Terrestrial Vegetation Monitoring in Forested Regions of Alberta

Monitoring of Terrestrial Vascular Plants and Structure in the Forested Regions of Alberta: Background, Indicators, and Protocols Philip Lee and Stephen Hanus Alberta Research Council, Postal Bag 4000, Vegreville, AB. T9C 1T4 [email protected] [email protected] October 1999 Disclaimer The views, statements, and conclusions expressed in this report are those of the authors and should not be construed as conclusions or opinions of the ABMP. Development of the ABMP has continued during the time since this report was produced. Thus, the report may not accurately reflect current ideas. Abstract This chapter focuses on the development of a monitoring program for terrestrial vascular plants within Alberta's forested regions. The steps in this process are 1) to establish objectives, 2) to select indicators, and 3) to develop protocols. We outline three objectives based on the spatial scales and types of changes likely to occur to terrestrial vascular vegetation. The first objective tracks the conversion of natural vegetation cover types to other types of cover including non-vegetation or heavily human-influenced vegetation cover types. It also includes the restoration or reclamation of developed land back to natural cover types. Six candidate indicators are identified for this objective. These indicators would be monitored at large spatial scales using remotely sensed data. The second objective tracks the impact of activities that while maintaining natural cover types potentially alters the sub-canopy assemblage of terrestrial vascular plants. Five candidate indicators are identified for this objective. The third objective tracks the integrity of forest structures produced by vascular plants. The underlying rationale for this objective is parallel to the second objective. Five candidate indicators are identified for this objective. The indicators for the second and third objectives require ground-level data collection. Various terrestrial plant and forest structure sampling methodologies were evaluated under a number of different criteria. A recommended protocol for the ground sampling of terrestrial vascular plants is outlined in Appendix 13.2. The protocol is similar to the ground methods for the National Forest Inventory. Appendix 13.1 is also included with a bibliography of references for monitoring terrestrial vascular plants. Introduction Monitoring vascular plants lies at the heart of sampling protocols for other biodiversity elements. Aside from being a large and diverse taxon, vascular plants also provide the basis for most ecological classifications. Though not as species rich as invertebrates, vascular plants are a significant portion of biodiversity of most ecosystems. In Alberta, there are 1,100 species of vascular plants (Anon. 1990) associated with the forested ecoregions. Moreover, ecological descriptions of Alberta’s landbase are based on vascular plant species. The system of ecosite, ecosite phase, and plant community classifications uses a combination of plants species and site characteristics (Archibald et al. 1996; Beckingham and Archibald 1996; Beckingham et al. 1996). At the highest levels of ecological organization, Alberta’s ecoregions and subregions are based primarily on predominant cover types (Anon. 1994). Aside from their contribution to biodiversity and ecological classification, the physical structure produced by plants also serves as important habitat for other species. Wildlife species are often less tied to a particular species than to the structure of the habitat created by plants. Forest structures derived from plant materials that support other biota include vertical stratification of foliage layers, canopy characteristics (gaps, transparency, roughness), deadwood resources, large trees, and soil microtopography. As an example, about ¼ of the vertebrate species in Alberta are dependent upon large live and dead trees (Schieck and Roy 1995). The actual species of tree or snags is not as important as the physical parameters, e.g., height, diameter, decay condition. Though these forest attributes are not a component of biodiversity, they are critical elements of a functioning plant community. A number of extensive reviews and bibliographies exist for monitoring terrestrial vascular plants (e.g., Elzinga et al. 1998). Based on these and other general literature on biodiversity monitoring, three development phases need to be considered (Silsbee and Petersen 1993; Stout 1993; Davis 1993; Hellawell 1991; Bunnell 1998): • Defining objectives • Selecting indicators 1 • Development of a sampling methodology Objectives should be broad enough to encapsulate the impacts of future developments on the landscape, but cannot be written so vague as to be of little use in selecting indicators. Statements such as “provide better data for management” and “examine how the ecosystem functions” provide little guidance for identifying indicators. On the other hand, very specific objectives such as evaluating short–term impacts of specific management practices maybe too narrow in scope to guide long-term monitoring. This program’s overall objectives are to provide biodiversity trend data on the cumulative impacts of multiple landuse practices. The scale of the monitoring effort provides resolution at a regional scale (100’s km2) over a long period of time (i.e., decades). Hence, the specific objectives for terrestrial plants must provide data on comparable changes in different forested ecoregions. Furthermore, these indicators must broadly represent groups of taxa or forest structures that are likely to change over time. If objectives are relatively unambiguous then indicator selection should flow easily. Indicators are represented by two classes: • Changes in a species, species group, or community whose abundances are most adversely affected by changes in land management. • Changes in a habitat variable, species, species group, or community whose response signals a change in the abundance of other, more sensitive species, species group, or community. Difficulties in the selection of indicators usually reflect poorly stated or vague objectives. In practice, indicators must be logistically and financially feasible. Hence, in considering indicators one has to be mindful of the sampling methodologies available. Once the indicators have been selected, sampling protocols can be developed. For terrestrial vascular plants, there is a long history and large body of literature associated with sampling and long term monitoring (Appendix 13.1). Our task is to select and integrate methods that are compatible and provide reasonable data quality. After these initial steps, most monitoring programs put forward pilot projects to test the statistical viability of linkages between indicators, methodology, and objectives (Hinds 1984). The remainder of this chapter discusses the foreseeable changes on the forested landbase that will impact terrestrial vascular plant species. These probable changes are used to derive objectives for monitoring. In turn, the objectives are used to nominate candidate indicators. Lastly, we will assess methodologies for measurement of indicators and a tentative protocol is described. A number of caveats should be considered when reading the remainder of this chapter. This document does not present a comprehensive catalogue of potential land development impacts nor an exhaustive review of vascular plants or forest structures for Alberta. Instead, we attempt to provide some underlying rationale for the definition of objectives, selection of indicators, and development of protocols. As the initial investigation of this issue, we have focused on impacts with a historical record. By doing this we will miss some potential objectives and indicators, however, the monitoring program is intended to be dynamic. As the impact of current and future land uses become apparent through research, these objectives and indicators have every opportunity of being incorporated into this program. Objectives in Monitoring Terrestrial Vascular Plants Objective 1: Trends in Land Conversion over the Forested Regions The largest scale of change for vascular plants is the direct conversion of the vegetation landbase as a result of anthropogenic activities. At its most severe, natural cover types (i.e., native tree species) are 2 converted to a non-vegetated cover (i.e., industrial, recreational, or municipal facilities), or to a heavily human-influenced cover type (i.e., agricultural lands, tree plantations, or some forms of enhanced forestry). A shortlist of activities responsible for land conversion includes: • Agricultural conversion • Enhanced forestry • Mining development • Municipal establishment and expansion • Oil/gas development • Recreational development • Transportation corridors • Waterway diversion Though less frequent, developed lands may be converted back to natural cover. Activities featuring back conversion would include: • Abandonment of agricultural land • Enhanced forestry • Mining reclamation • Oil/gas reclamation At gross levels, the area of cover type is the most important parameter in determining the diversity and abundances of species (Harris 1984; Franklin and Forman 1987). As a general rule, larger areas support more species (MacArthur and Wilson 1967). The conversion of landbase as measured by changes to cover type is a direct measurement of losses to vascular plants, particularly in forested regions. The success of back conversion to ease these losses depends upon the relative success of returning developed lands

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