Red Maple Trees Research Articles

Bottom-Up and Top-Down Effects of Forest Fragmentation Differ Between Dietary Generalist and Specialist Caterpillars

Ecological interactions increasingly occur in the context of anthropogenic landscape alteration, such as landscape fragmentation, which engenders numerous changes to abiotic and biotic processes. Theory and empirical evidence suggest that species that are ecologically specialized or positioned at higher trophic levels are most sensitive to the effects of landscape fragmentation, yet the mechanisms underlying this sensitivity remain hypothetical. Here we present an initial test of the hypothesis that landscape fragmentation affects tri-trophic interactions more severely for dietary specialist than for generalist insect herbivores. We specifically tested a bottom-up hypothesis, that fragmentation reduces hostplant food quality to herbivores, with the most pronounced effects for dietary specialists. We also tested a top-down hypothesis, that fragmentation reduces parasitism of caterpillars, with the most pronounced effects on dietary specialists. We studied interactions among trees, caterpillars, and parasitoids in forest fragments (3 – 1013 ha) in Connecticut, U.S.A. in 2017 and 2018. To address the bottom-up hypothesis, we measured the growth performance of multiple dietary specialist and generalist caterpillar species fed leaves from red maple and witch hazel trees sampled from large or small forest patches. We assessed the top-down hypothesis by quantifying mortality from insect parasitoids of many of the same caterpillar species on these tree species sampled from a range of forest patch sizes. Fragmentation did not reduce herbivore growth performance for either dietary specialist or generalist caterpillars even though it accelerated desiccation rates of leaves of both tree species over the growing season. However, dietary specialization increased herbivore sensitivity to yearly variation in food quality, as the growth efficiency of specialist caterpillars varied between 2017 and 2018, while that of generalist caterpillars did not. As predicted, parasitism rates of dietary specialist caterpillars declined as forest fragment size declined, whereas parasitism of generalists was independent of fragment size. Therefore, interactions involving dietary specialist herbivores were most sensitive to top-down environmental variation. Assuming that dietary specialist caterpillars are primarily attacked by host-specific parasitoids, this top-down effect is consistent with the trophic theory of island biogeography, which predicts the sharpest declines of ecologically specialized predators and parasites in small habitat patches.

White oak and red maple tree ring analysis reveals enhanced productivity in urban forest patches

Many aspects of the urban environment have the potential to affect tree growth and physiology in forest patches, including higher temperatures, elevated CO2 concentrations, and modified soil biogeochemistry from increased nutrient and heavy metal inputs. However, these changes in tree growth are likely to vary by species and across urban areas, reflecting the local environmental conditions associated with the idiosyncratic trajectory of development in a city. Here, we examine growth rates of two dominant native tree species (white oak (Quercus alba L.) and red maple (Acer rubrum L.)) across urban and reference forest sites of three major cities in the eastern United States (New York, NY (NYC); Philadelphia, PA; and Baltimore, MD). We also characterized soil physical and chemical properties around each tree and monitored air temperature over three growing seasons at each site. Throughout the growing season, the urban sites had consistently warmer daytime and nighttime temperatures than reference sites. Urban forest patch soils also had elevated calcium, magnesium, and heavy metal concentrations compared to reference forest soils. Urban vs. reference tree growth rates varied by species, by city, and over time. Despite differences in the two native species’ ecophysiology, both grew more rapidly in the urban environment than at nearby reference sites, particularly in recent decades. Over the entire 145-year tree ring record analyzed, white oak basal area increment was significantly higher in urban trees compared to reference trees. Changes in the relative production of white oak earlywood and latewood between site types in each city and over time may relate to precipitation patterns. Perhaps due to their ability to persist in a wide variety of environmental conditions, mature trees of both species appear to be acclimating to urban forest patch conditions of the eastern U.S. and in some cases are experiencing enhanced growth rates compared to trees in nearby reference forests. An understanding of past and present growth rates of trees in urban forest patches can provide insight into future ecosystem functioning of these urban green spaces as well as that of more rural ecosystems experiencing environmental change factors similar to those associated with urbanization.

