Values and Services of Nitrogen-Fixing Alder Based Cardamom Agroforestry Systems in the Eastern Himalayas - Smallholder Tree Growing for Rural Development and Environmental Services - page 387

traditional agriculture areas and fallow land, was the highest (9.6 percent) in the
traditional agriculture area and the lowest (2.2 percent) in cardamom agroforestry
(Rai and Sharma 1998). The amount of soil loss from cardamom agroforestry was
also the lowest, although it proved to be slightly higher than in temperate forests.
Records on soil organic carbon, total nitrogen and total phosphorus showed the
same trend, with the lowest losses for the cardamom system.
In another experiment, with five dominant types of crops or vegetation (maize,
finger-millet, mixed cropping, cardamom, broom grass), covers and bare land were
compared so as to determine the in situ soil and water conservation values. The data
showed here that the lowest losses of water and soil were recorded for the carda-
mom fields. Likewise, the conservation of both water and soil in cardamom fields
was 81 percent and 87 percent respectively (Sharma et al. 2001).
Soil fertility levels have a considerable influence on plant productivity. A compari-
son between the cardamom dominated system and the maize-potato dominated system
revealed higher levels of soil nutrients, particularly of organic carbon and total nitrogen
in the cardamom dominated system (Sharma and Sharma 1997). The soil erosion rate
measured during the rainy season was about 16 times lower in the cardamom agrofor-
estry system. The loss of nutrients through soil erosion and overland flow suggest that
the cardamom agroforestry system provides a much better protective cover. The low
volume of soil erosion and consequential low nutrient loss indicate that the cardamom
system is ecologically viable when compared to the maize-potato dominated system.
Measurements of the distribution of the incidental rainfall into the various pathways
revealed that the canopy interception was much higher in the cardamom system. The
amount of incidental rainfall contributing to overland flow was only 2.17 percent in the
cardamom system, whereas 9.2 percent in the maize-potato system. These values sug-
gest that the cardamom system retains more water from incident rainfall in its various
sub-components than the maize-potato system. This was attributed to the presence of
trees in the cardamom systems.

18.3.6 Carbon Budget and Flux

Globally, changes of land-use are transforming land cover at an accelerating rate.
In mountain ecosystems, such changes are closely linked to the issue of sustainable
socio-economic development. Since this can affect essential elements of natural
capital such as climate, soils, vegetation, water resources, and biodiversity, land
transformation may result in wide ranging changes, many of which are significant
on a global scale. These changes include an increase in greenhouse gases and
potential global warming, the loss of biodiversity and soil resources, and also other
regional impacts which contribute to climate change. In the mountains, watersheds
can be considered to be functional units of natural resource management for sus-
tainable development. Understanding the dynamics of watershed functions requires
knowledge about physical characteristics such as hydro-ecological links between
land uses, resource dimensions and socio-economic conditions. Socio-economic