Estimating Stem Volume Using QuickBird Imagery and Allometric Relationships for Open Populus xiaohei Plantations

There has been a great deal of interest in studying the crown of trees using remote sensing data. In this study, crown width was extracted from high-resolution QuickBird images for open Populus xiaohei plantations. Regression models for predicting the individual stem volumes of Populus xiaohei were established using extracted crown width, as well as estimated tree parameters （i.e. diameter at breast height [DBH] and tree height） as predictors. Our results indicated that crown width could be accurately extracted from QuickBird images using a multi-scale segmentation approach with a mean relative error of 5.74%, especially for wide-spacing stands. Using either extracted crown width alone or with estimated DBH and tree height can successfully estimate individual stem volume of Populus xiaohei with the R2 value ranging from 0.87 to 0.92 depending on different model forms. In particular, the two second-order polynomial models （model 2 and model 6）, based on QuickBird image-derived crown widths and estimated DBH and tree heights, respectively, were the best at describing the relationship between stem volume and tree characteristics.     

Estimating Stem Volume Using QuickBird Imagery and Allometric Relationships for Open Populus xiaohei Plantations

There has been a great deal of interest in studying the crown of trees using remote sensing data.In this study,crownwidth was extracted from high-resolution QuickBird images for open Populus xiaohei plantations.Regression modelsfor predicting the individual stem volumes of Populus xiaohei were established using extracted crown width,as well asestimated tree parameters(i.e.diameter at breast height[DBH]and tree height)as predictors.Our results indicated thatcrown width could be accurately extracted from QuickBird images using a multi-scale segmentation approach with a meanrelative error of 5.74%,especially for wide-spacing stands.Using either extracted crown width alone or with estimatedDBH and tree height can successfully estimate individual stem volume of Populus xiaohei with the R~2 value ranging from0.87 to 0.92 depending on different model forms.In particular,the two second-order polynomial models(model2 andmodel 6),based on QuickBird image-derived crown widths and estimated DBH and tree heights,respectively,were the bestat describing the relationship between stem volume and tree characteristics.     

How does tree age influence damage and recovery in forests impacted by freezing rain and snow?

The response and recovery mechanisms of forests to damage from freezing rain and snow events are a key topic in forest research and management. However, the relationship between the degree of damage and tree age, i.e., whether seedlings, young trees, or adult trees are most vulnerable, remains unclear and is rarely reported. We investigated the effect of tree age on the degrees of vegetation damage and subsequent recovery in three subtropical forest types-coniferous, mixed, and broad-leaved —in the Tianjing Mountains, South China, after a series of rare icy rain and freezing snow events in 2008. The results showed that damage and recovery rates were both dependent on tree age, with the proportion of damaged vegetation increasing with age(estimated by diameter at breast height, DBH) in all three forest types and gradually plateauing. Significant variation occurred among forest types. Young trees in the coniferous forest were more vulnerable than those in the broad-leaved forest. The type of damage also varied with tree age in different ways in the three forest types. The proportion of young seedlings that were uprooted(the most severe type of damage) was highest in the coniferous forest. In the mixed forest, young trees were significantly more likely to be uprooted than seedlings and adult trees, while in the broad-leaved forest, the proportion of uprooted adult trees was significantly higher than that of seedlings and young trees. There were also differences among forest types in how tree age affected damage recovery. In the coniferous forest, the recovery rate of trees with broken trunks or crowns(DBH 2.5 cm) increased with tree age. However, in the mixed and broad-leaved forests, no obvious correlation between the recovery rate of trees with broken trunks or crowns and tree age was observed. Trees with severe root damage did not recover; they were uprooted and died. In these forests, vegetation damage and recovery showed tree age dependencies, which varied with tree shape, forest type, and damage type. Understanding this dependency will guide restoration after freezing rain and snow disturbances.     

