Top 20 NRS Pubshttps://treesearch.fs.fed.us/pubs/Top 20 NRS Pubsen-usFri, 19 Apr 2019 17:34:13 +0000An integrated assessment of the potential impacts of climate change on Indiana forestshttps://treesearch.fs.fed.us/pubs/57853Forests provide myriad ecosystem services many of which are vital to local and regional economies. Consequently there is a need to better understand how predicted changes in climate will impact forest dynamics and the implications of such changes for society as a whole. Here we focus on the impacts of climate change on Indiana forests which are representative of many secondary growth broadleaved forests in the greater Midwest region in terms of their land use history and current composition. We found that predicted changes in climate for the statewarmer and wetter winterssprings and hotter and potentially drier summerswill dramatically shape forest communities resulting in new assemblages of trees and wildlife that differ from forest communities of the past or present. Overall suitable habitat is expected to decline for 1729 of tree species and increase for 4352 of tree species in the state depending on the region and climate scenario. Such changes have important consequences for wildlife that depend on certain tree species or have ranges with strong sensitivities to climate. Additionally these changes will have potential economic impacts on Indiana industries that depend on forest resources and products (both timber and nontimber). Finally we offer some practical suggestions on how management may minimize the extent of climateinduced ecological impacts and highlight a case study from a tree planting initiative currently underway in the Patoka River National Wildlife Refuge and Management Area.Mon, 01 Apr 2019 09:47:13 +0000Analysis of Climate Change Impacts on Tree Species of the Eastern US Results of DISTRIBII Modelinghttps://treesearch.fs.fed.us/pubs/57857Forests across the globe are faced with a rapidly changing climate and an enhanced understanding of how these changing conditions may impact these vital resources is needed. Our approach is to use DISTRIBII an updated version of the Random Forest DISTRIB model to model 125 tree species individually from the eastern United States to quantify potential current and future habitat responses under two Representative Concentration Pathways (RCP 8.5 high emissions which is our current trajectory and RCP 4.5 lower emissions by implementing energy conservation) and three climate models. Climate change could have large impacts on suitable habitat for tree species in the eastern United States especially under a high emissions trajectory. On average of the 125 species approximately 88 species would gain and 26 species would lose at least 10 of their suitable habitat. The projected change in the center of gravity for each species distribution (i.e. mean center) between current and future habitat moves generally northeast with 81 species habitat centers potentially moving over 100 km under RCP 8.5. Collectively our results suggest that many species will experience less pressure in tracking their suitable habitats under a path of lower greenhouse gas emissions.Wed, 03 Apr 2019 09:18:23 +0000Defects and Grading after Kiln Drying Hardwood Lumber Sawn from Smalldiameter Logshttps://treesearch.fs.fed.us/pubs/57920Close inspection of black cherry (Prunus serotina) sugar maple (Acer saccharum) and northern red oak (Quercus rubra) lumber before and after kiln drying revealed the factors that can affect the quality of kilndried lumber from smalldiameter logs. Speciesspecific kiln drying schedules with temperature and humidity modifications formulated by a kiln drying expert were employed in this study to determine whether alternate drying protocols could improve the drying outcomes. Comparing lumber grades of individual boards before and after drying indicated that overall grade loss in the kiln was common but was affected by both species and the applied drying schedule. Most lumber defects were attributed to stresses that occurred during the drying process and were more prevalent in the postdrying inspection with bow defects being the exception. The modified kiln schedules improved the drying defect outcomes for the black cherry and red oak compared with the conventional schedules for these species. For the sugar maple the schedulebased improvement was less consistent. For the black cherry and red oak the percentage of boards whose grade decreased using conventional kiln protocols was approximately 10 lower than that of the lumber that was dried using the modified kiln protocols. Sugar maple had a smaller change of 7.Tue, 16 Apr 2019 14:00:34 +0000Effects of prescribed fire and steminjection herbicide on Ailanthus altissima demographics and survivalhttps://treesearch.fs.fed.us/pubs/57852Ailanthus altissima ((Mill.) Swingle treeofheaven Chinese sumac stink tree) is a nonnative invasive tree that is common throughout much of the eastern United States. It can invade and expand dramatically when forests are disturbed. Anecdotal evidence suggests that fire might facilitate its spread but the relationship between fire and this prolific invasive tree is poorly understood. To better understand the impacts of fire on Ailanthus we conducted a study at Tar Hollow State