RESUMEN
The bird cherry ermine moth, Yponomeuta evonymellus L., is considered an obligatory monophagous insect pest that feeds only on native European Prunus padus L. In recent years, however, increased larval feeding on alien P. serotina Ehrh. has been observed. In both species, general defoliation is extensive for shade grown trees, whereas it is high in P. padus, but very low in P. serotina, when trees are grown in full light conditions. The aim of the present study was to identify how the plant host species and light conditions affect the performance of Y. evonymellus. The influence of host species and light condition on their growth and development, characterized by the parameters of pupation, adult eclosion, body mass, potential fecundity, and wing size, was measured in a 2 × 2 experimental design (two light treatments, two hosts). In comparison with high light (HL) conditions, a greater percentage of pupation and a longer period and less dynamic adult emerge was observed under low light (LL) conditions. The effect of host species on these parameters was not significant. In contrast, mass, fecundity and all of the studied wing parameters were higher in larvae that grazed on P. padus than on P. serotina. Similarly the same parameters were also higher on shrubs in HL as compared with those grown under LL conditions. In general, light conditions, rather than plant species, were more often and to a greater extent, responsible for differences in the observed parameters of insect development and potential fecundity.
Asunto(s)
Herbivoria , Mariposas Nocturnas/fisiología , Prunus , Animales , Femenino , Fertilidad/efectos de la radiación , Cadena Alimentaria , Especies Introducidas , Larva/crecimiento & desarrollo , Larva/fisiología , Larva/efectos de la radiación , Luz , Masculino , Mariposas Nocturnas/crecimiento & desarrollo , Mariposas Nocturnas/efectos de la radiación , Prunus/crecimiento & desarrollo , Especificidad de la Especie , Árboles/crecimiento & desarrolloRESUMEN
Spectra of leaf traits in northern temperate forest canopies reflect major differences in leaf longevity between evergreen conifers and deciduous broadleaf angiosperms, as well as plastic modifications caused by within-crown shading. We investigated (1) whether long-lived conifer leaves exhibit similar intra-canopy plasticity as short-lived broadleaves, and (2) whether global interspecific relationships between photosynthesis, nitrogen, and leaf structure identified for sun leaves adequately describe leaves differentiated in response to light gradients. We studied structural and photosynthetic properties of intra-tree sun and shade foliage in adult trees of seven conifer and four broadleaf angiosperm species in a common garden in Poland. Shade leaves exhibited lower leaf mass-per-area (LMA) than sun leaves; however, the relative difference was smaller in conifers than in broadleaves. In broadleaves, LMA was correlated with lamina thickness and tissue density, while in conifers, it was correlated with thickness but not density. In broadleaves, but not in conifers, reduction of lamina thickness was correlated with a thinner palisade layer. The more conservative adjustment of conifer leaves could result from a combination of phylogenetic constraints, contrasting leaf anatomies and shoot geometries, but also from functional requirements of long-lived foliage. Mass-based nitrogen concentration (N(mass)) was similar between sun and shade leaves, and was lower in conifers than in deciduous broadleaved species. Given this, the smaller LMA in shade corresponded with a lower area-based N concentration (N(area)). In evergreen conifers, LMA and N(area) were less powerful predictors of area-based photosynthetic rate (A (max(area))) in comparison with deciduous broadleaved angiosperms. Multiple regression for sun and shade leaves showed that, in each group, A (max(mass)) was related to N(mass) but not to LMA, whereas LMA became a significant codeterminant of A (max(mass)) in analysis combining both groups. Thus, a fundamental mass-based relationship between photosynthesis, nitrogen, and leaf structure reported previously also exists in a dataset combining within-crown and across-functional type variation.