Characteristics and underlying mechanisms of plant deep soil water uptake and utilization: Implication for the cultivation of plantation trees北大核心CSCD

Root water uptake is an essential part of tree water relations and plays a crucial role in tree physiological activities. Water resource in deep soil is relatively abundant and can provide plenty of water to trees to guarantee their survival and healthy growth during dry seasons. Thus, a good comprehension of the characteristics and underlying mechanisms of deep soil water uptake and utilization by trees will deepen the understanding of the interaction between trees and the environment, tree survival and growth strategies, coexistence and competition among different species, etc. This knowledge is important in establishing green cultivation schemes for plantations, which depend less on the external water resources input and avoid the adverse effects on the water ecological environment. From existing studies, the characteristics and underlying mechanisms of deep water uptake and utilization by trees are reviewed. Firstly, the definition of deep roots and deep soil is discussed, and 1 m depth is recommended as the average (reference) definition standard in main forest vegetation types except the boreal forest. The reasons for the formation of deep tree roots around the globe were also determined. Secondly, the observed deep soil water uptake characteristics of trees and their influencing factors are summarized. Then, from the aspects of the adjustment of deep root traits and the coordination of hydraulic traits of different organs, the mechanisms of deep water uptake by trees are discussed. For example, the spatial, temporal and efficiency adjustment strategies of deep roots can be used to facilitate the absorption of deep soil water. Finally, some implications of deep soil water uptake for the cultivation of plantations are proposed, such as “for water management in plantations, trees should be induced to moderately utilize some deep soil water and an appropriate irrigation frequency should be selected”, “appropriate mixed planting of different tree species can facilitate the buffering effect of deep soil water storage”, “developing techniques of selecting trees for thinning based on the water uptake depths of different species”, etc. Deficiencies of existing studies and some future research directions were also pointed out. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All Rights Reserved.     

Effects of fertilization and herbicides on growth of young loblolly pine and infestations of Nantucket pine tip moth（Lepidoptera： Tortricidae）

A 2-year-old pine plantation was selected to receive treatments of fertilizers and herbicides to evaluate effects on Nantucket pine tip moth infestations and the tree growth parameters of height, diameter and volume increment. Nitrogen and phosphorus fertilizers, and hexazinone and sulfometuron methyl herbicides were used in creating six treatments： （i） control; （ii） phosphorus; （iii） nitrogen and phosphorus; （iv） phosphorus and herbicide; （v） nitrogen, phosphorus and herbicide; and （vi） herbicide. Treatments were applied in 1987 and 1988. In 1987, trees treated with nitrogen, phosphorus and herbicide had significantly greater height, diameter and volume growth than trees not receiving fertilizer treatments, but did not have significantly higher tip moth infestations than control trees. Treatments receiving phosphorus only had much lower tip moth infestation rates than other treatments except nitrogen and phosphorus. In 1988, tip moth infestations were uniformly low, with no differences in treatment effects observed.     

Different Patterns of Changes in the Dry Season Diameter at Breast Height of Dominant and Evergreen Tree Species in a Mature Subtropical Forest in South China

Information on changes in diameter at breast height （DBH） is important for net primary production （NPP） estimates, timing of forest inventory, and forest management. In the present study, patterns of DBH change were measured under field conditions during the dry season for three dominant and native tree species in a monsoon evergreen broad-leaved forest in the Dinghushan Biosphere Reserve. For each tree species, different patterns of DBH change were observed. In the case of the fast-growing tree species Castanopsis chinensis Hance, large diurnal fluctuations occur, with a peak DBH in the early morning （around 05：00 h） that decreases to a minimum by about 14：00 h. Both Schima superba Gardn. et Chemp and Cryptocarya chinensis （Hance） Hemsh exhibited less diurnal swelling and shrinkage. Diurnal fluctuations for these species were observed on a few occasions over the period of observation. Graphical comparisons and statistical analysis of changes in DBH with meteorological variables indicate that for different trees, the different changes in DBH observed responded to different meteorological variables. Large stem changes were found to occur for Ca. chinensis trees that were associated with variations in solar radiation. However, both S. superba and Cr. chinensis were found to be less sensitive to solar radiation. Changes in the DBH of these two species were found to be controlled mainly by soil temperature and soil moisture. During the later dry season, with a lower soil temperature and soil moisture, all three tree species stopped growing and only negligible shrinkage, expansion, or fluctuation occurred, suggesting that the optimum time to measure tree growth in the Dinghushan Biosphere Reserve is the later dry season.     