Impact of Cover Cropping on Non-Target Arthropod Pests of Red Maple Trees in Nursery Production

Cropping practices can affect the complement of arthropod pests present in production. The impact of cover cropping on key red maple (Acer rubrum [L.]) (Sapindaceae) nursery pests was evaluated. Cover cropping has been identified as a sustainable management method for a key maple pest, flatheaded appletree borer (Chrysobothris femorata [Olivier]) (Buprestidae), but the impact of the cover crop on other non-target arthropod pests in maple production also must be taken into account when determining the usefulness of cover cropping as a pest management tool. In addition to flatheaded appletree borer, other important arthropod pests of red maple in the southeastern United States include maple shoot borer (Proteoteras aesculana [Riley]) (Tortricidae), maple leaftier (Episimus tyrius [Henrich]) (Tortricidae), potato leafhopper (Empoasca fabae [Harris]) (Cicadellidae), ambrosia beetles (e.g., Xylosandrus crassiusculus [Motschulsky]) (Curculionidae), and spider mites (Oligonychus aceris [Shimer] and Tetranychus urticae [Koch]) (Tetranychidae). In the fall of 2015, 400 red maple trees were transplanted into a cover cropped field of crimson clover (Trifolium incarnatum [L.]) (Fabaceae) and winter wheat (Triticum aestivum [L.]) (Poaceae). Four nursery tree row management treatments were evaluated: (1) cover crop, (2) cover crop + insecticide, (3) no cover crop, and (4) no cover crop + insecticide. Treatment plots consisting of 25 trees were replicated 4 times in a 2 × 2 factorial design. All trees were evaluated annually in 2016 and 2017 for damage by the previously mentioned arthropod pests. Overall, the cover crop did not increase damage by the common suite of red maple pests. However, the cover crop did compete with trees for nutrients, water, and space, thereby reducing tree growth and the formation of new maple shoots. The low number of new shoots on maple trees in the cover crop rows, and subsequent availability and suitability of host material was the main driver of pest damage differences among treatments.

Nitrogen deposition and climate change effects on tree species composition and ecosystem services for a forest cohort.

The composition of forests in the northeastern United States and the ecosystem services they provide to future generations will depend on several factors. In this paper, we isolate the effects of two environmental drivers, nitrogen (N) deposition and climate (temperature and precipitation) change, through an analysis of a single cohort of 24 dominant tree species. We assembled a tree database using data from U.S. Forest Service Forest Inventory and Analysis monitoring plots. Applying observed species‐specific growth and survival responses, we simulated how forest stands in a 19‐state study area would change from 2005 to 2100 under 12 different future N deposition–climate scenarios. We then estimated implications for three selected forest ecosystem services: merchantable timber, aboveground carbon sequestration, and tree diversity. Total tree biomass (for 24 species combined) was positively associated with both increased N deposition and temperatures; however, due to differences in the direction and magnitude of species‐specific responses, forest composition varied across scenarios. For example, red maple (Acer rubrum) trees gained biomass under scenarios with more N deposition and more climate change, whereas biomass of yellow birch (Betula alleghaniensis) and red pine (Pinus resinosa) was negatively affected. Projections for ecosystem services also varied across scenarios. Carbon sequestration, which is positively associated with biomass accumulation, increased with N deposition and increasing climate change. Total timber values also increased with overall biomass; however, scenarios with increasing climate change tended to favor species with lower merchantable value, whereas more N deposition favored species with higher merchantable value. Tree species diversity was projected to decrease with greater changes in climate (warmer temperatures), especially in the northwestern, central, and southeastern portions of the study area. In contrast, the effects of N deposition on diversity varied greatly in magnitude and direction across the study area. This study highlights species‐specific and regional effects of N deposition and climate change in northeastern U.S. forests, which can inform management decision for air quality and forests in the region, as well as climate policy. It also provides a foundation for future studies that may incorporate other important factors such as multiple cohorts, sulfur deposition, insects, and diseases.

Swirski Mite Controlled-release Sachets as a Pest Management Tool in Container Tree Production

