(guest post by lab PhD student + lead author Courtenay Ray)

Plants modify microenvironments by altering nearby abiotic conditions, such as ground temperatures, soil moisture, and nutrient availability. Microenvironment modification may lead to changes in species interactions (e.g. competition and facilitation) if the environment becomes more or less stressful for neighboring plants; however, the consequences of microenvironment modification for demography are unclear.

In a recent lab paper published in Oikos, “Linking microenvironment modification to species interactions and demography in an alpine plant community” (available here at the journal or as a PDF), we explore how plants modify their surroundings, as well as the consequences of this modification on the performance of neighboring plants using microclimate measurements and six years of spatial and demography data at our long-term demography field site at Mt. Baldy.  

The field site at Mt. Baldy–Photo by Lars Lønsmann Iversen

We asked:

Q1: How much are surface temperatures and soil moisture modified at fine spatial scales across several species?

Q2: How do vital rates (survival, growth, reproduction) vary in response to microenvironment modification, and do climate and plant size affect that response? 

To address Q1, we collected ground surface temperature and soil moisture measurements at the edges of plants and 10 cm away in non-vegetated areas. Selected focal individuals captured a range of sizes, small to large, within each species.

Then, to estimate microenvironment modification effects on vital rates (Q2), we used spatial co-occurrence as a proxy for modification strength. Plants at Mt. Baldy are very clustered with multiple individuals and species often occurring within the same cluster. We used spatial distribution data to determine the total area that each plant overlaps with other vegetation as a proxy for microenvironment modification strength. 

We found (Q1) significant differences in surface temperature and soil moisture for most species compared to non-vegetated areas. For most species, we observed higher soil moisture and buffered temperatures (high minimums and lower maximums) in plants compared to non-vegetated areas.

We also found evidence that vital rates varied in response to microenvironment modification proxies, though response varied by vital rate and across species. 

Our results suggest that fine-scale habitat modification is a strong contributor to spatial patterns and vital rates in alpine plant communities.

#ecology

#communityecology

#alpine