Timber Productivity Research Gaps For

SUPPLEMENTARY INFORMATION

Timber Productivity Research Gaps for

Extensive Forest Management -- Issues based on assessment conducted in the Eastern USA

Lloyd C. Irland

The Irland Group and Yale University

174 Lord Road, Wayne, ME 04284

207-685-9613

fax: None

1/4/2011

This supplementary material includes information on intensive management trends in the eastern USA in recent years, as well as brief discussions of forest conditions in four principal forest types in the eastern USA. On the basis of an assessment of research needs in these types, a series of propositions on extensive management and forest research have been developed that are believed to have wider application to small scale forest ownerships worldwide.

Intensive Management is Shrinking

It appears that, region-wide, intensive management is shrinking. This is occurring for different reasons and in different ways in different areas. Unfortunately, comprehensive national reporting on management practices seems to have ceased. Planting, one possible proxy for intensive management, declined dramatically from its 1988 peak to 2003, falling by 1.6 million acres (Fig. 1). Almost all of this decline took place in the South.[1] Measured from the average of the 1980's and 1990's, the decline is more modest but still significant. Data collected by the southeastern state foresters suggest that planting in the South continued to decline after 2003, falling below 1 million acres in 2008 (Southeastern State Foresters, var. yrs.). Surveys indicate that Timber Investment Management Organization (TIMO) acquirers of southern industry land have largely maintained previous intensive management programs (Arano and Munn 2002). In Mississippi, surveys do not show clear patterns of changing management intensity on nonindustrial ownerships (sample median size 90-100 acres) through 2006 (Deng and Munn 2008).

In Maine, location until recently of a heavy concentration of paper industry ownership, total intensive management treatment fell from 110,000 acres at its 1989 peak to only 22,000 acres in 2008. Planting peaked in 1998 at 13,625 acres, and fell to under 4,000 acres by 2008 (Irland 2010). In Minnesota, a recent survey found complex patterns (D'Amato et al. 2009). There, estimated artificial regeneration statewide increased both absolutely and as percent of area harvested from 1991 to 2008. Commercial thinning increased; pre commercial thinning declined. Site preparation fell on industry lands while increasing on state and county lands.

Fig. 1 Area planted, US and South, 1950-2003 (US Forest Service 2007)

Changes in land ownership, mill shutdowns, low industry profitability, changing management needs, changing public policies, and current pessimistic views of the market outlook have all contributed to this trend. In local areas, changing regulations and public land policies have been important. At present, it is difficult to see levels of intensive management returning to the peak levels of the past. This outlook should increase our motivation for systematically studying the opportunity to upgrade productivity by moving properties up the spectrum from custodial management to extensive regimes.

Situation: Context for Extensive Management

Four type groups are considered here: white red and jack pine; oak hickory in the North, northern hardwoods, and loblolly and shortleaf pine.[2] Two of the type groups (loblolly-shortleaf, and to a lesser extent red and white pine) are exemplars of intensive management, due to their rapid growth rates, high end product values, their adaptability to plantation culture, and the past availability of suitable land for planting, either on old fields or in clearcut natural stands. According to the USDA Forest Service Forest Inventory & Analysis (FIA) estimates, these type groups account for a total of 34 million acres of planted stands nationwide, or 20% of the area in these type groups (Table 2).

Table 2 Area of forest land by estimated stand origin, 2007, for type groups considered in this article (US Forest Service 2007a)

All owners
1,000 Acres
Forest-type group / Total / Planted / Natural origin / % Planted
North: / White-red-jack pine / 10,029 / 2,799 / 7,231 / 28%
Oak-hickory / 54,765 / 494 / 54,271 / 1%
Maple-beech-birch / 52,504 / 682 / 51,822 / 1%
South: / Loblolly-shortleaf pine / 54,826 / 30,092 / 24,734 / 55%
United States: / Total / 751,228 / 63,167 / 688,060 / 8%

White Red Jack Pine

White and red pine are perhaps the iconic “Northwoods” forest trees of the Northeastern US and the Upper Midwest. The tall lakefront pines, and the emergent, ragged pines along ridgelines are prominent visual images. Yet, the type itself occupies only a small share of the region’s forest area. It is the smallest in area of any addressed here, roughly 10 million acres. The key species occur prominently in a variety of other types, notably so in the case of hemlock and white pine, where they often occur as scattered emergents in northern hardwood or oak stands.

