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Regenerating Longleaf Pine Forests Naturally

Click to edit Master title styleNatural Regeneration

Click to edit Master title styleMature Longleaf Forest

Click to edit Master title styleRelevant Facts

• The southern pines are generally shade intolerant

• Natural disturbances occur on many scales• Southern pines occur naturally in both even-

aged and uneven-aged systems

Click to edit Master title styleManagement Choices

• Natural regeneration:• Requires a suitable, well distributed seed source• Can be used in even-aged and uneven-aged

management systems• Sacrifices advantages of stocking control for low

“upfront” regeneration costs• Uncertain seed crops make planning difficult if

time is a factor

Click to edit Master title styleEffect of gap size on stand conditions

• Small gaps or small scale disturbances can lead to stands of multiple ages as the gaps are filled in with regeneration.

• Large gaps can result in even-aged stands, with all trees being regenerated within a few years of each other following the disturbance.

Click to edit Master title styleCurrent Southern Pine Management Trends

• Most southern pines are managed today in even-aged systems :– Optimizes growth rates by allowing maximum

sunlight on growing crop– Takes advantage of economies of scale for

silvicultural treatments– Enables easy scheduling for harvests,

treatments

Click to edit Master title styleTrends favoring uneven-aged management

• Changing landowner demographics, owner’s objectives may favor uneven or all-aged management because:

Click to edit Master title styleFavoring Trends

– Retains appearance and much of the function of a forest throughout

– Can take advantage of natural regeneration, reducing upfront costs

Click to edit Master title styleRegeneration

• In all regeneration systems, the greatest challenge is to get reliable and timely regeneration and give it room to grow into the larger, more valuable size classes

Click to edit Master title styleRegeneration Management

• Competition may be intra-specific or interspecific

• Control usually means control of competing vegetation or release harvest

• Intermediate cuts, herbicides and fire are techniques of choice in most southern pine management schemes

Click to edit Master title styleRegeneration and Species Considerations

• Longleaf Pine– Sporadic seed producer– Seed generally only disperses 100 feet or so

from the seed tree

Click to edit Master title styleLongleaf Pine (contd.)– Fire tolerant at virtually any size after year

of germination – Could be planted in gaps to augment

natural seedling numbers– Two year cones allow for some planning

and preparation

Click to edit Master title styleRegenerating degraded longleaf stands naturally..

• The shelterwood system, as utilized in longleaf management, can result in either even-aged or multi-aged longleaf stands.

• The first step in natural regeneration should be to control the woody understory prior to opening up the canopy with a cut.

• Fire, particularly growing season fire, or fire and herbicide used in combination can be effective in this effort. Combinations of dormant season and growing season fires may be necessary to reduce initial fuel loads.

Click to edit Master title styleMixed Pine Stands

Click to edit Master title styleMixed pine stands• If sufficient numbers of well-distributed longleaf are present

in the overstory to provide some seed, the stand can be managed to regenerate naturally.

• Fire should be a regular part of a management regime until woody understory competition is controlled.

• One treatment to control woody brush that has proven successful employs Garlon 4TM (triclopyr) applied with ground equipment or backpack sprayers in early Fall, followed by an early Spring fire.

• Fire must be employed to prevent seedlings from other pine species from occupying the site before longleaf can become established. Longleaf has sporadic seed crops, unlike the annual seed crops of other southern pines, and may fail to capture the openings when they occur.

Click to edit Master title styleMixed stands containing other pine species might be thinned to create gaps to release longleaf seedlings already present in

the understory

Click to edit Master title styleMixed pine stands…

• Successive cuts to increase the number and/or size of the previous gaps will create a mixed stand of several age classes, that will, over time, become an all-aged longleaf stand.

• It may be desirable to keep some pines of species other than longleaf in the overstory to help provide fuel for fires.

• It is difficult to burn into the center of gaps larger than ¼ acre because of the lack of pine fuels.

Click to edit Master title styleEven-aged natural

• Low upfront costs• Fairly consistently successful• Stocking control can be a problem• Growth on best trees• Best trees at risk• Unreliable seed production• Can be used to begin transition to all-aged stand

condition (Modified Shelterwood)

Click to edit Master title styleThe Shelterwood System.. • When the understory is reduced to a manageable level, a

preparatory cut is used to reduce Basal Area to 50 to 60 square feet per acre, favoring trees of good form, large crowns, and good seed producers. The residual trees should be well-distributed across the area.

• After several years, the crowns will have expanded into the intervening gaps and regeneration has begun to accumulate. At that time, a second “seed” cut should be used to reduce Basal Area to 25 to 30 square feet per acre, again favoring well formed good seed producers distributed evenly across the stand.

• When a good seed crop is anticipated (through flower and/or cone crop counts), the stand should be burned in the winter or early growing season prior to seed fall to prepare a good seed bed.

