ORCID Profile
0000-0002-3742-9762
Current Organisation
Linnaeus University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Springer Science and Business Media LLC
Date: 31-08-2021
DOI: 10.1007/S41348-021-00523-1
Abstract: Myrtle rust is a serious fungal disease caused by Austropuccinia psidii affecting a number of Myrtaceae species in New Zealand and elsewhere. Control with fungicides or biologicals provides a mechanism to reduce the build-up of inoculum in the short-term while other strategies are being developed or deployed for long-term management. This study evaluated the efficacy of fungicides for control of myrtle rust under controlled conditions and identified adjuvants that would promote spreading of fungicidal active ingredients across the leaf surface. The spread of fungicide on detached M. excelsa leaves was assessed by applying three different adjuvants in combination with seven fungicides. Subsequently, M. excelsa plants were treated with three fungicides/mixes, (azoxystrobin + epoxiconazole, triademinol or a natural tea-extract) at a single rate followed by inoculation with A. psidii urediniospores on day 0, 7, 14 or 21 days after spraying. The response to infection in M. excelsa plants based on different inoculation timings at days 0, 7 and 21 significantly differed among fungicide treatments. The fungicide azoxystrobin + epoxiconazole was the most effective with infections significantly lower on the adaxial leaf surface than abaxial, despite good surface coverage of fungicide being achieved on both leaf surfaces. There were significant differences among fungicides based on the proportion of infected leaves on M. excelsa plants. Day 21 post-spray inoculation indicated a significant interaction between inoculation time and fungicide on leaf disease ratings. However, this was not the case at either 28 or 35 days post-inoculation. This research contributes to fungicide options for myrtle rust control in New Zealand.
Publisher: Wiley
Date: 04-01-2016
DOI: 10.1111/GCB.13102
Abstract: Rising atmospheric [CO2 ], ca , is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2 ], ci , a constant drawdown in CO2 (ca - ci ), and a constant ci /ca . These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying ca . The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to ca . To assess leaf gas-exchange regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ(13) C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca -induced changes in ci /ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca - ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci . Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca , when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca , when photosystems are saturated and water loss is large for each unit C gain.
Publisher: Springer Science and Business Media LLC
Date: 21-07-2020
Publisher: Wiley
Date: 26-11-2011
Publisher: Oxford University Press (OUP)
Date: 12-07-2021
DOI: 10.1093/JPE/RTAB071
Abstract: Despite a large number of studies examining the effects of abiotic stress factors on plants, the mechanistic explanations of drought-induced tree mortality remain inconclusive and even less is known about how multiple stressors interact. The role of non-structural carbohydrates (NSCs) in preventing or postponing drought mortality is gaining attention. Here, we tested the role of NSCs in mitigating the effects of drought and salinity in New Zealand mangroves, Avicennia marina subsp. australasica. We experimentally manipulated plant NSC levels, prior to subjecting them to combinations of drought and salinity. Plant growth and survival rates were 2- and 3-fold higher in the high-NSC (H-NSC) group than in the low-NSC (L-NSC) group under high salinity and drought conditions, respectively. After 12 weeks under high salinity–high drought conditions, the H-NSC group showed higher stem hydraulic conductivity (281 ± 50 mmol cm−1 s−1 MPa−1) compared with the L-NSC group (134 ± 40 mmol cm−1 s−1 MPa−1). Although starch levels remained relatively constant, we found a 20% increase in soluble sugars in the stems of H-NSC group under high drought and high salinity in week 8 compared with week 12. Our results suggest (i) an important role of NSCs in mitigating the effects of low soil water potential caused by drought and salinity, and (ii) sink-limited growth under conditions of combined salinity and drought.
Publisher: Wiley
Date: 15-12-2022
DOI: 10.1111/NPH.18618
Abstract: Optimal stomatal theory predicts that stomata operate to maximise photosynthesis ( A net ) and minimise transpirational water loss to achieve optimal intrinsic water‐use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO 2 (eCO 2 ), and whether it can capture differences in responsiveness among woody plant functional types (PFTs). We conducted a meta‐analysis of tree studies of the effect of eCO 2 on iWUE and its components A net and stomatal conductance ( g s ). We compared three PFTs, using the unified stomatal optimisation (USO) model to account for confounding effects of leaf–air vapour pressure difference ( D ). We expected smaller g s , but greater A net , responses to eCO 2 in gymnosperms compared with angiosperm PFTs. We found that iWUE increased in proportion to increasing eCO 2 in all PFTs, and that increases in A net had stronger effects than reductions in g s . The USO model correctly captured stomatal behaviour with eCO 2 across most datasets. The chief difference among PFTs was a lower stomatal slope parameter ( g 1 ) for the gymnosperm, compared with angiosperm, species. Land surface models can use the USO model to describe stomatal behaviour under changing atmospheric CO 2 conditions.