Many foresters have been fascinated by analyzing extremely long managed rotations for these pines, in contrast to other eastern pines where the focus has been almost exclusively on how to shorten rotations. Major studies of white pine growth and yield have used datasets extending well beyond a hundred years (Leak, et al. 1970; Buckman, et al. 2006; Lundgren and Buckman 1998). Some public agencies employ rotations exceeding a century on at least a portion of their white pine resource. Pine often appears as a welcome volunteer in other softwood plantations.

White pine management seems to be stuck in a vicious cycle. Many pure stands are so bedraggled from the effects of pests and lack of management that they seem hopeless. This poor condition, however, is often a result of past failure to manage. Surely many stands have “gone by” by any reasonable standard. The ragged appearance of most of these stands seems to have demoralized many foresters and landowners and discouraged attempts to manage (Irland, 1986). But many opportunities do exist – fine white pine stands on the exceptional ownerships that have pursued pine management with skill and determination show what can be done (for example, Stine and Baughmann, 1992; Desmarais and Leak 2005; Seymour 2007, Page and Smith, 1994).

Red pine, on the other hand, has been widely planted (some 250,000 acres in the Midwest alone). Significant management programs are underway in maturing plantations in the Lake States (Gilmore and Yount, 2002: Lundgren and Buckman, 1998, Kilgore and martin, 2002). Many of the earliest plantings were established at excessively high densities. Thinnings were often impossible as markets for small diameter wood were lacking, but markets for small sawlogs have now emerged. If first thinnings are conducted early enough, red pine on average sites can produce a cord per acre per year, and can support commercial thinnings every ten years – at good stumpage prices. Many of these stands will yield 2 to 4 such thinnings before final harvest.

At final harvest, will such stands will be replanted to red pine, be consciously regenerated to some sort of mixture, or simply regenerate to whatever comes along? This does not yet seem a major practical problem – in the main it is one or two cutting cycles away. Commercial thinnings that leave attractive stands of large trees by roadsides are showing the public a new and benign face for forestry. Originally established for general conservation purposes or to grow pulpwood, these stands have unexpectedly become productive sawlog machines. This is a highly successful resource management story.

Oak-Hickory – North

Oak-hickory is the most extensive forest type group in the North, covering an estimated 54 million acres. This type is currently managed almost exclusively by extensive methods across its range, though active research is being pursued on oak planting, regeneration, management of multi-storied stands, and related topics. The economic importance of this type group is hard to overestimate, with its oak, hickory, and related species supplying important lumber and wood product manufacturers. According to Census Bureau data for 2005, at least 35% of eastern lumber production was in the oak and hickory species group.

For generations, typical practice in this region consisted of periodic cuts removing only such trees as paid their way for lumber or higher value products. Those conducting such cuts often liked to describe them as “selective cutting.” Weak markets for low grade wood hindered management, but the end result was often high grading.[3] After the1960’s, extensive and repeated gypsy moth outbreaks across the Mid Atlantic states caused considerable oak mortality on thin-soiled ridges. In the mid to late 20th century, an additional stress factor appeared. Over extensive regions, regeneration of commercial species is damaged or eliminated by deer. In some areas, deer population levels are declining but the legacy of their overfeeding persists, in the form of extensive fern and grass understories and depleted seedling and sapling layers.

