GALBREATH MANAGEMENT ISSUES
(excerpted from West Coast Watershed (2007) undertaken as a collaborative management planning effort with Mendocino County Resource Conservation District with funding from the California State Coastal Conservancy)
Following is a list of natural resource management issues that require action on the Preserve.
Logging Debris/Slash Piles
Invasive Plants and Animals
Sudden Oak Death
Road Related Sediment
General Data Gaps
Bio-geomorphic Study Recommendation
There are numerous internal and boundary fences on the Galbreath Preserve - a legacy of cattle grazing (Photo Figure 1). These fences are predominantly multi-strand barbed wire, and are in various states of disrepair. These fences may interrupt the natural range of movement for some terrestrial species. Additionally, fences of this type have been demonstrated to injure wildlife when they are caught in the strands. Finally, the fences disrupt the visual aesthetic of the Preserve - which is dedicated to wildland conservation and education. There is an incomplete understanding of the linear extent of fencing on the Preserve, as well as boundary fencing between the Preserve and other properties.
- Recommendation: All non-essential fences - both internal and boundary fences - should be removed from the Galbreath Preserve and the materials recycled on-site or off-site. If labor resources are limited, the wire and metal posts should be removed, and the wooden posts left in place. Boundary fence removal will require the agreement and cooperation of adjacent landowners.
There are several large debris piles on the Preserve that are comprised of large trees and slash (Photo Figure 2). These are remnants of a logging operation. These piles pose a fire hazard to the surrounding forest, and are aesthetically inconsistent with the Preserve's mission of wildland conservation.
- Recommendation: The logs in the debris piles may be useful for augmenting pool formation and habitat in aquatic areas where LWD is limited. Once a riparian corridor assessment has been completed (see below) to determine pool frequency associated with LWD recruitment, a management recommendation may be the placement of large logs in stream to enhance pool formation and in-stream habitat values. The largest logs in the debris piles may be of sufficient size for this approach. The slash and smaller debris in the piles may be separated and spread into smaller piles throughout the Preserve as habitat for small mammals, insects and birds. This work can be accomplished with equipment, and/or by hand in areas where equipment will cause excess disturbance.
Numerous invasive plants and animals are predicted to exist, or have been documented via surveys, in the Navarro/Rancheria watershed and on the Preserve. Species with potential to negatively affect the watershed include:
Tree-of-heaven, Ailanthus altissima
Giant reed, Arundo donax
Yellow starthistle, Centaurea solstitialis
Poison hemlock, Conium maculatum
Jubata grass, Cortaderia jubata
Scotch broom, Cytisus scoparius
English ivy, Hedera helix
Klamathweed, Hypericum perforatum
Pennyroyal, Mentha pulegium
Himalayan blackberry, Rubus discolor
Sheep sorrel, Rumex acetosella
Tansy ragword, Senecio jacobaea
Milk thistle, Silybum marianum
Common spring vetch, Vicia sativa
Periwinkle, Vinca major
Wild turkey, Meleagris gallopavus
Wild pig, Sus scrofa
Virginia opossum, Didelphis virginiana
Feral cat, Felis catus
Bullfrog, Rana catesbeiana
Invasive flora and fauna have profoundly negative impacts on watersheds and ecosystems, and may be one of the most significant threats to conservation and restoration success. Although floristic surveys for presence/absence of plant species have been completed on the Preserve, no systematic surveys or mapping of invasive exotic plants have been completed. In order to effectively control invasive plants, a spatially explicit database of their locations and population size is needed. This lack of data inhibits the development of a logical, science-based approach to invasive species management.
- Recommendation: A map-based assessment of invasive plants should be conducted on the Preserve, using methods outlined in the Invasive Species Assessment Protocol (NatureServe 2004) and a spatially explicit prioritization framework for management and control should be developed. Invasive animals should be documented, a species-specific control plan should be developed, and those with the greatest potential impact on threatened or endangered plant or animal species (such as salmonids) should be priorities for control.
