Terry A. Kaplan-Henry, Forest Hydrologist
W. Thomas Henry, Silviculturist
Holly Eddinger, Fisheries Biologist
Sequoia National Forest, Porterville

Application of ecosystem management on the Sequoia National Forest is a relatively new procedure. The South Creek Ecosystem Environmental Analysis (South Creek) provided the Forest with its first opportunity to apply principles of ecosystem classification, consistent with R-5 FSH 2090.11. As a result of this opportunity new ideas began to surface.

The uniqueness of this analysis is that project planning data (fish habitat and channel stability surveys) has been applied to produce a landscape level analysis for the riparian ecosystem. This is significant because this type of information is readily available and has been collected for many years on the Forest.

The effort created a shift in the thinking of the interdisciplinary team towards a landscape level focus that considered the structure, function, and interaction of ecotypes. While both terrestrial and riparian ecosystems were considered in the environmental analysis, this article only discusses how the riparian ecosystem was evaluated.

The South Creek Basin is located on the Hot Springs Ranger District, Sequoia National Forest. South Creek Basin is about 23,000 acres in size and flows into the North Fork of the Kern River approximately 20 miles north of Kernville, California.

The analysis procedure used in the South Creek basin is displayed in Figure 1. Ecosystems are separated into ecotypes based on biotic and abiotic components. Ecotypes are further broken down into ecounits based on health or existing conditions of site specific reaches. The health of an ecounit is determined through evaluation of critical elements. The critical elements are adjusted through project implementation to create conditions favorable for achieving a desired condition.

Monitoring is an integral component of this modeling. Projects need to be evaluated to determine if manipulation of critical elements resulted in desired changes. Whereas monitoring of a project assesses implementation; monitoring of critical elements evaluates effectiveness of a prescribed treatment. Validation monitoring closes the loop by assessing the assumptions used to identify ecological relationships in both the modeling and its application.

Riparian ecotypes are identified using stream channel types as the abiotic component and plant communities as the biotic component. Channel type is identified using the Rosgen, 1985, stream classification which groups stream reaches as a function of channel entrenchment/confinement, channel gradient, and substrate composition. Plant communities are identified to the series level using Sugihara and Potter, 1993 draft. Although seven vegetative communities were identified within the South Creek Basin, only four were associated with riparian areas. Figure 2 illustrates the ecotypes in South Creek Basin as defined by channel type and plant community.

Critical elements for each ecotype were defined for the channel type being evaluated. For the following discussion it must be understood that channel types need to be segregated by vegetative community as displayed in Figure 2 before they become ecotypes. Figure 3 displays applicable critical elements by the channel types identified in South Creek Basin. Although five critical elements were adopted from Pfankuch, 1978, not all of these elements are applicable to all channel types in South Creek Basin.

Channels that are typically more stable have fewer critical elements for maintaining their function and structure in the riparian ecosystem. For example, A1 and B1 channel types are high- and moderate-gradient, bedrock-controlled channels. The one critical element at risk in these environments is deposition in the lower channel, which could result in the filling of pools necessary for fish habitat.

At the other extreme are the B4, B3, and A3 channels which are more unstable, have high and moderate channel gradient, and typically occur in landslide terrain or dissect terrace deposits. All of the elements displayed in Figure 3 are potentially at risk and are critical for maintaining function and structure.

C6, C4, and B6 channels can best be defined as low- to moderately-entrenched systems with a low to moderate gradient, and a substrate of sand and silt or clay. These channels need good vegetative bank protection and are susceptible to bank cutting and deposition. Therefore vegetative bank protection, lower bank cutting, and lower bank deposition are considered critical to maintenance of the function and structure of these channel types. Scour and deposition and percentage of stable material are not critical elements, as these channels typically occur in meadow environments with a low percentage of stable material and a naturally fluctuating channel bottom.

The remaining channel types, A2 and B2, are stable, high to moderate gradient channels with a substrate composed predominately of boulders and cobbles. Critical elements within these environments include bottom scour and deposition, deposition in the lower bank and maintenance of vegetation on the upper channel banks.

