Complications

     As with any study, there have been a few problems that have been identified.  The soil on area 2 was overtopped by heavy clay during construction of a house above the site prior to the purchase of this land by the Experiment Station in 1960.  The heavy clay content probably increased mortality for loblolly pine in the 8 x 10 plantation (Table 4), and resulted in  less survival for shortleaf pine in the tree clusters (Table 5).   Root rot has produced large amounts of  mortality for shortleaf pine.  By replanting in both 1998 and 1999 we have reduced mortality (Table 5).  Mortality could have been lessened by applying a slurry of Benlate to the root ball prior to planting.

Table 4.  Percent survival by areas in 1999 for loblolly pine in the regular 8 x 10 plantation comparative study. 

Table 5.  Percent survival by areas in 1999 for loblolly pine and shortleaf pine in the tree clusters. 

Figure 11.  A heavy clay soil was dumped onto area 2 during the construction of a house on the hill above the site prior to 1960, which does not seem to affect growth and survival of the pines (this picture of the clusters was taken in May of 2000).      

    Undesirable vegetation has been extremely competitive with forages and pine clusters.  Fertilization has exacerbated the problem. To control undesirable vegetation,  Arsenal AC, Fusilade DX, Oust, Poast Plus, and Velpar herbicides have been applied .  Despite these treatments, trees have been suffering from competition by horsenettle, a weed that is resistant to most chemical control.  Based on recommendations by Carroll Walls of Timberland Co., Escort was successfully applied to control it, beginning in June of 1999.  

Figure 12.  A shortleaf pine seedling (center) in July of 2000 surrounded by undesirable vegetation.  

Figure 13.  Horsenettle (white flowering forb) in area 3 during July of 2000.   

    Fire ants are also a deterrent to growth of plants in the forage alleys.  Paul Francis and Bob Colvin observed a mound about every 10 feet in July of 2000.  Concentration seemed to be higher along the boundaries of the tree clusters.  An "edge" effect has been observed in the clusters where production is lower in the hay alleys along the tree clusters.  It is not known exactly what is causing this, but it maybe competition from undesirable vegetation, applications of herbicides to control undesirable vegetation, and the presence of fire ants.

Figure 14.  Fire ant mounds were located approximately every 10 feet in the forage alleys during July of 2000, especially along the perimeters of the tree clusters.

Figure 15.  "Edge" effect observed in July of 2000 where the tree clusters and the forage alleys convene.

    Deer cause bark damage because they use the trees to rub the felt off of their antlers.  Mortality is small and is less than 1%.

Figure 16.  Scraping of bark by deer to remove the felt from their antlers.

    Due to mortality and higher than normal death rates from a severe drought in 1998, several shortleaf and loblolly pine seedlings had to be replanted in 1999.  Replanting was conducted only in the cluster study areas.  Actual survival rates in 1998 were: loblolly - 75%, and shortleaf - 62%.  Seven percent of the clusters did not have a surviving loblolly pine in the middle.  Survival rates in 1999 were 83% for loblolly pine, 82% for the interior shortleaf (seedlings planted in between the loblolly pine in the cluster rows) and 80% for the exterior shortleaf pine seedlings (seedlings planted adjacent to the loblolly clusters).  Nearly three percent of the clusters still had no surviving loblolly pine.  Replanting will not be conducted again so that there are not more than two age classes in this study.