Of course, everybody knows leaf and whole plant longevity. Leaf longevity is an important trait in leaf economic spectrum – an effective photosynthesis is connected with low leaf lifespan. And plants may be annual, biennial and perennial, completing their life-cycle in four weeks or hundreds of years. But shoot longevity? What is it and does it matter?
In annual and biennial plants, the whole plant body is usually formed by one shoot so that the plant lifespan is equal to the shoot lifespan – so, to consider the shoot lifespan is not especially important here. In trees, new shoots are produced from old shoots to form plant body and become part of perennial structures of a trunk and a crown – but the trunk with the crown is a functional entity of a tree so to consider the shoot lifespan is not important here as well. On the other hand, in perennial herbs which are losing aboveground parts of shoots each adverse season, new shoots are replacing old ones during plant lifespan. Because the shoots of the perennial herbs may be potentially independent of each other due to possessing their own root system, they are functional entities here and their lifespan is important to consider.
What tell us the shoot lifespan in perennial herbs about their ecology? It tells us how fast a plant is growing – the longer is the lifespan of shoots, the slower is growth rate of a plant and lower are its nutrient demands and vice versa is true for the short shoot lifespan. Does it remind you leaf economic spectrum? Rightly so, SLA is correlates negatively with shoot lifespan and positively with whole plant longevity. There are other functional consequences of shoot lifespan and you can read about them in our new paper here.