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United States Department of Agriculture

Agricultural Research Service

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Research Project: A Systems Approach to Seedling Establishment on Degraded Rangeland: Managing Ecological Processes Driving Recruitment Bottlenecks

Location: Northwest Watershed Management Research

2012 Annual Report

1a.Objectives (from AD-416):
Specific objectives include: 1. Evaluation of the spatial and temporal variation in seedling demographic transitions; 2.Using fixed factored treatments, evaluate the ecological factors causing variation in demographic transitions; 3. Evaluate the use of seed coating technology, plant materials and weather forecasting for improving seedling establishment.

1b.Approach (from AD-416):
The general approach for evaluating spatial and temporal variation in seedling demography as well as ecological processes associated with this variation and potential management solutions are as follows: In fall of each of the three study years we will seed monocultures of three representative species in 1m2 plots using three replicate plots per species per year. Species and years will be randomly assigned to plots. To keep the intensity of disturbance and seed bed conditions comparable among years plots were tilled to a depth of 8 cm and existing vegetation removed approximately one month before planting. Volumetric soil moisture and temperature sensors will be installed at three randomly selected locations within the study area and measurements were made hourly in the 5 cm and 15 cm soil layer. Germination will be measured using the buried bag technique (Abbott and Roundy 2003). For each species and year, 40 bags will be randomly paired with the seeded 1m2 plots and planted in fall at the same time the plots were seeded. Five bags of each species will be pulled approximately every two weeks starting in winter and continuing through spring. At the same time, seedling emergence and death will be tracked weekly on the seeded plots. Individual seedlings within a cohort will be marked with colored toothpicks. We will manipulate soil moisture through irrigation and soil pathogens through fungicide additions to examine effects on seedling establishment. We also will examine variation in emergence probabilities across 10 Elymus elymoides accessions and 10 Agropyron desertorum accessions. We will use the developed procedures of Madsen et al. (2011) to evaluate the effects of seed agglomeration and seed coating technology on seedling establishment. Our statistical estimates will be 95% Bayesian confidence intervals (CIs). Bayesian confidence intervals have a simple interpretation and are well-suited for quantifying survival probabilities and other parameters (Rinella and James 2010). When two 95% confidence intervals do not overlap, the probability is greater than 0.95 that the treatment with the larger-valued interval is larger than the other treatments.

3.Progress Report:

This cooperative agreement was established to fund field experiments and microclimatic modeling objectives under a USDA-NIFA-AFRI grant "A systems approach to seedling establishment on degraded rangeland: Managing ecological processes driving recruitment bottlenecks" in cooperation with USDA-ARS, Burns, OR, University of Nevada Reno, and Utah State University. In FY2012, 15 field sites were identified in Idaho, Oregon, and Nevada that represent a range of potential climate conditions within the Wyoming big sage vegetation zone in the Great Basin sagebrush steppe. These sites were fenced and treated for weed control in anticipation of field planting activities starting in October/November 2012. Each field site will contain monitoring equipment for tracking soil temperature and water at seed and seedling depth. Planted perennial bunchgrasses and cheatgrass will be monitored for germination, emergence and seedling establishment and life cycle stages monitored relative to microclimatic seedbed conditions. These data will be used to test a conceptual model for seed-population progress between life stages, establishment, growth and mortality. Historical seedbed microclimatic simulations will be used to extend the results and application of these data to a broader range of annual weather variability across the study region. Research status and progress are reported via email, project teleconference calls and group meetings in Boise, Burns, and regional professional conferences. The agreement was established in support of objective 3 of the in-house project, the goals being to improve scientific understanding and to transfer technology related to assessing and mitigating the impacts of ecological disturbances by invasive weeds within sagebrush ecosystems of the Intermountain West.

Last Modified: 4/21/2014
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