Each spring, the SCFC performs an aerial survey of South Carolina’s woodlands to detect losses from various damage agents. This year the surveys were conducted from late May through early July. During that time period woodlands were surveyed for bark beetles, defoliators, apparent annosus root rot, timber damage by beaver impoundment and mortality due to fire. The aerial surveys were done at the 20% level with one-mile strips of observation every 5 miles. Additional 100% surveys were done of bottomland hardwood infested with forest tent caterpillar. All survey data were plotted on county road maps with a scale of 1”= 2 miles. The only areas of South Carolina not included in this survey were those inside restricted airspace.
Cessna 172’s or 182’s were utilized for this survey, with crews of one or two SCFC observers. All flights utilized programmed GPS units to aid in air to ground tracking. Actual survey time per county ranged from 2 - 4 hours. Map and GPS preparation and data extraction from the sketch-maps required an additional 4 – 6 hours per county.
Our primary concern dealt with the extent of southern pine beetle activity. Pheromone surveys had predicted some beetle activity in several counties. However, most of last year’s spots had collapsed and mainly new small and isolated spots were detected. In twenty-five counties, some level of bark beetle activity was detected. These bark beetles, mostly the southern pine beetle, were found in 3,279 separate infestations which contained a total of 72,536 trees. These trees contained a volume of 4,122 cords and 2.9 million board feet. This timber had a green stumpage value of $927,223 (See Southern Pine Beetle Survey 2004-1). Ground checks were done on several plotted infestations in each county to determine causal agent and air to ground observer error. Approximately 75% of all infestations checked were due to the southern pine beetle and approximately half of those were active at the time they were checked.
Based on these surveys, five South Carolina Counties continued to be in outbreak status for southern pine beetle. These were Abbeville, Edgefield, McCormick, Oconee and Saluda. (See attached map of current outbreak area). The largest spots were in central Edgefield and McCormick and were only 75 trees in size. The SPB spots in other outbreak counties were small and spreading slowly. These will be monitored until fall at which time their outbreak status will be reconsidered. One hundred percent flights will be conducted in outbreak counties if the spots continue to develop.
The stunning drop in SPB infestations (since 2002) could be attributed to several factors. The predatory clerid beetles have built a respectable population and are busy eating pine beetles. Pine Sawyers also destroyed many SPB while feeding in the inner bark. Woodpeckers and other natural predators and parasites have taken their toll on the SPB. Perhaps the most significant factor was the end of our four-year drought. Although trees have not yet recovered fully from the drought stress, there was plenty of available moisture and subsequent pitch formation by attacked pines thwarted many southern pine beetle attacks.
In early May, the Forest Health Unit began to check areas affected in previous years by forest tent caterpillars. Subsequent ground checks found extensive defoliation by the forest tent caterpillar in stands of bottomland hardwoods in the upper and lower coastal plains. Aerial surveys delineated 433,218 acres of defoliation in 14 counties. This was over twice the acres infested in 2003. Affected river basins included the Great Pee Dee, the Little Pee Dee, the Santee and the Wateree. Many swamps outside river drainages also experienced defoliation (Four hole swamp in Orangeburg and Dorchester counties was heavily impacted). Pure stands of gums suffered the worst defoliation with as much as 100% of the foliage affected. Other bottomland hardwoods were affected to a lesser extent, but many had 50% or more of their leaves eaten by the caterpillars.
The forest tent caterpillar has only one generation each year, so their damage for this growing season is over. Hardwoods usually have no problem tolerating several complete defoliations. In the past, outbreaks have occasionally moved from the swamps to urban settings. Control has rarely been needed or performed.
The Forestry Commission will continue to monitor the status of this insect in the spring aerial surveys. The acreage affected by county is reported on the enclosed Forest Health Aerial Survey for Defoliation – 2004.
Tree Mortality Due to Beaver Activity
During the aerial survey, tree mortality due to beaver impoundment or girdling was mapped. All but three South Carolina counties experienced some forest losses due to beavers. Only trees which died during the last year were reported as lost. For instance, a 20-acre beaver impoundment with two acres of fresh tree mortality was recorded as two acres of beaver damage. The majority of this damage was in hardwood areas and losses were estimated based on 20 cords per acre with a value of $18/ cord. The total losses to beavers were estimated at 17,255 acres or 310,050 cords with a value of $5,580,900.
New mortality due to beaver impoundment nearly doubled from last year’s levels. This was likely due to the great increase in precipitation during the last two years.
Beaver-caused mortality is reported on the enclosed 2004 Forest Health Aerial Survey Summary.
Tree Mortality Due to Fire
Mortality due to wildfire and late or hot controlled burning was also plotted during the aerial survey. Fire damage was reported from 35 S.C. counties. Only damage that occurred in the last year was reported. Fire damage was only recorded if trees were actually killed. Needle singe was not considered as mortality.
Fire-caused mortality was recorded on 15,455 acres of forestland. The majority of this land was a pine type and losses were estimated at 20 cords/ acre with a value of $18/ cord. This timber had a green value estimated at $5,007,420. This was nearly twice the mortality recorded in 2003. These results are also reported on the enclosed 2004 Forest Health Aerial Survey Summary.
Annosus Root Rot Losses
This year we again surveyed for apparent losses to annosus root rot. This disease has been increasing in occurrence and severity for the last few years and this survey was an attempt to quantify affected acreage. Thinned pine stands with scattered mortality on sandy land were recorded as probable for annosus. Since this mortality is scattered, it is harder to see from the air and the results are likely conservative. Loss was averaged at 1.5 cords per acre of recorded damage. A total of 31 counties had some levels of apparent annosus detected. The total affected acreage was 36,740. Dollar loss on this acreage was estimated at $991,980. These results are also included in the attached 2004 Forest Health Aerial Survey Summary.
Losses to annosus declined slightly because that disease causes most mortality when infected pines suffer from drought stress. However, the disease can persist for about seven years in an infected root system and mortality will continue as additional drought occurs. In the absence of drought, windthrow is one of the most common symptoms of annosus.
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