Study Area
We conducted our research on the temperate rainforest of South America,
which comprise a narrow coastal strip between the Pacific Ocean to the
west, and the southern Andes Mountains to the east, from 37° to 48°
south latitude. The climate is maritime temperate, with frequent
sub-zero temperatures during winter and spring (di Castri & Hajek,
1976). The vegetation is mature Valdivian rain forest (Veblen, Schlegel
& Oltremari, 1983), dominated by the tree species Aextoxicon
punctatum R. et P. (Aextoxicaceae), Eucryphia cordifolia Cav.
(Cunoniaceae), Nothofagus dombeyi Mirb. Oerst (Fagaceae),Gevuina avellana Mol. (Proteaceae) and Luma apiculata (DC)
Burret (Myrtaceae). The forest canopy averages about 30 m in height,
with emergent N. dombeyi attaining c. 40 m. All liana species
frequently reach the forest canopy, and they all are evergreen. The
study sites have most of the lianas described in the region, includingBerberidopsis corallina Hook. f. (Berberidopsidaceae),Boquila trifoliolata (Dc.) Dcne (Lardizabalaceae), Cissus
striata R. et. P. (Vitaceae), Hydrangea serratifolia (H. et A.)
F. Phil. (Hydrangeaceae), Elytropus chilensis (A.DC.) Muell. Arg.
(Apocynaceae), Mitraria coccinea Cav (Lardizabalaceae),Campsidium valdivianum (Phil.) Skottsb (Bignoniaceae),Muehlenbeckia hastulata je sm (Poligonaceae), Griselinia
ruscifolia clos Ball (Griseliniaceae) and Lardizabala biternataRuiz & pav. (Lardizabalaceae). In general, the temperate rainforest
soil is derived from volcanic ash (andisols) (Luzio & Alcayaga, 1992)
and is characterized by low density, high clay content, high soil
moisture, high organic matter content and high phosphorus retention
(Godoy et al., 2014). We selected three study sites along a latitudinal
gradient between 37ºS and 45ºS. The northern site was “Nahuelbuta”
(37°42´S, 73°13´O; 176 m.a.s.l.) where the mean annual temperature is
16º C and mean minimum temperature is 4.8º C, is characterized by loamy
soils (Luzio & Alcayaga, 1992) with low fertility and low water
content. The intermediate site on the gradient was “Puyehue” (40°39´S,
72°10´O; 301 m.a.s.l) where the mean annual temperature is 10º C and
mean minimum temperature is 3.3º C, the soil is highly porous with high
organic matter content (Godoy et al. 2014), classified as andisoils. The
southern site was “Aysén” (45°27´S, 72°44´O; 10 m.a.s.l) where the
mean annual temperature is 8º C and mean minimum temperature is 2.7º C
(Table 1), and the soil is characterized as histosol (Luzio & Alcayaga,
1992).
We assessed the performance of liana species on each site by measuring
the apical growth rate (AGR) during the growing season. To establish the
trade-off between efficiency and safety of water transport, during
winter, we measured maximum specific hydraulic conductivity
(Ks_max), percentage of loss conductivity (PLC), root
pressure (Px), vessel diameter (VD),
vessel density (VDEN) and wood density (WD). We measured
these traits on 7 species in Nahuelbuta, 5 species in Puyehue and 4
species in Aysén, which corresponded to the maximum number of liana
species found on each study site (Supplementary information, Table S2),
adding up to 10 species total.