A maior rede de estudos do Brasil

Grátis
13 pág.
Agroforestry--Practices-and-Syst_2014_Encyclopedia-of-Agriculture-and-Food-S

Pré-visualização | Página 1 de 10

27
Agroforestry: Practices and Systems
PK Ramachandran Nair, University of Florida, Gainesville, FL, USA
r 2014 Elsevier Inc. All rights reserved.
Glossary
Agroforestry Purposeful growing of trees, crops,
sometimes with animals, in interacting combinations for a
variety of objectives. Agrisilviculture¼ treesþ crops;
Silvopasture¼ treesþpasture/animals;
Agrosilvopasture¼ treesþ cropsþ animals/pasture.
Alley cropping Growing crops in the interspaces between
rows of planted trees or shrubs. In the tropics, crops are
grown in the alleys between trees or regularly pruned
hedgerows of planted, usually nitrogen-fixing, shrubs or
trees. In temperate zones, crops are grown in the alleys of
widely spaced timber trees.
Community forestry A form of social forestry, where tree-
planting activities are undertaken by a community of people
on common or communally owned land.
Encyclopedia of Agricult0
Fallow Land resting from cropping, which may be grazed
or left unused, often colonized by natural vegetation. An
improved fallow refers to deliberate planting of fast-growing
species for rapid replenishment of soil fertility.
Farm forestry Tree planting on farms, usually as woodlots.
Homegarden A subsistence farming system consisting of
integrated mixtures of multipurpose trees and shrubs in
association with crops and sometimes livestock around
homes, the whole unit managed intensively by family labor.
Multipurpose tree (and shrub) A tree/shrub that is grown
for multiple products and/or services.
Multistoried or multistrata system An arrangement of
plants forming distinct layers from the lower (usually
herbaceous) layer to the uppermost tree canopy.
Social forestry Tree planting to pursue social objectives.
Introduction: A Brief History of the Development of practices of cultivating crops in mixed stands for more than
Agroforestry
Agroforestry is perhaps as old as agriculture itself. The practice
has been prevalent for many centuries in different parts of the
world, especially under subsistence farming conditions. For
example, homegardening is reported to have been associated
with fishing communities living in the moist tropical region
approximately 10 000 BC (Kumar and Nair, 2004; Nair and
Kumar, 2006), and in Europe, domestic animals were intro-
duced into forests to feed approximately 4000 BC (Mosquera-
Losada et al., 2012). It has, however, been only during the past
35 years that these indigenous forms of growing trees and
crops/animals together were brought under the realm of
modern, scientific land-use scenarios.
Several factors contributed to the above-stated develop-
ment. When the newly independent nations of the developing
world were faced with the problem of feeding their millions
during the 1950s and 1960s, the policy makers thought the
best solution was to focus on the model of modern intensive
monocultural agriculture that was successful in the indus-
trialized world. Several food-production technologies were
consequently developed with emphasis on production of
preferred species of crops in monocultural or sole-crop stands
with heavy input of agrochemicals (fertilizers, insecticides,
herbicides, etc.), mechanization, and irrigation. In the 1970s,
these efforts, collectively called the Green Revolution, resulted
in substantial gains in food production and helped avert large-
scale hunger in some regions of the world. At that time, most
of the international agricultural research centers (IARCs) of the
Consultative Group on International Agricultural Research
(CGIAR) system and the national programs focused on a few
individual food crops and their production technologies for
sole-crop production systems. However, for a variety of rea-
sons, many farmers, especially the poorer ones in the tropics
and subtropics, were often continuing their traditional
one season, and were commonly nurturing trees in their
cropping systems. In such circumstances, the production
technologies developed for individual crops were not wholly
applicable to these systems. Similar patterns of single-species
stands of trees were also adopted in plantation forestry and
fruit orchards in many parts of the tropics and that resulted in
significant gains in wood and fruit production. Typically, the
traditional, mixed production systems of raising food crops,
trees, and animals together as well as exploiting a multiple
range of products from natural woodlots did not fit into this
‘modern’ single-commodity paradigm, and were discouraged.
Serious doubts began to be expressed in the 1960s and 1970s
about the relevance of the single-commodity strategies and
policies promoting them. In particular, there was concern that
the basic needs of the poorest farmers were neither being
considered nor adequately addressed. Soon it became clear
that many of the technology packages that contributed to the
Green Revolution, such as irrigation systems, fertilizers, and
pesticides, were not affordable by the poor farmer on the one
hand, and their large-scale application had serious environ-
mental consequences on the other. It was also recognized that
most tropical soils, which are poorer and more easily degraded
than temperate-zone soils, were unable to withstand the im-
pact of high-input technologies. The disastrous consequences
of increasing rates of deforestation in the world's tropical re-
gions also became a matter of serious concern. It was clearly
understood that a major cause of deforestation was the ex-
pansion of agricultural land to provide food and fuelwood for
the rapidly increasing populations. Faced with these problems,
land-use experts and institutions intensified their search for
appropriate strategies that would be socially acceptable, en-
hance the sustainability of the production base, and meet the
need for production of multiple outputs. These collective ef-
forts led to taking a new look at the age-old practices based on
combinations involving trees, crops, and livestock on the same
ure and Food Systems, Volume 1 doi:10.1016/B978-0-444-52512-3.00021-8
dx.doi.org/10.1016/B978-0-444-52512-3.00021-8
Agroforestry: Practices and Systems 271
land unit. The inherent advantages of traditional land-use
practices involving trees – sustained yield, environmental
conservation, and multiple outputs – were recognized quickly.
Agroforestry thus began to come of age in the late 1970s. The
establishment of the International Council (Centre, since
1991) for Research in Agroforestry (ICRAF), now known as the
World Agroforestry Centre, in 1977, in Nairobi, Kenya, signi-
fied the institutionalization of agroforestry and heralded the
beginning of the era of agroforestry as a multidisciplinary
science (Nair and Garrity, 2012).
In the temperate, industrialized regions, the evolution
of ‘modern’ agroforestry was slower than in the tropics.
J. Russell Smith's classical work Tree Crops: A Permanent
Agriculture (Smith, 1950) is considered to have created a ‘new’
wave of interest in agroforestry; he argued that “an agricultural
economy based almost entirely upon annual crops such as
corn and wheat is wasteful, destructive of soil fertility and
illogical.” However, it was not until the late 1970s to early
1980s that the push for ecologically and socially friendly
management approaches such as integrated natural resource
management, the principles of which are encompassed in
agroforestry, gathered momentum. It started with the under-
standing about the undesirable environmental consequences
of high-input agriculture and forestry practices that focused
solely on the economic bottom line (Brown, 2004). Their
demand for environmental accountability and application of
ecologically compatible management practices increased when
it became clear that the land-use and land-cover changes as-
sociated with the removal and fragmentation of natural
vegetation for establishment of agricultural and forestry en-
terprises led to adverse ecological consequences (Garrett,
2009). Agroforestry initiatives have also sprung up and moved
forward in several industrialized regions