B. Stadler et B. Michalzik, Aphid infested Norway spruce are "hot spots" in throughfall carbon chemistry in coniferous forests, CAN J FORES, 28(11), 1998, pp. 1717-1722
Citations number
24
Categorie Soggetti
Plant Sciences
Journal title
CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
Throughfall chemistry in deciduous and coniferous forests is characterized
by a high spatial and temporal variability, the sources of which are largel
y unknown. Aphids on Norway spruce (Picea abies (L.) Karst.) produce large
quantities of honeydew, which is rich in sugars. We investigated the effect
of changes in aphid abundance on throughfall carbon chemistry of Norway sp
ruce using a rainfall simulation experiment. Aphid numbers in the experimen
t paralleled field infestations. Infested trees showed significantly higher
concentrations of dissolved organic carbon (DOC) and hexose-C in throughfa
ll solutions compared with uninfested trees. There was also a pronounced se
asonal trend in the concentrations of these carbon compounds with highest c
oncentrations recorded at the time of peak aphid abundance at the end of Ju
ne - beginning of July. The throughfall from a spruce tree showed no spatia
l (center vs. periphery) differences in DOC and hexose-C concentrations. Th
e number of aphids on a tree was the best predictor of the carbohydrate con
centration of throughfall, explaining more than 60% of the variability. Dur
ing the period of aphid infestation (May-September) average estimated field
fluxes of DOC in throughfall collected under heavily infested trees ("hot
spots") were 11.6 and 240 times higher than those recorded under moderately
and uninfested trees, respectively. The results implicate herbivores as a
major potential source of the spatiotemporal heterogeneity in flows of nutr
ients in forests.