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Vol. 2 | No. 3 | August 2009   

 

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2009 Longleaf Pine Cone Crop Report

By David Ray, Forestry Research Scientist

Thanks to the long-term efforts of Forest Service scientists we are provided with an estimate of the region-wide cone crop for longleaf pine each year. Observers visit the same locations (and individual trees; 10 per location) each year and count the number of cones and flowers (next years cones) in order to develop these reports. These data are valuable for documenting change over time as well as differences across the region for a given year. Interestingly, there appears to be a trend of increasing cone production across the region in recent years. Scientists responsible for the study speculate that this may be due to a general level of recovery following extensive harvesting, and perhaps also to improved growing conditions for longleaf pine related to a warming climate.

Longleaf pine coneThe regional cone crop study has one observation site in the Red Hills, others located relatively nearby include one on the Apalachicola National Forest in FL and another on the Jones Ecological Center in, Georgia. Historically the Red Hills site has been located on Pebble Hill Plantation, but in 2010 will be relocated to Tall Timbers Research Station. It makes sense to have these types of long-term studies located on ownerships that are focused on research, and thereby avoid potential conflicts with other land uses. We are excited to begin hosting this important study!

Longleaf pine is considered a masting species, meaning a large number of cones are produced at relatively infrequent intervals, approximately 5-7 years. However, this rule of thumb may need to be reigned in a bit in order to reflect the more frequent crops noted in recent years. While some seed is produced even in ‘off’ years, there is seldom enough remaining after consumption by wildlife for much germination to occur. Longleaf pine releases its seed in October and November, so site preparation treatments intended to capture natural regeneration need to be carried out before then, to increase your chances for success. The purpose of the site preparation treatment is to expose areas of mineral soil so seeds can germinate on a substrate that will provide a stable source of water. In most cases, sites that have been burned within the past year will be in good condition. Sites with a two or three year rough, or where fuels consumption was poor during a more recent burn, will likely need to be re-burned or treated mechanically. It is also important to remember that although longleaf pine is very tolerant of fire, newly germinated seedlings are vulnerable. To avoid problems here you will need to forego burning these areas until the seedlings have had at least a year to develop. This should not be an issue for landowners who are burning on a 2-3 year cycle.

To cut to the chase, the prediction for this year’s seed crop region wide is ’fair’, averaging approximately 38 cones per tree. Further, the cone counts from the Red Hill’s site were only about half the regional average, at 20 per tree (considered a ‘poor’ crop). Flower counts (next years cones), which are useful but less reliable than the current year cone counts, suggest next year will be worse (17 cones per tree predicted). To provide some indication of the regional variation in cone counts, observations from the nearby Apalachicola National Forest suggest a failed crop (6 cones per tree), yet those from the Jones Ecological Center indicated a good crop (65 cones per tree).

Finally, while the information contained in these reports is of value to land managers interested in regenerating longleaf pine naturally, it is no substitute for monitoring conditions on the ground. I recommend using this annual update as a heads up for when you should be looking for cones on your property, and noting whether your observations confirm or contradict those being reported in the regional study. This is not to suggest that you will need to do any kind of a formal survey. Fortunately, longleaf cones are large and conspicuous, so it will be pretty obvious when conditions are likely to be favorable. Forest Service scientists suggest that, on average, you should have around 30 cones per mature tree (14 to 16 inches diameter) for successful natural regeneration. And remember, planting longleaf pine seedlings, though more expensive, is the surest way to get the type of regeneration you want, and when and where you want it.

The mission of Tall Timbers Research Station & Land Conservancy is to foster exemplary land stewardship through research, conservation and education.