Environmental changes in biodiversity hotspot ecosystems of
South Ecuador: RESPonse and feedback effECTs (FOR2730)

Resumen:

Decomposition is a very important process. It is supporting nutrient cycles and for that reason crucial for the functionality of ecosystems. Various studies have shown that decomposition is driven by abiotic and biotic factors such as climate, seasonal weather conditions (like el Niño), soil organisms and disturbance of forests. In this study, the focus lies on investigating the impact of abiotic factors on the decomposition with a new simplified and standardised method, with tea bags as litterbags. Green tea bags were buried in two years, on different elevations between 1000 m a.s.l. and 3000 m a.s.l. in 500 m steps on disturbed and undisturbed plots in the Ecuadorian Andes. After 21 days in the soil, the decomposition rate were calculated and compared on different elevations and different disturbances in two different years. The disturbance had no effect, because the disturbed plots were fragmented and the study took place in the interior of these fragments; here no edge effects influenced the decomposition rate. As expected, the decomposition rate declined with an increase in elevation, due to changing climate conditions. In the lower, wet and warm elevations, it was faster than in the higher elevation where the climate is wetter but also colder. In the test series from 2015, the decomposition rate was higher in the upper elevations than in 2014, this could be explained by a weather phenomenon called el Niño, which took place in 2015. It leads to a slightly higher temperature and 60% more precipitation than what normally would be expected in 2015. These differences between the two years show the importance of taking seasonal and annual variations into account while investigating decomposition and the sensitivity of this important ecosystem process to changing weather and climate conditions.