Landscape management - Ecological Applications: Toward a Sustainable World - page 284

Table 10.1 Value of
different harvest-use
categories in three
successional stages of
tropical forest after
clearing for agriculture.
Results are for 67
households in the
Cordillera Azul region
of Peru. (After Gavin,
2004.)

Median Maximum

Use value value

Forest type category Number of species (US$ ha − 1 yr − 1 ) (US$ ha − 1 yr − 1 )

Fallow fi elds Total 45 animals, 138 plants 8.20 305.70

Food 79 1.19 66.78

Wood 28 0.00 281.63

Medicine 67 0.10 41.90

Weavings 10 0.00 21.50

Adornments 23 0.00 7.66

Young forest Total 49 animals, 109 plants 28.60 1034.80

Food 78 2.40 121.06

Wood 34 3.30 1000.90

Medicine 40 0.00 88.50

Weavings 12 0.00 110.82

Adornments 14 0.00 5.12

Old forest Total 81 animals, 143 plants 6.80 1183.00

Food 115 1.02 301.84

Wood 63 3.50 1167.20

Medicine 48 0.10 48.20

Weavings 21 0.20 15.50

Adornments 47 0.00 2.79

10.4 A landscape
perspective on pest
control

As with other kinds of resource management, the effectiveness of pest control can
be affected by the nature of the landscape in which it is carried out. In this section
I discuss how the surrounding landscape matrix can augment or diminish a pest
problem in forestry (Section 10.4.1), horticulture (Section 10.4.2) and arable settings
(Section 10.4.3).

10.4.1 Plantation
forestry in the
landscape

As a result of rising demand for wood and pulp products, plantation forests have
been expanding worldwide, matched by a growing concern about their vulnerability
to pest damage. Being a monoculture, plantation forestry may be particularly sus-
ceptible to pest attack. You might predict that the presence of a variety of tree species
in the vicinity of the plantation would foster a greater richness of natural enemies
of the pests. And if this is the case, forest pest damage might be reduced. In other
words, manipulation of tree species in the landscape may increase the likelihood of
bringing together pests and their enemies in the metacommunity (Box 10.1).
One important pest of pine trees ( Pinus pinaster ) is the European stem borer
Dioryctria sylvestrella , a moth caterpillar that induces trunk malformations and
increases the likelihood of wind damage to the trees. The moths are attracted from
a distance by a volatile chemical released from wounds caused by forestry practice
(pruning). In their study of French pine plantations, Jactel et al. (2002) measured
rates of borer infestation in stands of pine trees and found fewer attacks when the
trees were bordered by a mixture of broad-leaved tree species (Figure 10.8a). As
predicted, there was an increase in borer attack the greater the distance to the
nearest broad-leaved stand, and this was matched by a decrease in parasitism of the
pest by certain natural enemies (the parasitoid wasps Macrocentrus sylvestrellae and
Ve ntur ia robusta ) (Figure 10.8b,c). An understanding of how the confi guration of