Climate Signals from Tree Ring Chronologies of the Upper and Lower Treelines in the Dulan Region of the Northeastern Qinghai-Tibetan Plateau

The radial growth of trees In mountainous areas is subject to environmental conditions associated with changes In elevation. To assess the sensitivity of tree-ring growth to climate variation over a wide range of elevations, we compared the chronological characteristics of Sabina przewalskii Kom. and their relationships with climatic variables at the upper and lower treellnes In the Dulan region of the northeastern Qlnghal-Tlbetan Plateau. It was found that the radial growth in this region was controlled primarily by precipitation in late spring and early summer （from May to June）. In addition, a higher temperature from April to June could Intensify drought stress and lead to narrow tree rings. The significant similarity In climate-tree growth relationships at both the upper and lower treellnes Indicated that tree rings of S. przewalskU In this region are able to provide common regional climate information. However, the chronologies at the lower forest limits showed a higher standard deviation and more significant correlations with climatic factors, suggesting that the radial growth there was more significantly Influenced by climate variation. The first principal component of the four chronologies showed a common growth response to local climate. The second principal component showed a contrasting growth response between different sampling sites. The third principal component revealed different growth patterns In response to altitudinal variation. Further analysis Indicated that the precipitation In late spring and early summer controlled the growth of S. przewalskii on a regional scale and that other factors, such as mlcroenvlronment at the sampling sites, also affected the strength of the climatic response of tree growth.     

Colonization patterns of the red turpentine beetle,Dendroctonus valans （Coleoptera： Curculionidae）, in the Luliang Mountains,China

The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle in order to develop an effective monitoring and management strategy. In this study, the effects of hillside exposure （south- and north-facing）, host-tree locations according to relief （valley, mid-slope, and ridge-top） and tree diameters on RTB colonization were investigated in one valley （3 sites）. The results showed that （i） RTB clearly preferred colonizing pines growing on south-facing hillsides, especially in the valley; （ii） RTB preferred to colonize the pines growing at the valley rather than pines growing at mid-slope or on ridge-top; （iii） RTB preferred to colonize trees with large diameter over small and medium-sized pines; （iv） the attack density of RTBs （measured by pitch tubes/pine） was obviously higher on larger trees standing in the valley than other trees standing at other places. We conclude from RTB colonization patterns, that RTB prefers to attack large trees in the valley, which may be useful in developing a pest-management strategy.     

Spatio-temporal dynamics of two alpine treeline ecotones and ecological characteristics of their dominate species at the eastern margin of Qinghai-Xizang Plateau北大核心CSCD

Aims Temperature limit is the main cause of alpine treeline formation. Therefore, it is important to understand the response mechanisms of alpine treeline as well as their tree species under the global climate change. The present study focused on the spatio-temporal dynamics of treeline and ecological characteristics of the tree species in two treeline ecotones. Methods Two vertical belt-transect plots were established in each treeline ecotone of the Zheduo Mountain and Jianziwan Mountain of the eastern Qinghai-Xizang Plateau. Top and bottom of each transects were lain between species line and forest line, respectively. Detailed information of each tree species treeline, including species name, latitude, longitude, height, age, base diameter, and coordinates, was recorded accordingly. Important findings The temperatures of the two research areas have increased during the past 58 years. The precipitation has decreased slightly in both the Zheduo Mountain and Jianziwan Mountain. The age structure of Abies fabri from the Zheduo Mountain and A. squamata from the Jianziwan Mountain showed a reversed “J” shape curve and a bimodal shape, respectively. Within the two transects, due to the limitation of seed diffusion, the dominate species showed aggregated distributions at the small scale. At the large scale, A. fabri was aggregated at the Zheduo Mountain, while A. squanmata of the Jianziwan Mountain was randomly distributed due to the impact of surrounding environmental factors. Both tree height and base diameter decreased with the increase of elevation. The fir trees (Abies spp.) at the upper part of the treeline ecotone presented an allometric growth, whose height growth rate was higher than that of base growth, while the relationships between height growth and base growth were isometric at almost mid and lower part of the treeline ecotone. Compared with 10 years ago, there was no significant change at the position of treeline and tree species line of the Zheduo Mountain and the Jianziwan Mountain, neither of the tree density in the Jianziwan Mountain. However, the number of trees in the Zheduo Mountain increased by about 25%. Compared with 20 years ago, tree species lines of the Zheduo Mountain and Jianziwan Mountain were shifted upwards by 50 and 30 m, respectively. Besides, their treeline positions were increased by 75 and 40 m, respectively. Furthermore, the number of trees also increased significantly by 220% and 100%, respectively. Therefore, the treeline and its constructive species are mainly affected by temperature at the large spatio-temporal scale, while influenced by temperature and ambient environment at the small spatio-temporal scale. © Chinese Journal of Plant Ecology.     

