Randall W Long Tom L Dudley, Carla M D’Antonio, Kevin C Grady, Susan E Bush
In each of our lives we can probably think of individuals that are better at saving for rainy days, and those that cannot resist buying that new shiny object. But what about plants? Plants also have a limited resource pool, namely sugars acquired via photosynthesis, that they can either spend or save. Spending sugars gives plants an advantage much like the old adage “you need to spend money to make money” but saving can be equally important to survive through difficult times.
We often think broadly about plant species as either savers or spenders, for example we might consider a large redwood tree as growing slowly and saving its resources to support a long lifetime. At the other extreme annual grasses live fast and spend all their energy to produce seeds in one season. Rarely do we stop to consider the fine scale differences within species as we do in our own communities.
Here we studied populations of the non-native woody plant Tamarix to look at whether some plants were more likely to spend or save resources. To do this we collected plants from throughout the American southwest and grew them together in the same environment. Some of the populations we collected were from areas with spring freeze events that can kill sensitive leaf and stem tissue. We thought that these plants should save their resources to recover from these events, rather than spend their resources on growth or reproduction.
To determine if plants were saving resources, we measured the amount of sugars and starch the plants had stored in their stems and roots throughout the year. We then compared that to how much the plant had invested in growth and reproduction during the spring and summer. We found that, much like humans, some individuals were better at saving for difficult times. Specifically, in Tamarix, plants that were regularly exposed to lethal cold temperatures in the spring saved more for the winter then those from warmer sites.