A SYSTEMS APPROACH TO SEEDLING ESTABLISHMENT ON DEGRADED RANGELAND: MANAGING ECOLOGICAL PROCESSES DRIVING RECRUITMENT BOTTLENECKS
Range and Meadow Forage Management Research
2013 Annual Report
1a.Objectives (from AD-416):
The broad objective of this research is to build off of four years of seedling establishment work conducted at ARS Burns and a new seed coating technology program to lead a multi-institution research effort that examines the demographic stages, ecological processes and management solutions for increasing seedling establishment on disturbed rangeland. 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.
Progress was made on all objectives (1-3) in 2013 and these objectives relate directly to Objective 2 of the parent project, "Working with cheatgrass and medusahead, develop new ecological principles that contribute to the basis of EBIPM by investigating the potential interactions among management approach selection, site availability, species availability, and species performance during restoration of cheatgrass and medusahead-dominated rangeland". A network of 15 sites distributed across gradients of soil and precipitation in 3 states in the Great Basin were established. The goal is to develop a model and conduct sensitivity analysis on the effects of environmental conditions and management on native plant populations and restoration strategies. This work will provide a mechanistic understanding of seedling establishment to improve our ability to forecast and improve restoration outcomes. All plots were seeded in late 2012 and initial sampling and data collection occurred throughout the spring of 2013. A concept manuscript “A systems approach to restoring degraded drylands” was accepted and published by the Journal of Applied Ecology and was an “editor’s choice” selection (see publications on inhouse parent project report, 5360-22000-004-00D). Installment of the second phase of plots will occur in Fall 2013 and another round of data collection will begin in Spring 2014. Research aligning with Objective 3 has been implemented to evaluate the use of seed coating technology and data continues to be collected. The project is on track with initial timeline.