Forest in southeastern Ohio USA where Ailanthus is widely distributed. Our objective was to quantify the direct effects of prescribed fire on the demography of Ailanthus populations with and without the preburn application of the steminjected herbicide imazapyr. We quantified demographic attributes (survival density and sprouting) of Ailanthus germinants seedlings saplings and trees in a field experiment with four treatment combinations (1) no fire and no herbicide (2) herbicide (3) fire and (4) herbicide plus fire. Ailanthus stemsgt3 cm dbh were steminjected with the herbicide imazapyr in late summer to early fall followed by prescribed fire in April. We determined that herbicide plus prescribed burn treatment was highly effective in killing large saplings and trees with no resprouting evident after four growing seasons. In the season immediately after the burn with and without herbicide treatment small Ailanthus sapling and seedling abundance increased but did not persist. Over time Ailanthus germinants and sprouts from topkilled stems were poor competitors with fastergrowing postfire woody regeneration as forest floor shading increased. In addition the late growing season application of imazapyr was highly effective in killing Ailanthus and subsequent sprouts. This study the first to quantify the direct effects of fire on Ailanthus demonstrates that prescribed fire alone does not appear to facilitate the spread of Ailanthus.Mon, 01 Apr 2019 09:29:57 +0000Efficacy of Kamona strain Deladenus siricidicola nematodes for biological control of Sirex noctilio in North America and hybridisation with invasive conspecificshttps://treesearch.fs.fed.us/pubs/57863Sirex noctilio is an invasive woodwasp that along with its symbiotic fungus has killed pine trees (Pinus spp.) in North America and in numerous countries in the Southern Hemisphere. We tested a biological control agent in North America that has successfully controlled S. noctilio in Oceania South Africa and South America. Deladenus siricidicola nematodes feed on the symbiotic white rot fungus Amylostereum areolatum and can switch to being parasitic on S. noctilio. When parasitic the Kamona nematode strain can sterilise the eggs of S. noctilio females. However in North America a different strain of D. siricidicola (NA) presumably introduced along with the woodwasp parasitises but does not sterilise S. noctilio. We tested the sterilising Kamona biological control strain of D. siricidicola against S. noctilio in North America. Interactions between the biological control strain and the NA strain could include competitive exclusion coinfection within hosts or hybridisation. We reared D. siricidicola Kamona on an A. areolatum strain native to North America (IGSBE) and another strain (IGSBDF) used commercially to massproduce the nematode in Australia. We inoculated Kamona reared on either strain of A. areolatum into logs infested with S. noctilio larvae and compared parasitism rates against control logs. Individual nematodes were isolated from S. noctilio hemocoels and from sterilised eggs and were genotyped with eight microsatellite loci. A high rate of parasitisation of S. noctilio by D. siricidicola NA was found for all treatments and we found evidence of both coinfection and hybridisation. Surprisingly sterilisation rates were not related to the rates of parasitisation by D. siricidicola Kamona.Thu, 04 Apr 2019 12:19:12 +0000Forest ethnography An approach to study the environmental history and political ecology of urban forestshttps://treesearch.fs.fed.us/pubs/57869A landscape succession paradigm has shaped much of our understanding about the processes of forest emergence and transformation in the United States. Drawing heavily from theory and method in environmental history this paradigm has focused attention on the role of landscapescale shifts in land use and land cover in the production of forests. The geography of cities is patchy dynamic and heterogeneous with change and differences occurring at much smaller scales (e.g. Jacobs 1961 Clay 1973) compared to coarse scale of stand replacing successions affecting rural forests (Grove et al. Ecosyst Health and Sustain 2(9)e01239 2016 Pickett et al. Urban Ecosyst 20(1)114 2017). Therefore trying to understand how urban forests came to be as well as what they are requires a research approach that is specific to the land use dynamics of cities and attentive to the social life of urban forests. In response to this methodological gap this paper describes a research approach called forest ethnography which we are piloting in Baltimore Maryland as part of the Baltimore Ecosystem Study (BES) one of the National Science Foundations urban Longterm Ecological Research Programs (LTER). As we describe we propose that an urban forest ethnography approach can contribute to our understanding of both forest environmental history and urban political ecology.Fri, 05 Apr 2019 12:15:21 +0000Greenhouse gas emissions and removals from forest land and urban trees in the United States 19902017https://treesearch.fs.fed.us/pubs/57919As a signatory to the United Nations Framework Convention on Climate Change (UNFCCC) the United States has been reporting an economywide inventory of greenhouse gas (GHG) emissions and removals since the mid1990s (U.S. EPA 