Publisher: Wiley
Date: 19-04-2016
DOI: 10.1111/PPL.12442
Abstract: Phytophthora plant pathogens cause tremendous damage in planted and natural systems worldwide. Phosphite is one of the only effective chemicals to control broad-scale Phytophthora disease. Little work has been done on the phytotoxic effects of phosphite application on plant communities especially in combination with plant physiological impacts. Here, we tested the phytotoxic impact of phosphite applied as foliar spray at 0, 12, 24 and 48 kg a.i. ha(-1) . Eighteen-month-old saplings of 13 conifer and angiosperm species native to New Zealand, and two exotic coniferous species were treated and the development of necrotic tissue and chlorophyll-a-fluorescence parameters (optimal quantum yield, Fv /Fm effective quantum yield of photosystem II, ΦPSII ) were assessed. In addition, stomatal conductance (gs ) was measured on a subset of six species. Significant necrosis assessed by digital image analysis occurred in only three species: in the lauraceous canopy tree Beilschmiedia tawa (8-14%) and the understory shrub Dodonaea viscosa (5-7%) across phosphite concentrations and solely at the highest concentration in the myrtaceous pioneer shrub Leptospermum scoparium (66%). In non-necrotic tissue, Fv /Fm , ΦPSII and gs remained unaffected by the phosphite treatment. Overall, our findings suggest minor phytotoxic effects resulting from foliar phosphite application across erse taxa and regardless of concentration. This study supports the large-scale use of phosphite as a management tool to control plant diseases caused by Phytophthora pathogens in plantations and natural ecosystems. Long-term studies are required to ascertain potential ecological impacts of repeated phosphite applications.
Publisher: Elsevier BV
Date: 12-2023
Publisher: Scientific Societies
Date: 08-2019
DOI: 10.1094/PDIS-07-18-1247-RE
Abstract: Red needle cast is a significant foliar disease of commercial stands of Pinus radiata caused by Phytophthora pluvialis in New Zealand. The effect of copper, applied as a foliar spray of cuprous oxide at a range of doses between 0 and 1.72 kg ha −1 , was investigated in two controlled trials with potted plants and in an operational trial with mature P. radiata. In all trials, lesions formed on needles after artificial exposure to the infecting propagules (zoospores) of P. pluvialis were used to determine treatment efficacy, with the number and/or length of lesions as the dependent variable. Results across all trials indicated that cuprous oxide was highly effective at reducing infection of P. radiata with P. pluvialis. Application rates equivalent to ≥0.65 kg ha −1 significantly reduced infection levels relative to a control treatment, with foliar surface copper levels as low as 13 to 26 mg kg −1 of needle tissue preventing infection. Greater copper content was associated with a reduction in the proportion of needles with P. pluvialis lesions, with the probability of lesions developing decreasing approximately 1% for every 1 unit (in milligrams per kilogram) increase in copper content. Over a 90-day period, surface copper content declined to 30% of that originally applied, indicating an approximate period of treatment efficacy of 3 months. Our findings highlight the potential of cuprous oxide for the control of red needle cast in P. radiata stands. Further information about the optimal field dose, timing, and the frequency of foliar cuprous oxide application is key to prevent infection and also reduce the build up of inoculum during severe outbreaks of this pathogen.