Asunto(s)
Fotosíntesis/fisiología , Hojas de la Planta/fisiología , Tracheophyta/fisiología , Adaptación Fisiológica , Luz , Filogenia , Polonia , Tracheophyta/crecimiento & desarrollo , ÁrbolesRESUMEN
In evergreen plants, old leaves may contribute photosynthate to initiation of shoot growth in the spring. They might also function as storage sites for carbohydrates and nitrogen (N). We hence hypothesized that whole-plant allocation of carbohydrates and N to storage in stems and roots may be lower in evergreen than in deciduous species. We selected three species pairs consisting of an evergreen and a related deciduous species: Mahonia aquifolium (Pursh) Nutt. and Berberis vulgaris L. (Berberidaceae), Prunus laurocerasus L. and Prunus serotina Ehrh. (Rosaceae), and Viburnum rhytidophyllum Hemsl. and Viburnum lantana L. (Adoxaceae). Seedlings were grown outdoors in pots and harvested on two dates during the growing season for the determination of biomass, carbohydrate and N allocation ratios. Plant size-adjusted pools of nonstructural carbohydrates in stems and roots were lower in the evergreen species of Berberidaceae and Adoxaceae, and the slope of the carbohydrate pool vs plant biomass relationship was lower in the evergreen species of Rosaceae compared with the respective deciduous species, consistent with the leading hypothesis. Pools of N in stems and roots, however, did not vary with leaf habit. In all species, foliage contained more than half of the plant's nonstructural carbohydrate pool and, in late summer, also more than half of the plant's N pool, suggesting that in juvenile individuals of evergreen species, leaves may be a major storage site. Additionally, we hypothesized that concentration of defensive phenolic compounds in leaves should be higher in evergreen than in deciduous species, because the lower carbohydrate pool in stems and roots of the former restricts their capacity for regrowth following herbivory and also because of the need to protect their longer-living foliage. Our results did not support this hypothesis, suggesting that evergreen plants may rely predominantly on structural defenses. In summary, our study indicates that leaf habit has consequences for storage economics at the whole-plant level, with evergreen shrub species storing less carbohydrates (but not N) per unit plant biomass than deciduous species.
Asunto(s)
Berberidaceae/metabolismo , Metabolismo de los Hidratos de Carbono , Nitrógeno/metabolismo , Prunus/metabolismo , Viburnum/metabolismo , Berberidaceae/crecimiento & desarrollo , Biomasa , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Tallos de la Planta/crecimiento & desarrollo , Tallos de la Planta/metabolismo , Prunus/crecimiento & desarrollo , Árboles/crecimiento & desarrollo , Árboles/metabolismo , Viburnum/crecimiento & desarrolloRESUMEN
Field-grown trees of Alnus incana (L.) Moench, Alnus glutinosa (L.) Geartner and Betula pendula Roth displayed pronounced differences in responses of light-saturated net photosynthesis (Asat ) to herbivory by the alder beetle (Agelastica alni L., Galerucinae), a specialized insect which primarily defoliates alders. We found that photosynthetic rates of grazed leaves increased following herbivory in Alnus but not in Betula. Area- and mass-based Asat of grazed leaves declined linearly with increasing amount of leaf perforation in B. pendula, by as much as 57%. By contrast Alnus glutinosa and Alnus incana increased area-based rates of Asat by 10-50% at all levels of leaf grazing. Given increased Asat in the remaining portion of grazed leaves, a net reduction in photosynthesis per leaf occurred only when the proportion of leaf area grazed exceeded 40% for Alnus incana and 23% for Alnus glutinosa. Since vein perforation by Agelastica alni was observed much more frequently in leaves of Betula than in Alnus, we hypothesized that declining Asat in herbivorized Betula was related to this disruption of water transport. A field experiment with artificial leaf perforation demonstrated a greater decline in Asat in vein-perforated Betula leaves than perforated leaves with midrib veins intact. However, regardless of leaf perforation regime, birch never showed post-perforation increases in Asat . In all species, rates of transpiration of grazed leaves linearly increased and water-use efficiency decreased with increased amount of leaf perforation. In grazed Alnus incana leaves, increasing leaf area consumption by Agelastica alni resulted in an increase of total phenols, a reduction in starch content and no changes in nitrogen concentration in the remaining portion. The increase in photosynthesis in Alnus incana might be related to declining leaf starch concentration or increasing stomatal conductance, but was unrelated to leaf nitrogen concentration. These gas exchange and leaf chemistry measurements suggest that in contrast to B. pendula, Alnus incana and Alnus glutinosa, which are the major host species for Agelastica alni, possess leaf-level physiological adaptations and defence mechanisms which can attenuate negative effects of herbivory by the alder leaf-beetle.
