What we do

Our research combines large-scale observational studies across biogeographic regions, field experiments, functional and phylogenetic approaches, and advanced statistics and modeling to address environmental issues and to explore fundamental questions in ecology. We are broadly focused on two main themes: 1) Community assembly - mechanisms across local, landscape, and biogeographic scales; and 2) Global change biology - applying community assembly theory to environmental issues. We also explore other topics of interest including herbivory, disturbance and plant hemiparasites 

RESEARCH PROGRAMS

 -COMMUNITY ASSEMBLY-

Integrating mechanisms across local, landscape, and biogeographic scales 

 

A key challenge at the interface of ecology and conservation is to understand the mechanisms by which communities assemble and lead to the diversity observed in nature. These mechanisms range from the continental-scale influence of temperature and moisture, to the more localized influence of micro-climate, soil fertility and biotic interactions. In the Spasojevic lab, we integrate processes across multiple scales, from continental-scale biogeographic processes to local interactions among coexisting species, to better elucidate mechanisms of community assembly. Our approach focuses on using quantitative examinations of taxonomic, functional and phylogenetic diversity coupled with spatial and environmental data to elucidate the role of multiple interacting mechanisms.

 - GLOBAL CHANGE BIOLOGY - 

Applying community assembly theory to environmental issues 

 

Community assembly theory provides a powerful framework for understanding how multiple global change factors are influencing individual species, changing plant communities and altering ecosystem function. For example, predicting species distributions under future climate scenarios has been strengthened by including both continental scale processes and landscape scale processes. A key goal of the Spasojevic lab is to integrate multiple ecological processes to understand key questions related to global change. We conduct this research using a combination of experiments, observational studies, and data synthesis and do research in alpine, dryland, and forest ecosystems.  

 

Some of our current experimental and observational research projects

Pinyon Flats rainfall manipulation experiment

(Marko Spasojevic, Darrell Jenerette, Pete Homyak) 

We are examining how changes to the amount of rain in different seasons influences plant community dynamics and ecosystem functioning in a Pinyon-Juniper woodland. This system gets both summer (S) and winter (W) rain and our treatments include: 1) no S and ambient W; 2) ambient S and ambient W; 3) ambient S and two times W; 4) no W and ambient S; 5) ambient W and ambient S; 6) ambient W and two times S. We are collecting the second year of data and are already seeing shifts in community composition in the water addition plots.

San Jacinto Forest Dynamics Plot

(Marko Spasojevic, Jeff Diez)

Forests play key roles in biodiversity maintenance and climate regulation. Globally, forests support over half of all described species and provide many valuable ecosystem functions and services such as timber, clear air, clean water, and carbon storage. However, forests worldwide are being threatened by habitat loss, drought , and changes in fire frequency, which have all resulted in losses to biodiversity  and alterations to key ecosystem functions and services. Understanding and predicting how forests will respond to ongoing and pervasive changes to the environment is critical for biodiversity conservation and for the management and maintenance of ecosystem services. Our Forest Dynamics Plot on Mt. San Jacinto in Southern California will be part of the Smithsonian’s Forest Global Earth Observatory network. The overarching goal of this project is to conduct research on forest biodiversity and ecosystem functioning and to establish long-term monitoring of forest health in Southern California

Growing Season Length Experiment

(Niwot LTER project)

As part of the Niwot LTER, Marko is collaborating with a great group of PIs and grad students to understand how early snowmelt influences  biodiversity and ecosystem functioning in the alpine. In 2018 we initiated an experiment to manipulate growing season length by spreading a very fine layer of black sand on large (10x40m) plots at maximum snowpack at five sites. The black sand increases albedo and speeds melt by 5-15 days, depending on site. We have completed two years of data collection and are planning to continue these manipulations for 6-8 years to both identify shifts in limiting resources as well as the responses to those shifts in plant production, species composition, phenology, and woody plant demography. We are initiating work on how early growing season affects plant-pollinator interactions, in conjunction with shifts in plant phenology and on how structure-forming biota might affect climate exposure and create refugia.

Range shifts in Western Forests

(Erin McCann)

Understanding which species will be able to disperse to new habitats in response to changing climate is critical for conservation. Here, using FIA data Erin is modeling seedling and adult distributions to try and understand which species are showing elevational or latitudinal shifts. Erin has found that 18 of 25 species are shifting north and these species tend to have animal dispersal syndromes. 

Climate change alters the relative importance of Mass Ratio and Niche Complementarity effects 

(Jared Huxley)

Jared is examining how the mechanisms driving the biodiversity-ecosystem function relationship (niche complementarity and mass ratio effects) should be expected to shift under environmental change scenarios. Using long-term monitoring data from the Niwot Ridge LTER Jared found that that mass ratio effects were the dominant mechanism by which biodiversity influenced NPP in the alpine, but that niche complimentarity became more important in years with hot dry summers.

The Deep Canyon Transect: understanding vegetation responses to recent climate change

(Tesa Madsen-McQueen)

Climate change is inducing the rapid restructuring of vegetation globally, and particularly along elevational gradients in mountainous terrain. The Deep Canyon Transect, is a steep elevational gradient spanning an elevation gain of 2,438 meters over a distance of 16 kilometers and was previously sampled in 1977 and 2008. Tesa resampled this transect to understand how vegetation has responded to ongoing climatic changes. 

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