Winter’s bite D’Andrea, Ettore; Rezaie, Negar; Battistelli, Alberto ...
New phytologist,
October 2019, Letnik:
224, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Late frost can destroy the photosynthetic apparatus of trees. We hypothesized that this can alter the normal cyclic dynamics of C-reserves in the wood.
We measured soluble sugar concentrations and ...radiocarbon signatures (Δ14C) of soluble nonstructural carbon (NSC) in woody tissues sampled from a Mediterranean beech forest that was completely defoliated by an exceptional late frost in 2016. We used the bomb radiocarbon approach to estimate the time elapsed since fixation of mobilized soluble sugars.
During the leafless period after the frost event, soluble sugar concentrations declined sharply while Δ14C of NSC increased. This can be explained by the lack of fresh assimilate supply and a mobilization of C from reserve pools. Soluble NSC became increasingly older during the leafless period, with a maximum average age of 5 yr from samples collected 27 d before canopy recovery. Following leaf re-growth, soluble sugar concentrations increased and Δ14C of soluble NSC decreased, indicating the allocation of new assimilates to the stem soluble sugars pool.
These data highlight that beech trees rapidly mobilize reserve C to survive strong source–sink imbalances, for example due to late frost, and show that NSC is a key trait for tree resilience under global change.
Forest loss threatens biodiversity, but its potential effects on multitrophic ecological interactions are poorly understood. Insect herbivory depends on complex bottomup (e.g., resource availability ...and plant antiherbivore defenses) and top-down forces (e.g., abundance of predators and herbivorous), but its determinants in human-altered tropical landscapes are largely unknown. Using structural equation models, we assessed the direct and indirect effects of forest loss on insect herbivory in 40 landscapes (115 ha each) from two regions with contrasting land-use change trajectories in the Brazilian Atlantic rainforest. We considered landscape forest cover as an exogenous predictor and (1) forest structure, (2) abundance of predators (birds and arthropods), and (3) abundance of herbivorous arthropods as endogenous predictors of insect leaf damage. From 12 predicted pathways, 11 were significant and showed that (1) leaf damage increases with forest loss (direct effect); (2) leaf damage increases with forest loss . through the simplification of vegetation structure and its associated dominance of herbivorous insects (indirect effect); and further demonstrate (3) a lack of top-down control of herbivores by predators (birds and arthropods). We conclude that forest loss favors insect herbivory by undermining the bottom-up control (presumably reduced plant antiherbivore defense mechanisms) in forests dominated by fast-growing pioneer plant species, and by improving the conditions required for herbivores proliferation.
Las plantas responden a cambios bióticos y abióticos acorde a su plasticidad fenotípica. Estas variaciones pueden expresarse en características relacionadas a la morfología foliar, crecimiento y ...defoliación. Este estudio evalúa la influencia de la edad de las plantas y de hojas sobre las características foliares, y su relación con la defoliación en tres especies forrajeras, Tithonia diversifolia, Morus alba y Moringa oleifera. M. oleifera mostró hojas con mayores valores de grosor, peso seco, asimetría y área; M. alba hojas más duras y con mayor área foliar especifica. M. oleifera el área foliar, peso seco, grosor y dureza incrementaron en plantas de 30 días. En tanto, que en M. alba las hojas intermedias tuvieron mayor área; y, las plantas de 90 días mayores valores de SLA, grosor y dureza. El área foliar y peso seco fueron mayores a los 60 y 30 días, respectivamente. En T. diversifolia las hojas intermedias presentaron mayor peso seco y grosor, las plantas de 30 días mayor área foliar y peso seco; y, las de 90 días, mayor grosor. Se encontraron relaciones negativas en hojas jóvenes con el grosor, dureza y peso seco. La defoliación mostró asociaciones positivas con el SLA y la dureza; y, negativas con el grosor, peso seco, asimetría y área. Subrayamos la importancia de realizar estudios que contribuyan al entendimiento de interrelaciones entre la estructura de la hoja, su función y sus relaciones con la expresión de los rasgos morfológicos de resistencia y tolerancia en especies tropicales de importancia económica y ecológica.
