Unprotected Trees Research Articles

Conservation priorities for endangered trees facing multiple threats around the world.

Trees are vital to the survival of numerous species and to forest ecosystem functioning. However, the current distribution, vulnerability to extinction, and conservation priorities of globally endangered trees are not well known. We mapped the global distribution of 1686 tree species listed as endangered on the International Union for the Conservation of Nature Red List and identified conservation priority for them based on species richness, life-history traits, evolutionary distinctiveness, future climate change, and intensity of human activities. We also evaluated the impacts of various threats to these endangered tree species and evaluated the effectiveness of their protection based on the percentage of the species' range inside protected areas. The worldwide distribution of endangered trees, from the tropics through temperate zones, was uneven. Most endangered tree species were not protected in their native ranges, and only 153 species were fully protected. Hotspots of tree diversity occurred primarily in the tropics, and 79.06% of these were highly vulnerable to threats. We identified 253 areas of high priority for the conservation of endangered trees that are highly threatened and insufficiently protected. In particular, 43.42% of unprotected tree species in priority areas lacked recommended conservation measures or had no associated conservation plan. The priority conservation areas and unprotected trees we identified serve as a guideline for future management underpinning the post-2020 global biodiversity framework.

RESEARCH ON SEED GERMINATION STIMULATION AT PAULOWNIA TOMENTOSA THUNB. STEUD.

Paulownia tomentosa (Thunb.) Sieb. & Zucc. Ex Steud. (syn. P. Imperialis Sieb. & Zucc.), is a native species to China, popularly being called “Princess Tree”. In Romania, the species is sensitive to the early frosts, which cause frostbite of non-lignified stems. Unprotected trees can be destroyed to ground level, but recover vigorously from shoots. Paulownia tomentosa is an invasive species introduced to the US from China as an ornamental and landscape tree in the mid-1800s. The family name derives from its genus Paulownia Siebold & Zucc., 1835 whose name was given in honour of the Danish princess Anna Paulowna or Pavlovna (1795-1865), the consort of King William II of the Netherlands and the daughter of Tsar Paul I of Russia (Gledhill, D., 2008). The aim of the research was to speed up the germination of Paulownia tomentosa seeds with Nitrozyme (based upon a highly concentrated and purified extract of marine kelp) in different concentrations: 0.1%, 0.3%, 0.5%, 0.7%, 0.9%. The germination capacity of the seeds decreases from the moment of dispersal even in optimal conditions of storage in the laboratory. In the case of treated seeds with 0.1% Nitrozyme the values of height and diameter of the seedling increased slightly.

Role of Mangrove Rehabilitation and Protection Plans on Carbon Storage in Yanbu Industrial City, Saudi Arabia: A Case Study

Mangroves are one of the main considerations that might be used to mitigate the effects of climate change in coastal areas. Mangrove populations can be affected by industrial and civil activities on coasts. According to the Kyoto Protocol, protection and rehabilitation programs may play a pivotal role in conserving mangroves in industrial areas. Therefore, this study was designed to examine and evaluate the possible impact of conservation plans, implemented by the Royal Commission of Yanbu, in preserving mangrove trees’ ability to store carbon in the soil. Soil and plant samples were collected from three distinct locations, including a mangrove conservation site in Yanbu and natural unprotected sites in Umluj and Ar-Rayis. Organic-carbon (OC) stock, in both soil and plants, was calculated. Our results showed that at different depths, soil bulk density (SBD) in Yanbu ranged between 0.32–0.94 g cm−3. In Ar-Rayis and Umluj, SBD ranged between 1.43 to 1.99 and 0.90 to 1.57g cm−3, respectively. The average SBD values in Yanbu, Umluj, and Ar-Rayis were 0.68, 1.71, and 1.20 g cm−3, respectively. Similarly, the average soil OC density in Yanbu, Umluj, and Ar-Rayis was 165.19, 30.82, and 18.90 g C cm−3, respectively. Generally, the conserved mangrove tress grown in Yanbu industrial city showed higher (P ≤ 0.001) soil OC stock (0.39 t C ha−1) compared to the unprotected trees grown in Umluj (0.12 t C ha−1) and Ar-Rayis (0.11 t C ha−1) cities. Similarly, the highest (P ≤ 0.001) plant OC stocks (13.93 t C ha−1) were observed in protected mangroves of Yanbu, compared to the plant OC stocks observed in Umluj (8.06 t C ha−1) and Ar-Rayis (8.80 t C ha−1) cities. The results of the current study showed that the protected mangrove trees grown in Yanbu industrial city store more carbon in their sediments than those grown in the Umluj and Ar-Rayis sites without conservation or rehabilitation. These findings may provide evidence for the beneficial role of protecting mangrove forests in mitigating the effects of climate change.

