Climate Change and Virginia’s Forests – Part 1

While there is much debate and uncertainty about the extent and causes of climate change to be expected over this century, there is good evidence from pollen records that tree species do shift with climate. The pollen records also indicate that such shifts are neither smooth nor uniform among species.

A very useful modeling exercise has been recently updated by the US Forest Service. The new Climate Change Tree Atlas examines current distributions and modeled future-climate habitats for individual tree species and forest types. The maps below indicate a shift in climate potential for forest types in the Eastern US. They suggest a decline in Virginia for the potential area of oak-hickory forest type and an increase in potential area of oak-pine, loblolly/shortleaf pine, and oak/gum/cypress.

Figure 1 - Current forest types (from FIA data)

Figure 2 - Predicted Forest-Types (CGM3-High)

Maps from: Prasad, A. M., L. R. Iverson., S. Matthews., M. Peters. 2007-ongoing. A Climate Change Atlas for 134 Forest Tree Species of the Eastern United States [database]. Northern Research Station, USDA Forest Service, Delaware, Ohio.

Long-lived trees can persist in areas where they are no longer the most suited. Also, species tend to move individually rather than as existing species groups, potentially creating new forest types in both the short and long-terms. Studies have indicated that some species existed in disequilibrium with climate conditions for hundreds of years after the last retreat of the continental glaciers. As species persist in areas where they are no longer most suited, they may be subject to elevated stress and experience higher rates of mortality.

Species composition is not solely a function of climate, but is also a result of disturbance regimes. Disturbances arise from both natural and human causes. In Virginia, Native American use of fire influenced species composition for centuries before European settlement. Since European settlement, land clearing for agriculture, industrial logging, and fire use and fire exclusion have help create our current species composition. Global trade has introduced exotic diseases, pests and plants which have influenced the species mix. American chestnut and eastern hemlock have been greatly reduced; ash and oak are now threatened by recently introduced species.

Remember that the Climate Change Tree Atlas models indicate importance value potential under predicted climate scenarios and were developed using current species distributions and a combination of predicted climate, current climate, topography, soil, and land use parameters. The models do not specifically incorporate disturbance regimes or any changes in disturbance regimes (such as fire) arising from climate change or changes in human management of forests.

The work done for the Climate Change Tree Atlas has also produced predictions of importance values by species and these have been summarized by state, including Virginia. In my next post I hope to take a more detailed look at the species-specific changes and how these may affect future forest composition and health in Virginia. I hope to factor in, at least in a very subjective way, the interaction of changing disturbance regimes, exotic species and climate change in determining future forest composition and health.

Tree-of-Heaven (Ailanthus) Control in Virginia

Non-native invasive plants threaten natural ecosystems because they can replace diverse native plant communities with monocultures. Tree-of-heaven (Ailanthus altissima) - the 46th most abundant tree species in the Commonwealth - is considered by many to be the most serious non-native woody invasive plant in Virginia.

A study was initiated in early 2006 to evaluate the effectiveness of herbicide treatment in combination with different harvesting strategies. This was followed by separate tests of the same application technique earlier (March) or later (September) in the 2007 growing season.

All herbicide treatments in the tests involved a tank mix of triclopyr ester (Garlon 4) in a hydrocarbon / limonene oil carrier (JLB Oil Plus) at a ratio of 1:3 triclopyr : oil. The mix was applied using a Solo backpack sprayer. Individual Ailanthus trees were sprayed around their entire circumference approximately 12-18 inches above ground. The objective was to determine whether treatment effectiveness varied with season of application.

Mid-Season Test
Three herbicide application strategies – basal stem spray followed by chainsaw harvest one week later, basal stem spray followed by chainsaw harvest four weeks later, and chainsaw harvest followed immediately by a cut-stump treatment - were compared to harvesting with no herbicide treatment. Each of these four treatments was applied to ten stems in each of three dbh size categories ranging from 1 to 16 inches.

