Forest Site Classification 2007 Upland Hardwood Silviculture Training Bent Creek Experimental Forest Henry McNab Research Forester

Lesson Plan (23 July 2007, ) Class discussions – 15 min. –Review importance of site classification in silviculture and methods. Field demonstration – 10 min –Examine species composition method of classifying moisture regimes. Field trip: Blue Ridge Pkwy– 2 hr. –Species composition approach to site classification, American chestnut, and ?

Forest Site Quotations “Perhaps the single most important decision a forester can make is to manage for the right species on the right site. (Anon.) “No valid silvicultural decision can be made without reference to site quality... (Daniel, Helms, and Baker, Principles of Silviculture)

Site Classification: Definition Site:The continuously varying non-living (atmosphere and soil) components of forest ecosystems that make up the physical environment, or site. Classification: The arranging of complex relationships into fewer, simpler groups to facilitate understanding, communication, and application.

Site components Components that are relatively stable on a site and affect species composition: –Temperature (elev.) –Moisture (landform) –Fertility (geology, soil) Light – ~constant at top of canopy –Variable on forest floor depending on disturbance Disturbances vary by time of occurrence and level of intensity and primarily affect the density of a species: –Fire –Climate (ice, wind) –Insects (pine beetle) –Disease (chestnut) –Silviculture

Why classify sites? Silvicultural reasons –Species composition –Thinning response –Regeneration success –Biomass production –Sawlog grade –? (David M. Smith, The Practice of Silviculture) Other forestry reasons –Hazard rating (ice) –Equipment limitations –Taxes –Wildlife habitat –Recreation potential –?

Methods of site classification DIRECT – measure of actual crop production on a site: –Agricultural crops: bushels of wheat from a field. –Forest crops: cu ft of wood from a stand. –Not practical. INDIRECT - measure of something related to crop production: –Soil moisture –Growing season –Precipitation –Species –Site index

Site index definition & concept The average height of the dominant and codominant trees in a stand at a reference age, usually 50 years in eastern hardwoods. Assumptions (height is independent of stocking, fully stocked stands, free to grow, no previous damage, species native to site, and even-aged stand). Tree is phytometer of site components.

Site index curves Site index curves at an index age 50 years for yellow- poplar in the S. Appalachian Mtns. Sample 25 trees/ac!! Accuracy – a 10-ft site class.

Site Index - Evaluation Advantages –Widely used –Quick and easy(?) –Directly related to growth and yield –Works well for some species: conifers, yellow-poplar Problems –Multi-species stands –Multi-aged stands –Missing species –Previous damage –Inaccurate curves –Samples needed –Past suppression –Coring problems –Height measurement

Site Index - Problems Single stemmed species –Yel.-pop. (excurrent) Multi-stemmed species –Oaks (decurrent)

Site index method: guide curve vs stem analysis Schnur’s 1937 SI by guide curve method Carmean’s 1972 SE by stem analysis Note difference at older ages.

Site index conversion curves Central StatesS. Appal. Mtns

YP site index and soil series

B.C. Site classification work Site index (oaks, yellow-poplar, E. white pine) Soil-site (scarlet oak, black oak, yel.-poplar) Ecological modeling (quantify site variables that affect composition and distribution of species-moisture, temperature, fertility) Species composition (quantify species on a site as an indication of environmental conditions)

Soil-site relationships: Scarlet Oak and Black Oak Developed by Doolittle Block diagram for site index of scarlet and black oak as related to depth of A horizon, position on slope, and sand in A horizon.

SI of SO and BO by aspect; BCEF Aspect class ( Doolittle ’57) No. plotsAvg. SI N and NE E and SE S and SW W and NW758.6 N, NE, E, and SE S, SW, W, and NW5660.2

Soil-site relationships: white oak In the Boston Mtns of Arkansas, site index of white oak varies with aspect and slope shape / position. (1 = ridge, 5 = cove)

Moisture regime indicator species: trees

Species composition method Advantages –Intuitive for managers –Easy to apply/modify –Cost and time effective –Consistent among users –Computer can do it from inventory plots –Forest Vegetation Simulator (FVS) Problems –Must have field data –Can’t use with GIS –Not for planted stands –Must know dendrology –Lack of S.I. number

Species composition (species list) Method not new – Cajander (1926) forest site types in Finland. Physiological characteristics of species present on the site indicate the predominant environmental gradients: –Moisture regime (wet/dry) –Fertility regime (rich/poor) –Temperature regime (hot/cold) Almost any species can occur on almost any site, but only those species well adapted will be common (not rare) in the stand.

Moisture regime index and oak S.I.

Site classification literature Barnes, B.V., et al Ecological forest site classification. J. For. 80: Carmean, W.H Forest site quality evaluation in the U.S. Adv. Agron. 27: Jones, J.R Review and comparison of site evaluation techniques. Res. Pap. RM-51, 26 pp. Tesch, S.D The evolution of forest yield determination and site classification. Forest Eco. & Man. 3(1980/1981):

Components of site productivity SITE QUALITY Climate (Disturbance) Topography MANAGEMENT (Planned disturbance) Productivity Characteristic vegetation Geology / soil Light (top of canopy) More disturbances Productivity Mostly fixed (The one site component you can change using silviculture is…?) (Bugs, fire, disease) Light (in canopy)

Summary Why classify forest sites? –Subdivide the landscape for management purposes Environmental components of site quality –Moisture, fertility, temperature regimes Species composition method –Integrate environmental components Land owner recommendations –Management species Field trip – Moisture/fertility/species relationships in mid-elevation zone along Blue Ridge Parkway.