Are soil changes responsible for persistent slash pile burn scars in lodgepole pine forests?

Pile burning is the most common method of logging residue disposal in Rocky Mountain forests. Though the high temperatures reached during burning affect numerous soil properties in the short term, the longer-term effects of the practice are less clear. We previously identified a 50-year time series of burn scars created after clear cut harvesting in lodgepole pine stands where we reported sparse tree colonization across the entire chronosequence. Here we analyzed soil nutrients and chemistry and conducted in situ and greenhouse seedling bioassays to determine whether edaphic factors or poor seedling performance explain the pattern. Pile burning had a lasting effect on soil pH, but nutrient availability was 2–3 times higher in burn scars compared to unburned forest soils for many constituents and planted pine seedlings had good survival and growth. However, seedling growth was slightly less in burn scars compared to unburned soils indicating suboptimal soil pH or other belowground factors may contribute to sparse tree colonization of the openings. For example, seedling survival and ectomycorrhizal fungi colonization were both lowest in the most recently created scars where soils were alkaline and improved with time as pH declined, suggesting gradual amelioration of post-fire growing conditions. Survival in burn scars was comparable for unprotected trees and those in protective mesh tubes, indicating that herbivory was not a significant impediment to seedling establishment. However, a preliminary study suggests that seed predation may have contributed to the low tree colonization into the openings. Though large burn pile scars may require soil rehabilitation, and soil changes may have a lasting effect on understory plant composition, we found that they were not a significant barrier to tree establishment in these moderate-size burn scars.

Quantification of insecticide spatial distribution within individual citrus trees and efficacy through Asian citrus psyllid reductions under different application methods.

Citrus greening disease (Huanglongbing, HLB) has infected >90% of Florida's oranges and thus growers are desperate to improve pest management strategies. In this field study, insecticide application efficacy was investigated with liquid chromatography mass spectrometry to determine if insecticide concentration and distribution were effective at killing the target pest Asian citrus psyllids (ACP). Sample discs attached to leaves were sprayed with imidacloprid and malathion at a field site in Florida. Application method, canopy height and depth, cardinal side of tree, and leaf side were considered to assess the spatial distribution of insecticides throughout citrus trees. Furthermore, ACP were inspected before and after insecticide applications to quantify psyllid population response. Our findings show that although insecticide concentrations were high enough to kill ACP, the spatial distribution of insecticides throughout individual trees was highly variable and live ACP were detected after insecticide application. The top side of leaves received significantly more insecticide than the underside of leaves. Additionally, inadequate distribution to different areas of the tree canopy was observed for all application methods tested (aerial, ground speed-sprayer, and ground side-sprayer). Inspections of ACP populations before and after insecticide applications resulted in reductions of 85% (malathion) and 48-80% (imidacloprid). The variability in insecticide spatial distribution due to application method allows remaining ACP to continue spreading citrus greening disease to unprotected trees. Further research is needed to improve insecticide application methods and technology for citrus trees in order to implement effective pest management strategies and fully target ACP to eliminate HLB. © 2020 Society of Chemical Industry.

