Can School Children Support Ecological Research? Lessons from the Oak Bodyguard Citizen Science Project

Peer reviewe

Herbivory on the pedunculate oak along an urbanization gradient in Europe : Effects of impervious surface, local tree cover, and insect feeding guild

Urbanization is an important driver of the diversity and abundance of tree-associated insect herbivores, but its consequences for insect herbivory are poorly understood. A likely source of variability among studies is the insufficient consideration of intraurban variability in forest cover. With the help of citizen scientists, we investigated the independent and interactive effects of local canopy cover and percentage of impervious surface on insect herbivory in the pedunculate oak (Quercus robur L.) throughout most of its geographic range in Europe. We found that the damage caused by chewing insect herbivores as well as the incidence of leaf-mining and gall-inducing herbivores consistently decreased with increasing impervious surface around focal oaks. Herbivory by chewing herbivores increased with increasing forest cover, regardless of impervious surface. In contrast, an increase in local canopy cover buffered the negative effect of impervious surface on leaf miners and strengthened its effect on gall inducers. These results show that – just like in non-urban areas – plant-herbivore interactions in cities are structured by a complex set of interacting factors. This highlights that local habitat characteristics within cities have the potential to attenuate or modify the effect of impervious surfaces on biotic interactions.Agence Nationale de la Recherche, Grant/Award Number: ANR-10--LABX-45; Fondation BNP Paribas.info:eu-repo/semantics/publishedVersio

Herbivory on the pedunculate oak along an urbanization gradient in Europe: Effects of impervious surface, local tree cover, and insect feeding guild

Urbanization is an important driver of the diversity and abundance of tree-associated insect herbivores, but its consequences for insect herbivory are poorly understood. A likely source of variability among studies is the insufficient consideration of intra-urban variability in forest cover. With the help of citizen scientists, we investigated the independent and interactive effects of local canopy cover and percentage of impervious surface on insect herbivory in the pedunculate oak (Quercus robur L.) throughout most of its geographic range in Europe. We found that the damage caused by chewing insect herbivores as well as the incidence of leaf-mining and gall-inducing herbivores consistently decreased with increasing impervious surface around focal oaks. Herbivory by chewing herbivores increased with increasing forest cover, regardless of impervious surface. In contrast, an increase in local canopy cover buffered the negative effect of impervious surface on leaf miners and strengthened its effect on gall inducers. These results show that-just like in non-urban areas-plant-herbivore interactions in cities are structured by a complex set of interacting factors. This highlights that local habitat characteristics within cities have the potential to attenuate or modify the effect of impervious surfaces on biotic interactions

Search for top-down and bottom-up drivers of latitudinal trends in insect herbivory in oak trees in Europe

AimThe strength of species interactions is traditionally expected to increase toward the Equator. However, recent studies have reported opposite or inconsistent latitudinal trends in the bottom‐up (plant quality) and top‐down (natural enemies) forces driving herbivory. In addition, these forces have rarely been studied together thus limiting previous attempts to understand the effect of large‐scale climatic gradients on herbivory.LocationEurope.Time period2018–2019.Major taxa studiedQuercus robur.MethodsWe simultaneously tested for latitudinal variation in plant–herbivore–natural enemy interactions. We further investigated the underlying climatic factors associated with variation in herbivory, leaf chemistry and attack rates in Quercus robur across its complete latitudinal range in Europe. We quantified insect leaf damage and the incidence of specialist herbivores as well as leaf chemistry and bird attack rates on dummy caterpillars on 261 oak trees.ResultsClimatic factors rather than latitude per se were the best predictors of the large‐scale (geographical) variation in the incidence of gall‐inducers and leaf‐miners as well as in leaf nutritional content. However, leaf damage, plant chemical defences (leaf phenolics) and bird attack rates were not influenced by climatic factors or latitude. The incidence of leaf‐miners increased with increasing concentrations of hydrolysable tannins, whereas the incidence of gall‐inducers increased with increasing leaf soluble sugar concentration and decreased with increasing leaf C : N ratios and lignins. However, leaf traits and bird attack rates did not vary with leaf damage.Main conclusionsThese findings help to refine our understanding of the bottom‐up and top‐down mechanisms driving geographical variation in plant–herbivore interactions, and indicate the need for further examination of the drivers of herbivory on trees.</p

