lizardWelcome to the LEES Lab

The LEES Lab at the CGCEO of Michigan State University, directed by Dr.Jiquan Chen, is interested in scientific investigations and education on fundamental ecosystem and landscape processes for understanding ecosystem functions and management.

Our current studies are focused on the carbon and water cycles of different ecosystems (grassland, desert, forest, cropland, wetlands, freshwater) at multiple spatial and temporal scales, bioenergy systems and resource uses, coupled interactions and feedback between climatic change and human activities, and sustainable management and conservation.

Our research projects, spreading mostly across North American and Asian landscapes, are based on sound field experiments and monitoring stations, state-of-the-art equipment and technology, modeling, and remote sensing technology. The LEES Lab is also the home of book series on "Ecosystem Science and Applications—ESA" for the Higher Education Press (HEP) and De Gruyter. We maintain a high ethical and liberal standard for professional collaborations in research and education.

Featured Article

Grazing effect on grasslands escalated by abnormal precipitations in Inner Mongolia

Maowei Liang, Jiquan Chen, Elise S. Gornish, Xue Bai, Zhiyong Li, Cunzhu Liang

Grazing effects on arid and semi-arid grasslands can be constrained by aridity. Plant functional groups (PFGs) are the most basic component of community structure (CS) and biodiversity & ecosystem function (BEF). They have been suggested as identity-dependent in quantifying the response to grazing intensity and drought severity. Here, we examine how the relationships among PFGs, CS, BEF, and grazing intensity are driven by climatic drought.

We conducted a manipulative experiment with three grazing intensities in 2012 (nondrought year) and 2013 (drought year). We classified 62 herbaceous plants into four functional groups based on their life forms. We used the relative species abundance of PFGs to quantify the effects of grazing and drought, and to explore the mechanisms for the pathway correlations using structural equation models (SEM) among PFGs, CS, and BEF directly or indirectly.

Grazers consistently favored the perennial forbs (e.g., palatable or nutritious plants), decreasing the plants' relative abundance by 23% to 38%. Drought decreased the relative abundance of ephemeral plants by 42 ± 13%; and increased perennial forbs by 20 ± 7% and graminoids by 80 ± 31%. SEM confirmed that annuals and biennials had negative correlations with the other three PFGs, with perennial bunchgrasses facilitated by perennial rhizome grass. Moreover, the contributions of grazing to community structure (i.e., canopy height) were 1.6 to 6.1 times those from drought, whereas drought effect on community species richness was 3.6 times of the grazing treatment. Lastly, the interactive effects of grazing and drought on BEF were greater than either alone; particularly, drought escalated grazing damage on primary production.

Synthesis: The responses of PFGs, CS, and BEF to grazing and drought were identity- dependent, suggesting that grazing and drought regulation of plant functional groups might be a way to shape ecosystem structure and function in grasslands.

Ecology and Evolution, 2018

Figure 1. Structural equation modeling (SEM) of grazing and drought to predict CS and BEF by regulating PFGs (n = 108). Shown are (a) CS (Chi-square (χ2) = 17.910, degrees of freedom = 12, probability level = 0.118, Comparative Fit Index = 0.992, Root Mean Square Error of Approximation = 0.068, Akaike Information Criteria = 83.910), which include species richness, stand density, and canopy height; (b) BEF (Chi-square (χ2) = 14.809, degrees of freedom = 13, probability level = 0.319, Comparative Fit Index = 0.998, Root Mean Square Error of Approximation = 0.036, Akaike Information Criteria = 78.809), which was referred as species diversity, functional diversity, and aboveground biomass. The PFGs include perennial bunchgrasses—PB, perennial rhizome grass—PR, perennial forbs—PF, and annuals and biennials—AB. Solid and dashed arrows represent positive and negative pathways, respectively. Numbers indicate the standardized path correlation coefficients (r). Gray arrows and numbers only demonstrate correlations among PFGs. Significant at 95% confidence level: *p < 0.05; **p < 0.01; ***p < 0.001