Evaluation of Terpene-Volatile Compounds Repellent to the Coffee Berry Borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae).

The coffee berry borer (CBB) is one of the main coffee pests in the world including Colombia. This pest is difficult to manage because of its cryptic habits and the continuous availability of coffee fruits. Among the new management strategies being tested is the use of volatile compounds as insect repellents. In this work, the behavioral response of female adult CBBs to terpenes previously identified in the CBB-repellent plant species Lantana camara was evaluated. α-Terpinene, (R)-limonene, farnesene and β-caryophyllene terpenes were tested via a Y-tube olfactometer in which ripe coffee fruits were accompanied by terpenes at concentrations between 25 and 200ppm. Only β-caryophyllene induced a significant and consistent CBB repellent effect at all tested doses. The protective effect of microencapsulated β-caryophyllene was then determined under laboratory conditions by incorporating the terpene in a colloidosome-gel system at 2.8 × 105 ng/h in the middle of coffee fruits with adult CBBs. The coffee fruits in turn presented a decrease in fruit infestation. Furthermore, the protection of coffee fruits when β-caryophyllene gels were hung in coffee trees was evaluated in the field; infestations were artificially induced by the use of raisins (CBB-infested old coffee fruits) placed on the ground. Compared with unprotected trees, the trees treated with caryophyllene gels exhibited a 33 to 45% lower degree of infestation. Taken together, the results show that β-caryophyllene is a promising compound for an integrated pest management (IPM) program in commercial coffee plantations.

Long-Lasting Insecticide Netting for Protecting Tree Stems from Attack by Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae).

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are destructive wood-boring insects of horticultural trees. We evaluated long-lasting insecticide netting for protecting stems against ambrosia beetles. Container-grown eastern redbud, Cercis canadensis, trees were flood-stressed to induce ambrosia beetle attacks, and deltamethrin-treated netting was wrapped from the base of the stem vertically to the branch junction. Trees were deployed under field conditions in Ohio, Virginia, Tennessee, and Mississippi with the following treatments: (1) flooded tree; (2) flooded tree with untreated netting; (3) flooded tree with treated ‘standard mesh’ netting of 24 holes/cm2; (4) flooded tree with treated ‘fine mesh’ netting of 28 holes/cm2; and/or (5) non-flooded tree. Treated netting reduced attacks compared to untreated netting and/or unprotected trees in Mississippi in 2017, Ohio and Tennessee in 2018, and Virginia in 2017–2018. Inconsistent effects occurred in Mississippi in 2018. Fewer Anisandrus maiche, Xylosandrus germanus, and Xyleborinus saxesenii were dissected from trees deployed in Ohio protected with treated netting compared to untreated netting; trees deployed in other locations were not dissected. These results indicate long-lasting insecticide netting can provide some protection of trees from ambrosia beetle attacks.

Assessing an integrated biological and chemical control strategy for managing hemlock woolly adelgid in southern Appalachian forests

Abstract In the eastern United States, hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae) is considered an invasive pest of eastern hemlocks; an ecologically foundational tree species. Current management of HWA focuses on chemical and biological controls, with recent research suggesting that these two tactics could be integrated successfully. The approach is to protect a subset of hemlocks with systemic insecticides while releasing predatory insects onto adjacent, unprotected trees. The goal of this study was to assess the effects of chemical and biological control tactics, alone and in combination, on hemlock health and HWA densities at three southern Appalachian sites (KY, WV, and TN) from 2010 to 2016. Although insecticide applications were effective at protecting individual trees, none of the overall treatments (chemical, biological, or combined) had a significant effect on tree health or HWA population index values relative to untreated plots. Tree health generally declined at all sites over time. HWA populations were highly variable over time and were likely more strongly influenced by extremely low, winter temperatures than by the treatments. Cross-correlation analysis of tree health and HWA population indicated a time-lag effect. At two of the three sites, recovery of tree health lagged 0 – 3 years behind decline in HWA population, and decline in HWA populations lagged approximately 0 – 1 years behind decline in tree health. The predatory beetle, Laricobius nigrinus, was recovered two-years, post-release at the KY and WV sites in 2012 and 2013, but was not recovered from the TN site. The lack of sustained recovery of L. nigrinus may be attributable to the occurrence of extremely low, winter temperatures in 2014 and 2015, which produced subsequent crashes in the HWA populations. In TN, the L. nigrinus population may have been unrecoverable due to a decline in the HWA population shortly after initial release.