2019). Forest land harvested wood products (HWPs) and urban trees within the land sector collectively represent the largest net carbon (C) sink in the United States offsetting more than 11 percent of total GHG emissions annually (U.S. EPA 2019). Estimates of GHG emissions and removals are compiled by U.S. Department of Agriculture Forest Service scientists and are based primarily on national forest inventory (NFI) data collected and maintained by the Forest Inventory and Analysis (FIA) program within the USDA Forest Service. This reportthe first in a new series of annual updatesprovides an overview of the status and trends of GHG emissions and removals from forest land HWPs and urban trees in settlements in the United States from 1990 to 2017. The national estimates summarized here are based on the compilation reported in the Land Use LandUse Change and Forestry chapter of the U.S. EPA (2019) submission to the UNFCCC. The national scale estimates reported here will also be disaggregated by individual State in future Resource Updates and are currently available upon request (see contact information page 4).Tue, 16 Apr 2019 13:02:38 +0000Lawn mowing frequency in suburban areas has no detectable effect on Borrelia spp. vector Ixodes scapularis (Acari Ixodidae)https://treesearch.fs.fed.us/pubs/57858Forests have become increasingly fragmented throughout the US with residential development serving as the primary driver of these changes. These altered landscapes have provided suitable conditions for a broad range of wildlife including blacklegged ticks and their hosts. Lawns dominate residential landscapes and thus their management has the potential to reduce the likelihood of contact with ticks in residential yards. We tested the hypothesis that lawn mowing frequency influences tick occurrence in 16 suburban yards in Springfield MA. We conducted 144 tick drags in lawns of various lawn mowing frequencies (mowed every week every 2weeks and every 3weeks) and did not collect any ticks of any species. Promoting frequent mowing (i.e. shorter lawns) and the removal of grass clippings could have minimal impacts on tick microhabitats but is consequential for beneficial wildlife and other ecosystem services associated with urban biodiversity.Wed, 03 Apr 2019 13:45:14 +0000Life history and mortality factors of Agrilus mali Matsumura (Coleoptera Buprestidae) in wild apples in Northwestern Chinahttps://treesearch.fs.fed.us/pubs/57906Wild apple Malus sieversii (Ledeb.) M. Roem. (Rosales Rosaceae) the ancestor of cultivated apples is widely distributed in Central Asia and is recognized as an important germplasm bank. Recently the invasive pest Agrilusmali Matsumura (Coleoptera Buprestidae) originally distributed in eastern Asia has damaged endemic apple forests in the Yili River valley Xinjiang China and has spread rapidly infesting more than 80 of wild apple trees in this region. We investigated the lifehistory traits and native natural enemies in the recently invaded range during 2016 and 2017. Agrilus mali has a univoltine life cycle and overwinters as young larvae in galleries in the cambium. Adults emerged from early June to midAugust and their density peaked in midJuly. Several native natural enemies were identified from Agrilus mali larvae including Atanycolus denigrator (L.) (Hymenoptera Braconidae) the mite Pyemotes moseri Yu et Liang (Acari Pyemotidae) and fungal entomopathogens. Combined these natural enemies were responsible for mortality rates ranging from 20 to 80 during the summer and autumn. The most abundant and important natural enemy was A. denigrator which was responsible for up to 15 mortality of A. mali. The results of the present study suggest that augmentation and conservation of A. denigrator and P. moseri should be considered with respect to biological control against this devastating pest.Thu, 11 Apr 2019 07:51:58 +0000Microsatellite Borders and Microsequence Conservation in Juglanshttps://treesearch.fs.fed.us/pubs/57878Walnuts (Juglans spp.) are economically important nut and timber species with a worldwide distribution. Using the published Persian walnut genome as a reference for the assembly of short reads from six Juglans species and several interspecific hybrids we identified simple sequence repeats in 12 Juglans nuclear and organellar genomes. The genomewide distribution and polymorphisms of nuclear and organellar microsatellites (SSRs) for most Juglans genomes have not been previously studied. We compared the frequency of nuclear SSR motifs and their lengths across Juglans and identified sectionspecific chloroplast SSR motifs. Primer pairs were designed for more than 60000 SSRcontaining sequences based on alignment against assembled scaffold sequences. Of the gt60000 loci 39000 were validated by ePCR using unique primer pairs. We identified primers containing 100 sequence identity in multiple species. Across species sequence identity in the SSRflanking regions was generally low. Although SSRs are common and highly dispersed in the genome their flanking sequences are conserved at about 90 to 95 identity within Juglans and within species. In a few rare cases flanking sequences are identical across species of Juglans. This comprehensive report of nuclear and organellar SSRs in Juglans and the generation