Camp Creek, GA LiDAR

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#1)  Camp Creek, GA LiDAR

Postby Jess Riddle » Sat Sep 21, 2013 9:21 pm

Ents,

LiDAR data for northeast Georgia shows one of the greatest concentrations of high hits near the mouth of Camp Creek on the Chattooga River.  That location is not surprising given that the next watershed to the north is Cliff Creek, home to the tallest known trees in Georgia, and the general abundance of tall conifers in the Chattooga River watershed.  Most of the high hits are on a steep, north-facing slope.  White pines on such topography often produce very high LiDAR hits as they lean slightly down-hill leading to the canopy height (which is what LiDAR actually measures) significantly exceeding the tree height.  However, my dad and I visited Camp Creek in 2005, and found trees up to 165’ (see http://www.nativetreesociety.org/fieldt ... _creek.htm for site description and measurements).  So we knew a trip back to Camp Creek wouldn’t be a complete wild goose chase.  Also, a 207’ hit demanded checking, even if suspect.

Last September we returned to Camp Creek.  The gently rolling terrain of the surrounding Appalachian foothills and alternating bands of oaks and pine give little hint of the dark, moist, hemlock filled ravines that line the Chattooga River.  After measuring a high LiDAR hit in an adjacent ravine and in the process stumbling into a small grove of tall, but frustratingly difficult to measure, shortleaf pines, we arrived at the creek.  Liverworts cover ever boulder in the stream and add to the sense of moisture that pervades the shaded area.  High on north facing slope, scattered white pines thrust their crowns out of the shade and into the sky.  Below them, hemlocks and an understory of rhododendron cloak the 30 to over 40 degree slope.

We headed straight up the slope to the highest LiDAR hit, and when we arrived 100’ above the elevation of the stream we found a trio of pines that appeared slightly older than most on the slope.  Unfortunately, a terrain error appears to have exaggerated the height of these trees.  To add injury to insult, recent droughts (probably) damaged the trees.  The crown of the tallest of the three had died back and broken off at ~130’, where it was about a foot in diameter.  The tree was never close to 207’, but might have surpassed 160’.  Other high hits on that slope were free from data errors and healthier, but all of the ones we visited leaned downhill enough to exaggerate canopy height relative to tree height.  However, Camp Creek also has one alluvial flat dominated by white pines, and LiDAR heights better reflected tree height in this area.  The previously measured 165’ white pine grows at the edge of that flat, but forest in the flat was unmeasured.

               
                       
CampCreekMeasurements.JPG
                                       
               

Camp Creek is now the forth site in Georgia known to support trees over 170’ tall.  The mockernut hickory, dogwood, hophornbeam, and shortleaf pine are all within six feet of their respective state height records.  The silverbell, though dwarfed by the 170’ pines that it grows directly underneath, is a new state height record.

Many LiDAR hits in Georgia over 170’ remain to be ground-truthed, but almost all are on steep slopes along large streams.  Cliff Creek and Camp Creek are nearly unique in containing alluvial flats that support productive, white pine dominated forest, and the extra nutrients and water in those flats may explain the greater height of trees along these two streams.  However, I am somewhat surprised the height difference isn’t even greater.  The 166.7’ pine may impress me the most of any tree we measured that day.  It grows above the alluvial flat on a somewhat gentler (perhaps 20 degree), but apparently much drier section of slope.  Rather than hemlocks, that tree shoots out of a perhaps 100’ high canopy of drought tolerant hardwoods.  If a pine can exceed 160’ on a site with regular drought stress, why don’t they regularly exceed 180’ on moister sites?  White pine height seems to vary much less with topography than most tall species in the southern Appalachians.

Jess

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