Shifts of above ground productivity of pre- & alpine grasslands under climate change

Bernd Berauer1
1 Departement of Disturbance Ecology, University of Bayreuth

P 4.12 in BayCEERversity: Across scales, compartments & communities

Introduction

Alpine and pre-alpine grasslands cover a large area in the southern parts of Germany. They provide fodder for dairy and cattle farming and also home to unique, highly adapted plant communities. Climate change is altering length of growing season by altering temperature and precipitation, which may cause shifts in community composition as well as in productivity. Here we investigate how this alpine communities will react to climate change regarding productivity, using a translocation experiment

Material and Methods

The study is conducted along an altitudinal gradient in the Alps ranging from 350 to 2400 m.a.s.l. and spanning from pre-alpine to alpine grassland. Intact soil-plant-units (Mesocosms) were translocated downslope to passively simulate climate change. Additionally Mesocosm of the lowest site were translocated upslope to the two highest sites. The Mesocosms are cut at site specific peak growing season and above ground biomass is sorted to species.

Results

Above-ground net primary production (ANPP) decreases with an increase in altitudinal difference between origin and translocated site of the Mesocosms. The effect size of this decrease reaches up to -50% for the maximum translocation distance of each specific origin. Intrestingely ANPP of Mesocosms originating from the highest altitude site and translocated to the lowest site only show a slight decrease (-1.8%). Uphill translocation shows a trend of decreasing ANPP (-80%) and also narrowing the variance of productivity.

Conclusions

The effect of uphill translocation might be caused by a reduction in length of growing season due to decreasing temperature with altitude. Opposing this an increase in length of growing season by downslope translocation is not causing an increase in ANPP, which might be caused by shifts in climatic growth limitations towards precipitation limitation at low altitude sites. Further reasons might be soil respiration and root die back during the winter both caused by a missing snow cover.

 



Keywords: Climate Change, Alpine grasslands, Productivity, Community composition