RESUMEN
A study has been made of the influence of separate and simultaneous action of SO(2), NaCl and polyethylene glycol 8000 (PEG) on leaf injuries and free proline content of two poplar cuttings, Populus 'Robusta' and P. 'Hybrida 275', at an optimum (+15 degrees C), a lowered (+3 degrees C) and an increased (+35 degrees C) temperature. Proline accumulation was greatest in the most damaged cuttings of both cultivars for all three treatments. Simultaneous action of SO(2) and NaCl, as well as of SO(2) and PEG, caused significantly greater accumulation of this imino acid compared with the action of each factor separately, and the influence was more than additive. An increase in free proline content under the influence of the treatment combinations investigated here was proportional to the temperature during exposure. Greatest accumulation of proline under the experimental conditions was obtained by the simultaneous action of SO(2) and NaCl, as well as of SO(2) and PEG, at the temperature of 35 degrees C.
RESUMEN
Fungi play an important role in leaf litter decomposition due to their ability to break down the lignocellulose matrix, which other organisms are unable to digest. However, little is known regarding the factors affecting components of fungal diversity. Here, we quantified richness of internal fungi in relation to litter nutrient and phenolic concentrations, sampling season (spring or fall), and premature leaf shedding due to low precipitation and infestation of bark beetles (mainly Ips typographus and Ips duplicatus). The study was conducted in 37-year-old Norway spruce [Picea abies (L.) Karst.] stands, with three plots each in mixed forest (MF) and coniferous forest (CF) site conditions in south-central Poland. Fifty-four species of sporulating fungi were identified in 2,330 freshly fallen needles sampled during 2003-2005, including 45 species in MF and 31 in CF. The significantly higher number of species in MF was likely related to moister conditions at that site. Among isolated fungi, 22% (12 species) were identified as endophytes of Norway spruce in prior studies. During spring of 2005, we found less than half the number of isolates and fungal species at each forest site as compared to fall for the two prior years. This pattern was observed in typical soil fungi (e.g., Penicillium daleae, Penicillium purpurogenum) and endophytes/epiphytes (e.g., Aureobasidium pullulans, Alternaria alternata, Cladosporium spp., and Lophodermium piceae). Premature shedding of needles was the most likely cause of this decline because it shortened the time period for fungi to infect green needles while on the tree. For all sites and sampling periods, richness of internal fungi was strongly and positively related to the age of freshly fallen litter (assessed using needle Ca concentration as a needle age tracer) and was also negatively related to litter phenolic concentration. Richness of internal fungi in freshly fallen litter may be adversely affected by low soil moisture status, natural inhibitors slowing fungal colonization (e.g., phenolics) and biotic (e.g., insect infestation) and abiotic (e.g., drought) factors that shorten leaf life span.
Asunto(s)
Hongos/clasificación , Picea/microbiología , Corteza de la Planta/parasitología , Hojas de la Planta/microbiología , Gorgojos/fisiología , Animales , Hongos/aislamiento & purificación , Fenoles/análisis , Enfermedades de las Plantas/parasitología , Hojas de la Planta/química , Hojas de la Planta/metabolismo , Polonia , Estaciones del Año , Árboles , Gorgojos/clasificaciónRESUMEN
Established vegetation can facilitate the ectomycorrhizal infection of seedlings, but it is not known whether this interaction is limited by the phylogenetic relatedness of trees and seedlings. We use a series of bioassay experiments to test whether soil modification by different ectomycorrhizal tree species causes different levels of seedling infection, whether the extent of seedling infection is a function of the relatedness of tree and seedling, and whether the effect of trees on seedlings is mediated by biotic or abiotic soil factors. We found that soils from under different tree species do vary in their mycorrhizal infectiveness. However, this variation is not related to the genetic relatedness of trees and seedlings but instead, appears to be an attribute of the overstory species, irrespective of seedling species, mediated through a suite of humus- and base-cation-related abiotic effects on soils. Modification of abiotic soil properties by overstory trees should be considered as an important factor in the effect of different overstory trees on the extent of seedling mycorrhizal infection.