Click to edit Master title styleThe seed cut should lower basal area to about 30 square feet per acre

Click to edit Master title styleShelterwood Regeneration• Longleaf is a sporadic seed producer, producing seed

anywhere from annually to once every 20 years in some areas.

• Longleaf is a “two-year” cone, with female cones or flowers appearing one year and maturing the next, the year of seed fall.

• Surveys of female flowers anticipate cone crops but can be difficult for inexperienced observers. Cone counts are easier, but give less lead time to prepare the site to receive seed.

• There should be about 30 cones per tree or 1000 cones per acre to provide adequate seed to naturally regenerate an entire area with longleaf seed.

Click to edit Master title styleCone or flower counts can guide natural regeneration decisions

Click to edit Master title styleOne and two year cones may be present on the same branch

Click to edit Master title styleAlmost anyone can count cones, but it takes a trained eye to count flowers

Click to edit Master title styleShelterwood Systems

• A minimum of 4,500 germinants per acre are considered sufficient to consider a site successfully regenerated from natural seed. At least 75% of all 0.001 acre plots should have at least one live seedling present.

• If the above conditions can be met, the site can be considered stocked with new seedlings and, if desired, the overstory trees removed within two years of the seed year. This will yield an even-aged stand.

Click to edit Master title styleShelterwood system..• Naturally regenerated stands cannot be burned in the year

following seedfall without endangering the new seedlings. Seedlings with a root collar diameter of 0.25 inch or greater generally can survive most fires.

• If even-aged stands are not desirable, all or a portion of the seed trees may be retained, creating a two-aged stand. Subsequent repetitions of this process with later seed crops will eventually yield a multi-aged stand.

• Seedling growth rates may be adversely affected by competition from the residual overstory.

Click to edit Master title styleNaturally regenerated stands should have from 4,500 to 6,000 seedlings per acre the spring after

seed fall

Click to edit Master title styleHarvesting the Overstory

Click to edit Master title styleNew longleaf seedlings cannot survive fires until they reach a root collar diameter of at least 0.25 inches (6 mm)

Click to edit Master title styleRetaining some or all of the seed trees produces a two aged stand

Click to edit Master title styleShelterwood with Retention

• Overstory of 30-40 square feet of BA removed in several stages over an extended period to allow several cohorts of seedlings to develop, potentially creating an uneven-aged stand.

• Because longleaf is a sporadic seed producer, seed crops may be several years apart.

Click to edit Master title styleUneven-aged Systems

• Longleaf stands or stands that are predominantly occupied by longleaf may also be regenerated and managed using uneven-aged systems.

Click to edit Master title styleUneven-aged choices..

• Stands may be managed in uneven aged conditions using several natural management alternatives, assuming regeneration is obtained.• Single tree selection• Group selection• Stoddard-Neel System• Reverse “J” or BDQ method

Click to edit Master title styleOverview of “Natural” Stand Management (Uneven-Aged)

• Retains appearance of a “forest”• Retains full range of habitat/species diversity• Retains market flexibility• Can require individual attention• Economies of scale may be limiting• Should obtain regeneration catch before creating

gaps to release it

Click to edit Master title styleOverview (Continued)

• Provisions must be made for regeneration and fire• Produces constant flow of high value timber and

non-timber products • Requires fairly frequent entries and disturbances to

yield comparable income• Requires “informed” management to be successful• No upfront establishment costs

Click to edit Master title styleCreating the uneven age forest from regeneration

• With each successive seed crop, gaps can be created or enlarged to release the new seedlings.

• Gaps can be systematically or randomly located depending on the landowner’s objectives

• “Domes” of regeneration take shape over time, with the tallest seedlings in the center.

Click to edit Master title styleRegeneration “Domes”

Click to edit Master title styleAll-Aged or “All-Sized”

• Makes little difference for future management since longleaf responds to release at almost any age unless critically suppressed.

• Longleaf grows naturally at different rates, possibly as a hedge against lethal fires.

Click to edit Master title style“All-aged” or “All-sized”

Click to edit Master title styleStocking control• When natural regeneration works, it can work too

well.• The 1996 seed crop resulted in some stands at the

Dixon Center with over 400,000 longleaf germinants per acre

• Fire, drought and other mortality factors gradually reduced those numbers, but some stands retained high levels of stocking

Click to edit Master title styleOver-stocked?

Click to edit Master title styleSeedbed preparation

• If seeds fall on deep litter, they typically germinate anyway, but die at the first dry spell or first fire because roots are anchored in mineral soil.

• If seeds fall on bare soil, seed predators may devour the crop unless it is an unusually large crop.

Click to edit Master title styleTasty ?

• Not only is longleaf seed tasty and preferred by birds, small mammals, and other predators, it is edible and palatable for humans. At the current rate of $160 per pound, it would be an expensive meal.

• The new germinants reportedly make a tasty addition to salads!

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Questions???