Diversity and impact of herbivorous insects on Brazilian peppertree in Florida prior to release of exotic biological control agents

ABSTRACTBrazilian peppertree, Schinus terebinthifolia Raddi (Anacardiaceae), is a South American plant that is highly invasive in Florida. The impact of insect herbivores on the performance of Brazilian peppertree was evaluated at two locations in Florida using an insecticide exclusion method. Although 38 species of insect herbivores were collected on the invasive tree, there were no differences in growth or reproductive output of insecticide protected and unprotected trees, providing evidence that insect feeding had no measurable impact on tree performance. The majority of insects collected on Brazilian peppertree were generalists, and several were serious agricultural pests.

Wire netting reduces African elephant (<i>Loxodonta africana</i>) impact to selected trees in South Africa

African elephants (Loxodonta africana) are ecosystem engineers in that they substantially alter the environment through their unique foraging and feeding habits. At high densities, elephants potentially have negative impacts on the environment, specifically for large trees. Because of this, recent increases of elephants in the Associated Private Nature Reserves (APNR) on the western boundary of the Kruger National Park (KNP), South Africa, have caused concern regarding the survival of several tree species. Our objective was to assess the effectiveness of wrapping protective wire netting around the trunk of the tree for preventing and reducing bark stripping, branch breaking, and felling by elephants. We assessed 2668 trees – 1352 Sclerocarya birrea (marula), 857 Acacia nigrescens (knobthorn), and 459 Lannea schweinfurthii (false marula) – for elephant impact in the APNR, 1387 (52%) of which had previously been wrapped in protective wire netting (789, 548 and 50, respectively). Wire netting was effective in reducing the severity of bark stripping and the relative proportion of trees that were bark stripped. In addition, wire netting had an effect on the level of impact, with a higher relative frequency of wire-net-protected trees found in lower impact categories compared with unprotected trees. Since tree mortality has been attributed to high levels of elephant impact, the use of wire netting could serve to maintain individual trees or populations particularly vulnerable to elephant impact in areas with locally high densities of elephants.Conservation implications: Since wire netting is a relatively low cost and ecologically unobtrusive strategy, it could be used to reduce elephant impact in problem areas. This method focuses on protecting trees rather than some other strategies such as environmental manipulation, translocation, contraceptives, and culling that instead focus on reducing elephant numbers.Keywords: Elephant impact; bark stripping; large trees; wire netting; mitigation measures

SÍNTOMAS DEL HUANGLONGBING (HLB) EN ÁRBOLES DE LIMÓN MEXICANO [Citrus aurantifolia (Christm) Swingle] Y SU DISPERSIÓN EN EL ESTADO DE COLIMA, MÉXICO