Publisher: Wiley
Date: 12-09-2018
DOI: 10.1111/EEA.12710
Publisher: Springer Science and Business Media LLC
Date: 11-08-2010
DOI: 10.1007/S00425-010-1240-8
Abstract: Carbon uptake by forests constitutes half of the planet's terrestrial net primary production therefore, photosynthetic responses of trees to rising atmospheric CO(2) are critical to understanding the future global carbon cycle. At the Swiss Canopy Crane, we investigated gas exchange characteristics and leaf traits in five deciduous tree species during their eighth growing season under free air carbon dioxide enrichment in a 35-m tall, ca. 100-year-old mixed forest. Net photosynthesis of upper-canopy foliage was 48% (July) and 42% (September) higher in CO(2)-enriched trees and showed no sign of down-regulation. Elevated CO(2) had no effect on carboxylation efficiency (V (cmax)) or maximal electron transport (J (max)) driving ribulose-1,5-bisphosphate (RuBP) regeneration. CO(2) enrichment improved nitrogen use efficiency, but did not affect leaf nitrogen (N) concentration, leaf thickness or specific leaf area except for one species. Non-structural carbohydrates accumulated more strongly in leaves grown under elevated CO(2) (largely driven by Quercus). Because leaf area index did not change, the CO(2)-driven stimulation of photosynthesis in these trees may persist in the upper canopy under future atmospheric CO(2) concentrations without reductions in photosynthetic capacity. However, given the lack of growth stimulation, the fate of the additionally assimilated carbon remains uncertain.
Publisher: MDPI AG
Date: 28-02-2022
DOI: 10.3390/F13030399
Abstract: In many arid and semi-arid regions, increasing water scarcity pushes woody species to their physiological limits, making strong drought resistance essential for adaptive forest management. Here, we examined morpho-physiological and biochemical drought responses of the forestry-relevant Persian oak (Quercus brantii Lindl.) and black poplar (Populus nigra L.). In a 120-day greenhouse pot experiment, seedlings were subjected to three watering regimes (FC100, FC60, and FC30, indicating percentages of field capacity). Under FC100 conditions, all biomass measures and the total and specific leaf area of oak were significantly greater compared to those of poplar. FC60-exposed poplar seedlings exhibited strong declines in relative water content (RWC −33%) and carotenoids (−46%) and a surge in electrolyte leakage (EL +51%), while these parameters did not change significantly in oak. Although both species showed 80% EL under FC30 conditions, poplar suffered more severe drought damage than oak as evidenced by a 65% lower survival, stronger reductions in RWC and total chlorophyll, as well as stronger increases in oxidative stress markers. Accordingly, poplar seedlings displayed a drought-related 56% decline in quality index while only statistically insignificant reductions occurred in oak seedlings. The superior drought resistance of oak seedlings implies economically more viable nursery production and better seedling establishment, suggesting a shift towards Persian oak-dominated forestry in its natural range under future climate projections.
Publisher: Springer Science and Business Media LLC
Date: 25-08-2018
Publisher: Springer Science and Business Media LLC
Date: 27-06-2018
Publisher: Elsevier BV
Date: 12-2022
Publisher: Springer Science and Business Media LLC
Date: 03-04-2014
DOI: 10.1007/S00442-014-2935-5
Abstract: There is evidence of continued stimulation of foliage photosynthesis in trees exposed to elevated atmospheric CO2 concentrations however, this is mostly without a proportional growth response. Consequently, we lack information on the fate of this extra carbon (C) acquired. By a steady application of a (13)CO2 label in a free air CO2 enrichment (FACE) experiment, we traced the fate of C in 37-m-tall, ca. 110-year-old Picea abies trees in a natural forest in Switzerland. Hence, we are not reporting tree responses to elevated CO2 (which would require equally (13)C labeled controls), but are providing insights into assimilate processing in such trees. Sunlit needles and branchlets grow almost exclusively from current assimilates, whereas shaded parts of the crowns also rely on stored C. Only 2.5 years after FACE initiation, tree rings contained 100% new C. Stem-respiratory CO2 averaged 50% of new C over the entire FACE period. Fine roots and mycorrhizal fungi contained 49-56 and 26-43% new C, respectively, after 2.5 years. The isotopic signals in soil CO2 arrived 12 days after the onset of FACE, yet it contained only ca. 15% new C thereafter. We conclude that new C first feeds into fast turnover C pools in the canopy and becomes increasingly mixed with older C sources as one moves away (downward) from the crown. We speculate that enhanced C turnover (its metabolic cost) along the phloem path, as evidenced by basipetal isotope signal depletion, explains part of the 'missing carbon' in trees that assimilated more C under elevated CO2.
