Terrestrial ecosystems, increased solar ultraviolet radiation and interactions with other climatic change factors

TLDR: Based on research to date, some expectations about terrestrial ecosystem response as several elements of global climate change develop in coming decades are state.

Abstract: Based on research to date, we can state some expectations about terrestrial ecosystem response as several elements of global climate change develop in coming decades. Higher plant species will vary considerably in their response to elevated UV-B radiation, but the most common general effects are reductions in height of plants, decreased shoot mass if ozone reduction is severe, increased quantities of some phenolics in plant tissues and, perhaps, reductions in foliage area. In some cases, the common growth responses may be lessened by increasing CO2 concentrations. However, changes in chemistry of plant tissues will generally not be reversed by elevated CO2. Among other things, changes in plant tissue chemistry induced by enhanced UV-B may reduce consumption of plant tissues by insects and other herbivores, although occasionally consumption may be increased. Pathogen attack on plants may be increased or decreased as a consequence of elevated UV-B, in combination with other climatic changes. This may be affected both by alterations in plant chemistry and direct damage to some pathogens. Water limitation may decrease the sensitivity of some agricultural plants to UV-B, but for vegetation in other habitats, this may not apply. With global warming, the repair of some types of UV damage may be improved, but several other interactions between warming and enhanced UV-B may occur. For example, even though warming may lead to fewer killing frosts, with enhanced UV-B and elevated CO2 levels, some plant species may have increased sensitivity to frost damage.

Figures

Fig. 3 The response of four plant characteristics in field studies in the order of increasing positive effects. These experiments all employed supplemental UV-B from lamp systems. Each symbol represents a different study. The dashed line in each represents the average response calculated by the meta-analysis over all studies shown. The average responses shown were significant at P < 0.05. For shoot mass, the studies are grouped into two arrays corresponding to studies in which the level of simulated stratospheric ozone reduction is between 10 and 20%, and those in which the simulated ozone reduction was greater than 20%.

Fig. 2 Types of vegetation examined in the meta-analysis. The numbers refer to studies for individual species. Photographs of three different systems are also shown (a. wheat and wild oat experiments in Logan, Utah, USA, W. Beyschlag; b. Loblolly pine in Maryland, USA, A. Teramura; c. Subarctic heath in Sweden, from ref. 5).

Table 1 Effects of UV-B radiation on insect herbivory

Fig. 1 Major interactions of elevated UV-B with other climate change factors in terrestrial ecosystems. Lines indicate influence of climate change factors on different trophic levels (in rectangles) that affect processes (in ovals). Colors of lines: black, elevated CO2; red, elevated temperature; violet, enhanced UV-B; blue and brown, abundance and deficit of moisture, respectively. The symbols > and < refer to more and less, respectively.

Table 2 Effects of UV-B radiation on plant-microbe interactions for living plants and plant litter