This work was carried out in orchards of Mexican lime [Citrus aurantifolia (Christm) Swingle] affected by Huanglongbing (HLB) disease and located in the state of Colima, Mexico. The objectives of this work were to characterize the symptoms of the disease in the trees, to evaluate the effect of HLB on the yield and other physical characteristics of the fruit, to determine its dispersion within an orchard andquantify the total orchards affected by HLB. Results showed that in this citrus species, the new vegetative shoots grow strong and healthy looking despite having emerged from symptomatic branches. The symptoms start as small yellowish spots on the leaves when the shoots are 45 to 60 days old. And they show the asymmetric diffuse mottling characteristic of HLB disease when they are 60 to 70 days old. This damage was observed in trees located inside of a structure covered with anti-aphid mesh and also in unprotected trees in the field. There was a significant yield reduction proportional to the percentage of canopy affected by the disease. In HLB symptomatic branches of diseased trees, the fruit was smaller but no misshapen fruits, inverted ripeness or an increase in the number of aborted seeds were detected. In an orchard without HLB vector control, the disease was detected in 53 % of the trees in only one year. HLB is widely spread throughout Colima state. This is the first report on HLB disease symptoms in Mexican lime and their effects on yield and fruit quality.

Role of rainfall in the development of coffee berry disease in Coffea arabica caused by Colletotrichum kahawae, in Cameroon

The development of coffee berry disease (CBD) epidemics (caused by Colletotrichum kahawae) in Cameroon was monitored over two successive years (2004 and 2005) on coffee trees protected from rainfall by transparent plastic sheets and on unprotected control trees. This work was done to assess how rain affected disease development when it did not fall directly onto the coffee trees and to determine the influence of primary inoculum on the severity of CBD. Weekly observations over the 2 years showed that there were 1·1% diseased berries on coffee trees completely protected from rainfall, compared with 45% diseased berries on unprotected coffee trees. Disease severity on unprotected trees during the 2 years of the experiment was estimated at 53% diseased berries, compared with 27% on trees only protected in the first year. These results confirmed rainfall as one of the key physical factors in the development of Arabica CBD. They also provided evidence of a subsequent effect of protecting coffee trees from rainfall in 2004 on the severity of CBD in 2005. This suggested some practices that might lead to very effective cultural control of CBD in regions where severe epidemics of the disease occur.

Nest protectors provide a cost-effective means of increasing breeding success in Giant Ibis Thaumatibis gigantea

SummaryA main cause of nestling loss of the ‘Critically Endangered’ Giant Ibis Thaumatibis gigantea appeared to be mammalian predation. Predator-exclusion devices were added to a randomly selected half of 52 nesting trees, with the other half acting as controls. The number of young fledged per nest was 50% higher for protected nests than control nests. Each protected nest produced almost two-thirds (0.63) of an extra chick. During the nestling period, the daily nestling survival rate was (99.9%) (equivalent to 90% survival over the nestling period) for protected nests and 99.3% (61.3% survival over the whole period) for control nests. Nest protection devices cost US$5 per tree. Each extra nestling fledged as a result of this intervention therefore cost $8. If it was also necessary to pay to locate the nests, then the cost of protecting each nest would be $140 and the cost of producing each extra chick $224. Trees with protectors added were significantly more likely to be reused in the next year than unprotected trees.

Whole-tree sap flow is substantially diminished by leaf herbivory

Ecohydrological models consider the relationship between tree size and structure (especially leaf area index) and water use but generally treat herbivory as a source of unwanted noise in the data. Little is known of how insect damage to leaves influences whole-plant water use in trees. Water use is driven by environmental demand and the total leaf area through which transpiration can occur, but the effects of insects are expected to be complex. Different kinds of insects could have different effects; for example, chewing insects reduce leaf area, whereas sucking and tissue mining insects reduce leaf function without reducing area. Further, plants respond to herbivory in a range of ways, such as by altering leaf production or abscising leaves. We examined the effect of insects on Eucalyptus blakelyi in a woodland near Canberra, Australia, using sap flow velocity as a measure of whole-plant water use. We applied insecticide to 16 trees matched to an untreated control group. After 6 months, we examined the effects on sap flow velocity and crown condition. There was a general increase in sap flow velocity as trees produced leaves over the growing season, but the increase in sap flow for trees without insecticide protection was half that of the protected trees (increase: 4.4 vs. 9.0 cm/h, respectively). This dramatic effect on sap flow was consistent with effects on crown condition. Unprotected trees had 20% less leaf mass per unit stem in the crown. In addition, unprotected trees had a 20% greater loss of leaf functional area from necrosis. It should be noted that these effects were detected in a year in which there was not an outbreak of the psyllids (Homoptera) that commonly cause severe leaf damage to this tree species. It is predicted that the effect in a psyllid outbreak year would be even more substantial. This result underscores the significant impact that insect herbivores can have on an ecological process of significance to the ecosystem, namely, the movement of water from the soil to the atmosphere.