of validated SSR primers will be a useful resource for future genetic analyses walnut breeding programs highlevel taxonomic evaluations and genomic studies in Juglandaceae.Mon, 08 Apr 2019 11:37:11 +0000Northern mixedwood composition and productivity 50years after wholetree and stemonly harvesting with and without postharvest prescribed burninghttps://treesearch.fs.fed.us/pubs/57916Wholetree harvesting (WTH) is increasingly used to extract forest biomass for energy and commercial wood products. Slash burning which is used for fuels reduction and site preparation also reduces aboveground biomass. Yet effects of incremental biomass reduction from either WTH or slash burning on longterm forest productivity and composition are poorly understood. This research uses data from a 50yearold study in northern mixedwood (Picea Abies hardwood) stands on the Penobscot Experimental Forest in Maine U.S.A. to address these concerns. Clearcutting was conducted in 196465 with WTH stemonly harvesting (SOH) and SOH with postharvest prescribed burning of logging residues (SOHB). Growing stock composition and soil properties (O horizon thickness and soil drainage) were measured 50 years after treatment. Hardwood composition (percent of total basal area) increased from pretreatment levels in all treatments but was greater in SOHB than SOH and WTH. Eastern white pine (Pinus strobus) though a minor species was significantly more abundant in WTH than SOH or SOHB. Results indicated no other significant differences in species composition or in stand structure or productivity (total basal area stem density dominant height quadratic mean diameter and total aboveground carbon stock) among treatments. Independent of treatment we observed relationships between soil properties and stem density and quadratic mean diameter (qmd) such that lower stem density and greater qmd were observed on sites with greater O horizon thickness. These findings suggest that relative to SOH WTH and SOHB do not degrade northern mixedwood stand productivity as expressed by stand structure and stocking 50 years after a single treatment even on a site with low to moderate production potential. Nevertheless species shifts associated with clearcutting (i.e. shadetolerant conifer to intolerant hardwood composition) and prescribed burning in this forest type should be considered in light of the potential application of either for intensive silviculture treatments.Mon, 15 Apr 2019 11:02:55 +0000Observations of Turbulent Heat and Momentum Fluxes during Wildland Fires in Forested Environmentshttps://treesearch.fs.fed.us/pubs/57901Turbulent fluxes of heat and momentum in the vicinity of wildland fires contribute to the redistribution of heat and momentum in the fire environment which in turn can affect the heating of fuels fire behavior and smoke dispersion. As an extension of previous observational studies of turbulence regimes in the vicinity of wildland fires in forested environments this study examines the effects of spreading surface fires and forest overstory vegetation on turbulent heat and momentum fluxes from near the surface to near the top of the overstory vegetation. Profiles of highfrequency (10 Hz) wind velocity and temperature measurements during two prescribed fire experiments are used to assess the relative contributions of horizontal and vertical turbulent fluxes of heat and momentum to the total heat and momentum flux fields. The frequencydependent temporal variability of the turbulent heat and momentum fluxes before during and after firefront passage is also examined using cospectral analyses. The study results highlight the effects that surface wildland fires and forest overstory vegetation collectively can have on the temporal and vertical variability of turbulent heat and momentum fluxes in the vicinity of the fires and the substantial departures of heat and momentum cospectra from typical atmospheric surfacelayer cospectra that can occur before during and after firefront passage.Wed, 10 Apr 2019 08:15:44 +0000Sensitivity of lowlevel jets to landuse and landcover change over the continental U.S.https://treesearch.fs.fed.us/pubs/57855Lowertropospheric wind maxima known as lowlevel jets (LLJs) play a vital role in weather and climate around the world. In this study two 10year (20062015) regional climate simulations using current (2011) and future (2100) landuselandcover (LULC) patterns over the continental United States (CONUS) are used to assess the sensitivity of LLJ properties including jet occurrence maximum speed and the elevation of the maximum to changes in LULC. The three simulated LLJ properties exhibit greater sensitivity in summer than in winter. Summertime jets are projected to increase in frequency in the central CONUS where cropland replaces grassland and decrease in parts of the OhioRiver Valley and the Southeast particularly Florida where urban expansion occurs. Little change is projected for wintertime jet frequency. Larger modifications to jet speed and elevations are projected in parts of the Ohio River Valley the upper Southeast and the Intermountain West. While there is some evidence of weaker more elevated jets with urban expansion the connection between changes in jet speed and elevation and changes in LULC patterns at a given location