The underlying concept of agroforestry, or the practice of cultivating tree
species and agricultural crops together or in sequence, has been in practice
throughout human agricultural history and was used to maintain soil fertil-
ity while supporting crop growth. For example, before modern agricultural
developments, a common practice was to clear and burn forests before cul-
tivating crops, and this is still the method of choice in many tropical regions
today (see Chapter 8, this volume). Trees are then often planted with the
agricultural crops (see Chapter 10, this volume). Today, in central and equa-
torial South America, combinations of plants with different growth habits,
such as coconut, bananas, coffee, and maize, enhance agricultural land-
scapes. In Zambia, cassava is grown in small cleared plots within the larger
matrix of the Miombo woodland. Other agroforestry practices include con-
tour hedgerows for soil and water conservation, trees in croplands, improved
fallows, and shaded perennial crops. Hedgerow, trees in cropland (see Chap-
ter 11, this volume), and shaded perennial crop systems (see Chapter 9, this
volume) combine trees and crops simultaneously in the same field, whereas
fallow systems (see Chapter 8, this volume) involve crop and tree rotation
over time.
Besides offering some secondary habitat, agroforestry can be used as an
indirect conservation tool to protect natural areas from exploitation. Refor-
estation of corridors between protected areas is necessary to improve connec-
tivity between patches (see Chapter 3, this volume). There are many areas
where corridors would be useful and where protected forests are subjected to
intense human activity such as fuelwood collection. When unprotected forests
are depleted of fuelwood, protected areas often are targeted. Agroforestry sys-
tems can be integrated into such corridors, where they would play a conserva-
tion role by producing timber and nontimber forest products and thereby
minimizing the exploitation of protected areas. Similarly, managed forest
plantations and forest mixed with agriculture can be planned and managed for
increased conservation value.
The indirect value of agroforestry systems can also extend to other envi-
ronmental benefits, such as carbon sequestration, watershed maintenance,
and buffering against climate change biome shifts (see Chapter 20, this vol-
ume). Furthermore, nutrient cycling in natural forest systems often is
highly conservative as nutrients are quickly and efficiently recycled within
the system, whereas agricultural systems often exist at the other extreme
with high nutrient losses. Agroforestry may help to maintain a sustainable
agriculture-forest coupled system in which nutrients are conserved within
the system.
The use of science to guide the search for innovative agroforestry systems
that integrate production objectives with environmental services can comple-
ment a solid biodiversity conservation strategy anchored around protected
areas and therefore help to mitigate biodiversity losses.
- Biodiversity Conservation in Deforested and Fragmented Tropical Landscapes 29