Principle – Ecological integrity

Indicator – Community guild structure does not show significant changes in the representation of especially sensitive guilds, and pollinator and dispersal guilds. Revised: Representation of selected key and sensitive guilds occur in the community guild structure.

Box B: Definition:

Guilds are groups of species that occupy the same ecological niche and compete for similar resources.

Birds are considered an excellent group for assessing the impact of disturbance on forest ecosystems. Ecologically and taxonomically they are the most understood animal class (Karr et. al. 1990). Birds are highly diverse and represent a range of feeding guilds and habitat niches (MacArthur and MacArthur 1961, Erdelen 1984, Gilmore 1985). They have furthermore been shown to respond to changes in habitat and landscape structure resulting from anthropogenic disturbance (Thiolly 1992, Canaday 1997).

The forest floor invertebrate community consists of several guilds representing important ecological processes that include decomposition and seed predation and seed dispersal. Furthermore, many invertebrates in the leaf litter assemblage are highly sensitive to micro-climatic changes induced by canopy reduction and this will be reflected in their populations (Uhl and Kaufman 1990).

Box D: Applicability to Different Landowners. Explain any differences:

The required surveys of bird and forest invertebrates would be carried out primarily by large landowners. It could be done at any scale however.

Box E: Overlap.

CIFOR : 2.4.4 – Richness diversity of selected groups shows no significant change

2.4.5 – population sizes and demographic structures do not show significant changes, and demographic and ecological critical life-cycle stages continue to be represented.

CCFM : 1.2.2 – population levels and changes over time for selected species and species guilds

Box F: Geo-Political Scale:

Notes:

Community guild structure must be studied at a site level, but will be extrapolated to apply to larger areas.

Notes:

The indicator is both diagnostic and predictive. It provides information about the current state of the forest, but the information provided can be used to predict the forest condition in future.

Notes:

Guild structure refers to structure at the forest community level. The indicator is also a measure of function or process because the guilds to be monitored are chosen due to their influence on ecosystem function. Changes in community guild structures imply changes in function.

Box I: Underlying Concepts:

Assessment of the abundance and species richness of the bird community is relatively straight-forward as birds are mostly obvious and easily identified compared to other animal groups. Their abundance permits rapid accumulation of large data sets. The widespread availability of bird identification guides covering almost all regions allows the universal use of birds as assessment tools.

Predaceous leaf litter invertebrates are generally less constrained but will respond indirectly to changes in the densities of their prey. The sensitivity to disturbance of the forest floor invertebrate assemblage and its prominent role in several ecosystem processes makes it a highly relevant verifier.

Pollinators are particularly important in maintaining ecosystem processes. The pollinator guild includes bees, small flies and wasps. Tree species in Idaho are wind-pollinated, but many of the associated shrubs and herbaceous species depend on insect pollination. Fragmentation of forest communities may have serious negative impacts on pollinators.

Box J: Relevance to Sustainable/Unsustainable Management:

The bird seed-dispersal guild is very important in maintaining forest community structure and function. For example, the relationship between Clark’s nutcracker and whitebark pine suggests a process of coevolution culminating in a high degree of dependency (Tomback, et al. 1990). Other birds in this guild would include jays and crossbills.

Forest floor invertebrates have key roles in decomposition, nutrient cycling and seed predation. The predaceous ant guild that feeds on Lepidoptera species is important to ecosytem function. For example a number of ant species are known to feed on the western spruce budworm and other species of Lepidoptersa, to the extent that they can influence population dynamics of the species (Brookes, et al. 1987). The spruce budworm, in turn, influences population dynamics and community structure of coniferous forest

Insect pollinators constitute a vital component of the reproductive cycle of many forest plants.

Box K: Measurement Methods:

Methods from CIFOR: methods for bird monitoring involve observation along line transects for fixed time duration can be described as follows:

• Transects of not less than 500 meters, and separated by at least 300 meters, are necessary to encompass site heterogeneity. A two hour observation period is suitable as it is likely that observation efficiency decreases beyond this.
• At the start of the transect two observers should record all birds seen in a 15-minute period within a 30 m by 30 m area centered upon the observers.
• Birds are identified to species if possible, but otherwise entered into a table similar to that in Table 1.
• After the initial 15-minute period the observers proceed slowly and quietly along the transect to subsequent observation stations located at 100 m intervals where there should be further 15-minute periods of stationary observation.
• Thus a two hour transect will consist of six 15-minute observation periods allowing six minutes between stops. The 15-minute period is a compromise between the time required to detect secretive species and to avoid the risk of adding birds that are passing through.

Trapping techniques to characterize the forest floor invertebrate community are described as follows:

Table 2. Feeding guilds represented by litter and soil invertebrates which are likely to be caught in pitfall traps.

Food Type Invertebrate group

Invertebrates spiders and scorpions, centipedes, ground beetles, rove beetles, small ants

Detritus cockroaches, woodlice, springtails, millipedes

Leaves crickets and grasshoppers, bugs (Hemiptera), some ants (neotropics only)

Seeds weevils and scolytid beetles, large ants

Dung feeders dung beetles

To usefully interpret data, sample plots should always be located in reference areas, where little or no human-caused forest disturbance occurs and forest condition is as natural as possible, as well as in actively managed forest areas.

