The interaction of rangeland management and environmental conditions in regulating forage quality - quantity and other ecosystem services

The interaction of rangeland management and environmental conditions in regulating forage quality - quantity and other ecosystem services

Summary

With substantial input from a broad group of stakeholders, the database format has been completed (with the expectation that it will be periodically updated to accommodate new types of management practices and dataset structures). The database and its web interface are currently under construction, with a planned release date of April 2016. This is later than scheduled, due to the technical challenges associated with designing a database to accommodate the diverse management types and response factors incorporated into the project, and in having dedicated developer time. While the database professionals have been researching the best approaches to designing the database, the research team has focused on field sampling, so that the data can be incorporated into the database as soon as it is ready.

On-ranch sampling of the effects of management on multiple ecosystem services has continued and has been used to fine-tune the draft of the monitoring protocols. The severe drought that California has experienced for the past four years (the duration of this project), has provided a unique opportunity to study one of the top priorities of land managers – a better understanding of drought responses and management. To take advantage of this opportunity (and by necessity, given the weather conditions during the project), sampling has focused on how environmental and management conditions influence the effect of drought on: plant production, plant species composition, plant cover, erosion, and water infiltration and storage. In the current 2015-16 growing season, we are assessing how interactions between management and environmental conditions determine the timing and extent of recovery from drought (in terms of plant production and cover, species composition, and soil conditions). Based on meetings with stakeholders, we sampled more sites but measured fewer ecosystem services to assess drought responses.

Objectives/Performance Targets

Our objectives and performance targets are summarized below, including the status (and projected dates of completion) for each of these. (These new dates assume approval of the no-cost extension, which is being submitted separately, as requested).

Objective 1: Assess how local to regional differences in environmental conditions determine:

1. Site-specific potential to provide multiple ecosystem services.
2. The impacts of range management practices on suites of ecosystem services, and which practices are most effective for a given service at a given site.

1. In addition to the original sub-objectives (1a, 1b), we have also added the following: Determine the effects of site environmental conditions and management practices on the response of vegetation production, cover, and composition to drought, and recovery after drought. Soil responses to drought have been focused on erosion, and to a lesser extent, water infiltration and storage.

Performance targets related to this objective:

1. Develop a web database of management practices and their impacts on ecosystem services.

While we had anticipated the database being public by now, this likely will not occur until April 2016, because the development of the database has been more complex than we had initially anticipated. Complexities are due to the multiple types of services being measured, the multiple measurement approaches for each of these services, the diversity of management approaches, and the multiple environmental factors that are determining these services (with focal services, measures, management practices, and environmental factors differing across projects, so that most of them are not directly comparable, without calibration). The database structure has been determined, and the database and web interface are being developed in collaboration with database developers and GIS professionals at the University of California’s Division of Agriculture and Natural Resources (the group that runs UC Cooperative Extension), which will ensure a web-host for this database over the long-term.

On the advice of the database professionals, we are focused on collecting data, which will be incorporated into the database once it is completed (rather than first building the database and then focusing on collecting data, as was originally planned). We have been sampling ranches for the effects of local environmental conditions and management practices on multiple ecosystem services. Key findings are summarized in the “accomplishments/ milestones” section.

A key field activity is needed to allow the database to compare and summarize across diverse measurement approaches: field trials to calibrate across multiple measures for a given service. This was supposed to occur over the past three field seasons but has been delayed due to the drought in California (we have assumed the severe drought conditions may not provide the most reliable calibrations across multiple measures). Field calibrations will occur in spring of 2016, which appears to be a year with adequate rainfall.

2. Develop a “Measuring ecosystem services handbook” and “toolkit for measuring ecosystem services”. Based on workshops and surveys of stakeholders, we have decided to revise the initial plans. Rather than one set of ecosystem service measurements, we have divided them into two. The first set will be a more comprehensive, quantitative set of measurements, appropriate for research, official monitoring programs, and managers who are enthusiastic to monitor the impacts of their practices. We are fine-tuning a draft of this currently and are using this as a template to sample our field sites. We are adjusting the handbook draft in response to user feedback and will further refine it based on field measurements in spring of 2016 that are being used to calibrate across sampling techniques. This new data will allow us to finalize the set of ecosystem service measures and determine to what extent one “ideal” type of measurement can be used for each service, or to what extent we can’t make correction factors across different measures, so that a menu of options should be available.

The second set of protocols is more informal, providing a quick, qualitative assessment by managers. For example, rather than official determination of invasive species cover, they would assess invasive cover by selecting the closest match in cover from 5-8 photos depicting different levels of invasion (this would calibrate across individual assessors). The same type of approach will occur for production, visible erosion events, and visible runoff (lack of water infiltration). The handbooks for measurements should be completed in summer 2016.