is weak. This result suggests that LULC will primarily affect the largescale atmospheric conditions that contribute to the formation of LLJs particularly in winter.Tue, 02 Apr 2019 13:35:17 +0000The Laser Vegetation Detecting Sensor A Full Waveform LargeFootprint Airborne Laser Altimeter for Monitoring Forest Resourceshttps://treesearch.fs.fed.us/pubs/57907The use of satelliteborne largefootprint LiDAR (light detection and ranging) systems allows for the acquisition of forest monitoring data. This paper mainly describes the design use operating principles installation and data properties of the new Laser Vegetation Detecting Sensor (LVDS) a LiDAR system designed and developed at the Academy of Forest Inventory and Planning (AFIP) and the Beijing Institute of Telemetry (BIT). Data from LVDS were used to calculate the mean height of forest trees on sample plots using data collected in the Hunan province of China. The results show that the full waveform data obtained by LVDS has the ability to accurately characterize forest height. The mean absolute percentage error of mean forest height per plot in flat areas was 6.8 with a mean absolute deviation of 0.78 m. The airborne LVDS system provides prototype data sets and a platform for instrument proofofconcept studies for Chinas Terrestrial Ecosystem Carbon Monitoring (TECM) mission which is an Earth remote sensing satellite due for launch in 2020. The information produced by LVDS allows for forest structure studies with high accuracy and coverage of large areas.Thu, 11 Apr 2019 14:26:45 +0000Timing is Not Everything Assessing the Efficacy of Pre Versus PostHarvest Herbicide Applications in Mitigating the Burgeoning Birch Phenomenon in Regenerating Hardwood Standshttps://treesearch.fs.fed.us/pubs/57917Sweet birch (Betula lenta L.) is aggressively recruiting in temperate forest understories of the eastern United States and often dominates the postdisturbance seedling community diminishing diversity and hindering sustainable silviculture. The type and timing of silvicultural actions affect birch recruitment via their effects on seedling recruitment survival and growth. Here we examine birch regeneration under two contrasting treatment sequences pre versus postshelterwood harvest herbicide application (HS vs. SH) in combination with whitetailed deer (Odocoileus virginianus Zimmerman) browsing (fenced vs. unfenced) at 22 sites in northwestern Pennsylvania USA. Additionally we examine how treatments interact with additional site factors including potential propagule sources and site productivity (i.e. integrated moisture index). We found the SH sequence initially reduced birch density by 71 relative to the HS sequence however the magnitude of this reduction waned over five growing seasons. Furthermore birch proliferated following the HS sequence only where mature birch were present. Deer browsing reduced birch height by 29 relative to fenced areas protected from browsing however by the fifth growing season birch seedlings were over twice as tall as other hardwood species across all treatments. Finally increasingly mesic sites enhanced birch height growth. In sum although postharvest herbicide (SH) provides shortlived control over birch land managers should also consider browse pressure seed source and site productivity as these may enhance or diminish the efficacy of postshelterwood herbicide sequence effects on birch.Mon, 15 Apr 2019 11:10:04 +0000Tree compensation rates Compensating for the loss of future tree valueshttps://treesearch.fs.fed.us/pubs/57918When healthy trees are removed common methods of compensation are either monetary or replanting new trees. Accurate monetary compensation for large healthy trees is difficult to ascertain and often uses formulas based on tree attributes such as species size location and condition. Compensation based on leaf area is more direct as most tree values are related to healthy leaf area. Using leaf area a tree compensation rate can be determined (how many new trees are needed to compensate for the removal of a healthy tree). However compensation also needs to consider the future benefits provided by both the removed tree and newly planted trees. This paper provides a new method of tree compensation based on comparing the net present value of leaf area between a removed tree and planted replacement trees. This proposed method is not intended to replace existing methods but rather facilitate discussion and science to improve estimating tree values and compensation. Using this new approach with a threepercent discount rate and a four percent annual mortality rate maximum compensation rates using comparable trees reached 13.7 trees for large trees and 3.3 trees for small trees. An overall maximum compensation of 41.1 trees was reached when large trees with a onepercent mortality rate were replaced with small trees with a fourpercent mortality rate. Compensation rates vary with tree size estimated life span remaining (mortality rate) discount rates and type of replacement tree used (large vs. small trees). Compensation for tree loss can either be through planting of replacement trees or the conversion of replacement trees to a monetary value based on local planting costs.Tue, 16 Apr 2019 07:49:11 +0000Les effets des arbres et de la fort