Speciile de Agrilus (Col., Buprestidae) și relația lor cu declinul stejarilor în România

Stejarul (Quercus robur L., 1753) și gorunul (Q. petraea (Matt) Liebl., 1784) sunt specii de arbori longevive, deosebit de valoroase sub aspect ecologic și economic, constituind componente importante ale pădurilor de foioase din zonele de câmpie și deal din România. Deși pădurile de stejari au o mare capacitate de refacere, în ultimele decenii acestea au fost afectate în numeroase rânduri de episoade de declin, având drept consecință volume mari de arbori uscați. În ultima perioadă s-a constatat creșterea frecvenței, precum și manifestarea diferită a acestora. Rolul important al speciilor de Agrilus în fenomenul de declin al stejarilor rezidă în faptul că acestea acționează în faza terminală a succesiunii de factori ce conduc la declin, împiedicând refacerea și provocând moartea arborilor. Cu toate acestea, nu sunt suficiente date privind infestările produse de speciile de Agrilus în România. Scopul acestei lucrări este de a prezenta o sinteză a informațiilor referitoare la caracteristicile speciilor de Agrilus care infestează stejarii și a simptomelor arborilor afectați de declin infestați cu Agrilus spp., pentru o mai bună înțelegere a relațiilor dintre aceste specii și declinul stejarilor, respectiv pentru o mai ușoară identificare a infestărilor produse

Aspecte privind aplicarea pesticidelor în silvicultura din România

Pesticidele sunt produse de natură chimică sau biologică, utilizate în controlul populațiilor de organisme dăunătoare de orgine animală sau vegetală. Au cunoscut o largă utilizare în agricultură, unde au fost folosite din cele mai vechi timpuri. În silvicultura din România au fost promovate mai ales după naționalizarea pădurilor, atât silvicultorii cât și conducerea țării fiind preocupați de obținerea unor producții cât mai ridicate de masă lemnoasă. Cele mai utilizate au fost și rămân în continuare insecticidele. Acestea au fost folosite în mod deodebit în controlul populațiilor de insecte defoliatoare a pădurilor de stejar (Lymantria dispar, Tortrix viridana, specii de geometride). Se disting trei perioade importante în aplicarea insecticidelor, acestea fiind strâns legate de substanța activă ce a stat la baza obținerii, cât și de eficiența economică a utilizării lor. În prima perioadă (1954-1985) au fost utilizate produse organoclorurate, total neselective și persistente, pe bază de DDT și HCH, inițial în doze deosebit de mari (30-40 kg/ha), cu efecte nefavorabile majore asupra mediului, faunei și sănătății umane. S-a impus derularea unor lucrări de cercetare, care să conducă la eliminarea acestor neajunsuri, reușindu-se reducerea considerabilă a normelor de consum ale acestor categorii de insecticide  la doar un 1kg/ha. Utilizarea îndelungată a produselor organoclorurate a condus însă la apariția fenomenului de rezistență încă de la începutul anilor 1960, manifestat de către un număr important de specii. S-a procedat la utilizarea unor altfel de insecticide, de asemenea neselective, precum produsele organofosforice și piretroizii de sinteză (1986-1990). Nici aplicarea acestor categorii de insecticide nu a fost benefică din punct de vedere ecologic, majoritatea studiilor indicând concentrații ridicate ale acestor produse în sol și în lanțurile trofice din ecosistemele forestiere. O etapă nouă (după anul 1990), legat de folosirea insecticidelor în combaterea dăunătorilor forestieri, a constituit-o cea a utilizării pesticidelor selective, chimice și biologice, aplicate în doze extrem de reduse și cu impact minimal asupra entomofaunei utile, mediului și sănătății omului. În prezent ne aflăm într-o perioadă de tranziție, certificarea FSC a pădurilor fiind deosebit de limitativă în folosirea pesticidelor în controlul organismelor dăunătoare