Publisher: Informa UK Limited
Date: 15-01-2018
Publisher: Wiley
Date: 27-07-2020
DOI: 10.1111/MMS.12637
Publisher: Springer Science and Business Media LLC
Date: 12-06-2019
DOI: 10.1038/S41598-019-44976-9
Abstract: Unmanned aerial vehicles (UAVs) represent a novel and cost effective research tool to investigate cetacean behaviour, as conventional aircraft are expensive, limited in the altitude they can fly at and potentially disturb sensitive wildlife. In addition, the aerial observation from the UAVs allows assessment of cetacean behaviour from an advantageous perspective and can collect high spatial and temporal resolution data, providing the opportunity to gather accurate data about group size, age class and subsurface behaviour. However, concerns have been raised about the potential risks of disturbance to animals caused by the UAV’s visual and acoustic stimuli. Boat-based surveys were conducted to assess the short-term behavioural responses of resting bottlenose dolphins ( Tursiops truncatus ) to a lightweight Vertical take-off and landing (VTOL) UAV flown at 10, 25, and 40 m altitude. Changes in group swim direction and frequencies of surface and aerial behavioural events were recorded from an anchored research vessel before (control) and during the aerial survey. The number of reorientation and tail slap events increased significantly between controls and flights when the UAV was flown at 10 m over the animals. In contrast, no significant differences were detected when the aircraft was flown at 25 and 40 m altitude. However, a precautionary approach is recommended for research applications requiring lower flight altitudes, with further research recommended to assess how different cetacean species and age class may respond to the UAV presence.
Publisher: Frontiers Media SA
Date: 2012
Publisher: Scientific Societies
Date: 07-2017
DOI: 10.1094/PDIS-12-16-1738-RE
Abstract: Phytophthora pluvialis is associated with early defoliation and shoot dieback in Douglas-fir in Oregon and New Zealand. In 2013, P. pluvialis was described from mixed tanoak-Douglas-fir forests in the Pacific Northwest and concurrently recognized as the main causal agent of red needle cast (RNC) in New Zealand radiata pine plantations. Little is known about its infection cycle and impact on host physiology. P. pluvialis studies in Douglas-fir are challenging due to the ubiquitous presence of the endophyte Phaeocryptopus gaeumannii, which produces similar symptoms and premature defoliation with persistent needle wetness, known as Swiss needle cast (SNC). Nonetheless, our study showed P. pluvialis infection in the presence of SNC. Exclusive expression of P. pluvialis is difficult to achieve as both diseases are promoted by high humidity. Here we established a ‘dry leaf’ strategy to suppress SNC when inoculating Douglas-fir needles for RNC studies. Sheltering plants along with drip irrigation to avoid needle wetness during the P. gaeumannii sporulation period suppressed its development in the new season flush. The diminished endophyte inoculum enabled bias-reduced studies of P. pluvialis impacts on Douglas-fir without the confounding effects of stomatal blockage and premature defoliation caused by P. gaeumannii.
Publisher: Frontiers Media SA
Date: 07-03-2017
Publisher: Elsevier BV
Date: 04-2016
Publisher: Wiley
Date: 18-07-2016
Publisher: Wiley
Date: 28-08-2013
Publisher: Springer Science and Business Media LLC
Date: 12-2014
Publisher: Oxford University Press (OUP)
Date: 17-10-2015
DOI: 10.1093/JEE/TOV303
Abstract: Two saproxylic forest insects, Hylurgus ligniperda (F.) (Coleoptera: Scolytinae) and Arhopalus ferus (Mulsant)(Coleoptera: Cerambycidae), were reared on artificial or natural diet at 15 or 25°C to compare larval growth rates and survival. A significant diet by temperature interaction was observed in the growth of H. ligniperda larvae,which developed faster when reared on natural diet at 15°C, but grew faster and pupated significantly earlier when reared on artificial diet at 25°C. However, H. ligniperda survival by the end of the experiment was low on both diets when reared at 25°C (10.1%, 95% CI: 5.2–15.1%), which suggests that rearing at lower temperatures may be required. A. ferus larvae gained significantly larger body size when reared on artificial diet than on natural diet at both temperatures. Survival of A. ferus reared on artificial diet was significantly lower than larvae reared on natural diet at 25°C. The significant differences between A. ferus larval development rates when reared on artificial and natural diets preclude the use of artificial diet to collect meaningful data to construct temperature development models for ecological comparisons. Artificial diet provided a suitable medium for mass production of in iduals for research purposes, e.g., test mortality in response to treatments. However, additional rearing studies are needed to determine whether the larger artificially reared larvae result in adults that are healthier, more productive, and live longer.