Assessment of associated insects and leaf damage caused by insects is essential concerning decisions to contribute to developing suitable rehabilitation techniques. Few studies have been done to ...identify the insect species associated with dipterocarp species and determine the damage caused by insects and their growth performance. Six species of dipterocarps, namely: Dipterocarpus alatus (hairy leaf apitong), Hopea philippinensis (gisok-gisok), Shorea malibato (malibato), Shorea assamica (manggasinoro), Shorea polita (malaanonang), and Shorea almon, were studied. This study was conducted to determine the insect-associated fauna using the visual and handpicking method of insect collection, leaf damage assessment using the Bioleaf app, and the morphological traits (i.e., basal diameter and plant height) on the growth performance of dipterocarps. There were eight orders of insects associated with the dipterocarps: Coleoptera, Diptera, Hemiptera, Heteroptera, Hymenoptera, Lepidoptera, Odonata, and Orthoptera. There was a significant difference (p ≤ 0.05) in the leaf damage among the six dipterocarps species after 25 months from planting. Shorea assamica had the highest leaf damage (8.68% ± 0.09), and Shorea almon had the least leaf damage (2.57% ± 0.09). In terms of basal diameter, the species with the highest significant increment (p ≤ 0.05) was Shorea polita (2.49 ± 0.67 mm), while Shorea almon had the least growth increment (0.98 ± 0.67 mm) 25 months after planting. Dipterocarpus alatus grows faster for the plant height than other species with a significant increment (p ≤ 0.05) of 32.90 ± 0.19 cm, while Shorea assamica had the least increment of (4.95 ± 0.19) cm. The study indicated eight orders of insects associated with the dipterocarps showing significant damage on the S. assamica. Despite the insect association, the plants grow significantly with the rapid increase observed on D. alatus.
•Large-scale international survey of a protected riparian forest in Central Europe.•Every biotic threat needs their own measures.•Tree diversity negatively affects fungi leave damage.
In a changing ...world, riparian forests are coming under more and more stress from biotic threats. This impacts all stages from saplings to older trees. One of the most dominant biotic threats are alien species and eruptive pest species. Sustainable silvicultural methods are required to reduce the risk of such biotic threats. We investigated the influence of climate, site, tree, and silvicultural characteristics on leaf damage by insect pests or fungal pathogens, herbaceous alien plant species, browsing, and the abundance of native tree saplings. Transects across the Danube-Mura-Drava biosphere reserve from Austria in the northwest to Serbia in the southeast, each containing 7–8 plots, were established to assess tree and site characteristics, regeneration, as well as fungal and insect leaf damage. We found that the horizontal stand structure affected insect leaf damage in different ways. Insect leaf damage was positively correlated with fungal leaf damage and tree height, and negatively correlated with intensity of forest management (from natural forests to coppice/plantations), temperature and precipitation during the vegetation season. Fungal leaf damage was negatively associated with intensity of forest management, and negatively with public ownership and tree species richness. Browsing was positively influenced by the number of saplings. The abundance of alien herbaceous plant species was negatively associated with distance to the watercourse, mean tree height, mean temperature of the vegetative period (MTVP), competition level, and the number of trees per layer, and positively associated with the DBH.
•Both drought-tolerant and sensitive plants were impaired by waterlogging.•Stomatal closure correlated with declines in plant hydraulic conductance.•Plants exhibited low water potentials after ...waterlogging relief.•Drought-sensitive plants were severely damaged after waterlogging relief.•Many drought-sensitive plants died after waterlogging relief.
Soil waterlogging negatively impacts plants due to reduced oxygen availability in the rhizosphere. Here we selected two Coffea canephora clones with contrasting tolerance to drought and oxidative stress to test whether they would also exhibit contrasting tolerance to waterlogging and post-waterlogging reoxygenation. Plants were exposed to six days of waterlogging followed by 40 days of reoxygenation. During waterlogging, both clones exhibited lower leaf gas exchange rate, electron transport rate and photochemical quenching as well as increased non-photochemical quenching; overall, these changes were stronger in the drought tolerant (DT) clones over the drought sentitive (DS) ones. Photosynthetic limitations were essentially linked to diffusional constraints regardless of clone. In both clones, declines in stomatal conductance were not associated with foliar ABA or ethylene levels, however stomatal conductance correlated with the plant hydraulic conductance. After reoxygenation, DT plants mostly recovered leaf function and plant mortality was less than 10%. Conversely, DS plants displayed very low water potentials after reoxygenation, which was accompanied by photosynthetic and membrane damage and 40% plant mortality. Our findings confirmed that the DT clone is less impaired by soil waterlogging and reoxygenation than the DS one. The differences between clones were more evident during the reoxygenation than during waterlogging, likely due to the drought experienced by the DS but not DT plants. Collectively, this information leads us to a common path to find new coffee genotypes with increased tolerance to both drought and waterlogging aiming at increased coffee sustainability under an ongoing climate changing scenario.
Abstract
Ongoing global climate change is increasing the risk of drought stress in some areas, which may compromise forest health. Such drought events also increase outbreaks of insect herbivores, ...resulting in plant defoliation. Interactions between drought and defoliation are poorly understood. In a greenhouse experiment, we selected a native species, Quercus acutissima Carr. and an alien species, Quercus rubra L. to explore their physiological responses to drought and defoliation treatments. After the treatments, we determined the seedlings’ physiological responses on Days 10 and 60. Our results showed that the defoliation treatment accelerated the carbon reserve consumption of plants under drought stress and inhibited the growth of both seedling types. Under the drought condition, Q. rubra maintained normal stem-specific hydraulic conductivity and normal growth parameters during the early stage of stress, whereas Q. acutissima used less water and grew more slowly during the experiment. Sixty days after defoliation treatment, the stem starch concentration of Q. acutissima was higher than that of the control group, but the stem biomass was lower. This indicates that Q. acutissima adopted a ‘slow strategy’ after stress, and more resources were used for storage rather than growth, which was conducive to the ability of these seedlings to resist recurrent biotic attack. Thus, Q. acutissima may be more tolerant to drought and defoliation than Q. rubra. The resource acquisition strategies of Quercus in this study suggest that the native Quercus species may be more successful at a long-term resource-poor site than the alien Quercus species.
