Land Stewards Maintaining Healthy Trees & Forests. Max Bennett Extension Forestry & Natural Resources Agent

Transcription

1 Land Stewards Maintaining Healthy Trees & Forests Max Bennett Extension Forestry & Natural Resources Agent

2 After this presentation you will be able to: Describe the major talents of eight local tree species Identify six potential benefits from thinning List five features of a tree you can eyeball to evaluate its health Describe the thinning technique called thinning from below List five important considerations in thinning

3 First, a little review from the Ecology Module

4 SW Oregon s natural environment is very diverse Climate Geography Geology History Land Use Flora Fauna We live in the Klamath Mountains Ecoregion, shown here in green. It is noted GLOBALLY as a hotspot of biodiversity. For example, there are more kinds of cone-bearing trees found in the Klamath Mountains Ecoregion than anywhere else in North America. For more info, see:

5 78 Klamath Mountains Ecoregion 78 encompasses the highly dissected ridges, foothills, and valleys of the Klamath and Siskiyou mountains. It was unglaciated during the Pleistocene epoch, when it served as a refuge for northern plant species. Its mix of granitic, sedimentary, metamorphic, and extrusive rocks contrasts with the predominantly volcanic rocks of the Cascades (4). The mild, subhumid climate of the Klamath Mountains (78) is characterized by a lengthy summer drought. It supports a mosaic of both northern Californian and Pacific Northwestern conifers and hardwoods Frank Lang slide

6 Environmental Factors That Affect Tree Growth The most important environmental factors governing tree and plant growth at the local level and across broad landscapes are moisture and temperature. Hotter Almost all of these are found in SW Oregon! Steve Fitzgerald slide Drier

7 Influence of Topography on Temperature and Moisture Elevation - As elevation increases, temperature decreases. Rate of decrease is to F per 1000 feet increase in elevation. Aspect - Refers to the the direction the slope faces. Slope steepness (percent slope) also influences the amount of direct sunlight received. Steve Fitzgerald slide

8 Soils Soil is the mantle of mineral particles, organic matter, water, air space and living organisms that covers the terrestrial surface of the earth. Dirt is under your finger nails or what you sweep under the rug. Classification (named types based on characteristics) Characteristics (texture, horizons, chemistry, moisture) Factors Climate Parent Material Organisms

9 Soil Survey of Jackson County, Oregon Soil Conservation Service (SCS) nka Natural Resource Conservation Service (NRCS) 2A Abin silty clay loam 0-3% 17C Brader-Debenger loam 0-3% 17E Brader-Debenger loam 15-40% 23A Camas-Newberg-Evans complex 0-3% 27B Carney clay 5-20% 31A Central Point sandy loam 33A Coker clay 0-3% 34B Coleman loam 0-7% 35A Cove clay 0-3% 76A Gregory silty clay loam 0-3 % 127A Medford silty clay loam 0-3% 139A Padigan clay 0-3% 146 Gravel pits 154 Riverwash 127A Medford silty clay loam 0-3% Listed in Soil Survey as prime farm land. Soils influence what can grow on a site and the site s management potential, e.g., potential to grow certain trees or crops. Soils are highly variable across the landscape!

10 Disturbance and Succession Forests are dynamic and are always changing. Change involves an initial disturbance and subsequent succession of plant species over time. Steve Fitzgerald slide

11 Disturbance Disturbance creates an initial change in forest composition and structure as well in the microclimate. Disturbances can be classified according to their size, intensity, and frequency, all of which have a profound affect on forest succession. Disturbances free up resources for remaining to use and for newly established plants to claim. All plants must compete for these resources. Steve Fitzgerald slide

12 Natural and Human-Caused Disturbances Natural Human-Caused Fire Fire Ungulate herbivory Livestock herbivory Disease Timber harvesting Insects Land use Climate change Climate change?? Floods Landslides Landslides Non-native plants Volcanic activity Wind Glacial Steve Fitzgerald slide

13 Disturbance Forest management activities on your property are basically planned disturbances to encourage plant species (trees) to respond according to a desired outcome. To be successful, you must know how the plant community will respond to your management actions Steve Fitzgerald slide