Adoption of biological control tools in woody ornamental nursery production has lagged behind other agriculture fields. One of the major obstacles to adoption is lack of information on the efficacy of various biological control agents in nursery production systems. The predatory mite Amblyseius swirskii, sold commercially as “swirski mite,” is a generalist predatory mite that has recently been adopted as a generalist control for a wide range of mite and insect pests, including thrips (Thripidae), whiteflies (Aleyrodidae), eriophyid mites (Eriophyidae), broad mite (Polyphagotarsonemus latus), and spider mites (Tetranychidae). A controlled-release sachet formulation of swirski mite was evaluated in three experiments to determine whether size of the tree, timing of first application, or sun intensity would affect treatment efficacy. Pest numbers on plants was evaluated biweekly for 12 weeks. The swirski mite sachets controlled broad mite and spider mite outbreaks on red maple trees (Acer rubrum) grown in nos. 3 and 15 nursery containers, respectively. Application at the time of red maple rooted cutting transplant was not necessary to achieve summer-long control of pests. No outbreaks of target pests on flowering dogwood (Cornus florida) in no. 5 containers grown under both full sun and shade, but with low levels of broad mite persisting in the shade treatment and thrips persisting in sun. These results suggest that swirski mite is a promising candidate for biological control in woody ornamental nursery production.

Impervious Surface Thresholds and the Pace to Plant Technique for Planting Urban Red Maple Trees

A foundation of integrated pest management (IPM) in urban landscapes is to put the right plant in the right place. This preventive tactic can reduce plant stress, pest infestations, and subsequent pesticide applications. Many urban tree species have more insect and mite pests in urban landscapes than in surrounding natural areas. This is due in part to stress created by impervious surfaces, such as roads and sidewalks that can increase air temperature and reduce soil moisture. For red maples (Acer rubrum), more impervious surface area leads to more stress and worse tree condition. This publication focuses on selecting red maple planting sites that will help reduce tree stress and scale insect pests by maximizing surfaces permeable to water.

Long-term banding modifies the changes to foliar coloration of Acer rubrum L. ‘Brandywine’

Abstract To more thoroughly characterize the mechanism regulating the conversion of red maple tree (Acer rubrum L. ‘Brandywine’) foliar coloration in autumn, we analyzed the leaf coloration process using the Lab color space scale, and compared the anthocyanin concentrations, photosynthetic pigment contents, soluble sugar contents, and the phenylalanine ammonia lyase and polyphenol oxidase activities between control and band-treated red maple seedlings. We observed that stem banding enhanced the development of leaves exhibiting brilliant red coloration in the upper treated branches, and weakened the brightness of yellow leaves. Additionally, studies also revealed that leaf anthocyanin contents increased significantly. Moreover, carotenoid contents and polyphenol oxidase activity decreased considerably by banding. In contrast, the chlorophyll pigment, phenylalanine ammonia lyase activity and soluble sugar contents were only minimally affected by the long-term banding of trees. Our results indicate that the Lab color model is appropriate for quantifying leaf coloration changes, and for revealing the relationship between leaf coloration and internal physiological changes. Changes to leaf coloration are a consequence of the actions of photosynthetic pigments and anthocyanins. Our results also demonstrate that anthocyanin accumulation influences the underlying biochemical mechanism. The successful manipulation of leaf coloration changes highlights the significance of anthocyanins in this process, and is consistent with the possibility that anthocyanin accumulation influences the underlying biochemical activities.

Description of an establishment event by the invasive Asian longhorned beetle (Anoplophora glabripennis) in a suburban landscape in the northeastern United States.

The establishment of non-native species is commonly described as occurring in three phases: arrival, establishment, and dispersal. Both arrival and dispersal by the Asian longhorned beetle (Anoplophora glabripennis Motschulsky), a xylophagous Cerambycid native to China and the Korean peninsula, has been documented for multiple locations in both North America and Europe, however the transitional phase, establishment, is not well understood for this species due to the need to rapidly remove populations to prevent dispersal and assist eradication, and the evident variation in the behavior of populations. Here we describe the dynamics of an establishment event for the Asian longhorned beetle in a small, isolated population within the regulated quarantine zone near Worcester, Massachusetts, USA. These data were collected during an opportunity afforded by logistical limits on the Cooperative Asian Longhorned Beetle Eradication Program administered by state, federal, and local government partners. Seventy-one infested red maple (Acer rubrum) trees and 456 interspersed un-infested trees were surveyed in an isolated, recently established population within a ~0.29 ha stand in a suburban wetland conservation area in which nearly 90% of the trees were host species, and nearly 80% were Acer rubrum. Tree-ring analyses show that within this establishing population, Asian longhorned beetles initially infested one or two A. rubrum, before moving through the stand to infest additional A. rubrum based not on distance or direction, but on tree size, with infestation biased towards trees with larger trunk diameters. Survey data from the larger landscape suggest this population may have generated long-distance dispersers (~1400 m), and that these dispersal events occurred before the originally infested host trees were fully exploited by the beetle. The distribution and intensity of damage documented in this population suggest dispersal here may have been spatially more rapid and diffuse than in other documented infestations. Dispersal at these larger spatial scales also implies that when beetles move beyond the closed canopy of the stand, the direction of dispersal may be linked to prevailing winds.

