​Riparian forest dynamics in aridland river basins

In river ecosystems in dryland regions, flood disturbance and drought are important drivers of riparian forest dynamics because they regulate habitat creation, tree mortality, and resource fluxes of water and nutrients critical for growth. I am working in riparian ecosystems in California and southern Europe to understand the drivers of riparian forest dynamics, and to assess their sustainability under changing land uses, climate and streamflow regimes.

Along the middle reach of the Sacramento River, CA, California's largest river, we are studying the community dynamics of forests dominated by Fremont cottonwood (Populus fremontii), a keystone riparian tree in river ecosystems of the U.S. southwest. Currently we are studying how restored riparian forests follow or diverge from natural succession trajectories. In prior work we modeled riparian forest succession, documented an important pathway for forest initiation in abandoned channels, and used simulation models to predict corridor-wide forest response to flow regulation.

Along the Rhône River in SE France, we are documenting how climate drives patterns of riparian forest health and how current forest ecosystems have responded to long-term river modifications from 19th century channelization and 20th century flow regulation.  Together with collaborators in California and France, we are providing this research as guidance for river corridor planning and conservation under multiple management constraints.

In prior work, my lab conducted field studies and experiments on mechanisms of riparian seedling establishment along regulated rivers in California's Central Valley. A major stressor to riparian communities in semi-arid regions is the lack of tree recruitment on regulated rivers as a result of modifications to the flow regime. These studies include demography and competition, ecophysiology and isotope biogeochemistry, and environmental controls on life history timing of riparian trees. This research provides quantitative criteria for river managers to slow the decline of riparian forests along regulated rivers by optimizing natural recruitment with the highest degree of certainty and lowest water cost.

Collaborators: 
Related publications: (* indicates student contributors)
Williams, J.**, A.M. Lambert, J.C. Stella. In press. Long-term restoration monitoring reveals contrasting trajectories and timelines for riparian vegetation development. Restoration Ecology.

​Constantz, B.*, J.C. Stella, K.D. Holl. 2025. Diverging restoration pathways for overstory and understory communities in a Mediterranean-climate riparian ecosystem. Ecological Applications 35:e70043. DOI: 10.1002/eap.70043

Lochin, P.*, P. Malherbe, B. Marteau, J. Godfroy, F. Gerle, J. Marshall, S Puijalon, M.B. Singer, J.C. Stella, H. Piégay, A. Vernay. 2024. The Ant and the Grasshopper: contrasting responses and behaviors to water stress of riparian trees along a hydroclimatic gradient. Science of the Total Environment 952:175916 DOI: 10.1016/j.scitotenv.2024.175916

Lochin, P.*, H. Piégay, J.C. Stella, K.K. Caylor, L. Vaudor, M.B. Singer. 2024. Drivers of spatiotemporal patterns of riparian forest NDVI along a hydroclimatic gradient. Ecohydrology e2729 DOI: 10.1002/eco.2729

Fichot, R., M. Lefebvre*, M. Pégard, D. Chassagnaud, M. Bliard, J. Ferdinand, F. Laurans, D. Le Thiec, A. Deveau, J.C. Stella, P. Rozenberg, M. Villar. 2024. Distinct trait syndromes and plasticity maintain similar performance between seedlings populations of the riparian tree species Populus nigra L. Environmental and Experimental Botany. DOI: 10.1016/j.envexpbot.2023.105598

​Rodríguez-González, P., S. Dufour, J.C. Stella, et al. 2022. Bringing the margin to the focus: 10 challenges for riparian vegetation science and management. WIRE Water. DOI: 10.1002/wat2.1604

Jayasuriya, M.T.*, R.H. Germain, J.C. Stella. 2022. Applying the "Goldilocks Rule" to Riparian Buffer Widths for Forested Headwater Streams across the Contiguous US – How Much Is "Just Right"? Forests. DOI: 10.3390/f13091509

Stella, J.C., L. Kui, G.H. Golet, F. Poulsen. 2021. A dynamic riparian forest structure model for predicting large wood inputs to meandering rivers. Earth Surface Processes and Landforms. DOI : http://doi.org/10.1002/esp.5229

