I think the term is quite widespread, especially in the USA. I've found plenty of results. And especially there are several academic articles that use that expression.

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Note added at 7 mins (2005-10-07 09:12:12 GMT)
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http://fwie.fw.vt.edu/rhgiles/ARuralSystem/PrivateFarmsHelpi...
The typical decisions within Rural System include those for **agro-silvo-pastoral ecosystems**, their constraints, services, and potentials. In summary review, we use general systems theory; clarify and advance new statements of objectives relating to social and economic development; link "benefits" with diverse objectives as well as present-discounted net monetary values of rural goods, services, and opportunities (SPOVIMM).

http://www.hort.purdue.edu/newcrop/tropical/lecture_12/lec_1...
A significant beneficial interaction is claimed between inputs.
# Agro-silvicultural: mixture of woody perennials plus traditional agricultural crops
# Silvo-pastoral: woody perennials plus animals
# **Agro-silvo-pastoral**: Combination of woody perennials, crops, and animals.

http://www.ies.wisc.edu/ltc/afbk9706.html
Thomson, James T.
Renewable natural resources management in **agro-silvo-pastoral** systems : institutional aspects. [S.l. : s.n.], 1986. 33 p.
Steenbock Library, 3rd Floor, South: Files Afr 81.4 T36