M. Diemer, MICROCLIMATIC CONVERGENCE OF HIGH-ELEVATION TROPICAL PARAMO AND TEMPERATE-ZONE ALPINE ENVIRONMENTS, Journal of vegetation science, 7(6), 1996, pp. 821-830
Plant microclimates of three tropical superparamo sites at 4100 - 4600
m a.s.l. in Ecuador were monitored over a five-month period and resul
ts were evaluated in local and biogeographical contexts. Soil temperat
ures tended to decrease with altitude, whereas quantum flux density (Q
FD) exhibited no consistent altitudinal pattern. Leaf temperatures of
prostrate rosette and cushion plants exhibited diurnal amplitudes of 3
0 degrees C independent of altitude, while herbaceous perennials and w
oody shrubs, which were situated higher above the soil surface, had lo
wer maxima and lower daily amplitudes as a result of aerodynamic coupl
ing to the atmosphere. Longterm growth measurements and an analysis of
a stem cross-section of the shrub Loricaria indicated that growth con
ditions at 4060 m a.s.l. were constant over a 4-yr to > 25-yr period.
Means and frequency distributions of QFD as well as soil and leaf temp
eratures in the Ecuadorean Andes closely resemble growing season avera
ges at high alpine sites in the European Central Alps at 2600 m a.s.l.
Equivalent growth conditions in equatorial tropical paramo sites and
seasonal temperate zone mountains extending to the arctic, suggest tha
t, aside from the duration of the growing season, similar abiotic sele
ction pressures operate on high elevation plants in humid mountain eco
systems, which are largely independent of latitude.