Effects of advancing treelines and melting glaciers on alpine lake ecosystems: A mesocosm experiment

Climate warming promotes the upward advance of mountain treelines, thereby increasing allochthonous inputs of terrestrial organic matter into alpine lakes. Higher temperatures also accelerate glacial ablation, altering inputs of finely eroded rock particles, termed “glacial flour”. Organic matter (OM) and glacial flour (GF) both affect aquatic ecosystems; however, a knowledge gap exists concerning their combined impact. To test for the direct and interactive effects of OM and GF, we conducted a crossed two-factor outdoor mesocosm experiment. We hypothesized that GF sequesters OM through adsorption, thus reducing its effects on the abiotic environment and phytoplankton community. Addition of GF decreased underwater attenuation of ultraviolet radiation by the OM amendment (i.e., a GF-OM interaction), but not the pronounced positive effects of OM on nutrients and phytoplankton chlorophyll. GF did mediate the effect of OM on phytoplankton community composition by suppressing diatoms. These ..., , , # Effects of advancing tree lines and melting glaciers on alpine lake ecosystems: A mesocosm experiment

[https://doi.org/10.5061/dryad.hqbzkh1sj](https://doi.org/10.5061/dryad.hqbzkh1sj)

## Description of the data and file structure

Data collected for:

Effects of advancing treelines and melting glaciers on alpine lake ecosystems: A mesocosm experiment

Authors: Colleen Dawson, Janet M. Fischer, Mark H. Olson, Rolf D. Vinebrooke

Collection: 07/2023 to 08/2023 at Barrier Lake Field Station in Kananaskis, AB, Canada.

### Files and variables

#### File: gfomexp_radiometer.csv

**Description:** 

Underwater light attenuation data from the start and end of organic matter x glacial flour mesocosm experiment. 

Missing values are indicated by n/a. Light attenuation coefficients were not calculated when shading effects resulted in weak fitting log-linear relationships.

##### Variables

* tank: Unique numerical identifier assigned to each mesocosm tank.
* treatment: Experimental treatment ...,