Sudden Oak Death (SOD) has been documented on the Preserve, and some locations have been mapped. Dr. Hall Cushman (Galbreath Preserve Manager and Biology Professor at Sonoma State University) is a leader in SOD research in California, and is engaged in ongoing evaluations regarding the pathogen and its impacts. Substantial data gaps remain regarding the extent of the pathogen on the Preserve and the surrounding watershed.
Road related sediments are a non-point source pollutant detrimental to aquatic environments. Many of the current and abandoned roads and trails on the Preserve are contributing sediment to in-stream environments. A preliminary assessment of the roads on the Preserve was performed by Pacific Watershed Associates. However, many roads and trails have yet to be assessed.
- Recommendation: Road-related sediment recommendations are included in Appendix B. Next steps include an expansion of the road assessment to those roads not covered in PWA's preliminary assessment (including trails, old logging roads, etc) as well as the larger Rancheria watershed.
Galbreath Preserve was grazed by cattle and sheep during the 18-20th centuries, with the potential effects of this grazing including soil disturbance and the presence of large numbers of invasive exotic species in the rangeland environments on the Preserve. There are inadequate data regarding the history of grazing on the Preserve and in the larger watershed, and no detailed assessments of the impacts have been performed.
- Recommendation: An assessment of historic grazing patterns should be developed, to determine the degree to which current vegetation patterns are natural or the result of grazing-related disturbance, and to help inform management decisions regarding native plant revegetation and/or natural regeneration. An evaluation of grazing as a management tool for invasive plant control and enhancement of floristic diversity should be undertaken.
The Preserve has a history of timber harvest. There has not been a detailed, spatially explicit assessment of the history of logging on the Preserve.
- Recommendation: A GIS-based assessment of the actual logging history of the Preserve (ie, not just THP data) as well as an assessment of forest health will help to inform forest management decisions.
The riparian corridors on the Preserve appear to be responding to various historic and current land uses - including grazing, logging and road development. Floodplains are mostly devoid of riparian habitat and are predominantly populated by exotic herbaceous species. Bank height in general appears typical of alluvial gravel bed rivers - with the exception of where the River has eroded into an older alluvial terrace deposit, where bank heights appear to exceed 25 feet (Photo Figure 3). Pool formation, due to large woody debris (LWD), associated with bedrock outcrops, or in alluvial reaches is evident, yet there are no data regarding the frequency of pools formed by LWD.
There are numerous data gaps on the Preserve in addition to those outlined above. Many of these data gaps are applicable to the larger Rancheria and Navarro watersheds, and include a lack of stream gages, a lack of high quality current aerial photography, detailed information regarding landslide potential, and the lack of a comprehensive GIS database for the Navarro or Rancheria watersheds. The development of a GIS database would allow for analysis of multiple management factors at various temporal and spatial scales, and would support long term monitoring and change detection in response to management activities.
- Recommendation: A stream gage(s) should be established for the Preserve. High quality, current aerial photography should be obtained. A change detection analysis should be performed that evaluates landscape-scale changes (based on historic aerial photos and maps). GIS data for the Preserve should be developed in a manner consistent with the larger watershed databases, and with established state and federal protocols. LiDAR data should be acquired as a new baseline data set to help understand factors that influence the Galbreath Preserve.
A series of bio-geomorphic management and research sites should be established (see Map E and Photo Figure 4) that will allow for a multi-year investigation of the riparian corridors along Rancheria Creek, and upslope processes affecting these areas. Following are recommendations to aid in understanding the relationship between geomorphic features and ecology.