Publisher: Springer Science and Business Media LLC
Date: 10-11-2016
DOI: 10.1007/S10886-016-0792-X
Abstract: Plant-feeding insects use visual and olfactory cues (shape, color, plant volatiles) for host location, but the relative importance of different cues and interactions with non-host-plant volatiles in ecosystems of varying plant bio ersity is unclear for most species. We studied invasive bark beetles and wood borers associated with pine trees to characterize interactions among color, host and non-host volatiles, by employing traps that mimic tree trunks. Cross-vane flight intercept traps (black, green, red, white, yellow, clear) and black funnel traps were used with and without attractants (α-pinene + ethanol), repellents (non-host green leaf volatiles, 'GLV'), and attractant/repellent combinations in four pine forests in New Zealand. We trapped 274,594 Hylurgus ligniperda, 7842 Hylastes ater, and 16,301 Arhopalus ferus. Trap color, attractant, and color × attractant effects were highly significant. Overall, black and red traps had the highest catches, irrespective of the presence of attractants. Alpha-pinene plus ethanol increased trap catch of H. ligniperda 200-fold but only 6-fold for H. ater and 2-fold for A. ferus. Green leaf volatiles had a substantial repellent effect on trap catch of H. ligniperda but less on H. ater and A. ferus. Attack by H. ligniperda was halved when logs were treated with GLV, and a similar effect was observed when logs were placed among broadleaved understory shrubs emitting GLV. Overall, H. ligniperda was most strongly affected by the olfactory cues used, whereas H. ater and A. ferus were more strongly affected by visual cues. Collectively, the results support the semiochemical ersity hypothesis, indicating that non-host plant volatiles from erse plant communities or artificial dispensers can contribute to resistance against herbivores by partly disrupting host location.
Publisher: Springer Science and Business Media LLC
Date: 02-11-2016
Publisher: MDPI AG
Date: 21-02-2021
DOI: 10.3390/F12020247
Abstract: The charcoal disease agents, Biscogniauxia mediterranea and Obolarina persica are two latent, ascomycetous oak pathogens in the Middle Eastern Zagros forests, where they have devastating effects, particularly during drought. Under greenhouse conditions, we investigated the effects of the two charcoal disease agents in idually and in combination with drought on survival, growth, foliar gas-exchange, pigment content, oxidative stress and the antioxidant response of Quercus infectoria and Q. libani, two of the dominant tree species in this region. Commonly, the strongest negative effects emerged in the drought–pathogen interaction treatments. Q. infectoria showed less severe lesions, higher survival, more growth, and less leaf loss than Q. libani under combined biotic and abiotic stress. In both oak species, the combination of pathogen infection and drought resulted in more than 50% reduction in foliar gas-exchange parameters with partial recovery over time in Q. infectoria suggesting a superior defense system. Indeed, enhanced foliar anthocyanin, total soluble protein and glutathione concentrations imply an upregulation of the antioxidant defense system in Q. infectoria under stress while none of these parameters showed a significant treatment response in Q. libani. Consequently, Q. infectoria foliage showed no significant increase in superoxide, lower lipoxygenase activity, and less electrolyte leakage compared to the highly elevated levels seen in Q. libani indicating oxidative damage. Our findings indicate greater drought tolerance and pathogen resilience in Q. infectoria compared to Q. libani. Under future climate scenarios, we therefore expect changes in forest community structure driven by a decline in Q. libani and closely associated organisms.