Fire historically played a key role in oak ecosystems. As Abrams (2005) notes: “It is doubtful that oaks on mesic sites represent a true self-perpetuating climax in the absence of fire… There has been a nearly complete cessation of oak recruitment over the last 50-100 years in all but the most xeric and nutrient-poor sites” (p. 19). Abrams goes on to argue that the dense understories now in place mean that the opportunity for using fire to reverse this situation may rapidly pass. Due to all these factors, failure of oak regeneration is widespread. An example from Pennsylvania will illustrate: considering only desirable commercial species, advance regeneration occurred on only 23 to 44 percent of plots across the state’s Survey Regions (McWilliams et al. 2007, p. 50). In areas most strongly affected, oak growing stock has been declining in the most recent inventories (Moser et al. 2006; see also Woodall et al. 2008). In Missouri and adjacent states, a general oak decline has been observed for decades, intensified by recent drought (Clatterbuck and Kauffman 2006, Kromroy et al. 2008, Woodall, et al. 2010). Maintaining oak in overstories will clearly be a challenge (e.g. Povak, Lorimer, and Guries, 2008). This is a wildlife habitat issues as wel as a timber issue (McShea, et al. 2009)

Northern Hardwoods

Thistype group covers roughly 50 million acres across the northern states. It includes a number of distinctive subtypes, but is usually dominated by the classic trilogy of maples (red and sugar), beech and yellow birch. While dominated by the tolerant species, it also contains important admixtures of species of medium and low tolerance. In the past, foresters often noted that the best grade of white pine and spruce was found in trees mixed in northern hardwood stands. The type is spoken of as occupying mesic soils, yet some of its species are quite aggressive and will occupy harsh conditions as well, sometimes well into mountain elevations, and also drier sites.

Tree grades are generally low, reflecting past management practice. To some degree this has been offset by technology as mills have used smaller and lower quality logs to produce lumber and other products. The premium hardwoods in terms of value have been the sugar maple, and since World War II, yellow birch. In the past few decades, prices have been rising for the abundant red maple, and markets have developed for other associates. Red maple has been increasing in volume and tree numbers, especially in seedling and smaller size classes (Alderman et al. 2005). This has often been at the expense of species considered more valuable. The species is a vigorous sprouter, spreads well by seed and resists deer browsing.

Northern hardwoods have been subjected to the full range of silvicultural practices in the foresters’ arsenal. In limited areas, long-term experience has accumulated a range of management schemes for this type group, ranging from "loggers choice" and diameter limit methods (Nyland, 2005), to intensive regimes of uneven aged, individual tree selection. Some of these have been carefully studied.[4] Studies have been done on thinnings, cleanings, and improvement cuttings. Methods such as one or two-cut shelterwoods, crop tree release, patch cuts, and group selection have all been implemented, as have prescriptions aimed at retaining structure for habitat and ecological reasons.

Loblolly - Shortleaf Pine Type Group

Loblolly and shortleaf pine occur commonly in mixture and are the most widely distributed of the southern pines. They occur on a variety of sites, with loblolly preferring wetter areas; shortleaf pine will grow on xeric ridges in northerly portions of its range. Natural pine area has declined in the South, from 72 million acres in 1952 to 33 million by 1999 (Wear and Greis 2002, p. 374; McCullough, Straka, and Dubois, 2005). By then, in several states, planted pine area exceeded natural pine. Currently, shortleaf pine representation in the eastern forest is decreasing, giving rise to concerns about its future (Moser et al. 2007).

Natural stand growing stock stood at 47 billion cubic feet (bcf) in 1999 compared to 18 bcf in plantations (Wear and Greis 2002, p. 383). Total net annual growth in natural pine in 1999 remained above that in planted stands (Wear and Greis 2002, p. 386). Hence, the natural pine forest remains a wood resource of high potential importance. Any actions that could improve volume and value growth in these natural forests would have powerful industrial implications. Land use history and management have severely compressed the age distribution in this forest: in Georgia, only 3,000 acres of timberland were recorded as being over 100 years, only about 370,000 acres were age 61 or older. This is less than the area of one large Georgia county. Large trees are few (Fig. 2). Ingenuity in pursuing extensive management of natural stands, or even converting plantations to long-lived mixtures, could reverse this trend towards elimination of older age classes and large trees.