Box L: Data Required:

• Methods for classifying birds by their habitat and guild associations and experience of local people who are often able to identify the habitats and feeding guilds of birds very accurately
• Community differences among sites can be tested using a log-linear model approach to analyzing three-way contingency tables (site x species x presence/absence, Sokal and Rohlf 1994).
• To test for differences in species frequencies between sites chi-squared test with arcsine transformed data is suitable for relatively common species (i.e. recorded more than 20 times) or Fischer’s exact test for rarer species.

• Diversity indices such as those described for birds could be applied to invertebrate groups sorted to higher taxonomic group. Likewise across-site comparisons of frequency distributions can use Chi-squared tests in a similar way to bird survey data, or similarity indices such as the Morisita-Horn index (following Wolda 1973).

Box M: Data Used for the North American Test:

Specific data were not found for the Boise test.

Birds: the indicator relates specifically to pollinator and disperser guilds. For tree species in Idaho, seed-disperser species would include nuthatches, crossbills, and jays. Data are available from a variety of bird surveys, for example Boise Cascade has initiated a songbird survey and tracks several other species. At present there does not appear to be a survey designed specifically for the seed disperser guild, but studies have targeted some of the species that would fall in this group, for example, Clark’s nutcracker.

Insects: Work has been done on ants in their role as natural control agents of spruce budworm .

The pollinator guild: butterflies, moths, flies, bees and wasps; would not apply to any Idaho tree species, but would be relevant for shrub and herbaceous understory species.

Box N: Example Results:

Results cannot be reported because of lack of data. Data were not found, in part perhaps because of the timing and difficulty experienced in contacting the appropriate local experts at short notice. Data has probably not been collected for the specific guilds proposed for monitoring.

Box O: Assessing the Practicality:

This indicator can be tracked over time and measured repeatedly without high costs. In some cases, identification can be done to the genus level if taxonomic expertise is lacking.

Box P: Assessing the Information Value:

If appropriate information is collected, this indicator should efficiently track key process-level changes in ecosystems.

Box Q: Overall assessment:

Accepted.

Strengths: the indicator, by including, groups of species, is more responsive to ecosystem function and processes than individual species approaches are. If appropriate information is available the indicator has high information value. Collection of the necessary information is fairly straight-forward and inexpensive.

Weaknesses: management agencies may not have the information or be prepared to set up the required sampling procedures. Insect populations fluctuate naturally, highlighting the importance of concurrent sampling of reference populations. The natural fluctuation may cause difficulties in setting targets or thresholds triggers.

Box R: Did you rewrite or revise to a new indicator. If so what?

Yes. Representation of selected key and sensitive guilds occur in the community guild structure.

Box S: References:

• Brookes, M., R.W. Campbell, J.J. Colbert, R.G. Mitchell, and R.W. Stark. 1987. Western Spruce Budworm. Canada/ United States Sruce Budworms Program-West. Cooperative State Research Service Technical Bulletin No. 1694. United States Forest Service USDA. Washington, DC. 198 pp.

• Canaday, C. (1997) Loss of insectivorous birds along a gradient of human impact in Amazonia. Biological Conservation 77: 63-77.

• Digweed, S.C., Currie, C.R., Cárcamo, H.A. and Spence, J.R. (1995) Digging out the "digging-in effect" of pitfall traps: Influences of depletion and disturbance on catches of ground beetles (Coleoptera: Carabidae). Pedobiologia 39: 561-576.

• Erdelen, M. (1984) Bird communities and vegetation structure. I. Correlations and comparisons of simple and diversity indices. Oecologia 61: 277-284.

• Gardner, S.M., Cabido, M.R., Valladares, G.R. and Diaz, S. (1995) The influence of habitat structure on arthropod diversity in Argentine semi-arid Chaco forest. J. Vegetation Science 6: 349-356.

• Gilmore, A.M. (1985) The influence of vegetation structure on the density of insectivorous birds. Pages 21-31 in A. Keast et al., eds. Birds of Eucalypt Forests and Woodlands. Surrey Beatty, Chipping Norton, N.S.W. Australia.

• Karr, J.R., Robinson, S., Blake, J.G. and Bierregaard, Jr, R.O. (1990) Birds of four neotropical forests. In A.H. Gentry (ed.) Four Neotropical Forests. Yale University Press, New Haven, CT, pp. 237-269.

• MacArthur, R.M. and MacArthur, J.W. (1961) On bird species diversity. Ecology 42: 494-498.

• Sokal, R.R. and Rohlf, F.J. (1994) Biometry. Freeman & Co., New York, USA.

• Thiollay, J-M. (1992) Influence of selective logging on bird species diversity in a Guianian rain forest. Conservation Biology 6: 47-63.

• Thiollay, J-M. (1995) The role of traditional agroforests in the conservation of rain-forest bird diversity in Sumatra. Conservation Biology 9: 335-353.

• Tomback, D.F., L.A. Hoffmann, and S.K. Sund. 1990. Coevolution of whitebark pine and nutcrackers: implications for forest regeneration. In Proceedings of the Symposium on Whitebark Pine ecosystems: ecology and management of a high-mountain resource, Bozeman , MT, March 29-31, 1989, pp. 118-129.

Please record your notes on evaluating the indicator here

All of the information provided is from CIFOR and not necessarily applicable to this region.

The two guilds recommended by CIFOR that do not significantly overlap other indicators are seed dispersing birds and a group of forest floor invertebrates. An invertebrate guild that lends itself to monitoring is ants. The ants have been studied here and in addition to many other functions in the forest they have been shown to be important in predation of western spruce budworm which is important food for a number of songbird species, and is periodically important in shaping the structure of the forest.