3. Recruit managers to participate in the database. This has been an on-going, successful effort. We have provided stakeholder feedback sessions, as well as talks and posters highlighting the project at a number of venues and write-ups in newsletters including: California Rangeland Conservation Coalition, California Climate and Agriculture Network, Cooperative Extension field days, as well as to a number of conservation groups utilizing grazing as a management tool (California Native Grassland Association, California Invasive Plant Council).

Through our work with stakeholders, we have added a new feature to the database – in addition to the public-available search of case studies, each data contributor (e.g. Sacramento County) will have a private portal of a collection of their entries in the database. This is a critical tool for individual stakeholders to track their project outcomes, using the database as a long-term data repository and analysis tool.

Objective 2:  Improve the effectiveness of range management by enhancing the availability of information for developing management plans.

The initial two steps are described above: developing the database and the measuring services handbook and toolkit. The other two performance targets will be provided towards the end of the project, once the work is synthesized.

1. Develop an on-line decision support tool for managing multiple services.
2. Develop regional maps of the distribution of multiple services.

Accomplishments/Milestones

As stated above, the major accomplishments include:

1. Fine-tuning the priority ecosystem services, measurements, environmental conditions, and management practices to include in the database.
2. Recruiting agencies, nonprofits, and individual ranchers to participate in the database project.
3. Field sampling of ecosystem services across diverse environmental conditions and management approaches on California’s rangelands.
4. Developing the quantitative ecosystem measures handbook (qualitative one is still in development).

Data is still being analyzed, but trends from measurements and collected datasets are emerging:

– After the 3^rd year of drought, we reported that drought increased the prevalence of native perennial grasses. After the 4^th year of drought, impacts are much more site-dependent. In relatively wetter areas (e.g. coastal hills, riparian), the drought continues to enhance native perennial grasses. However, in drier areas (e.g. Central Valley and the lower foothills), previously robust stands of perennial grasses are failing to produce viable seed, and in many cases, are dying.

– Last year we reported that local seasonality of precipitation patterns determined whether a site was grass dominated (enough rainfall to sustain early grass germinants through the winter drought) vs. forb and legume dominated (grass mortality due to winter drought, so that once substantial rainfall occurred in February/March, only forbs and legumes remained in the seedbank). This year, precipitation patterns were generally more favorable to grasses (rain was more spaced-out, so didn’t lead to a die-off of grasses). However, many sites had minimal grass seed production from the 2013-14 growing season, so remained forb dominated. This suggests that (1) the forb seedbank is critical for resilient vegetation cover and production during drought, and (2) recovery of grass production may be delayed once the drought is over, as it may take a few growing seasons to reestablish grass seed density.

– While vegetation composition changed due to drought at many sites, plant aboveground production was minimally impacted. However, drought greatly decreased grass seed production. It also significantly enhanced aboveground litter accumulation, suggesting that decomposition may be more water-limited than plant production. We have implemented litter reduction trials across a precipitation gradient to assess the impacts of litter accumulation, and potential management options (e.g. grazing).

– While grassland restoration projects on non-irrigated lands were minimal this past growing season, replicated trials do indicate that the 4^th year of drought provided a strong opportunity for selectively targeting key pest species (particularly yellow starthistle), which will hopefully improve restoration outcomes in the 2015-16 growing season.

-Grassland fires were frequent over the 2014 summer, providing many opportunities to assess vegetation trajectories post-fire. Soil water availability (largely determined by topographical position, aspect, and soil texture) seemed to have the largest impact on vegetation community composition and production in the growing season following fire. Partly due to the drought, weed management (e.g. herbicide, tilling) was extremely effective, and may enhance long-term native establishment.

-Restoration effects on ecosystem services were highly variable across Northern California grasslands. However, effects of native grass restoration on ecosystem services were relatively consistent within similar ecological sites (e.g. similar climate, soil, aspect). For example, on clay soils in the Central Valley, compared to unrestored sites, native grass restoration sites tended to have higher control of noxious weeds (goatgrass, medusa head), higher deep-soil carbon (40-90 cm), higher mineralizable nitrogen, lower erosion resistance, and lower alleviation of soil compaction. However, in the coastal hills, restoration effects on mineralizable nitrogen were opposite, with little impact on the other soil properties. More case studies will allow us to tease apart the mechanisms determining these site-dependent effects, but evidence to date suggests that variation in plant composition within the native grass community can have a stronger effect than the general difference between native vs. exotic grassland communities.

Impacts and Contributions/Outcomes

The main impacts of this project will occur towards the end, as the database and decision support tool are deployed. But current outreach efforts to gain stakeholder input and participation have initiated important discussions about the importance of multiple ecosystem services and realistic monitoring protocols across a wide group of stakeholders.

Collaborators: