Animals in Agroecosystems - Agroecology: The Ecology of Sustainable Food Systems - page 274

Wherever animals were domesticated, they became an
integral part of human societies, receiving both care and
respect. In this way the mutualistic sense of “coevolution”
was carried through. The raising of livestock is often called
animal husbandry , and in the older meaning of the term
husbandry , the concept of caretaking is clear. Husbandry is
defined in Webster's 1913 dictionary as “care of domestic
affairs; economy; domestic management; thrift.” Thus “ani-
mal husbandry” links the stewardship of domestic animals
with the welfare of humans and their households.

G RAZING AND P ASTURE S YSTEMS

First, we will examine the development of systems based on
the domestication of grazing herbivores. This strand of agri-
cultural evolution resulted in animal-only systems that sur-
vive to this day, but it also played a direct role in the evolution
of integrated systems employing both plants and animals.
As explained in Chapter 14, humans transitioned from
observant hunter-gatherers, to careful managers of wild
populations, to caretakers of livestock domesticates. During
this process, animals became dependent on humans for
protection, feed, and reproduction, and humans came to
depend on animals for a range of services and products.
Depending on local environmental constraints and the
availability of native mammals and birds suitable for
domestication, various types of food production systems
incorporating animals were developed by human societies.
These systems evolved over time in different ways, but
overall it is possible to describe a general process of
coevolution in which the animals became more thoroughly
domesticated, humans intensified their management prac-
tices, and the plant species eaten by the animals developed
more desirable characteristics in response to management.
The earliest form of animal husbandry was pastoral
nomadism, in which humans accompanied animals as they
made their way across the landscape in search of feed and
water (Koocheki and Gliessman, 2004). Pastoral nomad-
ism still exists in some very arid and mountainous lands,
where it is doubtful that human communities would be
able to survive without their herds of domestic animals.
In regions where crop agriculture would be extremely
difficult or even impossible, at least without considerable
technological intervention, these animals are able to for-
age for scarce resources and turn vegetation that humans
cannot consume directly into harvestable animal products.
As the caretakers of these systems, humans must respect
the limits of the carrying capacity of the landscape for
grazing, understand the seasonal and regional variations
in resource availability, and develop social structures
around the needs of their animals. There are examples of
well-managed present-day nomadic systems that date
back to the early times of animal domestication, with some
of the most notable in the arid regions of the Middle East
(Figure 19.5).

FIGURE 19.5 Sheep being herded by pastoralists in a
nomadic system in the Negev Desert of Israel. Rainfall in this
region rarely exceeds 30 mm per year, too little for crop agriculture.

In parts of the world with more rainfall and more access
to water resources, pastoral nomadism evolved into a type
of managed grazing. People established permanent settle-
ments, and animals were taken out for periods of time to
forage on well-defined grazing areas. Good husbandry
evolved into not just caretaking the animals, but also main-
taining the health of the range lands. As discussed in
Chapter 10, fire was most likely one of the earliest tools
used for pasture and range improvement in these systems.
They proved to be sustainable when the human managers,
using natural ecosystems as the benchmark, developed and
maintained a thorough knowledge of vegetative structure,
species composition, forage quality, and other indicators of
healthy range or forage lands. Managed grazing systems
exist today in most parts of the world, in arid to humid
rainfall regimes, from warm to cold climates, and across
most soil types and conditions, in ecosystems that include
natural grasslands, shrublands with forage and grasses,
savannahs or open woodlands with trees interspersed in
grassland, or forests with understory vegetation appropriate
for animal consumption (Hodgson and Illius, 1996).
Ultimately, the coevolution of the human-livestock
relationship reached another stage, in which humans
planted and managed pasture species for improved feed
quality and quantity. The transition from managing natural
grazing ecosystems to the direct sowing of edible forage
and pasture species probably occurred hand-in-hand with
the domestication of livestock that were capable of pulling
cultivation implements and producing manures that could
be applied as soil improving amendments. Obviously a
parallel coevolution was taking place as well on the plant
side of the equation, as grain size, forage quality, and growth
vigor all increased. Grasses, grains, and legumes all became
part of the pasture mix, each providing complementary
nutrition for livestock, and balanced nutrient inputs to the
soil. In places where there was an extended time of the
year when the planted pasture would not grow, such as