松材线虫(Bursaphelenchus xylophilus)入侵对马尾松(Pinus massoniana)林分生长的影响及相关生长模型

松材线虫（Bursaphelenchus xylophilus）是一种松树上发生严重的有害生物,它不仅改变了生态系统的结构和功能,而且改变了系统内生物的原有特性和地理分布。松材线虫及其引起的松树萎蔫病已对中国马尾松林（Pinus massoniana）的树木成长产生了巨大影响。基于此,使用＂每木调查法＂和＂样方法＂,对松材线虫入侵后的马尾松林内松树的各项生长指标因子进行了调查分析,其结果表明：自松材线虫1996年入侵所调查地区的松林后,对于受害松树不管是伐倒木（被伐倒）还是倒木（自然倒地）,其对周围马尾松胸径生长的影响是显著的,而对树高生长的影响不显著。最后建立了一系列的灰色和灰色-马尔可夫链数学模型,其预测结果精度高,可用于今后受害和未受害区马尾松林分因子的生长预测。     

Nitrogen Cycling Responses to Mountain Pine Beetle Disturbance in a High Elevation Whitebark Pine Ecosystem

Ecological disturbances can significantly affect biogeochemical cycles in terrestrial ecosystems, but the biogeochemical consequences of the extensive mountain pine beetle outbreak in high elevation whitebark pine (WbP) (Pinus albicaulis) ecosystems of western North America have not been previously investigated. Mountain pine beetle attack has driven widespread WbP mortality, which could drive shifts in both the pools and fluxes of nitrogen (N) within these ecosystems. Because N availability can limit forest regrowth, understanding how beetle-induced mortality affects N cycling in WbP stands may be critical to understanding the trajectory of ecosystem recovery. Thus, we measured above- and belowground N pools and fluxes for trees representing three different times since beetle attack, including unattacked trees. Litterfall N inputs were more than ten times higher under recently attacked trees compared to unattacked trees. Soil inorganic N concentrations also increased following beetle attack, potentially driven by a more than two-fold increase in ammonium (NH₄ ⁺) concentrations in the surface soil organic horizon. However, there were no significant differences in mineral soil inorganic N or soil microbial biomass N concentrations between attacked and unattacked trees, implying that short-term changes in N cycling in response to the initial stages of WbP attack were restricted to the organic horizon. Our results suggest that while mountain pine beetle attack drives a pulse of N from the canopy to the forest floor, changes in litterfall quality and quantity do not have profound effects on soil biogeochemical cycling, at least in the short-term. However, continuous observation of these important ecosystems will be crucial to determining the long-term biogeochemical effects of mountain pine beetle outbreaks.     

额尔齐斯河流域垂枝桦林群落结构特征与物种多样性相关分析

为阐明植物群落结构特征和物种多样性之间的相互关系,选择额尔齐斯河流域白桦林国家森林公园的天然垂枝桦(Betula pendula)纯林、垂枝桦苦杨混交林、垂枝桦白柳混交林为研究对象,分林层调查群落的基本特征参数(高度、枝下高、冠幅、胸径、盖度等),计算物种重要值、丰富度指数、多样性指数、均匀度指数,并进行典范对应分析。结果表明:(1)垂枝桦白柳混交林的乔木层树高、枝下高和灌木层的地径、盖度均最高;3种群落的草本层特征参数(除基径)均具有显著差异;垂枝桦白柳林的盖度分别比垂枝桦苦杨林和垂枝桦纯林高19.1%和51.8%。(2)3种群落的乔木层重要值最高为垂枝桦,灌木层为疏花蔷薇(Rosa laxa)、阿尔泰山楂(Crataegus altaica),草本层为莎薹草(Carex bohemica)。(3)3种群落类型中乔木层的丰富度指数R、Simpson指数、Shannon-Wiener指数和灌木层的Pielou指数、Alatalo指数呈现出相同规律,即垂枝桦白柳混交林>垂枝桦苦杨混交林>垂枝桦纯林;草本层中除Alatalo指数之外,其他指数均呈现垂枝桦纯林>垂枝桦苦杨混交林>垂枝桦白柳混交林(P>0.05)。(4)CCA排序结果表明,不同垂枝桦林群落结构特征与物种多样性关系有差异。其中,垂枝桦纯林中,对物种多样性影响最大的是乔木枝下高、灌木株高、冠幅以及草本盖度;垂枝桦苦杨混交林中,对物种多样性影响最大的是乔木高度和冠幅、灌木冠幅和草本高度;垂枝桦白柳林中,对物种多样性影响最大的是乔木胸径、灌木冠幅、盖度以及草本高度。研究表明,乔木枝下高度、灌木冠幅、草本高度是影响3种群落类型物种多样性的主要因素。     

