Print PageGlobal environmental changes, such as climate warming, earlier snowmelt, and altered precipitation are affecting plant life cycles. For example, a longer growing season was one of the most widely observed biological changes in response to climatic warming during the 20th Century. In contrast, warming often shortens the duration of plant species’ life histories. This apparent contradiction in plant responses to climate warming can be explained by considering shifts in the timing of species’ life history events and the duration of species’ life histories, which together determine plant community life history responses. The objectives of our recent research have been to: 1) develop a low-cost instrument array to monitor plant community life histories through observing surface greenness and 2) use this system to monitor the response of plant communities to global environmental changes. Plant community life histories can be observed through daily measurements of surface greenness from ground-based platforms, which are increasingly used in phenological studies. Our instrument arrays include upward- and downward-facing light sensors with photodiodes for visible and broadband wavelengths on a steel platform that extends the sensors away from its base and microclimate sensors that extend out from the sides of the array. The timing of key life history events, such as the start of the growing season, can be estimated by fitting a piece-wise linear model to the data.
Results/Conclusions
Using this instrumentation in a precipitation manipulation experiment in a shortgrass steppe ecosystem, we found that rainfall pulses extended the growing season by delaying the end of senescence but did not affect the onset of senescence, which marks the end of peak season. Although the rainfall pulses varied in magnitude, plant community life histories were primarily affected by whether a pulse occurred and not be the magnitude of the pulse. In the Arctic, we used similar instrumentation to determine the effect of earlier snowmelt and climate warming on plant community life history. We found that the onset of greening, which marks the start of the growing season, was not affected by earlier snowmelt or climate warming nor was the timing and duration of peak season affected. Our data suggest that environmental changes have a more subtle effect on peak season length than on growing season length, possibly due to species life history traits that constrain peak season.