Jayasuriya, M.T.*, J.C. Stella, R.H. Germain. 2021. Can Understory Plant Composition and Richness Help Designate Riparian Management Zones in Mesic Headwater Forests of the Northeastern United States? Journal of Forestry DOI: 10.1093/jofore/fvab034

Janssen P., J.C. Stella, B. Räpple**, C.R. Gruel**, G. Seignemartin*, B. Pont, S. Dufour, H. Piégay. 2020. Long-term river management legacies strongly alter riparian forest attributes and constrain restoration strategies along a large, multi-use river. Journal of Environmental Management DOI: 10.1016/j.jenvman.2020.111630

Janssen P., J.C. Stella, H. Piégay, B. Räpple**, B. Pont, J-M Faton, J.H.C. Cornelissen, A. Evette. 2020. Divergence of riparian forest composition and functional traits from natural succession along a degraded river with multiple stressor legacies. Science of the Total Environment 720. DOI: 10.1016/j.scitotenv.2020.137730

Matzek, V., J.C. Stella, P. Ropion*. 2018. Development of a carbon calculator tool for riparian restoration. Applied Vegetation Science DOI: 10.1111/avsc.12400

Thorel, M., H. Piégay, C. Barthélémy, B. Räpple**, C-R Gruel*, P. Marmonier, T. Winiarsky, J-P Bedell, F. Arnaud*, G. Roux, J.C. Stella, G. Seignemartin*, A. Tena-Pagan, V. Wawrzyniak*, D. Roux-Michollet, B. Oursel, S. Fayolle, C. Bertrand*, E. Franquet. 2018. Socio-environmental stakes associated with process-based restoration strategies in large rivers: should we remove novel ecosystems along the Rhône (France)? Regional Environmental Change DOI: 10.1007/s10113-018-1325-7

Räpple, B.**, H. Piégay, J.C. Stella, D. Mercier*. 2017. What drives riparian vegetation establishment in river channels at patch to corridor scales? Insights from annual airborne surveys (Drôme River, SE France). Ecohydrology DOI: 10.1002/eco.1886

Kui, L.**, J.C. Stella, P.B. Shafroth, P.K. House, A.C. Wilcox. 2017. The long-term legacy of geomorphic and riparian vegetation feedbacks on the dammed Bill Williams River, Arizona, USA. Ecohydrology DOI:10.1002/eco.1839

Dufour, S., M.K. Hayden*, J.C. Stella, H. Piégay, J.J. Battles. 2014. Maintaining channel abandonment processes increases riparian plant diversity within fluvial corridors. Ecohydrology. DOI: 10.1002/eco.1546  [pdf]

Stella, J.C., M.K. Hayden*, J.J. Battles, H. Piégay, S. Dufour, and A.K. Fremier. 2011. The role of abandoned channels as refugia for sustaining pioneer riparian forest ecosystems. Ecosystems 14: 776-790. DOI 10.1007/s10021-011-9446-6 [pdf]

Harper, E.B., J.C. Stella, A.K. Fremier. 2011. Global sensitivity analysis for complex ecological models: a case study of riparian cottonwood population dynamics. Ecological Applications 21: 1225-1240. DOI:10.1890/10-0506.1[pdf]

Stella, J.C., J.D. Riddle*, J.J. Battles, M.K. Hayden*, and A.K. Fremier. 2012. Riparian forest dynamics on a large, regulated river (California, USA): impacts and implications for management. Proceedings of the Integrative Sciences and Sustainable Development of Rivers (IS Rivers) Conference, Lyon, France, 26–28 June 2012. [pdf]

Stella, J.C., and J.J. Battles. 2010. How do riparian woody seedlings survive seasonal drought? Oecologia 164:579–590. DOI 10.1007/s00442-010-1657-6 [pdf]

Stella, J.C., J.J. Battles, J.R. McBride, B.K. Orr. 2010. Riparian seedling mortality from simulated water table recession, and the design of sustainable flow regimes on regulated rivers. Restoration Ecology 18: 284-294. DOI: 10.1111/j.1526-100X.2010.00651.x [pdf]

Stella, J.C., J.J. Battles, B.K. Orr, J.R. McBride. 2006. Synchrony of seed dispersal, hydrology and local climate in a semi-arid river reach in California. Ecosystems 9:1200-1214. DOI: 10.1007/s10021-005-0138-y [pdf]