The pre-harvest herbicide treatments were applied on June 5-6, 2006. These stems were then harvested either one week later (June 12-14, 2006) or four weeks later (July 5-6, 2006). Also on July 5-6, 2006, the stems receiving the cut-stump treatment and those left unsprayed were harvested.

The number of stump sprouts was tallied on September 25, 2006. All of the herbicide treatments had worked well to that point; fewer than ten percent of stumps from the treated stems had resprouted, compared to nearly 70 percent of those left unsprayed. Sprouting was evaluated again in July of 2007. The earlier results appeared to be holding, as only those stumps that did not receive the herbicide treatment had sprouted, and the largest trees had the most stump sprouts (see Figure below). Since there was no resprouting even in the plots where the trees were cut a week after treatment, it appears they were dead within one week.

These results show that a mixture of Garlon 4 herbicide in an oil-based carrier applied as a basal or cut-stump spray shortly after leaf development in the spring is a good treatment for removing tree of heaven up to 16 inches in diameter.

Early- and Late-Season Tests
Results of the early and late season application are shown below.

The early-season (March 28, 2007) trial was established in Nelson County, VA. Fifty-five Ailanthus ranging from 2 to 16 inches in dbh were treated. Within two months, roughly half of the trees had died while the other half had most or all of their foliage intact and healthy. Virtually all (96%) of them had died within 6 months.

The late-season (September 12, 2007) study plots were established near Batesville in Albemarle County, VA, where 65 Ailanthus ranging from 2 to 11 inches in dbh were treated. By the end of May 2008, only 40 percent of the trees were dead; the remaining 60 percent had stunted leaves on a few branches. By August, only 18 percent of the trees still had any leaves, and it appears likely (due to their poor condition, tiny crowns, and secondary infestations with wood boring insects) that all of them will die. At this site, we have observed a (not unexpected) relationship between tree size and the amount of time required for control. Only 30 percent of trees smaller than 6 inches in dbh had any leaves in May compared to over 70 percent of the larger trees. And by August, all of the trees less than 7 inches in diameter were dead while 18 percent of those larger than 7 inches still had small tufts of stunted leaves.

Summary
Tree-of-heaven was consistently controlled by basal sprays of triclopyr ester (Garlon 4) in a hydrocarbon / limonene oil carrier (JLB Oil Plus) at a ratio of 1:3 triclopyr : oil, but the response pattern varies depending on application timing. With a March application, about half of the trees leafed out although all were dead by the end of the growing season. After a June application, the trees were already at full leaf but wilted and were dead within one week after application. Following a September application, more than half of the trees leafed out in the spring although all of the foliage was severely stunted and very few branches had any leaves at all. By August over 80 percent are completely dead and indications are that none will be alive by the end of the season.

2008 Timber Tax Tips

The United States Forest Service - Cooperative Forestry unit has released a 2-page document called Tax Tips for Forest Landowners for the 2008 Tax Year by Linda Wang, Forest Taxation Specialist and John L. Greene, Research Forester, Southern Research Station.

This bulletin provides useful information for forest landowners, loggers, and timber businesses to prepare their 2008 tax return. More tax information can be found at the VDOF Website Tax Information page, including Agriculture Handbook 718, titled, "Forest Landowners' Guide to the Federal Income Tax.

Are Family Forest Landowners Well Informed?

Are the estimated 402,000 family owners of forest land in Virginia receiving sufficient information to sustainably manage their forests? The results of the 2006 National Woodland Owner Survey (NWOS) suggest not as less than 15% report that they have received advice on forest management and less than 4% have a forest management plan.

Owners of larger parcels tend to get more advice and this is reflected in the NWOS estimates that some form of advice was received for 38.4% of family forestland, and that 15.3% of family forestland was reported as covered by a management plan.

The NWOS also looks at the source of advice. The most common source (reported by 52% of owners receiving advice) was loggers, followed by state agency foresters (25%) and private consultants (25%). These categories are not mutually exclusive but they do suggest that many landowners are not seeking or receiving advice from professional foresters when making management decisions.