Attack by Hylobius warreni on grafted lodgepole pine and its relationships with monoterpene composition and scion : rootstock diameter ratio

1 A lodgepole pine seed orchard at the Prince George Tree Improvement Station (PGTIS), with up to 60% of grafted trees attacked by the Warren root collar weevil Hylobius warreni was investigated to determine whether relative monoterpene composition or scion : rootstock interactions of grafts affected susceptibility to attack. 2 There was a significant relationship between relative levels of α‐pinene, β‐thujene, β‐pinene, δ‐3‐carene and limonene in scion and rootstock in unattacked trees, indicating a potential effect of the scion monoterpene composition on their composition in the rootstock. 3 Relative content of δ‐3‐carene and β‐phellandrene differed significantly in root stocks of attacked and unattacked trees but, for individual clones, a significant difference was only detected for β‐phellandrene in one clone. δ‐3‐Carene levels may have been too low in the examined trees to exert a strong effect. 4 Interestingly, attack status was significantly associated with two scion monoterpenes: α‐thujene and α‐terpinolene, both of which had higher levels in unattacked than in attacked trees. 5 Warren root collar weevils appear largely unaffected by monoterpene content, but further study is required to determine whether high levels of δ‐3‐carene imparts some level of resistance to attack, and to verify whether the observed effects of scion monoterpenes are real or artefacts of the analysis. 6 Hylobius warreni‐attacked trees had smaller scion : rootstock diameter ratio (i.e. a large rootstock diameter relative to the scion diameter) than unattacked trees. This effect was consistent among clones, and was not due to the absolute diameter of the rootstock or the scion. Trees with increased diameter‐growth at the root collar (e.g. some grafted trees) may have increased susceptibility to attack by H. warreni, or diameter‐growth at the root collar is affected by the attack.     

不同坡位对火力楠生长的影响

对广东高明云勇林场的火力楠Michelia macclurei纯林及其混交林2004～2007年的生长状况进行调查。运用多重比较方法分析上、中、下坡位的火力楠地径、树高、冠幅。结果表明,4年间(林分当年至3年生)所有样地的火力楠幼树平均地径、树高和冠幅均有显著增长。坡位对火力楠的地径生长具有显著影响,各坡位的火力楠平均地径为上坡>中坡>下坡,而坡位对树高和冠幅的影响不明显。     

中亚热带湿地松(Pinus elliottii)人工林生长过程

基于树干解析和树轮分析,结合野外调查,揭示了我国主要外来树种--湿地松(Pinus elliottii)的生长规律,从而为人工林经营管理和生态系统服务功能评估提供了依据。2005年调查了1948年江西吉安青原山引种后存留的564株湿地松(1954 1958年生)。胸径(DBH, diameter at breast height)平均值为34.2 cm(18.4-58cm),树高平均值为19.5 m(9-33m)。青原山湿地松树轮分析结果显示:52年间,年树轮宽度增长量平均值为0.32 cm,最大年增长量不超过1.14 cm。胸径年生长量总体上呈下降趋势,直径生长高峰出现在10a左右;林龄达到20a左右时,直径年生长量开始下降;林龄40a后,生长变得极为缓慢。距青原山西南100km的千烟洲湿地松林(20年生)胸径和树高平均值分别为15.9 cm和11.0 m;20a的胸径生长量平均值为0.86 cm;材积方程为V= 0.0000213 D^2.9870924(V为带皮材积,D为胸径)。千烟洲湿地松林生物量低于同期营造的马尾松(Pinus massoniana)林生物量,也明显低于中亚热带地带性植被樟树(Cinnamomum camphora)林的生物量。经比较发现,引种营造的湿地松林,其生长量远不如原产地美国佛罗里达州湿地松林。     

Measure of simultaneous tree sways and estimation of crown interactions among a group of trees