sur la qualit de lair et la sant humaine dans et autour des zones urbaines Tree and forest effects on air quality and human healthhttps://treesearch.fs.fed.us/pubs/57862The problems associated with air pollution and higher air temperatures in cities have been known for over a century but so have the impacts of trees and forests on improving air quality and regulating air temperatures. Science has advanced our understanding on the various ways that trees affect air quality and temperatures. Trees affect air quality and consequently human health in both positive and negative ways by regulating air temperatures altering the local microclimates altering building energy use removing air pollutants and emitting various chemicals. While the overall effect of trees and forests is an improvement in air quality local scale forest designs near pollutant sources need to be considered as trees alter wind flow and can affect pollutant dispersion and local concentrations. Forests can limit pollution dispersion and increase local pollutant concentrations (e.g. along streets) but can also protect sites from pollutant emissions and have substantial impacts on lowering local pollution concentrations (e.g. in forest stands). By understanding how trees affect air quality and air temperatures better landscape designs can be implemented to use trees and forests to improve human health.Thu, 04 Apr 2019 12:13:04 +0000Woody Debris and Nutrient Retention following Alternative Biomass Harvesting Guidelineshttps://treesearch.fs.fed.us/pubs/57861Concern about excessive woody debris removals during biomass harvests has led to the development of biomass harvesting guidelines (BHGs) for retaining woody debris for habitat and nutrient cycling. However the efficacy of BHGs has not been experimentally examined. Two BHG treatments applied during clearcutting and thinning operations were examined in a replicated completeblock experiment. The first BHG treatment included the retention of onethird of tops of trees 8 in. dbh and onethird of trees lt8in. dbh. The second included the retention of all tops of trees 8in. dbh and no restriction on the removal of smaller trees. In clearcuts the two BHGs each increased the biomass of woody debris retained by 1.7 times compared to where no BHG was applied. However in thinned units there were no differences in retained woody debris regardless of BHG application. Nutrient retention trends followed those of biomass. Nutrients retained in woody debris generally exceeded nutrient removals in harvested wood except for calcium for which removals equaled retention where BHGs were applied and exceeded retention in the absence of BHGs. Findings suggest that applying BHGs for retaining woody debris becomes more important as harvest intensity increases.Thu, 04 Apr 2019 07:31:33 +0000Orchard management using cover crops to improve soil health and pollinator habitat in the Midwestern United Stateshttps://treesearch.fs.fed.us/pubs/57902National initiatives have emergedthat could benefit future establishment and management of nut production orchards. The 2008 and 2014 Farm Bills put forward agendas to address declining soil health on agricultural soils by promoting the use of cover crops to improve soil health during the fallow period in rotation with agronomic crops. Corn wheat and soybean yields have been increased by 2 to 4 percent when grown in rotation with cover crops (SARE 2017). The USDA reported over 10 million acres were planted with cover crops in 2012 and has increased to over 20 million acres by 2017. Cover crops could play an even bigger role in managing soil health in orchards because we can include perennial ground covers and because annual cover crops if not invasive do not need to be terminated to establish another crop and can grow to maturity.Wed, 10 Apr 2019 08:35:11 +0000Genetic Diversity and Population Structure of Pinus yunnanensis by Simple Sequence Repeat Markershttps://treesearch.fs.fed.us/pubs/57854Pinus yunnanensis is the main species used for reforestation in Yunnan province China. To manage the genetic resources of this economically and ecologically important species efficiently greater knowledge of the distribution of its genetic diversity is needed. In this study the genetic diversity of 20 natural populations representing most of the P. yunnanensis range was examined using seven simple sequence repeats. No loci showed significant departure from HardyWeinberg equilibrium. Most genetic diversity was found within populations and overall genetic differentiation was low (FST 0.045). There was no sign of isolation by distance. Clustering of populations using both neighbor joining pair groups and principal coordinates analysis based on Neis genetic distance showed the presence of two major clusters. This result was reinforced using the Bayesian software STRUCTURE which identified two southern populations as clearly separate from the others. There were no signs of genetic erosion but some populations should be a focus of conservation efforts because of their higher level of genetic diversity and the presence of private alleles. These results will inform conservation and management of P. yunnanensis and will guide future studies of population genetics and breeding programs.Tue, 02 Apr 2019 13:13:51 +0000