Each spring, the SCFC Insect and Disease Section performs an aerial survey of South Carolina’s woodlands to detect losses due to bark beetles, defoliators, apparent annosus root rot or Black Turpentine Beetle (BTB) mortality, timber damage by beaver impoundment, and mortality due to fire. These aerial surveys were performed at the 20% level (one-mile observation strips every 5 miles) statewide utilizing Cessna 172 or 182 aircraft. We have completed the 2008 Spring Aerial Survey; the results of this survey are attached.
S.C. Forestry Commission
Forest Health Aerial Survey
August - 2008
Each spring, the SCFC Insect and Disease Section 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 July. 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 172s or 182s 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 (SPB) activity. The spring SPB pheromone surveys had predicted scattered beetle activity in several counties: Abbeville, Edgefield, McCormick, Newberry, and Union Counties. These counties trapped sufficient amount of SPB to receive a prediction of static – moderate pine mortality. In 33 counties, some level of bark beetle activity was detected during the aerial survey, however, there were mainly new small and isolated spots detected. These bark beetles, mostly Ips and SPB, were found in 940 separate infestations, which contained a total 31,963 trees. These trees contained a volume of 1,813 cords and 1.27 million board feet. This timber had a green stumpage value of $408,046. Results can be found on Southern Pine Beetle Survey 2008-1. Ground checks were done on several plotted infestations to determine causal agent and air to ground observer error.
Based on these surveys, no South Carolina counties continued to be in outbreak status for southern pine beetle. The largest spots detected were in Charleston and Berkeley counties in the Francis Marion National Forest. 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 can be attributed to several factors. The predatory clerid beetles have built a respectable population, although lower than 2007, 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.
In early May, the Forest Health Unit began to check areas affected in previous years by Forest Tent Caterpillars. In 2007, ground checks found extensive defoliation by the Forest Tent Caterpillar in stands of bottomland hardwoods in the upper and lower coastal plains in eight counties. Aerial surveys in 2008 found little acreage of defoliation compared to previous years. In previous years, 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 – 2008.
Tree Mortality Due to Beaver Activity
During the aerial survey, tree mortality due to beaver impoundment or girdling was mapped. Forty-one 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. The observed losses due to beaver damage were estimated at 738 acres (acreage is based on 20% survey).
Beaver-caused mortality is reported on the enclosed 2008 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 38 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 observed on 2,191 acres of forestland (acreage is based on 20% survey); the majority of this land was a pine type. The observed acreage of mortality due to fire observed was less than the mortality recorded in 2007. These results are reported on the enclosed 2008 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 recorded 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 30 counties had some levels of apparent annosus/ BTB detected. The total affected acreage was 7,170. Dollar loss on this acreage was estimated at $258,120. These results are included on the attached 2008 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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