14 Succession Succession - sequence of plants and animals that successively occupy an area over a period time. Succession is the sorting of species over time according to levels of exploitable resources, seed availability, growth and reproductive potential of plants, and tolerances of existing and new plant species to the changed environment. Steve Fitzgerald slide

15 Succession (continued) Sere - entire sequence of community and ecosystem change. Seral stage - each stage in a successional sequence (sere) characterized by a different plant community. Steve Fitzgerald slide

16 Two Successional Patterns (Paths) Steve Fitzgerald slide

17 Succession (continued) Management activities (planned disturbances) can accelerate or steer succession to meet your objectives. The general goal is to favor the establishment and growth of trees. * Site preparation * Planting and species selection * Release * Thinning/stand improvement Steve Fitzgerald slide

18 Fire scars on Douglas-fir stump SW Oregon s forests evolved with frequent fire. Fires were variable in severity, but in many cases trees survived the fire.

19 Tom Sensenig slide The most successful advertising symbol of all time We ve been fairly successful at putting out most fires

20 Tom Sensenig photo With some unintended consequences, including a large increase in forest density in some areas

21 Large old pines are often surrounded by a sea of younger Douglas-fir Ponderosa pine 170 years Tom Sensenig photo Douglas-fir 95 years

22 Fires, when they do occur, are often more intense than they were historically Tom Sensenig photo

23 Increases in stand density, combined with periodic drought, set the table for bark beetles, resulting in death of trees. Insects often thin from above, i.e., attack the largest trees. Tom Sensenig photo

24 Complexity Biscuit fire, mosaic pattern. While there has been an overall increase in uncharacteristically severe fire, especially in drier, lower elevation forests, it s important to note that there is much variability in fire intensity and effects, both currently and historically.

25 Historic Fire Regimes, Western OR Fire Return Fire Regime/ Forest Type Interval (Yrs) Severity Valley Oak 2-20 Low Ponderosa Pine 4-25 Low Dry mixed conifer Low Wet mixed conifer Mixed/Mod. Coastal Forests High Lodgepole Pine High Subalpine Forests 100+ High Historically, some forests burned frequently, and others much less frequently. Forests with frequent fire tended to burn at lower intensity, with most trees surviving. Forests with infrequent fire burned at high intensity, with most trees killed. Mixed severity regimes burned with a highly variable mix of low to high intensity. Note that all of these forest types and fire regimes are found in Jackson & Josephine Counties, except coastal forests.

26 Shifting gears, to focus on the main topics and objectives for this module Tree species talents Eyeballing trees Thinning

27 Each tree species varies in its talents namely, its ability to tolerate different environmental conditions such as drought, shade, & flooding. These differences are extremely important! Tree species talents

28 Ponderosa pine Talents: Very tolerant of drought & heat; poorly drained soils Won t regenerate & grow in shade Needs lots of growing space

29 Douglas-fir Talents: Adapted to a wide range of sites, good growth, very long lived Tolerant of partial shade Not good on hot, dry sites or poorly drained soils

30 Talents: Good growth, large size, longevity Needs lots of growing space Susceptible to bark beetles & blister rust, an introduced disease Seldom if ever dominant in stands, now uncommon due to past logging, insects, & disease Sugar pine

31 Incense cedar Talents: Tolerates heat, cold, dry Regenerates abundantly, a prolific seeder Grows in partial shade

32 White fir Talents: Very shade tolerant, survives in very dense stands, cold tolerant Susceptible to fir engraver (bark beetle) during droughts

33 Pacific madrone Talents: Very heat & drought tolerant; sprouts readily after fire or cutting Not shade tolerant

34 California black oak Talents: Very tolerant of drought & heat Won t regenerate & grow well in shade Needs lots of growing space Tendency to develop heart rot / cavities makes it a very valuable wildlife tree; also acorn production

35 Talents: Very tolerant of drought & heat; poorly drained soils Won t regenerate & grow in shade Needs lots of growing space Valuable wildlife tree: mast (acorn) production, cavities Oregon white oak

36 Other SW OR tree species/genera Hardwoods: alder, ash, cottonwood, cherry, chinkapin, dogwood, hawthorne, maple, mountain ash, mtn mohagany, apple, tanoak Conifers: Cypress, hemlock, juniper, spruce, true firs, white cedar, yew See OSU s Common Trees of the PNW website: /trees/

37 Typical SW Oregon landowner objectives for their forests 1. Reduce fire hazard/risk 2. Maintain healthy trees 3. Provide habitat 4. Maintain as a special place (recreation, beauty, spirit) 5. Obtain products for personal use or sale These objectives can often be promoted through careful thinning!