Eficacitatea combaterii larvelor de Clostera anastomosis L. la ieșirea din hibernare [Treatment efficacy of Clostera anastomosis L. caterpillars control in postdormancy phase]

Clostera anastomosis is an important poplar and willow defoliator which, especially since 1950, caused important damages to intensive hybrid poplar crops in Europe and Asia. The need to reduce the loss caused by this insect, often led to radical control tactics, consisting in spraying chemical insecticides with low specificity and high impact on biodiversity. Other control methods (biological control) had not the expected effect. Considering the above mentioned aspects and the fact that C. anastomosis overwinters as larvae, mainly in bark crevices of the stems of infested trees, it was tested the possibility of controlling this pest, by chemical control of the larvae, early in spring. There were designed two trials in lab and in field, in order to test the efficacy of 5 insecticides [Proteus (thiacloprid + deltamethrin), Ovipron (horticultural oil), Nuprid (imidacloprid), Confidor (imidacloprid) and Karate Zeon (lambda-cyhalothin)], sprayed directly on the stem of the poplar trees colonized with overwintering larvae nests. The treatment efficacy was assessed based on the survival rate of larvae after chemical spraying, by comparing it to the control samples. All surviving larvae were trapped in sticky barriers placed around the stems, above the sprayed area. Of the tested insecticides, the most efficient was Confidor, causing mortality of the 90.2 ± 1.8% of the larvae, significantly higher than the rest of the tested insecticides (Proteus, Ovipron, Nuprid). In field conditions, Confidor caused the decrease of the larvae population with 78.2 ± 7.4% for poplar clone AF2, and with 92.9 ± 6.4% for poplar clone AF8, and Karate Zeon caused 100% mortality. Control of the larvae in spring was efficient. It is a matter of course that this control method will have a lower environmental impact due to both the application moment (early spring, before poplars flush), and high control of the sprayed area (only the lower section of the infested tree stems). Successfull might be the application of mechanical control, by trapping the overwintering larvae in sticky barrier

Growth and Mortality of Hybrid Poplar Short Rotation Culture (AF8 Clone) in Response to <i>Clostera anastomosis</i> L. (Lepidoptera: Notodontidae) Defoliation

The increasing worldwide interest in renewable energy and carbon storage has led to the development of relatively fast solutions to obtain wood biomass. The cultivation of fast-growing tree species in short-rotation crops, such as hybrid poplar clones, is one such solution, at least in temperate areas. Sometimes these monocultures are affected by disturbing factors, including severe insect defoliation, with strong destructive effects. The impact of defoliation on the growth and productivity of poplar crops is often estimated in the context of artificial defoliation. There have been few studies in which the effect of defoliation was calculated after natural defoliation. Among defoliating insect species, Clostera anastomosis L. is one of the most important defoliators of young poplars. This species developed severe defoliation in a 4-year-old poplar clone AF8 crop, from the northeastern part of Romania, in the spring and summer of 2017. The study aimed to assess the impact of defoliation both on the growth and mortality of defoliated trees and the productivity of the affected crop. To reach this goal, the height and radial growth of 150 trees with different defoliation rates (50 non-defoliated, 50 partially defoliated, and 50 completely defoliated) were measured and the defoliation symptoms and mortality were also evaluated for 4780 poplars (10% of the analyzed population). The defoliation caused a significant decrease in the annual height growth (28.6% of the partially defoliated trees and 38.5% of the completely defoliated trees) and a severe decrease in the radial growth, between 82.2% and 90.4%, respectively, depending on the defoliation rate. These strong decreases led to a significant decline in tree-level biomass accumulation, approximately 74.8% for partially defoliated trees and 83.1% for completely defoliated trees, for the year of defoliation. As a result, the loss in total biomass (for the four years of the rotation) was between 28.1% and 34.6%, respectively, depending on the defoliation rate. Therefore, the total biomass loss was 5 t·ha−1, representing approximately 70% of the forecasted production for 2017 only (approximately 7 t·ha−1)