Channel morphology. The channel contains areas of complex structureólarge woody debris, multiple channels, bars, vegetation, topographic variation and bedrock that benefit habitat. Baseline morphologic surveys of Rancheria Creek to document morphology and trends include:
LiDAR survey of the channel and adjacent hillslopes to provide a high resolution topographic base map including bars, floodplains, and the terrace;
augment LiDAR survey with total station topographic survey of channel bed unless water penetrating LiDAR is used;
longitudinal profile surveys of channel bed to assess character of riffles, pools, and to quantify channel deposition and scour;
topographic survey of the channel cross section surveys to integrate physical character of channel with biological attributes (habitat composition, structure, successional stage, LWD potential, etc);
establish a flow discharge and sediment transport gaging station to provide baseline data to understand aquatic ecology, geomorphic changes and climate change;
establish a rain gage to correlate channel changes to various storm events. Pools. Whereas some pools are a component of riffle-pool sequences, many pools are associated with obstructions such as tree roots or bedrock. Riparian trees are present alongside the main low flow channel Tree roots protruding into the channel increase roughness and scour pools locally, fallen branches and woody debris trapped by the live vegetation creates complex pool-bar habitat.
Investigate the relationship between riparian vegetation and adjacent channel pool morphology.
Document and monitor changes in the spatial distribution and depths of pools
Bars. Bars exist adjacent to the low flow channel at a lower elevation than the floodplain. Small patches of fine sediment are present over coarse sediment downstream of trees or other roughness elements.
Investigate the interaction of vegetation establishment and gravel deposition on channel bars to help understand the mechanisms of bar formation and stability.
Document bar morphology, spatial distribution, and monitor changes in bar volume and sediment size in relation to riparian vegetation.
Floodplains. The presence of floodplains appears dependent on valley width - with limited floodplain development where the valley is narrow. Floodplains are generally composed of coarse sediment, similar to the channel material. Their surfaces appear relatively level and are vegetated with grass. They contain some woody debris deposition, but few trees. In one location, a coarse cobble levee is about 0.5 m higher than the floodplain further from the channel. Riparian trees are generally present along the floodplain-channel margin. Secondary channels are incised within the floodplains - with fine patches of sand and silt deposited over gravel in topographic low spots.
Investigate vegetation changes to determine if lack of riparian trees on the floodplain is a result of land use practices such as grazing, if frequent large floods scour any trees that establish on the surface, or if the large sediment size of the floodplain material precludes riparian vegetation establishment.
Monitor floodplain deposition and erosion processes including sediment accretion during floods and erosion of the floodplain edge as the channel migrates or widens.
Conduct a photographic time-series to understand the natural dynamics of secondary channel incision and migration.
Bank Erosion. Bank erosion appears to be relatively significant source of sediment of fine material derived from erosion of the inactive terrace. Bank erosion is also active in some areas along floodplain channel margin. Some evidence of recent widening exists, with channels apparently recently cut into adjacent floodplain; recent bank erosion on channel-floodplain margin; and tension cracks along edge of floodplain.
Document spatial frequency and extent of bank erosion through mapping of various erosion features.
Monitor rates of change using methods such as erosion pins or ground based lidar.
Hillslope Channel Interactions. In mountain streams, hillslope-channel interactions are important. Small debris slides are present along the edge of the terraces, and on hillslopes adjacent to Rancheria Creek. Inactive terrace is a large deposit of fine sedimentóbest exposure is downstream of barn where a portion of the terraces is undergoing active erosion.
Document landslides that contribute sediment to Rancheria Creek and its tributaries using high resolution aerial images. Compare to historical photographic images to aid in understanding sediment supply rates to Rancheria Creek.
Revegetation Research Trials. Plan and implement native plant revegetation trials in selected active channel and floodplain areas to compare natural regeneration with active revegetation. Revegetation plots should be distributed along a cross-sectional gradient in each of the research zones shown on Map E, with revegetation data correlated to geomorphic features (ie, elevation, distance from low-flow channel, sediment characteristics, etc). Corresponding cross-sectional controls should be implemented up and downstream of the revegetation trial zones. Plant selection for the revegetation trials should be based on reference sites up or downstream from the research areas, in areas with similar hydrologic and geomorphic features. Native plants for revegetation should be collected from within the upper Rancheria watershed to ensure that they are genetically appropriate and well-adapted to the site. Baseline assessment and monitoring should evaluate plant survival, growth, reproductive status and influences on physical features and processes (ie, temperature and sediment) over a 5-10 year period.