Existing condition of each ecotype defines ecological units. Existing condition is determined through comparison of the stability value for each critical element and the stability value for that same element in a channel having good stability as determined by Pfankuch, 1978. Pfankuch evaluates channel stability based on upper bank, lower bank, and channel bottom attributes. Attributes are assigned a numerical value representative of the stability of the stream reach relative to the attribute being evaluated. Figure 4 illustrates the relationship of the stability value received for the critical elements identified for ecounit 911, a Lodgepole-B4 ecotype, and the threshold value assigned to those elements adopted from Pfankuch, 1978.

The overall level of impact for each ecounit is based on how many applicable critical elements are above an assigned threshold level. As displayed in Figure 4, critical elements over threshold for ecounit 911 are as follows: cutting in the lower bank, deposition in the lower bank, percent stable material in the channel bottom, and scour and deposition in the channel bottom. Of the five critical elements evaluated in this ecounit, four exceed threshold values. Therefore ecounit 911 is a Lodgepole-B4 ecounit with four critical elements over threshold and is assigned an impact level of high.

The usage of the term "level of impact" or "impact level" is not intended to place a blame. It is intended as a ranking scale relative to specific values. It appears to be impossible to rank anything without using some type of relative term. This poses a risk in that value judgements are associated with certain terminology which varies among individuals.

Figure 5 displays the relationship between the assigned level of impact and the number of critical elements exceeding threshold. Ecotypes with fewer critical elements will not reach impact levels greater than the rating assigned to the number of available critical elements. For example, regardless of plant community, the bedrock-controlled, extremely stable A1 or B1 ecotype will never receive an impact level rating greater than low, which reflects the inherent stability of this ecotype.

The location of riparian ecounits and the health or impact level of these units is displayed in Figure 6. Their condition has been determined by using the procedure described above. The source of the impacts (natural processes such as beaver activity versus management practices such as grazing and road building) are identified from the field surveys. Such surveys identify which critical elements are being affected. Treatment prescribed for improving existing conditions is based on the manipulation of those critical elements exceeding their threshold.

The South Creek project interdisciplinary team established a twofold desired condition: 1) stream channels which are highly or extremely impacted from past management activity are rehabilitated and management practices modified, and 2) stream channels which are less impacted and which are showing a trend toward higher impact levels had their management practices modified and their current conditions stabilized. This way of establishing desired condition allows for an efficient and logical way of moving from the landscape ecosystem analysis to project identification and prioritization and provides the foundation for subsequent NEPA analysis and decision-making.

In summary, one of the things that we have learned is that there are still many interactions that need to be explored. We realize that a weakness in this analysis is understanding the role that plant series play in the riparian ecosystem and what critical elements exist for that relationship. Likewise, information to develop a natural range of variability is beginning to come together. However, the interactions between channel types, plant communities and how they change over time is unclear.

What we do know from this analysis is that it is possible to segregate riparian areas into ecotypes and further define ecounits based on health or impact level. We are able to evaluate critical elements to provide direction for project implementation. We have a clear idea of what needs to be monitored and if we are moving toward a desired condition.

The most significant knowledge that has been gained is that through evaluation of stream and fisheries inventory there exists not only the information to evaluate the ecosystem at the landscape level for a given basin but also knowledge for appllication on adjacent areas of similar ecotypes.

This approach to riparian ecosystem analysis was developed through the planning process for South Creek. Numerous individuals were involved in the application of this process. We would like to acknowledge Barbara Machado and Deborah Walker for their involvement during the planning process; and Julie Allen and Barbara Johnston for their review of the text. A special thanks goes to David Rosgen for taking the time to review our early work.

Pfankuch, Dale, J. 1978, Stream Reach Inventory and Channel Stability Evaluation, United States Department of Agriculture, Forest Service, Northern Region.

Rosgen, David, A. 1985, A Stream Classification System.

Sugihara, Neil, and Donald Potter. 1993, Potential Natural Vegetation (PVN) Types Occurring in the Central And Southern Sierra Nevada Mountains of California, 11/3/93 Draft.

USDA-Forest Service, Pacific Southwest Region-5. 1991, Ecological Classification and Inventory Handbook, Forest Service Handbook 2090.11.

USDA-Forest Service, Sequoia National Forest.

South Creek Basin Ecosystem Analysis And Environmental Assessment Preface, Draft. 1994