Effects of repeated cottonwood leaf beetle defoliation on Populus growth and economic value over an 8-year harvest rotation

The effects of 8 years of cottonwood leaf beetle, Chrysomela scripta, defoliation on growth and economic value of four Populus clones (91 × 04-03, D105, Eugenei, and NM2) was investigated in a split-plot randomized complete block design with unprotected and insecticide-protected plots. After 8 years clones 91 × 04-03 and D105 had significantly greater survival than Eugenei or NM2. This difference in survival was not attributed to chemical protection, and while not qualified, was most likely the result of disease and storm breakage. Protected trees had significantly greater height, diameter, and stem volume than unprotected trees, with clone 91 × 04-03 consistently growing the largest. Protected plots had greater basal area and stem biomass than unprotected plots, but branch biomass was greatest in unprotected plots. Differences in branch biomass were most likely due to loss of apical dominance, and subsequent increased branching, resulting from C. scripta defoliation. Aboveground biomass was unaffected by treatment because of the increased branch biomass of unprotected trees. Clone 91 × 04-03 responded the most positively to chemical protection, as stem volume of unprotected trees was over 30% less than in protected trees. A financial analysis of our data indicated that none of the clone × treatment combinations would be economically acceptable due to the high land costs in the midwestern US. However, the use of less expensive insecticides may make clone 91 × 04-03 an economically viable crop in this region.

Freeze Risk and Protection Measures of Satsuma Mandarins Grown in the Southeastern United States

The northern fringe of the Gulf of Mexico has an excellent climate for growing high-quality satsumas that are available in U.S. retail chain stores before most other citrus. In part because of high fruit quality, satsuma mandarin production grew into a major industry in Alabama, Louisiana, Mississippi, and the panhandle of Florida in the early 1900s. Freeze protection measures were not sufficient to prevent devastation of the industry by severe freezes. For the period encompassing the late 1900s, freeze risk was estimated using a mathematical approach that determined killing temperature based on air temperature. Freeze injury was determined to occur 1 out of every 4 years on average, although the freezes tended to come in clusters that have as yet not been correlated with long-term climate patterns. Within-tree microsprinkler irrigation, which was not available in the early 1900s, has been shown to reduce the severity of injury. Within-tree microsprinkler irrigation allows full production the year after the freeze, whereas unprotected trees must be grown from the base or replanted. The northerly geographical limit in the southeastern United States whereby satsumas can be successfully grown commercially is currently not known. Methods of protecting the entire tree, including overtree microsprinkler irrigation plus windbreaks and high tunnel houses, are being evaluated. More cold-tolerant satsuma cultivars have been selected, but they reduce freeze risk by at most 2 °C in this region compared with current commercial cultivars. Genetic modification is one possible mechanism for improving cold tolerance sufficiently to reduce freeze risk similar to that of the citrus industry in Florida.

Restoration of woodpasture on former agricultural land: The importance of safe sites and time gaps before grazing for tree seedlings

