M. Diemer, LIFE-SPAN AND DYNAMICS OF LEAVES OF HERBACEOUS PERENNIALS IN HIGH-ELEVATION ENVIRONMENTS - NEWS FROM THE ELEPHANTS LEG, Functional ecology, 12(3), 1998, pp. 413-425
1. Leaf life spans, determined as half-lives, of 16 herbaceous perenni
al plant species from the aseasonal, tropical Andes at altitudes betwe
en 4000 and 4600 m were on average 193 +/- 19 days and thus two to thr
ee times greater than those of herbaceous perennials from the seasonal
northern hemisphere. The duration of lamina expansion was positively
correlated with life span. Growth was continuous all year round, but r
ates of leaf initiation in the high-elevation tropics were lower than
in the temperate zone. 2. Significant positive inter-relationships wer
e found between leaf life span and mass based foliar nitrogen concentr
ation of Andean taxa. The correlation between life span and leaf mass
per area (LMA) was marginally significant, while life span and area-ba
sed foliar N content were unrelated. 3, Leaf traits of 46 Andean herba
ceous perennials (forbs and graminoids), spanning an altitudinal range
of 1500 m, indicated that the 16 taxa utilized for growth and leaf li
fe span determinations were representative. For graminoids no altitudi
nal changes in LMA or foliar N were observed across species. However,
in forbs LMA and area-based foliar N increased significantly with alti
tude. No differences in leaf traits were observed between herbaceous r
osette and cushion growth forms. 4, The Andean data set was used in co
njunction with data from the temperate, sub-arctic and arctic zones to
evaluate the significance of leaf life spans in herbaceous plants fro
m a biogeographical perspective. Leaf life span declined significantly
with increasing seasonality, expressed as latitude and duration of th
e annual growth period. Because temperature regimes are similar along
this gradient during the respective growth periods (Diemer 1996), obse
rved differences should be the result of variation in the day length a
nd/or duration of the growing season. 5. Data on leaf life spans and l
eaf traits of herbaceous plants from contrasting latitudes were used t
o evaluate the validity of general inter-relationships proposed by Rei
ch (1993). The high correlation between LMA and life span observed in
both data sets indicates that this relationship holds for various grow
th forms. On the other hand, the apportionment of mass-based foliar N
concentration in relation to life span appears to differ between herba
ceous and woody growth forms.