able development goals. This SI policy goal applies also
to research on tropical pastures and forages and is reflect-
When considering livestock production in the tropics and
ed, for example, in the theme of the last International
its impact on the environment, a few issues should be
Grassland Congress (New Delhi, India, November 2015):
highlighted:
Sustainable Use of Grassland Resources for Forage Pro-
In the scientific and non-scientific communities,
duction, Biodiversity and Environmental Protection.
livestock production, including grazing, is blamed for
Two recent overview analyses of tropical forage-based
severe negative impacts on the environment (e.g.
livestock production systems vis-à-vis the environment and
Steinfeld et al. 2006; Hyner 2015). Livestock production the need for SI concluded that such systems can have a
is estimated to contribute 14.5% of all anthropogenic
positive impact on the environment (Peters et al. 2013; Rao
GHG emissions globally (Gerber et al. 2013).
et al. 2015). In tropical production systems, the term
The demand for animal products, especially foods derived
‘forages’ refers mostly to grasses, since adoption of legume
from livestock, is expected to increase consid-erably in the
technology in the past has been rather low (Shelton et al.
future, particularly in South, East and Southeast Asia, and
2005). We hypothesize, however, that tropical forage
to a lesser extent in Sub-Saharan Africa, as a consequence
legumes do have the potential to play a particular, positive
of increasing living standards (Rosegrant et al. 2009;
role in addressing environmental concerns.
Therefore, complementing the above-mentioned over-
In view of physical limitations to expansion of land
views and in order to contribute to the development of
area for agricultural production (both crop and
research strategies, in this paper we analyze the effects of
livestock), future production increases must come
tropical forage legumes (pasture plants for grazing or
mainly from intensification of production systems
fodder plants for cut-and-carry or browsing) on the
environment. For this, we briefly: outline the main anthro-
Ruminant livestock (e.g. cattle, buffalo, sheep, goats)
pogenic environmental issues; highlight some essentials
play an important role as they convert vegetation,
related to livestock production and the environment; and
which is unsuitable as food for humans, into high-
discuss the key attributes of forage legumes that con-
quality products for human consumption. Nonethe-
tribute to natural resource conservation and environ-
less ruminants are fed grain-based diets (such as in
mental protection with a particular emphasis on
feedlots), and this practice is in direct competition with
adaptation to and mitigation of climate change. We then
humans for that food source (Mottet et al. 2017).
examine the potential of tropical forage legumes to have
Tropical grazing lands often occupy marginal land that
a positive impact on environmental issues and provide
is unsuitable or only marginally suitable for crop
ecosystem services.
production, because of constraints imposed by soil
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Tropical forage legumes and environment 3
physical and chemical properties, topography
3. Many legumes have a deep-reaching taproot system,
(including slopes and waterlogging) and climatic
providing access to water and nutrients in deeper soil
conditions (Rao et al. 2015). Similarly, some lands are
layers (Rao 1998; Dubeux et al. 2015), which temporarily unsuitable for crop production due to
contributes to improved cycling of both N and P
drought or excess of water, and these areas are
(Thomas 1995; Oberson et al. 2006).
expected to increase in the tropics (Zabel et al. 2014).
4. There is an enormous organismal (taxonomic) and
Here, crop production could benefit from a crop-
genetic diversity in the Leguminosae (or Fabaceae)
forage rotation.
family with almost 20,000 species (Williams 1983;
As far as research on tropical pastures and forages is
Lewis et al. 2005) in formerly 3, now 6 (LPWG 2017), concerned, the literature provides almost no indication
subfamilies. This includes annuals and peren-nials,
that, in the past, environmental issues have played a
growth forms ranging from herbaceous, prostrate
major role in forage development and utilization.
species (e.g. Arachis pintoi) to vines (e.g. Centrosema
spp.), subshrubs (many Stylosanthes spp.), shrubs (e.g.
Notable exceptions are the concerns expressed by
Cratylia argentea) and trees (e.g. Leucaena spp.).
McIvor et al. (1997; 2005) and Noble et al. (2000).
Such diversity suggests that a very wide range of
production-relevant features, in terms of adaptations to