Agriculture Reference
In-Depth Information
2.4.2 Temperate rain forests
Temperate rain forests mainly occur in coastal parts of relevant continents, for example
inWestern Canada and the Pacific Northwest of the United States, where the prevailing
westerlyweather brings a high rainfall. However, legumes are rare in these forests, for a
variety of reasons, butmost probablydue to low light levels under conifers. On the other
hand, parts of the world heritage temperate rain forest of Tasmania (Australia) have a
prominent nodulated legume flora, both trees such as
Acacia melanoxylon
and shrubby,
scrambling endemics such as species of
Hovea
. These are found underneath species of
Eucalyptus
, whose isobilateral leaves allow considerable light penetration, even though
they are evergreen (personal observations). There are no studies on nitrogen fixation
within these areas.
2.4.3 Tropical rain forests
Tropical rain forests are a topic of years of research and numerous publications and it
is impossible to summarise the role of the legume component here. Instead, examples
will be used to illustrate some of the variations in occurrence of nodulated legumes and
possible factors affecting how much nitrogen is fixed. Table 2.3 summarises data from
Tab l e 2 . 3
Summary of legume genera in three areas of equatorial rain forest. (? indicates nodulation
status unknown.) Nodulation is taken to be a generic character
Genera
Species
Nod
Non-nod
?
Nod
Non-nod
?
A.
Borneo (data from the University of Leiden database)
Caesalpinioideae
2
18
2
2
83
3
Mimosoideae
5
2
0
27
8
0
Papilionoideae
28
1
4
79
1
22
B.
Guineo-Congolean (African) forests (data from Lock, 1989)
Caesalpinioideae
2
28
3
3
116
88
Mimosoideae
5
6
4
21
29
9
Papilionoideae
18
6
7
143
11
14
C.
Guyanas and Reserva Ducke (South America) (data from Clarke et al., 2001)
Caesalpinioideae
5
27
0
29
86
0
Mimosoideae
17
1
0
104
9
0
Papilionoideae
20
5
0
126
11
0