Fortunately larger parcels are more likely to receive professional advice with an estimated 25% of family forest land receiving advice from state agency foresters and 14.4% from forestry consultants (again, not mutually exclusive).

While not surprising to those in the forestry community, that fact that most family forest owners do not receive professional advice poses a major challenge in the sustainable management of our forest resources.

The NWOS is based on a survey of 444 Virginia forest landowners and contains many more details. Both the nationwide report Family Forest Owners of the United States, 2006 and the Virginia tables can be accessed online.

Economic Impact of Forestry on Virginia - $23 Billion

The forestry sector in Virginia contributes $23 billion each year to the economy and supports 144,400 jobs. This is according to a study relased on September 24, 2008 by Governor Timothy M. Kaine on the economic impact of agriculture and forestry in Virginia. Together the agriculture and forestry sectors contribute about $79 billion annually to Virginia’s economy.

The report also noted that forests provide many values not accounted for in the study. “Forests provide benefits in the form of carbon sequestration, wildlife habitat and biodiversity, flood mitigation and improved water quality. Rural scenic amenities may also improve quality of life.”

One section of the report is especially worth reading – the section discussing the opportunities and challenges facing the forestry sector. Opportunities and challenges are discussed in the areas of forest management, production technology, consumer demand, energy prices, urban population growth, government policy, and the global economy.

The report mentions the increasing contribution of plantation management to the softwood supply, while pointing out that the hardwood resource supply is threatened by the following trends:

• increasing fragmentation and parcelization,
• non-industrial ownership patterns (and, I would add lack of sound management), and
• forest health challenges from invasive pests, air pollution and ecological change due to fire suppression.

On the demand side the report offers a discussion of the role of housing demand, global competitiveness and rising energy prices. While rising energy prices act to increase the cost of production, they also offer a possible increase in demand for woody biomass, whether in traditional fuel or the potential cellulosic ethanol market.

The study was led Dr. Terry Rephann of The Weldon Cooper Center for Public Service at the University of Virginia. The full report can be accessed at the Department of Forestry website. I would recommend its reading to anyone interested in the future of forest resources in Virginia. The forestry section starts on page 17. The Economic Impact Of Agriculture And Forestry On The Commonwealth Of Virginia

Virginia forests are facing new threats

Dr. Chris Asaro, the Department of Forestry's Forest Health Specialist, was recently featured on a radio news report on WVTF. Reporter Sandy Hausman interviewed Chris on the new health threats facing our forests from invasive plants and pests.

Click here to listen to the report.

Foreign Ownership of Forestland on the Increase, But Not in Virginia

Thanks to Brian Fiacco and his post on the Timberland Blog for informing me of this data source on foreign land ownership in the United States. The Agricultural Foreign Investment Disclosure Act of 1978 requires all foreign owners to report any transactions of agricultural and forest lands within the United States. A recent report by the Farm Service Agency shows an increase of foreign forestland ownership from just over 7 million acres in 1997 to approximately 13.5 million acres in 2007. (See Figure 3 from the report.)

Much of the increase can be attributed to land sales by forest product companies to a handful of buyers from Canada (2.8 million acres in Maine) and the Netherlands (3.3 million acres in Alabama, Arkansas, Florida, Louisiana, Michigan, Mississippi, North Carolina, South Carolina, Tennessee and Texas).

Virginia has not participated in this trend of increasing foreign forest ownership. Reported foreign ownership in Virginia declined slightly from 139,000 acres in 1997 to 116,000 acres in 2007. In 2007, 60,230 of the 116,000 acres were reported as forest land. Only 5 counties (Albemarle, Botetourt, Loudoun, Patrick and Tazewell) had more than 2,000 acres of foreign forest ownership reported.

A map from the report (Figure 2) shows the distribution of all foreign-owned agricultural and forest land by state.