K. Heinemann et al., Influences of gap microheterogeneity on the regeneration of Nothofagus pumilio in a xeric old-growth forest of northwestern Patagonia, Argentina, CAN J FORES, 30(1), 2000, pp. 25-31
Citations number
38
Categorie Soggetti
Plant Sciences
Journal title
CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
We experimentally examined the influences of within-gap environmental heter
ogeneity on regeneration patterns of Nothofagus pumilio (Poepp. & Endl.) Kr
asser near the xeric limit of its distribution in northern Patagonia, Argen
tina. Results from this xeric old-growth forest are compared with patterns
previously described for the same species in mesic forests. Survival of N.
pumilio seedlings beneath tree-fall gaps in this relatively xeric forest ap
pears to be strongly influenced by moisture availability. Seedlings and sap
lings that have survived this demographic bottleneck are found at microsite
s where soil water potentials are higher, such as in the shady northern edg
es of tree-fall gaps (Psi = -0.46 MPa compared with less than -0.6 MPa in o
ther gap positions) and on coarse woody debris (Psi = -0.29 MPa, compared w
ith -0.51 MPa on the forest floor). Although gap creation in this dry N. pu
milio forest is favorable to tree regeneration by releasing light resources
, decreased water resources may switch the system from a light- to a water-
limited system in some positions of the gap. This may explain the lack of r
egeneration of N. pumilio often observed after creation of large gaps towar
ds the xeric end of its range and needs to be considered in the management
of this important timber species.