs together. There will also be a need to improve
timber and non-timber product markets, but these benefits will only accrue when
farmers are willing to participate; therefore, extension services need to inform
farmers about the impacts of climate change and the importance of their participation. Further studies aimed at analyzing the feasibility of C sequestration in landuse systems should focus on the long-term continuity of C storage and biodiversity,
as well as on the potential for BLG C sequestration and on social factors that may
influence adoption of C sequestration practices.
3.6 Water Quality
6
The change from subsistence to market-oriented agriculture in northern Thailand
over the last few decades has been connected to the introduction of mineral
fertilizers and pesticides into farming systems (see Chap. 4). In particular,
pesticides, as toxic chemical compounds used to control pests, diseases or weeds
in agricultural production, pose a serious threat to human health and aquatic
ecosystems, particularly in cases where these compounds enter ground or surface
waters. After being applied, a pesticide undergoes several transformation processes
in the environment, the most important to mention here being pesticide biodegradation in the soil and adsorption to the soil matrix. Both these processes result in a
strong decline in pesticide concentrations in the water phase, which is the key phase
with regard to the transport, bioavailability and adverse ecological impact of a
pesticide. The intensity of these two processes depends on the physico-chemical
properties of both the compound (such as biodegradability and sorption) and the
soil (e.g., organic C content and clay content). The biodegradability of a pesticide is
typically characterized by its so-called half-life time, which is defined as the time
needed for 50 % of the initially applied pesticide mass to degrade. One way to
measure the sorption strength of a pesticide is to establish its distribution coefficient
K d , that is, the ratio of the sorbed phase concentration to the dissolved concentration
6 Written by Joachim Ingwersen.
140
H.L. Fro ¨hlich et al.
contribute to the redistribution of C and matter flows in cultivated tropical mountainous watersheds (Schmitter et al. 2011), or in Chieng Koi’s case, are deposited in
the reservoir (Weiss et al. 2008).
Within the perennial land use systems studied, ABG C stocks varied by an order
of magnitude, which clearly shows the potential for (and variation in) C sequestration in agroforestry systems, depending on the specifics in terms of stands, species
and management practices. CDM projects may provide new income opportunities
for local farmers, and Nguyen et al. (2010b) indicated that shifting from an
extensively managed mango plantation to a teak plantation regime may lead to
additional income opportunities for local farmers, but needs to operate within a
framework that links individual HHs together. There will also be a need to improve
timber and non-timber product markets, but these benefits will only accrue when
farmers are willing to participate; therefore, extension services need to inform
farmers about the impacts of climate change and the importance of their participation. Further studies aimed at analyzing the feasibility of C sequestration in landuse systems should focus on the long-term continuity of C storage and biodiversity,
as well as on the potential for BLG C sequestration and on social factors that may
influence adoption of C sequestration practices.
3.6 Water Quality
6
The change from subsistence to market-oriented agriculture in northern Thailand
over the last few decades has been connected to the introduction of mineral
fertilizers and pesticides into farming systems (see Chap. 4). In particular,
pesticides, as toxic chemical compounds used to control pests, diseases or weeds
in agricultural production, pose a serious threat to human health and aquatic
ecosystems, particularly in cases where these compounds enter ground or surface
waters. After being applied, a pesticide undergoes several transformation processes
in the environment, the most important to mention here being pesticide biodegradation in the soil and adsorption to the soil matrix. Both these processes result in a
strong decline in pesticide concentrations in the water phase, which is the key phase
with regard to the transport, bioavailability and adverse ecological impact of a
pesticide. The intensity of these two processes depends on the physico-chemical
properties of both the compound (such as biodegradability and sorption) and the
soil (e.g., organic C content and clay content). The biodegradability of a pesticide is
typically characterized by its so-called half-life time, which is defined as the time
needed for 50 % of the initially applied pesticide mass to degrade. One way to
measure the sorption strength of a pesticide is to establish its distribution coefficient
K d , that is, the ratio of the sorbed phase concentration to the dissolved concentration
6 Written by Joachim Ingwersen.
140
H.L. Fro ¨hlich et al.