Landscape Establishment for Baldcypress, Red Maple, and Chaste tree is Delayed for Trees Transplanted from Larger Containers1

Abstract With container-grown trees offered to the public in an increasing array of sizes, it is important to determine the effects of different sizes of container stock on transplant establishment. Clonal replicates of Vitex agnus-castus, Acer rubrum var. drummondii, and Taxodium distichum grown under common nursery conditions in five container sizes, 3.5, 11.7, 23.3, 97.8, or 175.0 L (#1, #3, #7, #25, or #45, respectively), were transplanted to a sandy clay loam field. Physiological stress was measured using xylem water potential and photosynthetic gas exchange rates. Height, trunk diameter, and canopy spread were monitored post-transplant for three growing seasons and root growth was sampled for the first two growing seasons. Trees of all three species from smaller-sized containers, 23.3 L (#7) or less, exhibited reduced transplant shock, decreased establishment time and increased growth rates in comparison to larger-sized containers, apart from increased mortality in 3.5 L (#1) A. rubrum and slower growth in 3.5 L (#1) T. distichum compared to those transplanted from 11.7 L (#3) or 23.3 L (#7) containers Reduced stress levels and increased growth rates corresponded in timing with greater change in root extension of smaller container-grown trees. At the end of three growing seasons, no statistical differences in height or trunk diameter were present for V. agnus-castus container sizes. With a modest wait, consumers may find that smaller container-grown trees will overcome transplant stress more quickly and exhibit growth rates that surpass those of larger container-grown trees. Index words: Acer rubrum, Taxodium distichum, Vitex agnus-castus, container-grown trees, transplant shock, transplant establishment, photosynthesis, transpiration, water stress. Species used in this study: Chaste tree (Vitex agnus-castus L. [an unnamed white flowering clone]); red maple (Acer rubrum L. var. dummondii [Hook. & Arn. ex Nutt.] Sarg. ‘Maroon'); bald cypress (Taxodium distichum (L.) Rich. [test clone TX8DD38]).

Biological Evaluation of a Novel Red Maple Leaf Extract for Nutraceutical Applications

The red maple (Acer rubrum) and sugar maple (Acer saccharum) species, which are endemic to eastern North America, are widely known for their sap which is used produce the natural sweetener, maple syrup. Interestingly, various parts of the red maple tree have been used as traditional medicines by the indigenous people of North America and our laboratory has identified a series of glucitol‐core containing gallotannins (GCGs) from its aerial parts. These GCGs show a wide range of biological activities including antioxidant, anti‐diabetic, anti‐glycation, and anti‐proliferative effects. Herein, we report the biological evaluation of a red maple leaf extract (MLX) for functional food/nutraceutical applications. The MLX was evaluated in a panel of in vitro assays antioxidant, anti‐glycation, and anti‐acetylcholinesterase effects. At concentrations ranging from 20 to 500 μg/mL, MLX scavenged free radicals in the DPPH assay, as well as displayed ferric reducing antioxidant power in the FRAP assay. MLX showed inhibitory effects against the formation of advanced glycation endproducts and acetylcholinesterase enzyme with IC50 values of 157.6 and 327.3 μg/mL, respectively. In summary, this study suggests that MLX should be further investigated for functional food/beverage applications given its GCGs content and biological activities. Future studies in our laboratory will include the evaluation of MLX in animal models.

