In this video, Magda Garbowski summarises their recent article: Nutrient enrichment alters seasonal beta-diversity in global grasslands:

📽️ Transcript:

Plant communities are constantly changing, sometimes even with in a single growing season. For example, some species may grow in the spring, whereas others may dominate in the fall. This temporal niche partitioning allows plants to use resources at different times, and allows unique assemblages of insects and animals to interact with plant communities during distinct time periods. However, because ecologists usually study plant communities at just one timepoint each year, we do not fully understand how within season dynamics are altered by global change drivers, such as nutrient enrichment or fertilization.

We used plant community data collected early and late in the growing season from 10 grassland sites around the world, to ask how nutrient enrichment influences within-season segregation of plant species. We used seasonable beta diversity, a measure of dissimilarity between early and late season communities, to address this question. We also asked how specific functional groups, such as grasses, forbs, and legumes, respond to fertilization early firstly in the growing season.

We found that nutrient enrichment alters seasonal beta diversity by increasing dissimilarity between early and late season communities. However, fertilization reduces the abundance of legumes and late season or C4 grasses, within and between sampling time points. It also eliminates seasonal differences in these groups. In contrast, fertilization increases the abundances of early season or C3 grasses and annual forbs, both early and late in the growing season.

Our results suggest that fertilization increases dissimilarity or seasonal beta diversity between early and late season communities. However, fertilization also results in temporal homogenization of C4 grasses and legumes. These changes may have cascading affects on critters that depend on specific plants at specific timepoints, and may hinder the ability of plant communities to respond to various components of global change.

Magda Garbowski, University of Wyoming, USA

Read the full article online: Nutrient enrichment alters seasonal beta-diversity in global grasslands.