Publisher: Oxford University Press (OUP)
Date: 06-05-2021
Abstract: Seedlings of New Zealand’s treeline-forming Fuscospora cliffortioides (Hook.f.) perform poorly beyond the established canopy, limiting treeline advance. To test the long-standing assumption that photoinhibition impairs regeneration in the subalpine belt of New Zealand’s Southern Alps, we assessed photosystem II (PSII) performance of seedling-sized in iduals and microclimate variation. We performed diurnal, non-invasive chlorophyll-a-fluorescence measurements on exposed and canopy-sheltered in iduals at two sites in New Zealand’s Southern Alps during summer and winter. Diurnal recordings of the effective (ΦPSII) and optimal (Fv/Fm) photosynthetic quantum yield were supplemented with light response curves and micro-temperature recordings. ΦPSII returned to near-optimal values around 0.8 after 30 min of shading, which rules out accumulative or long-term photoinhibition effects. The maximum electron transport rate derived from rapid light curves was significantly higher (+12%) in exposed compared with canopy-shaded in iduals. Summer temperature fluctuated widely on the scree (−0.5 to 60.5 °C) and near seedlings (−2 to 26.5 °C). Our results revealed a remarkable level of light adaptation and contradict previous studies hinting at high light-induced photoinhibition as a treeline-limiting factor in the Southern Alps. By linking low ΦPSII on winter mornings, and large, sudden temperature drops in summer, we suspect that cold-induced photoinhibition might occur but the rapid recovery of ΦPSII seen across a wide temperature range makes lethal photo-oxidative damage rather unlikely. Given the demonstrably low summer frost tolerance of F. cliffortioides, cold-related damage resulting from frost events during the growing season or embolism induced by frost drought may offer more plausible explanations for the poor seedling establishment. Duration and frequency of these events could diminish with global warming, which may promote treeline advance.
Publisher: Public Library of Science (PLoS)
Date: 28-05-2019
Publisher: Scion
Date: 24-05-2014
Publisher: Scion
Date: 23-05-2014
Publisher: Wiley
Date: 26-12-2016
DOI: 10.1111/EEN.12371
Publisher: Elsevier BV
Date: 11-2019
Publisher: Wiley
Date: 09-09-2022
DOI: 10.1111/DDI.13622
Abstract: Biological invasions are a major threat to bio ersity in aquatic and terrestrial habitats. Insects represent an important group of species in freshwater and terrestrial habitats, and they constitute a large proportion of non‐native species. However, while many non‐native insects are known from terrestrial ecosystems, they appear to be less represented in freshwater habitats. Comparisons between freshwater and terrestrial habitats of invader richness relative to native species richness are scarce, which hinders syntheses of invasion processes. Here, we used data from three regions on different continents to determine whether non‐native insects are indeed under‐represented in freshwater compared with terrestrial assemblages. Europe, North America, New Zealand. We compiled a comprehensive inventory of native and non‐native insect species established in freshwater and terrestrial habitats of the three study regions. We then contrasted the richness of non‐native and native species among freshwater and terrestrial insects for all insect orders in each region. Using binomial regression, we analysed the proportions of non‐native species in freshwater and terrestrial habitats. Marine insect species were excluded from our analysis, and insects in low‐salinity brackish water were considered as freshwater insects. In most insect orders living in freshwater, non‐native species were under‐represented, while they were over‐represented in a number of terrestrial orders. This pattern occurred in purely aquatic orders and in orders with both freshwater and terrestrial species. Overall, the proportion of non‐native species was significantly lower in freshwater than in terrestrial species. Despite the numerical and ecological importance of insects among all non‐native species, non‐native insect species are surprisingly rare in freshwater habitats. This is consistent across the three investigated regions. We review hypotheses concerning species traits and invasion pathways that are most likely to explain these patterns. Our findings contribute to a growing appreciation of drivers and impacts of biological invasions.
Publisher: Cold Spring Harbor Laboratory
Date: 25-03-2022
DOI: 10.1101/2022.03.22.485042
Abstract: Biological invasions are a major threat to bio ersity in both aquatic and terrestrial habitats. Insects represent an important group of species in freshwater and terrestrial habitats, and they constitute a large proportion of non-native species. However, while many non-native insects are known from terrestrial ecosystems, it remains unclear how they are represented in freshwater habitats. Comparisons of the richness of invaders relative to the richness of native species between freshwater and terrestrial habitats are scarce, which hinders syntheses of invasion processes. Here, we used data from three regions on different continents to determine whether non-native insects are under- or overrepresented in freshwater compared to terrestrial assemblages. Europe, North America, New Zealand We compiled a comprehensive inventory of the native and non-native insect species established in freshwater and terrestrial habitats of the three study regions. We then contrasted the richness of non-native and native species among freshwater and terrestrial insects for all insect orders in each region. Using binomial regression, we analysed the proportions of non-native species in freshwater and terrestrial habitats across the three regions. In most insect orders living in freshwater, non-native species were under-represented, while they were over-represented in a number of terrestrial orders. This pattern occurred in purely aquatic orders as well as in orders with both freshwater and terrestrial species. Overall, the proportion of non-native species was significantly lower in freshwater than in terrestrial species. Despite the numerical and ecological importance of insects among all non-native species, non-native insect species are surprisingly rare in freshwater habitats, and this pattern is consistent across the three investigated study regions. We briefly review hypotheses concerning species traits and invasion pathways that are most likely to explain these patterns. Our findings contribute to a growing appreciation of drivers and impacts of biological invasions.