Growth and stability of deep planted red maple and northern red oak trees and the efficacy of root collar excavations

Trees with root systems established well below grade due to deep planting or soil disturbance are common in urban landscapes, yet the long term effects of buried trunks and subsequent remediation strategies, such as root collar excavation are poorly documented. We evaluated the consequences of deep planting over a 10-year period on tree growth and stability, with and without root collar excavation, for red maple [Acer rubrum L. Red Sunset® (‘Franksred’)] and Northern red oak (Quercus rubra L.) planted at grade or 30-cm below grade. Sleeves to prevent soil-trunk contact were installed around trunks on a subset of deep trees. Root collar excavations were made during the 6th growing season for both species and trees were grown for an additional 4 and 3 growing seasons for red maples and Northern red oaks, respectively. Within two weeks of root collar excavations, pulling tests compared the effect of treatments on stability of red maples. Deep planting generally slowed growth of red maple but had no clear effect on Northern red oak. Root collar excavation had no lasting effect on growth of either species. Approximately 55% of deep red maples and 33% of deep Northern red oaks had roots crossing and in intimate contact with buried trunks, suggesting a potential for future girdling roots. Approximately 25% of deep maples had substantial adventitious rooting. All deep Northern red oaks had new roots emerging just above the first original structural roots but none were clearly adventitious. Trunk sleeves had no effect on growth for either species. Neither deep planting nor root collar excavation resulted in a loss of tree stability compared to trees planted at grade, although failure patterns varied among treatments. Overall, the biggest long term concern for deep-planted trees is the potential for girdling root formation.

Comparison of Carbon Footprint and Variable Costs of Selected Nursery Production Systems for a 5-cm-caliper Red Maple

The objective of this study was to examine the differences in global warming potential (GWP) and variable cost structure of a 5-cm-caliper red maple tree grown using two alternative production methods including a traditional field [balled and burlapped (BNB)] production system and a containerized, pot-in-pot (PIP) production system. Feedback from nursery growers was obtained to model each production system including the labor required for each cultural practice, materials used, and the hourly usage of tractors and other equipment. Findings from the study indicate that the total system GWP and variable cost for the PIP tree system is −671.42 kg of carbon dioxide equivalent (CO2e) and $250.76, respectively, meaning that the tree sequesters much more carbon during its life than is emitted during its entire life cycle. The same holds true for the BNB tree; however, in this system, the GWP of the tree −666.15 kg CO2e during its life cycle at a total variable cost of $236.13. Thus, the BNB tree costs slightly less to produce than its PIP counterpart but the life cycle GWP is slightly less positive as well.

Evapotranspiration and Above Ground Biomass of <i>Acer rubrum</i> from Liners to 8 m Tall Trees

To meet minimum spring flows, water management districts in Florida sought to make both agriculture and urban landscapes water efficient, which includes tree farms. Acer rubrum L. (red maple) trees are endemic to Central Florida and native to the eastern portion of the United States. Urban and suburban expansion has increased use of A. rubrum in landscape plantings and their production in nurseries. In Florida A. rubrum is planted around stormwater retention areas, but also in urban landscapes. To provide a basis for irrigation allocations both during production and in landscapes, daily actual evapotranspiration (ETA) for three red maple trees were measured with weighing lysimeters, beginning with rooted cuttings and continuing until trees averaged 8 m in height. Empirical models were derived to calculate ETA based on crown horizontal projected area or trunk caliper, adjusted daily by changes in reference evapotranspiration (ETo). Water use efficiency, based on carbon sequestered in above ground wood mass, was calculated at the end of five growing seasons. Average ETA to produce these maples was 29,107 L over 4.75 years, with an average water use efficiency of 1 kg dry mass of wood per 709 L of water lost by transpiration.

Potential New Associations of North American Parasitoids With the Invasive Asian Longhorned Beetle (Coleoptera: Cerambycidae) for Biological Control.

The Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), is a polyphagous wood-boring insect native to Asia. Since it invaded North America in the 1990s, the beetle has been continuously targeted by quarantines and eradication programs in the United States and Canada. We examined the potential for development of new species-associations between A. glabripennis and hymenopteran parasitoids collected from cerambycids and other wood-boring insects infesting red maple (Acer rubrum L.) trees in the mid-Atlantic region of the United States. Results of our study showed that five groups of braconid parasitoids (Ontsira mellipes Ashmead, Rhoptrocentrus piceus Marsh, Spathius laflammei Provancher, Heterospilus spp., and Atanycolus spp.) successfully attacked early instars of A. glabripennis larvae infesting red maple logs and produced both male and female progenies. One species, O. mellipes, was continuously reared on A. glabripennis larvae inserted inside small red maple sticks for over 50 generations, and produced female-biased progeny (∼6:1 female to male ratio) at each generation. Continuous rearing of O. mellipes on A. glabripennis larvae did not significantly increase the parasitism and mean number of progeny produced per parasitized host. Together, these findings demonstrate that some North American parasitoids may be able to develop new associations with A. glabripennis and thus should be further studied under semifield or field conditions for possible use in biocontrol.

