Janet L. Ohmann - Trends in Early Seral Forest at the Stand and Landscape Scale
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Janet L. Ohmann - Trends in Early Seral Forest at the Stand and Landscape Scale

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Janet L. Ohmann - Trends in Early Seral Forest at the Stand and Landscape Scale

Janet L. Ohmann - Trends in Early Seral Forest at the Stand and Landscape Scale

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  • Given short time available, will shamelessly focus on westside forests. I’m going to show alot of data, but most likely raise more questions than I’ll answer.
  • Why are we here today? Transition from a historical landscape that was a dynamic mosaic of forest types shaped by natural disturbances, primarily fire, to one where disturb. regime has been almost completely supplanted by timber harvest.
  • Last 30 yrs or so, moved to landscapes dominated predominantly by harvest disturbance, patterns constrained largely by ownership and management goals. Unprecedented dataset understanding recent disturbance regimes, based on change detection of stand-replacing disturbance from multi-date Landsat. This shows coast range, and patterns also vary with ecoregion, but message is: disturbance regime overwhelmingly dominated now by timber harvest and forest management activities.
  • Comparison of age-class distribution in HRV and current (1996) landscape shows that we have no shortage of ES in current landscape: ~30% now vs. 3-12% historically. Distribution now is flip-flop of HRV.
  • Although early seral forest is plentiful, the character of these forests have changed. Nonaka used Wimberly’s LADS HRV model to characterize dead wood biomass in seral stages – here shown for forest <20 years. Note hollow circles showing amount of wood in current landscape – a small fraction of what would be expected in historical landscapes.
  • Over past 60-70 years in Coast Range, early seral story is playing out very differently depending on ownership. Major increase in ES on private lands, and decrease on public lands, for net increase of 21%. Most of our attention over this period, of course, has been in the major loss of late-successional forests -- large conifer -58% over this period.
  • We can define ownership and various management classifications along a continuum of management emphasis, from ecological goals to economic goals. This illustrates the range of forest policies, goals, and management strategies on different ownerships. Federal lands split into wilderness (legislative reserves), other fed. reserves (policy or administrative) such LSRs under NWFP and Roadless Areas. On opposite end, timber production is primary emphasis of forest industry owners, governed by laws to protect the environment (forest practices law). Most emphasis from perspective of biological conservation has been on federal lands and reserves. Message here is to consider all components of the landscape, espec. private lands and how they contribute in a large, multi-ownership region.
  • Coastal and Central Oregon have very different mixes of land ownerships. In Coast, much more private land (both industrial and non-industrial), significant amount of State (Elliot and Tillamook SFs), very little wilderness. Federal land is a mix of FS and BLM (note checkerboard O&C lands). Central is predominantly (~3/4) federal, almost all of it FS. Also a large component of wilderness, mostly at high elevations in Cascades. Small amt. of tribal (Warm Springs) in N. corner.
  • In Coast, ES 20% of forest area, mostly private lands, mostly managed forest. In Cascades, 31% of forest but misleading -- includes eastside juniper/pine; much more in federal ownership than Coast.
  • Forest types range from Picea along coast to Quercus woodlands of Willamette Valley.
  • Cascades: longer and stronger environmental gradients than coast, willamette valley foothills, over high cascades, down to juniper woodlands on eastside. Again, strongly tied to gradients in species composition and hence forest vegetation types.
  • Greatest total area of early seral is in WLCH, but it has lower % of area in early seral conditions compared to all but high-elev. forests. Westside, across the board the % of types in early seral condition is less than coastal Oregon. % of high-elev is the same (7%) in both areas. See great influence of envt. in eastside types, where much greater % of forest is open-canopied – probably need a different def. of ‘early seral’ here. Also, how do these distributions compare to HRV?
  • Although we may perhaps have ample amounts of early seral, its character has changed.
  • In Coast Range (no data for Cascades)... Remnant s nags and down most abundant on state lands – legacy of Tillamook Burn. Legacy down wood also quite abundant on FI lands. Snags most abundant on public lands and in older forests, diminished in young managed forests. Down wood: longer legacy time, more evenly distributed across forest ages and owners. Remnant wood in young forests a function of preceding stand, type of disturbance. FI owns much of the most productive forest, much of which was old growth.
  • Hardwoods (red alder, bigleaf maple, oak) important as habitat to many species, also in ecosystem processes. Associated with Very little hardwood in Cascades – mostly confined to riparian areas, plus small area of oak woodland. Coast has significant amounts of red alder forest along coast and northwestern part of region.
  • Most dramatic result of simulations was emergence of a new, highly contrasting landscape: older conifer forests developing on public lands, young conifer forests on private lands. Mature and old-growth conifer forest increase, as we expected under the NWFP. An unexpected result was the loss of broadleaf forest, with many implications for biodiversity.
  • Unlike OG, there is no shortage of early seral forest – we’re creating more of it every day. HOWEVER, the character of this forest has changed, and the issues become more nuanced. Reserve paradigm won’t work for a forest condition that’s tied to disturbance and short-lived in the successional sequence – new approaches needed
  • Sources of uncertainty need to be explicitly recognized: error in data, only some of which can be quantified; changing climate, disturbance regimes; ecoregions have unique ecological and ownership patterns and need to be considered individually (not ‘one-size-fits-all’).