Fall armyworm (FAW) is a multi-generational invasive insect pest of maize. Field experiments were conducted in diverse ecologies at Hyderabad, Telangana (Location 1); Dholi, Bihar (Location 2); ...Kolhapur, Maharashtra (Location 3) during the rainy season from July-November, 2023 to assess the impact of maize intercropping with legumes and leafy vegetables on FAW damage, abundance of beneficial insects, weed dynamics, and yield. In the present study, location-specific intercrops were selected for the experimentation. In location 1, maize intercropped with cowpea followed by groundnut reduced the level of FAW infestation compared to sole maize. The increased natural enemy population (coccinellids, spiders, earwigs); weed suppression, and higher yields were observed in maize when intercropped with cowpea followed by groundnut and red amaranthus. In location 2, maize intercropped with cowpea followed by green gram and black gram reduced the FAW damage and higher natural enemy population. Maximum yield was obtained in maize intercropped with black gram followed by green gram and cowpea. However, concerning weed suppression and cost-benefit ratio, green gram followed by black gram was found to be superior. Minimum FAW infestation, abundant natural enemy population, weed suppression, and improved economic returns were observed in maize when intercropped with cowpea followed by groundnut and fenugreek in location 3. Each intercrop had its advantages concerning pests, weed suppression, an abundance of natural enemy populations, and higher yields. Therefore, it is suggested that the selection of plants as intercrops with maize should be based on the location-specific importance of particular aspects to attain multifunctional benefits. The present results revealed that crop diversification with location-specific intercrops can reduce significant yield losses caused by FAW and promote higher yields in maize.
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•Location-specific intercropping in maize reduced FAW damage as compared to sole maize.•Plant diversity increased the natural enemy population such as coccinellids, spiders and earwigs of FAW.•Growing intercrops in maize resulted in weed suppression as the intercrops increase the competition for light.•Improved maize yield and higher benefit-cost ratio were obtained with location-specific intercrops in maize.
Seedlings in regenerating layer are frequently attacked by herbivorous insects, while the combined effects of defoliation and shading are not fully understood. In the present study, two Leguminosae ...species (
and
) were selected to study their responses to combined light and defoliation treatments. In a greenhouse experiment, light treatments (L+, 88% vs L-, 8% full sunlight) and defoliation treatments (CK, without defoliation vs DE, defoliation 50% of the upper crown) were applied at the same time. The seedlings' physiological and growth traits were determined at 1, 10, 30, and 70 days after the combined treatment. Our results showed that the effects of defoliation on growth and carbon allocation under high light treatments in both species were mainly concentrated in the early stage (days 1-10).
can achieve growth recovery within 10 days after defoliation, while
needs 30 days. Seedlings increased SLA and total chlorophyll concentration to improve light capture efficiency under low light treatments in both species, at the expense of reduced leaf thickness and leaf lignin concentration. The negative effects of defoliation treatment on plant growth and non-structural carbohydrates (NSCs) concentration in low light treatment were significantly higher than that in high light treatment after recovery for 70 days in
, suggesting sufficient production of carbohydrate would be crucial for seedling growth after defoliation. Plant growth was more sensitive to defoliation and low light stress than photosynthesis, resulting in NSCs accumulating during the early period of treatment. These results illustrated that although seedlings could adjust their resource allocation strategy and carbon dynamics in response to combined defoliation and light treatments, individuals grown in low light conditions will be more suppressed by defoliation. Our results indicate that we should pay more attention to understory seedlings' regeneration under the pressure of herbivorous insects.
Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin, a native pest of coconut in Central America, has recently been introduced to South-East Asia. Little is known about the spread of ...RSW in Bangladesh, the effect this pest has on coconut plants, or the full range of its plant hosts. To fill this knowledge gap, we conducted surveys across the southern coastal coconut producing region of Bangladesh. Coconut plant damage from RSW was high throughout all the areas surveyed, and this was correlated with the population density of RSW. Areas, such as Khulna, which had the highest population density of RSW, had the highest level of RSW leaf damage. Coconut plants with an infestation of RSW had significantly fewer leaves and fruits. The coconut fruits were also smaller, both in terms of size and weight, and contained less water and lighter endosperm compared to non-infested plants. This highlights the need for the management of RSW in coconut growing regions. We also report 39 new host plant species for RSW from 22 plant families, including the economically important mangrove plant Nipa palm, Nypa fruticans Wurmb.
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