38 Six benefits of thinning Make forests more resilient to fire Promote tree vigor and growth Protect legacy trees Promote understory development Promote structural diversity = more habitat Generate wood products for personal use and/or sale

39 Fire-resistance Treat surface fuels (slash) Increase height to base of tree crowns Reduce density of trees Retain larger trees of fire-resistant species This stand was thinned, piled, and burned using the four principles of creating fire resilient forests above. The stand survived the Squire Fire, while in nearby unthinned stands all the trees were killed. Following these principles doesn t guarantee tree survival, but increases its probability.

40 Vigorous, healthy trees Douglas-fir trees all grown in same area of Applegate valley. The larger tree had more site resources, mainly water and growing space.

41 Thinning response Widening of growth rings shows response to thinning

42 Protect legacy trees T This old growth pine is surrounded by small trees that are competing for the limited supply of water. Removing them will promote its vigor. Sugar pine. Nearby trees have been removed (radial thinning).

43 Protect legacy trees This oak has been overtopped by surrounding fir trees. Earlier thinning of the fir may have enabled it to survive.

44 More understory development Before After

45 More structural diversity Dense stand with little structural diversity Thinned stand with skips and gaps has more diversity

46 Generate products

47 Eyeballing trees to evaluate health: what do you look for? Overall vigor Crown ratio Color, density, and amount of foliage Height growth & crown shape Ratio of height to diameter

48 Vigor

49 Crown ratio = Crown length/total height x100 30% or better preferred

50 Foliage Color & Density Healthy crown Tree under attack by flatheaded fir borer. Dark green, dense foliage=healthy Yellow-green, sparse foliage=unhealthy Poor color & density. Tree died within a year.

51 Height Growth C heck distance between internodes (pines, true firs, D-fir) each internode = 1 year of growth Fast growth Slow growth

52 Crown Shape Trees with pointy crowns are growing faster in ht. & are more vigorous Trees with round or flat tops are growing slowly; they are often suppressed or old & of low vigor

53 Height:Diameter ratio Skinny trees (large height to diameter ratios), with lopsided crowns, are especially vulnerable to blowdown and snow/ice damage

54 Eyeballing summary All other things equal, good leave trees are vigorous trees with good crown ratios (30%+), dark green, dense foliage, rapid height growth, and good form. Good take trees have poor vigor, crown ratios, etc.

55 Describe low thinning Generally removes overtopped, intermediate, and a few co-dominant trees; leaves most of the co-dominants and dominants. Mimics natural patterns of stand development. May increase tree and stand vigor and growth, fire resilience, and understory development. A common (but not the only) approach to thinning; relatively easy to implement.

56 Crown classes I I CD CD I D D O CD C D I CD CD I O D D CD CD S S

57 Before thinning After thinning

58 Stand marked for low thinning; trees with blue flagging to be removed.

59 After low thinning

60 Five considerations in thinning Thin for vigor and quality Avoid damaging leave trees Treat slash Leave some dead and defective trees Start gradually, think long term

61 Thin first for quality & vigor, then spacing After Before

62 HIGH GRADED STAND The opposite: Take the best, leave the rest.

63 In natural stands, trees are often distributed in a random to clumpy fashion. Thinning can mimic this by leaving some clumps and gaps. It s OK to leave two or more trees close together, if they have good vigor. Just thin a litle more heavily around the clump. Don t get hung up on exact spacing.

64 Avoid damaging leave trees

65 Consider slash disposal needs Excessive slash is fire hazard. Treatment needed. Lop and scatter may be acceptable in other areas.

66 Leave some dead & defective trees A healthy forest includes some dead & defective trees! They are important for habitat and nutrient cycling.

67 Start gradually, think long term

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