Reduced Winter Snowpack and Greater Soil Frost Reduce Live Root Biomass and Stimulate Radial Growth and Stem Respiration of Red Maple (Acer rubrum) Trees in a Mixed-Hardwood Forest

Northeastern U.S. forests are currently net carbon (C) sinks, but rates of C loss from these ecosystems may be altered by the projected reduction in snowpack and increased soil freezing over the next century. Soil freezing damages fine roots, which may reduce radial tree growth and stem respiration. We conducted a snow removal experiment at Harvard Forest, MA to quantify effects of a reduced winter snowpack and increased soil freezing on root biomass, stem radial growth and respiration in a mixed-hardwood forest. The proportion of live fine root biomass during spring (late-April) declined with increasing soil frost severity (P = 0.05). Basal area increment index was positively correlated with soil frost severity for Acer rubrum, but not Quercus rubra. Rates of stem respiration in the growing season correlated positively with soil frost duration in the previous winter, ( $$ R^{2}_{{{\text{LMM}}({\text{m}})}} $$ = 0.15 and 0.24 for Q. rubra and A. rubrum, respectively). Losses of C from stem respiration were comparable to or greater than C storage from radial growth of Q. rubra and A. rubrum, respectively. Overall, our findings suggest that in mixed-hardwood forests (1) soil freezing has adverse effects on spring live root biomass, but at least in the short-term could stimulate aboveground processes such as stem respiration and radial growth for A. rubrum more than Q. rubra, (2) stem respiration is an important ecosystem C flux and (3) the increasing abundance of A. rubrum relative to Q. rubra may have important implications for C storage in tree stem biomass.

Great swamp natural effluent management system – a summary of thirteen years of operations

Beaufort-Jasper Water & Sewer Authority has discharged reclaimed wastewater continuously for thirteen years to a 194ha natural swamp forest in coastal South Carolina (USA). Wastewater inputs have increased from an average of 363m3/d in 1999 to an average of 8823m3/d in 2011. Natural inflows of rainfall and runoff to the swamp forest, averaging 9757m3/d exceed anthropogenic inputs. Wastewater inputs have increased the swamp’s inundation frequency in the lowest areas from 43 to 100%. Reclaimed water receives advanced secondary pretreatment with concentrations averaging 2.9mg/L five-day biochemical oxygen demand (BOD5), 2.8mg/L total suspended solids (TSS), 0.5mg/L ammonium nitrogen (NH4-N), 6.7mg/L total nitrogen (TN), and 2.2mg/L total phosphorus (TP). A variable percentage of these pollutants are assimilated within the swamp. Concentrations of chlorides, specific conductance, and TP are the only downstream water quality evidence of discharge. The dominant gum (Nyssa spp.) and baldcypress (Taxodium distichum) trees are thriving; however, red maple (Acer rubrum) trees have reduced dominance primarily due to increased hydroperiod. Macroinvertebrate and fish populations in the swamp forest have increasing biomass in response to increased wetted area. The Great Swamp Effluent Management System is an example of adaptive ecological engineering, protecting downstream recreational and shellfish waters by creating a productive interface between reclaimed wastewaters and natural wetlands.

Urban warming trumps natural enemy regulation of herbivorous pests.

Trees provide ecosystem services that counter negative effects of urban habitats on human and environmental health. Unfortunately, herbivorous arthropod pests are often more abundant on urban than rural trees, reducing tree growth, survival, and ecosystem services. Previous research where vegetation complexity was reduced has attributed elevated urban pest abundance to decreased regulation by natural enemies. However, reducing vegetation complexity, particularly the density of overstory trees, also makes cities hotter than natural habitats. We ask how urban habitat characteristics influence an abiotic factor, temperature, and a biotic factor, natural enemy abundance, in regulating the abundance of an urban forest pest, the gloomy scale, (Melanaspis tenebricosa). We used a map of surface temperature to select red maple trees (Acer rubrum) at warmer and cooler sites in Raleigh, North Carolina, USA. We quantified habitat complexity by measuring impervious surface cover, local vegetation structural complexity, and landscape scale vegetation cover around each tree. Using path analysis, we determined that impervious surface (the most important habitat variable) increased scale insect abundance by increasing tree canopy temperature, rather than by reducing natural enemy abundance or percent parasitism. As a mechanism for this response, we found that increasing temperature significantly increases scale insect fecundity and contributes to greater population increase. Specifically, adult female M. tenebricosa egg sets increased by approximately 14 eggs for every 1°C increase in temperature. Climate change models predict that the global climate will increase by 2–3°C in the next 50–100 years, which we found would increase scale insect abundance by three orders of magnitude. This result supports predictions that urban and natural forests will face greater herbivory in the future, and suggests that a primary cause could be direct, positive effects of warming on herbivore fitness rather than altered trophic interactions.