Janet L. Ohmann - Trends in Early Seral Forest at the Stand and Landscape Scale Janet L. Ohmann - Trends in Early Seral Forest at the Stand and Landscape Scale Presentation Transcript

  • Trends in Early-Seral Forest at the Landscape Scale Janet L. Ohmann, PNW Research Station, USDA Forest Service, Corvallis, Oregon
  • Landscape trends in early-seral forest
    • Regional context for landowners and land managers
    • Information for regional planning and policy
    • Emphasis on western Oregon
      • Coastal Oregon (CLAMS)
      • Central Oregon Cascades (COLA)
  • 300 years of simulated fire history in Oregon Coast Range (LADS model: Wimberly, Nonaka, Spies, et al.) < 10 11 - 40 41 - 80 81 - 200 > 200 Stand Age
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 1972-1977
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 1978-1984
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 1985-1988
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 1989-1991
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 1992-1995
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 1996-2000
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 2000-2002
  • Stand-Replacing Disturbance and Forest Land Ownership in Coastal Oregon, 1972-2004 (Cohen, Healey, et al.) 2002-2004
  • Age Class Distributions in Coastal Oregon (various CLAMS analyses, Spies et al. 2007) Early seral
  • Historical Range of Variability (HRV) of Dead Wood in Early-Seral Forest in Coastal Oregon Dead wood biomass level % of area (Nonaka et al., in press)
  • Change in Forest Cover Type, 1936-1996 + 21% open/young + 101% hardwood + 87% small conifer - 58% large conifer (Wimberly and Ohmann 2004) 1936 1996
  • Current Landscape Distributions of Early-Seral Forest
  • A Continuum of Ownership and Forest Biodiversity Policies Economic goals Ecological goals Private Public Many, green-tree retention Multiple Management Plans Federal general forest Reserves, Adaptive Management Areas Late-successional forest, T&E species, aquatic, timber Policy, administrative (NWFP, Roadless) Federal reserves Timber production Forest industry FPA: tree retention in clearcuts , streamside protection rules Multiple Forest Practices Act (FPA) Nonindustrial private Structure-based management , Habitat Conservation Plans Healthy forests, native species, timber, T&E species State Forest Plans State of Oregon Consistent with wilderness character Natural conditions and other values Legislative Federal wilderness Management strategies Goals Policies Owner/ allocation
  • Forest Land Ownership Coast (5.7 mill. acres) Cascades (3.4 mill. acres) (GIS data from Oreg. Dept. of Forestry) Oregon
  • Forest Structural Conditions
    • Coast: linked to disturbance history and ownership
    • Cascades: confounding of environment, disturbance, ownership
    (Ohmann and Gregory, unpublished) Young Old
  • Forest Distribution by Structural Condition and Ownership, 1996 (10%) (26%) (6%) (11%) (38%) (10%) (6%) (15%) (6%) (16%) (32%) (25%) 1000 acres 1000 acres (Ohmann and Gregory, unpublished) Coast Cascades
  • Coastal Oregon: Dominant Ecological Gradients Sitka spruce (1.0 mill.ac.) Westside lowland conifer-hardwood (3.1 mill.ac.) Montane conifer (0.1 mill.ac.) Westside lowland dry/mixed evergreen (1.0 mill.ac.) Forest Vegetation Types (Ohmann et al. 2007) Foothill hardwoods (42,000 ac)
  • Central Oregon Cascades: Dominant Ecological Gradients Ponderosa pine (0.7 mill.ac.) Montane conifer (0.7 mill.ac.) Juniper (0.2 mill.ac.) Foothill hardwoods (11,000 ac) W. lowland con-hdw (1.3 mill.ac.) Lodgepole pine (0.4 mill.ac.) White fir (0.1 mill.ac.) (Ohmann and Gregory, unpublished) Forest Vegetation Types
  • Forest Types and Structural Conditions
    • % in early seral varies widely
    • Most early seral is westside lowland
    • eastside types predominantly open-canopy
    • little high-elevation forest is early seral
    (Ohmann and Gregory, unpublished) 1000 acres (22%) (16%) (7%) (17%) (43%) Coast 1000 acres (9%) (10%) (7%) (22%) (93%) (60%) (61%) % early seral (sparse+open) Cascades
  • Remnant (Legacy) Trees Natural legacies after wildfire Lack of legacies under intensive management Forest management w/ legacy retention
  • Coastal Oregon: Legacy Trees in Young Forest,* 1996 * Stand <40% cover and tree > 50 cm, or stand > 40% cover and <50 cm QMD and tree > (QMD+50 cm). (Ohmann et al. 2007) Total dead wood (m3/ha)
  • Hardwoods
    • Associated with:
      • Particular habitats (maritime climate, riparian, foothills)
      • Disturbance (legacy, early seral)
    • Reduced by intensive forest management favoring conifers
    • More abundant in coastal Oregon, on private lands
    Area of hardwood forest (>65% of basal area) (Ohmann and Gregory, unpublished) % hardwood basal area
  • Future (Projected) Landscape Conditions
  • CLAMS Projected 100-Year Change Under Current Policies 1996 (GNN) 2096 projected (base policy) 1996 (GNN) 2096 projected (base policy)
  • Potential Effects of Alternative Scenarios on Bird Habitat in coastal Oregon Northern Spotted Owl Western Bluebird Pileated Woodpecker (CLAMS, Spies et al. 2007) Current policy Green tree retention No Fed thinning
  • Summary: landscape trends in early-seral forest
    • No shortage of early seral:
      • more than HRV, more than 1936
    • But character has changed:
      • Linked to ownership and management practices rather than natural disturbance
      • Fewer legacy trees of lesser quality, shorter residence time, changes in patch size and shape
    • Diverse young forest will continue to decline under current policies
  • Implications for Landscape and Conservation Planning
    • Requires perspective that is multi-ownership, beyond reserves:
      • Much of early seral is on nonfederal lands
      • Reserves not designed for active management for early seral
      • Reserves not distributed across regional gradients
    • Forest policies:
      • Small shifts can make a difference (e.g., leave trees)
      • Much can be done (beyond regulation) to influence private landowner behavior
    • New tools and data available for landscape analysis can inform management and policy decisions as never before