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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Research Project #433103

Research Project: Using Diversity and Facilitation to Enhance Establishment and Resilience During Restoration of Invaded Sage-Steppe Rangeland

Location: Range and Meadow Forage Management Research

Project Number: 2070-21630-003-04-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2017
End Date: Aug 31, 2022

Objective:
Our goal is to develop a system to use plant diversity and positive plant-plant interactions to facilitate and enhance seedling establishment, invasion resistance, and plant community resilience during restoration of invaded sage-steppe rangeland. Our objectives are to: 1) examine which attributes of plant diversity (functional diversity, species diversity, population diversity) can be most effectively leveraged to stabilize rangeland restoration establishment and plant community resilience, 2) create a bioclimatic understanding of how environmental conditions interact with diversity to influence restoration outcomes, and 3) identify those groups of species that have positive effects on one another during establishment and growth.

Approach:
We will select up to 40 sites stratified across western rangeland distributed along major gradients in climatic water deficit (CWD), which is the evaporative demand not met by soil water and indicates the amount of heat stress that cannot be regulated by plant transpiration, snow pack, and mean annual winter temperature. Several small plots (2 x 2 m) will be established at each site and we will seed plots with either 6 introduced grass and forb species or 6 native grass and forb species. Within these fixed species designs, plots will be sown with one of three varieties of each species. Lastly we will seed all plots at either a high or low rate so we can develop a density dependent population model for establishment. This results in a total of 36 plots per site (3 species varieties x 6 species x 2 rates = 36). We will use conditional probability models coupled with simulations to partition how the multiple layers of diversity influence restoration outcomes over broad environmental gradients. A species within each plot will be subjected to network analysis to assess the direction and magnitude of their individual interactions.