Frederick Curtis Lubbe, Jitka Klimešová, and Hugh A. L. Henry
Perennial herbaceous plants that live in areas with cold winters can survive thanks to special overwintering belowground organs made of stems and/or roots. Those overwintering organs store carbohydrates and bear the buds from which new stems and leaves are regrown in the spring. To overwinter successfully, herbaceous plants need to accumulate enough resources and be well-protected from winter frosts by soil, litter and snow. They also need to time their spring growth and movement of resources belowground to best take advantage of warmth, but avoid the cold.
Under climate warming, winter conditions are changing and this varies greatly across regions. Some places will get more snow and plant belowground organs may be better insulated, whereas other places will get less snow and overwintering organs might be exposed to increased frost. Moreover, in some places warm spring conditions may begin earlier in the year and cold winter conditions may begin later. While some plants will be able to take advantage of these changes, others may be harmed, because there is great variety in overwintering organs and their traits. Thus, with changing winter conditions, some plants will be more vulnerable and may be out-competed by others.
Because they are hidden underground, it can be difficult to study overwintering structures, and they are often ignored. In our review, we look at what is known regarding overwintering organs and their traits, and we propose important questions for how to learn more. For example, how will the growing depth of these organs be affected by changing winter and spring temperatures? Plants deep within the soil will be protected from increased soil freezing, but when it warms up, plants with shallow buds may be able to out-compete those with deep buds. These belowground organs and their traits are very important for how plants can adapt to and survive changing winters. At a broader scale, changes in plant species composition and belowground structures can have a strong influence on soil carbon storage, nutrient availability, water holding capacity and erosion.