Friday, April 27, 2012

Long live longleaf pine...

I just returned from visiting State Forests in North Carolina and South Carolina that are part of our Regional Longleaf Pine Cone Production StudySandhills State Forest is in Chesterfield and Darlington counties of SC and Bladen Lakes State Forest is located just northeast of Lumberton, NC.  This is the 47th monitoring year of this work, which was initiated by Bill Boyer and is now coordinated by Dale Brockway

Longleaf pine (Pinus palustris) is monoecious (i.e., “one house”), which means that both male and female strobili reside on the same tree.  The male strobili, called catkins, produce all that wonderful pollen we see in the spring-time and are generally found in the lower portion of the tree crown. 

Male strobili
Photo courtesy of Forestry Images

The female strobili are initially called flowers (then conelets during the following spring and mature cones by the fall), are generally found in the upper portion of the tree crown. 
Female strobili
Photo courtesy of Forestry Images

Conelets turn into the seed-bearing cones, synonymous with members of the Pinaceae family, and typically shed their seed during October.

Photo courtesy of Forestry Images

During our survey, we count the number of female flowers (newly pollinated but undeveloped small conelets), conelets (pollinated about one year earlier and developed into large “green cones”), and brown cones currently on the tree (that shed their seed during the previous fall).  The female strobili emerge during January/February and are pollinated during the infamous spring pollen flush that occurs between late-February and April.  Those strobili are now pollinated, but don’t become conelets until the following spring when fertilization occurs.  Those conelets then become seed-bearing cones, maturing during mid-September and mid-October.

Cone count data from ten widely-dispersed locations in the Southern Region are compiled and then assembled into a report that forecasts the longleaf pine cone crop for each state and for the region. 

In the past, landowners and land managers had trouble naturally regenerating longleaf pine, because of what was thought to be erratic seed production.  Through research, we now know that longleaf cone crops are highly variable from year to year because of the interaction of many physical and biological variables.  The longleaf pine cone production survey helps predict when a good or poor seed year is coming.  This alerts forest managers so they can be prepared to implement site-preparation treatments when more seeds are likely to fall on a receptive seedbed.

For more information on longleaf pine ecosystems, please see our research page.