Here are the results of our spring aerial survey. Southern Pine Beetle activity continues to decline. There are no South Carolina counties in outbreak status. The largest spots were detected in central Edgefield and McCormick and were only 40 trees in size .
Results of defoliator, fire damage, beaver damage, and annosus root rot surveys are also included in the report. Defoliation and beaver damage decreased from last year, fire damage increased, and annosus root rot remained approximately the same.
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S.C. Forestry Commission
Forest Health Aerial Survey
September - 2006
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 late June. During that time period, woodlands were surveyed for bark beetles, defoliators, apparent annosus root rot or Black Turpentine Beetle (BTB) mortality, 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. (The annosus/ BTB survey was at the 10% level due to the difficulty of detecting annosus symptoms from the air). 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 preprogrammed 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 scattered beetle activity in several counties. However, most of last year’s spots had collapsed and mainly new small and isolated spots were detected. In 33 counties, some level of bark beetle activity was detected. These bark beetles, mostly the southern pine beetle, were found in 2,267 separate infestations which contained a total of 41,245 trees. These trees contained a volume of 2,349 cords and 1.6 million board feet. This timber had a green stumpage value of $529,541. Results are reported on Southern Pine Beetle Survey 2006-1. Ground checks were done on several plotted infestations in each county to determine causal agent and air to ground observer error. Approximately 50% of all infestations checked were due to the southern pine beetle and approximately 25% of those were active at the time they were checked.
Based on these surveys, no South Carolina Counties continued to be in outbreak status for southern pine beetle. The largest spots detected were in central Edgefield and McCormick and were only 40 trees in size. The SPB spots in other counties were small and spreading slowly. These will be monitored until fall at which time county outbreak status will be reconsidered. One hundred percent flights will be conducted if outbreaks develop.
The drop in SPB infestations since 2005 can be attributed to several factors. The predatory clerid beetles have built a respectable population, although lower than 2005, 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 (in 2002). Trees recover from drought stress over a period approximately equal to the duration of the drought. Our pines have not yet recovered fully from the drought stress, but there is plenty of available soil moisture. This allows prolific pitch formation by attacked pines, which thwarts 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 371,700 acres of defoliation in 14 counties. This was approximately 20,753 acres less than was infested in 2005. Affected river basins included the Edisto, the Little Pee Dee, the Santee and the Savannah. Many swamps outside river drainages also experienced defoliation (Four-hole swamp in Orangeburg and Dorchester counties was heavily impacted again this year). 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 Forest Tent Caterpillar.
The Forest Tent Caterpillar has only one generation each year; therefore the damage seen in this growing season is complete. 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 continued to monitor the status of this insect in the Spring Aerial Survey. The acreage affected by county is reported on the enclosed Forest Health Aerial Survey for Defoliation – 2006.
Tree Mortality Due to Beaver Activity
During the aerial survey, tree mortality due to beaver impoundment or girdling was mapped. All forty-six 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 13,870 acres or 277,400 cords with a value of $4,993,200.
New mortality due to beaver impoundment declined slightly from last year’s levels. This was likely due to the continued heavy precipitation during 2005. Also, the drains in some Pee Dee Counties have previously lost almost all their forest cover.
Beaver-caused mortality is reported on the enclosed 2006 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 42 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 20,360 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 $7,329,600 . This was approximately double the mortality recorded in 2005. These results are also reported on the enclosed 2006 Forest Health Aerial Survey Summary.
Annosus Root Rot / Black Turpentine Beetle Losses
This year we again surveyed for apparent losses to annosus root rot. We also added in scattered pine mortality due to infestation by Black Turpentine Beetle. Annosus has been increasing in occurrence and severity for the last few years and this survey was an attempt to quantify affected acreage. Also, we have observed a significant increase in damage by BTB. Scattered mortality in pine stands were recorded as probable for annosus or BTB. Since this mortality is scattered, it is harder to see from the air and the results are likely conservative. Loss was averaged at two cords per acre of recorded damage. A total of 34 counties had some levels of apparent annosus/ BTB detected. The total affected acreage was 50,980. Dollar loss on this acreage was estimated at $ 1,832,040 . These results are also included on the attached 2006 Forest Health Aerial Survey Summary.
Once a pine stand becomes infected with annosus, the disease can persist for about seven years in the infected root systems. Infestations by Black Turpentine Beetle may persist for several years, depending mostly on stand stress.
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