|
| The short summers of the High Arctic pose a strong time constraint on the
annual cycle of all organisms in this region. Although arctic arthropods can
complete their development at very low temperatures, the predicted climatic
changes may shift their phenology outside its normal range. Hence, arctic
arthropods may become exposed to conditions to which they are not
adapted. On the basis of long-term data from several plots of pitfall and
window traps at Zackenberg in high-arctic Northeast Greenland, we document
that the timing of emergence is closely related to date of snowmelt in
nine taxa of common surface-active and flying arthropods. Average air
temperature seemed to play a lesser role, although the duration from snowmelt
to the date when 50% of the individuals in the season were caught
(date50) was negatively related to the average daily air temperature during
the same time interval in three of the nine taxa. Since short-term weather
fluctuations appeared to have a small eVect on capture numbers in pitfall and
window traps, we suggest that timing of snowmelt is a good predictor of the
phenology ofmost arthropods in high-arctic Greenland. The spatial synchrony
of capture numbers between individual traps within plots was high. However,
among pairs of plots, the spatial synchrony varied between taxa and habitats
and declined with distance between plots for surface-dwelling taxa and with diVerence in timing of snowmelt for the most abundant families of Diptera
(Muscidae and Chironomidae). Detritus feeders (collembolans,mites andmost
larvae of Diptera) and predators (spiders of the families Linyphiidae and
Lycosidae) were abundant throughout the summer season. In contrast, the
abundance ofmore specialized groups, like butterflies (e.g., Nymphalidae) and
parasitoid wasps (e.g., Ichneumonidae), was restricted to a narrow seasonal
time window in the warmest part of the summer. Because of their narrow
phenological range and their host specialization, these taxa may be most
vulnerable to trophicmismatch. Furthermore, snowmelt is predicted to become
more variable, and this may aVect organisms in areas of late snowmelt most
severely. | |
|