2015 Florida Southern Pine Beetle Forecast

Transcription

1 2015 Florida Southern Pine Beetle Forecast Anthony Ayers, OPS Forester and Christopher Pearce, Survey Coordinator Florida Forest Service, Forest Health Section Summary A pheromone trap survey was conducted in March 2015 as part of an ongoing program to monitor the populations of Southern Pine Beetle (SPB) and its associated predators. The purpose is to provide an early-season prediction of the potential level of SPB activity in select Florida counties, and identify areas which may be at increased risk for an outbreak. The results of the 2015 survey indicate that SPB populations are low at all trap locations and suggest that the risk of widespread SPB infestations in the surveyed counties is low. Introduction Since 1995, the Florida Forest Service (FFS) has participated in an annual southwide Southern Pine Beetle (Dendroctonus frontalis, or SPB) spring trapping survey. This survey monitors numbers of adult SPBs and their clerid predators captured in pheromone-baited flight traps during the SPB primary spring dispersal phase. The results are used as an early-season prediction of SPB population trends and activity levels, allowing forest managers to identify areas of potential SPB activity in advance of aerial detection flights. The survey also provides data for monitoring SPB population levels from year to year. The survey technique and accompanying prediction model were developed by Dr. Ron Billings at the Texas Forest Service, have been employed throughout the Southeast since 1986, and have proven to be 75-85% accurate in predicting SPB activity at the county level for a given year. The Florida survey successfully predicted outbreak levels for several counties in 2001 as well as statewide low levels of activity from 2003 through In 2012 and 2013 the survey correctly predicted moderate activity in St. Johns County. Methods The 2015 Florida survey was conducted using from one to three traps (Lindgren funnel traps baited with alpha- and beta-pinene and the primary SPB aggregation pheromone frontalin) in each of 26 counties, with each trap located in a different stand of susceptible forest type. The 26 counties surveyed included those that are most likely to experience SPB problems based on historical outbreaks and/or their relative abundance of loblolly pines. As in previous years, effort was made to place traps in stands containing sawtimber size loblolly pine or areas where loblolly pine is most abundant. Traps were distanced at least 40 feet from any pine tree and checked weekly by FFS foresters in March. Numbers of SPBs and their clerid beetle predators (Thanasimus dubius) were counted for each of the four weekly collections per trap. Numbers of SPB/trap/day and the %SPB were then applied to the Modified SPB Prediction Chart model (Ron Billings, Texas Forest Service) to provide a forecasted level of SPB activity for the remainder of the year. Forecasted activity was based on a relative scale of Low, Moderate, High, or Outbreak.

2 Results and Discussion The 2015 survey results suggest that SPB populations will remain low at all trap locations in the 26 counties surveyed across northern and central Florida (Figure 1). Both the total number of SPB/trap/day and %SPB remained static and relatively unchanged from 2014 in a majority of counties surveyed (Table 1). This suggests that the generally low levels of SPB activity that the state has experienced since 2003 will continue. Both Putnam and Clay counties were shown to be declining in predicted population trends involving SPB activity. Putnam County was predicted to have moderate activity in 2014 and Clay County was one of three counties in 2014 to have SPB infestations. Despite the predicted decrease in SPB activity, both counties will continue to be monitored closely. Duval County, which has already experienced SPB activity earlier this year, was shown to have an increase from 2014 in the number of SPB/Trap/Day collected. Special attention and monitoring will be applied to Duval County during the summer SPB aerial surveys. As in previous years, all counties in FFS Districts/Centers 1-12 will be asked (via a memo issued in May) to conduct an initial aerial SPB detection survey. Procedural guidelines for aerial surveys, ground checking, and reporting are available to FFS foresters on the Forest Health website at: Health/Forest-Insects/Southern-Pine-Beetle/Southern-Pine-Beetle-Aerial-Survey-Procedures The USDA Forest Service Forest Health Technology Enterprise Team (FHTET) has completed the National Insect and Disease Risk Map Project which integrates 187 risk models that accounts for regional variation in forest health conditions. Projected BA loss to host tree species from Southern Pine beetle is shown in Figure 2 and may be helpful in prioritizing areas for surveillance. FFS Foresters who would like to obtain detailed map files of projected risk modeled in GIS or other formats for specific areas may contact Chris Pearce at christopher.pearce@freshfromflorida.com. Links to SPB control information can be reached from the Forest Health Section SPB website at: Health/Forest-Insects/Southern-Pine-Beetle. Because of limited survey inputs, a vast resource of potential habitat, and the limitations of the predictive model, the forecast presented here cannot be expected to be 100% accurate. Low/Static SPB predictions do not guarantee that troublesome infestations will not develop on a local or limited basis in some counties. Activity predictions are likely to be more accurate for the 5-mile radius region around each trap than for the county as a whole. Given the limitations of the forecast, the recent drought and/or flooding experienced by some areas in the state, and the potential for environmental conditions to change after the survey, areas of suspicious pine mortality should be promptly inspected for evidence of SPB in the coming months. Sincere thanks to all the foresters who were involved in installing traps, making weekly collections, and submitting jars for sample processing. Please forward any and/or all of this report and the accompanying attachments to anyone you think may be interested. In the near future, this report will be available on the Florida Forest Service s website.