We present a technique to measure the simultaneous sway of a group of trees and reconstruct the frequency of crown collisions and sway dynamics of individual or groups of trees. We placed a biaxial clinometer (tiltmeter) at the live crown base in each of ten neighboring 15-m-tall lodgepole pine trees in Alberta, Canada. Tree bole rotation at tiltmeter mount height was recorded during windy conditions at a rate of 10 times/s for the cluster of trees. Rotation angles were used in a bole curve calculation to estimate tree displacement in 2-dimensional (x, y) space. Collision reconstruction was done in Arc/Info by assigning asymmetrical crown area dimensions (polygons) to calculated bole displacement for each tree. Reconstruction of each time step measured any overlaps between crown polygon areas. Crown polygon overlaps estimated in this manner allowed assessment of collision frequencies, area of crown overlap during collisions, and identification of the tree(s) that a subject tree contacted. Collision statistics are only given for trees interior to the sensored cluster (n=3). For 15.0 min of data with an average wind speed of 4.5 m/s and a maximum of 10.0 m/s there was an average of 65 collisions/min for each tree, and an average collision overlap area of 24%. This frequency and depth of collisions supports the notion that wind-induced crown interaction inhibits lateral shoot extension and is an important mechanism for the development of crown asymmetry and crown shyness. Insight into dynamic tree sway behavior and crown interactions will allow estimation and cultivation of a forest stand structure that is more resistant to damage from wind. The techniques of recording multiple simultaneous bole sway and their reconstruction are applicable to a broad range of wind-forest interaction research.     

大青山赤松林和黑松林生态适应研究

针对山东省大青山省级自然保护区典型植物群落,设置21个样方,分析主要乔木种群和群落特征.结果表明:1)大青山样方内共发现维管植物111种,其中乔木29种、灌木14种、草本植物68种,群落植物种类少,物种多样性低.2)29种乔木根据径级结构划分为13种扩展种、2种隐退种,5种稳定侵入种、6种随机侵入种和3种随机隐退种.主要乔木种群径级结构型为2种:黑松种群、栓皮栎种群、麻栎种群、小叶朴种群、黄檀种群、君迁子种群和槲树种群为增长型;刺槐种群和赤松种群为稳定型.大青山群落乔木整体上为增长型群落.3)大青山乔木层物种丰富度指数、Shannon-Wiener多样性指数和Simpson多样性指数从高到低依次为赤松林、黑松林、刺槐林,而Pielou均匀度指数从高到低依次为黑松林、赤松林、刺槐林,显示赤松更适合作为大青山造林树种.     

Mountain Pine Beetles Use Volatile Cues to Locate Host Limber Pine and Avoid Non-Host Great Basin Bristlecone Pine

The tree-killing mountain pine beetle (Dendroctonus ponderosae Hopkins) is an important disturbance agent of western North American forests and recent outbreaks have affected tens of millions of hectares of trees. Most western North American pines (Pinus spp.) are hosts and are successfully attacked by mountain pine beetles whereas a handful of pine species are not suitable hosts and are rarely attacked. How pioneering females locate host trees is not well understood, with prevailing theory involving random landings and/or visual cues. Here we show that female mountain pine beetles orient toward volatile organic compounds (VOCs) from host limber pine (Pinus flexilis James) and away from VOCs of non-host Great Basin bristlecone pine (Pinus longaeva Bailey) in a Y-tube olfactometer. When presented with VOCs of both trees, females overwhelmingly choose limber pine over Great Basin bristlecone pine. Analysis of VOCs collected from co-occurring limber and Great Basin bristlecone pine trees revealed only a few quantitative differences. Noticeable differences included the monoterpenes 3-carene and D-limonene which were produced in greater amounts by host limber pine. We found no evidence that 3-carene is important for beetles when selecting trees, it was not attractive alone and its addition to Great Basin bristlecone pine VOCs did not alter female selection. However, addition of D-limonene to Great Basin bristlecone pine VOCs disrupted the ability of beetles to distinguish between tree species. When presented alone, D-limonene did not affect behavior, suggesting that the response is mediated by multiple compounds. A better understanding of host selection by mountain pine beetles could improve strategies for managing this important forest insect. Moreover, elucidating how Great Basin bristlecone pine escapes attack by mountain pine beetles could provide insight into mechanisms underlying the incredible longevity of this tree species.