Fig. 2 Number of live trees on timberland by size class, Georgia, 2007 (US Forest Service 2007b)

Burton (1980) studied stands thinned at age 20 under a number of thinning regimes, on a good and a medium site. This report is especially valuable as it presents results from measured stands, not simulation. The study also employed a rich set of thinning options. These ranged from maintaining basal area at 70 feet to 130 feet, including one regime in which the postcut basal area increased over time, and a “judgment thinning." The mean annual increments (MAI's) were highest at age 45, making one wonder if they might have increased for yet another cut cycle (Fig. 3).

On the good site, Burton’s estimated sawtimber MAI's of 350 board feet per acre per year would represent a gross annual income in the neighborhood of, say, $50 per acre per year, sustained over a 25 year period, with no cash investment beyond administration and property taxes. This is attractive, even assuming no escalation in stumpage prices. On the medium site, returns were far lower, but they would likely have been marginal for any intensive regime. A summary of past studies shows strong periodic annual increments from uneven aged management (Baker et al. 1996, p. 31; Cain and Shelton, 2001).

Fig. 3 MAI's, natural Loblolly-Shortleaf stands, high site, first thin at age 20 (Burton 1980).

Typically, to maintain pine in the understory and bring it into overstory canopy layers, “natural regeneration” cannot be left entirely to nature (Shelton and Cain, 2000). It requires at least suitable scarification, if not prescribed fires and herbicides on the higher sites. Such a regime, especially when using a large-tree product objective, could still be considered an extensive form of practice. Plainly, continued erosion of natural pine area and volume is in prospect if large areas of southern forests continue to receive the limited management attention that they have received in the past.

A Process for Developing Priorities and Responses

No brief multiregional regional “desk study” can fully identify specific needs for assessment, research, and outreach on any one of these forest types. Instead, for each type, by regions, an orderly process should be followed, perhaps something like this:

1. Commission annotated bibliographies of information relevant to the management issues identified above[5]. These should be selective and should not ignore older work. They should pay close attention to studies whose re-measurement or updating could be valuable.

1. Conduct workshops involving forest managers, landowners, resource and technical specialists, consultants, and scientists to “brainstorm” the most important issues and the information needed to make better management decisions. In particular, all existing long-term silvicultural studies and management programs would be assessed to learn the important lessons. Needs may emerge to re-measure post studies, or re-analyze them; in other instances, it may seem wise to mothball others. For some problems, systematic assessments of a sample of existing treatments may be cost-efficient. It is critical to involve a wide range of practitioners and stakeholders in this process, possibly through webinars, remote conferencing, and web-based surveys.

1. Such workshops might include identifying specific practice/condition situations that attendees consider promising. What is “promising” primarily concerns landowner return on investment and other owner goals, but also larger social concerns. Resort could then be had to FIA and other data to identify how widespread this opportunity may be on the ground. Simply revising past examples, such as were done for the South’s Fourth Forest, may do the job, although the level of attention to extensive regimes has often been cursory in such assessments.

1. Further, analysis of FIA data can reveal trends in regeneration, tree quality, and stocking levels that can suggest research priorities for management practices.

1. The workshops should also review existing management guides and yield prediction systems, to determine if they need updating based on new science, different objectives, changing prices and markets, or other factors (e.g. Baker et al. 1996; Sander 1977; Leak et al. 1987; Baker et al. 1996; Gilmore and Palik 2006). Are user-friendly, credible, and low cost software programs available? If not, what can be done?

1. Publications of various kinds would be developed to make information available to users. It may be found desirable to commission major resource documents or monographs summarizing the updated information and lessons from practice in the field.

1. Case studies of long-term management results achieved by landowners should be commissioned, focusing on how adopting active management, instead of custodial approaches, has helped owners achieve their objectives.

1. Conferences on extensive management of the principal forest types should be held in every region as a venue for exploring the above issues and developing outreach of the newest ideas and information. These could be conducted as major sessions in existing venues such as the Central States Hardwood conferences.

1. The above steps are in the nature of assessment and outreach. As they are accomplished, ideas for specific needed research tasks will emerge. Very likely, many of them will be of a practical nature.

References