Pruning of Buttress Roots and Stability Changes of Red Maple (Acer rubrum)

The purpose of this study was to evaluate the effects of buttress root pruning on tree stability and to compare different methods of correlating various root parameters to force levels. Ten plantation-grown Acer rubrum (red maple) trees were pulled to an angle of one degree from vertical with measured force, then roots were individually severed near the trunk and the pull tests were repeated until roots had been pruned from 50% of the circumference. Test trees had 6 to 10 buttress roots. There was a nearly direct linear relation between the number of roots removed and the force applied. When comparing four assessment methods to determine pull force change associated with root pruning, the method that had the greatest amount of variability explained by the regression was the comparison of the cross-sectional area of roots cut to the force. However, relating the percentage of buttress roots cut to the force provided only slightly less accurate information, and was more easily collected prior to tree removal.

A New Species of Micropsectra Kieffer Midge (Diptera: Chironomidae)

The chironomid midge Micropsectra wendigo Taber is described from the western Lower Peninsula of Michigan. Adult males were collected in a Malaise trap in April in a woods with paper birch (Betula papyrifera Marshall), red maple (Acer rubrum L.), black ash (Fraxinus nigra Marshall), and black cherry (Prunus serotina Ehrhart) trees. The new species belongs to a little-studied genus but seems to be most closely related to the flies of the recurvata group.

Costs and Benefits of Implementing Sensor-controlled Irrigation in a Commercial Pot-in-Pot Container Nursery

Irrigation scheduling in ornamental plant production is complex due to the large number of species grown by individual growers and the need to consider plant, environment, and substrate conditions to make correct irrigation decisions on a daily or more frequent basis. The engineering team in our project has developed a smart wireless sensor node that is capable of integrating outputs from a range of soil moisture and environmental sensors to schedule irrigation events. In addition, an advanced monitoring and control software enables growers to manage irrigation based on set-point or model-based protocols, which are then independently executed by the nodes, enhancing or replacing human decision making. During 2012, we implemented a sensor-controlled vs. grower-controlled irrigation study at a pot-in-pot nursery in Tennessee. Sensor networks were installed in two separate production blocks of 3-year-old dogwood (Cornus florida ‘Cherokee Brave’) and 2-year-old red maple (Acer rubrum ‘Autumn Blaze’) trees grown in 15- and 30-gal containers, respectively. One row of trees in each block was irrigated based on the average reading of soil moisture sensors inserted in individual trees using micropulse irrigation, i.e., sensor controlled. Trees in the adjacent row and the rest of the block were independently irrigated by the grower using standard practices, i.e., grower controlled. Sensor volumetric water content (VWC) readings and irrigation volumes were logged by nodes on a 15-min basis and were relayed to a base station on the farm. For the study period between Mar. 2012 and Nov. 2012, average daily water applied by the grower-controlled irrigation to the dogwood block was 0.92 gal/tree, compared with 0.34 gal/tree applied using sensor-controlled irrigation; for red maple, these values were 1.72 gal/tree and 1.13 gal/tree, respectively. No significant differences in tree caliper or quality were noted between the two irrigation treatments in either species over the year. The cost of water for this particular operation was negligible consisting only of pumping costs, as water is drawn from a perennial stream with excellent water quality. Consequently, a conservative return on investment for a wireless sensor network capable of covering the entire operation was 37.5%, corresponding to a payback period of 2.7 years, associated almost entirely from a reduction in irrigation management time. Pricing in a nominal cost for water of $326 per acre-foot ($1 per 1000 gal) increased annualized net savings 9-fold, reducing the payback period to less than 4 months. This analysis did not factor in additional economic benefits such as reductions in production time, losses due to disease, or increased plant quality, which have been associated with the use of sensor-based irrigation control in other studies.