Asunto(s)
Ecosistema , Micorrizas/fisiología , Pinus sylvestris/microbiología , Quercus/microbiología , Suelo , Pinus sylvestris/crecimiento & desarrollo , Enfermedades de las Plantas/microbiología , Raíces de Plantas/microbiología , Quercus/crecimiento & desarrollo , Plantones/crecimiento & desarrollo , Plantones/microbiología , Especificidad de la EspecieRESUMEN
We explored environmental and genetic factors affecting seasonal dynamics of starch and soluble nonstructural carbohydrates in needle and twig cohorts and roots of Scots pine (Pinus sylvestris L.) trees of six populations originating between 49 degrees and 60 degrees N, and grown under common garden conditions in western Poland. Trees of each population were sampled once or twice per month over a 3-year period from age 15 to 17 years. Based on similarity in starch concentration patterns in needles, two distinct groups of populations were identified; one comprised northern populations from Sweden and Russia (59-60 degrees N), and another comprised central European populations from Latvia, Poland, Germany and France (49-56 degrees N). Needle starch concentrations of northern populations started to decline in late spring and reached minimum values earlier than those of central populations. For all populations, starch accumulation in spring started when minimum air temperature permanently exceeded 0 degrees C. Starch accumulation peaked before bud break and was highest in 1-year-old needles, averaging 9-13% of dry mass. Soluble carbohydrate concentrations were lowest in spring and summer and highest in autumn and winter. There were no differences among populations in seasonal pattern of soluble carbohydrate concentrations. Averaged across all populations, needle soluble carbohydrate concentrations increased from about 4% of needle dry mass in developing current-year needles, to about 9% in 1- and 2-year-old needles. Root carbohydrate concentration exhibited a bimodal pattern with peaks in spring and autumn. Northern populations had higher concentrations of fine-root starch in spring and autumn than central populations. Late-summer carbohydrate accumulation in roots started only after depletion of starch in needles and woody shoots. We conclude that Scots pine carbohydrate dynamics depend partially on inherited properties that are probably related to phenology of root and shoot growth.
RESUMEN
Nutrient availability varies across climatic gradients, yet intraspecific adaptation across such gradients in plant traits related to internal cycling and nutrient resorption remains poorly understood. We examined nutrient resorption among six Scots pine (Pinus sylvestris L.) populations of wide-ranging origin grown under common-garden conditions in Poland. These results were compared with mass-based needle N and P for 195 Scots pine stands throughout the species' European range. At the common site, green needle N (r(2)=0.81, P=0.01) and P (r(2)=0.58, P=0.08) concentration increased with increasing latitude of population origin. Resorption efficiency (the proportion of the leaf nutrient pool resorbed during senescence) of N and P of Scots pine populations increased with the latitude of seed origin (r(2) > or = 0.67, P < or = 0.05). The greater resorption efficiency of more northerly populations led to lower concentrations of N and P in senescent leaves (higher resorption proficiency) than populations originating from low latitudes. The direction of change in these traits indicates potential adaptation of populations from northern, colder habitats to more efficient internal nutrient cycling. For native Scots pine stands, results showed greater nutrient conservation in situ in cold-adapted northern populations, via extended needle longevity (from 2 to 3 years at 50 degrees N to 7 years at 70 degrees N), and greater resorption efficiency and proficiency, with their greater resorption efficiency and proficiency having genotypic roots demonstrated in the common-garden experiment. However, for native Scots pine stands, green needle N decreased with increasing latitude (r(2)=0.83, P=0.0002), and P was stable other than decreasing above 62 degrees N. Hence, the genotypic tendency towards maintenance of higher nutrient concentrations in green foliage and effective nutrient resorption, demonstrated by northern populations in the common garden, did not entirely compensate for presumed nutrient availability limitations along the in situ latitudinal temperature gradient.