Woodpastures (open, grazed woodlands with a mosaic of grassland, shrub and tree patches) are of high biological and cultural value and have become a threatened ecosystem in Europe. Spontaneous tree regeneration in the presence of large herbivores, is an essential process for management and restoration of this structurally diverse habitat. We examined the suitability of five vegetation types (grasslands, ruderal vegetations, tall sedges, rush tussocks and bramble thickets), grazed by large herbivores, for tree regeneration. We hypothesized that bramble thickets and tall herb communities operate as safe sites for palatable tree species through the mechanism of associational resistance. We set up a field experiment with tree seedlings in grazed and ungrazed conditions and recorded mortality and growth of seedlings of two palatable tree species ( Quercus robur and Fraxinus excelsior) during three growing seasons. In the same experiment, we studied the effect of a two year’s initial time gap before grazing. Bramble thickets were suitable safe sites for survival and growth of seedlings of both species. Tall sedges, soft rush tussocks and ruderal vegetations with unpalatable or spiny species provided temporal protection, allowing seedlings to survive. Tree regeneration in livestock grazed grassland was highly constrained. Rabbits may undo the nursing effects of bramble thickets. The first year’s survival is of major importance for the establishment of trees. Subsequent grazing affects growth rather than survival. A two year’s initial time gap before grazing, had positive effects on survival, but did not enhance outgrowth of unprotected trees.

Suppression of growth and reproduction of an exotic invasive tree by two introduced insects

The invasive tree Melaleuca quinquenervia experienced substantial declines in growth and reproduction in response primarily to chronic herbivory by the defoliating weevil Oxyops vitiosa. Herbivory was mediated on individual trees using regular applications of the insecticide acephate during a 2-year period to minimize populations of O. vitiosa and later the phloem-feeding psyllid, Boreioglycaspis melaleucae. Half of the trees also received drip irrigation to evaluate the influence of water on plant responses to herbivory. Insecticide-protected trees grew in height nearly six times faster and became 108% taller. In contrast, unprotected trees produced only 19% as much woody biomass, 13% as much leaf biomass, and 0.9% as much seed as protected trees. The mean (±SE) of total above ground biomass was 873.1 ± 191.4 g in unsprayed trees and 3856.2 ± 491.5 g in sprayed trees. Unprotected trees produced more stem tips per unit of height, resulting in a more bushy structure. Greater amounts of water increased leaf biomass, but all other plant variables were influenced most by herbivory. The seed-fueled invasive capacity of melaleuca will probably be reduced in areas favorable to the biological control agents, especially O. vitiosa.

Protecting Red-Cockaded Woodpecker Cavity Trees Predisposed to Fire-Induced Mortality

Abstract Reducing fire-induced mortality of cavity trees used by red-cockaded woodpeckers (Picoides borealis) is a challenge and concern in managing this federally endangered species. Prior to the 2001 burning season, 814 active and inactive longleaf pine (Pinus palustris) cavity trees on Eglin Air Force Base (AFB) in northwest Florida, USA, were prepared via 6 protection methods (combinations of mechanical, hand, and backfiring preparation) and monitored for postburn survival after 1 year. We collected data on a suite of variables that may be useful in determining cavity tree predisposition to fire-induced mortality. Mortality of protected trees (2.62%) was significantly lower than that of unprotected trees (6.18%), and protection methods did not differ in their effectiveness at preventing mortality. Bark char was significantly more prevalent on unprepared control trees than protected trees, but no differences were apparent among protection treatments. Mechanical clearing alone took the least amount of t...

Comparison of Exclusion and Imidacloprid for Reduction of Oviposition Damage to Young Trees by Periodical Cicadas (Hemiptera: Cicadidae)

Insecticides are traditionally used to control periodical cicadas (Homoptera: Cicadidae) and to reduce associated injury caused by oviposition. However, research has shown that conventional insecticides have low or variable season-long efficacy in reducing injury caused by cicadas. New systemic neonicotinoid insecticides provide excellent levels of control against a variety of sucking insects. We compared the efficacy of a neonicotinoid insecticide, imidacloprid, and a nonchemical control measure, netting, to reduce cicada injury. Netted trees sustained very little injury, whereas unprotected trees were heavily damaged. Fewer eggnests, scars, and flags were observed on trees treated with imidacloprid compared with unprotected trees; however, the hatching of cicada eggs was unaffected by imidacloprid.