3 (See Table 1 and Figures 1 and 2 below) Table 1: 2015 Florida SPB Trapping Survey: Results, Trends, and Predictions No. of Predictions No. of spots # of SPB/trap/day %SPB b Population Activity County traps In Trend a Trend a Trend a Level c Alachua 3 1 <1 <1 S 33% 60% S S Low Baker 1 0 <1 <1 S 100% 89% S S Low Bradford 1 0 <1 <1 S 100% 62% D S Low Clay D 91% 13% D D Low Columbia 3 0 <1 <1 S 29% 9% S S Low Duval 1 5 <1 4 I 94% 26% D S Low Gadsden 2 0 <1 <1 S 15% 32% S S Low Hamilton 1 0 <1 <1 S 15% 17% S S Low Hernando <1 S 67% 100% I I Low Holmes 1 0 <1 0 S 2% 0% S S Low Jackson <1 S 0% 3% S S Low Jefferson S 0% 0% S S Low Lake S 0% 0% S S Low Leon <1 S 0% 21% S S Low Levy <1 S 0% 8% S S Low Madison S 0% 0% S S Low Marion 3 0 <1 <1 S 37% 24% S S Low Nassau 2 0 <1 <1 S 87% 71% S S Low Okaloosa S 0% 0% S S Low Orange S 0% 0% S S Low Putnam D 95% 37% D D Low Seminole <1 S 0% 92% I I Low St. Johns S 100% 80% S S Low Suwannee 2 0 <1 <1 S 25% 50% S S Low Walton S 0% 0% S S Low Washington S 0% 0% S S Low STATE TOTAL <1 <1 S 34% 31% S S Low a D=Declining, S=Static, I=Increasing. Annual changes of <3 units or <30% were considered 'Static'. b %SPB is the ratio of SPBs to the combined clerid-plus-spb (predator + prey) population, expressed as a percent. c Activity level prediction based on model developed by Ron Billings, Texas Forest Service.

4 Figure 1: 2015 Southern Pine Beetle Forecasted Infestation Levels at Five Mile Trap Radii. All counties surveyed were show to fall into a low class for forecasted SPB activity.

5 Figure 2: The Southern Pine Beetle Florida Township Hazard Rating Map is based on a model developed by the USDA Forest Service Forest Health Technology Enterprise Team as part of a hazard mapping project for the southeastern United States. The model computes hazard scores based on input variables that estimate the density and basal area of the most susceptible host pine species (e.g., loblolly and shortleaf pine) and soil drainage characteristics. Each township score represents an average for the forested areas within the township. The hazard map is subject to change from year to year with changing forest conditions and improvements made to the hazard model. Hazard is an estimate of where SPB infestations may be likely to develop based on forest conditions; it does not mean that SPB infestations are predicted for a certain area in a given year.