Publisher: Scientific Societies
Date: 11-2019
DOI: 10.1094/PHYTO-12-18-0479-R
Abstract: The emergence of Phytophthora pluvialis as a foliar pathogen of Douglas fir in New Zealand and the Pacific Northwest United States has raised questions about its interaction with the widespread Swiss needle cast (SNC) disease. During Spring 2017, we repeatedly s led 30 trees along an environmental gradient in each region and 292 additional trees in a longitudinal transect to assess the P. pluvialis epidemic and the association between P. pluvialis and Nothophaeocryptopus gaeumannii, which are causal agents of SNC. Both pathogens were consistently more abundant in the host’s exotic environment in New Zealand. In both areas, the two pathogens co-exist in different spatial scales for regions and needles. The relative abundance of both pathogens was negatively correlated in the Pacific Northwest, where both presumably have co-existed for longer. Our findings confirmed the interaction of P. pluvialis and N. gaeumannii as foliar pathogens of Douglas fir and suggest a within-site spatial variation in the Pacific Northwest.
Publisher: Frontiers Media SA
Date: 27-05-2022
Abstract: Common myrtle ( Myrtus communis L.) occurs in (semi-)arid areas of the Palearctic region where climate change, over-exploitation, and habitat destruction imperil its existence. The evergreen shrub is of great economic and ecological importance due to its pharmaceutical value, ornamental use, and its role in urban greening and habitat restoration initiatives. Under greenhouse conditions, we investigated the effect of soil inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on biomass allocation, water relations, and nutritional status of drought-stressed myrtle seedlings. Single and dual AMF ( Funneliformis mosseae and Rhizophagus irregularis ) and PGPR ( Pseudomonas fluorescens and P. putida ) soil inoculations were applied to myrtle seedlings growing under different soil water regimes (100, 60, and 30% of field capacity) for 6 months using a full factorial, completely randomized design. AMF and PGPR treatments, especially dual inoculations, alleviated negative drought effects on biomass and morpho-physiological traits, except for water-use efficiency, which peaked under severe drought conditions. Under the greatest soil water deficit, dual inoculations promoted leaf biomass (104%–108%), root biomass (56%–73%), mesophyll conductance (58%), and relative water content (1.4-fold) compared to non-inoculated controls. Particularly, dual AMF and PGPR inoculations stimulated nutrient dynamics in roots (N: 138%–151%, P: 176%–181%, K: 112%–114%, Ca: 124%–136%, and Mg: 130%–140%) and leaves (N: 101%–107%, P: 143%–149%, K: 83%–84%, Ca: 98%–107%, and Mg: 102%–106%). Our findings highlight soil inoculations with beneficial microbes as a cost-effective way to produce highly drought resistant seedling stock which is vital for restoring natural myrtle habitats and for future-proofing myrtle crop systems.
Publisher: Wiley
Date: 18-09-2009
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier BV
Date: 12-2011
Publisher: Elsevier BV
Date: 09-2019
Publisher: Oxford University Press (OUP)
Date: 05-12-2008
Abstract: Shoot water relations were studied in Siberian larch (Larix sibirica Ledeb.) trees growing at the borderline between taiga and steppe in northern Mongolia. Larix sibirica is the main tree species in these forests covering 80% of Mongolia's forested area. Minimum shoot water potentials (Psi(m)) close to the point of zero turgor (Psi(0)) repeatedly recorded throughout the growing season suggest that the water relations in L. sibirica were often critical. The Psi(m) varied in close relation to the atmospheric vapor pressure deficit, whereas Psi(0) was correlated with monthly precipitation. Young larch trees growing at the forest line to the steppe were more susceptible to drought than mature trees at the same sites. Furthermore, isolated trees growing on the steppe exhibited lower Psi(m) and recovered to a lower degree from drought overnight than the trees at the forest line. Indications of drought stress in L. sibirica were obtained in two study areas in Mongolia's forest-steppe ecotone: one in the mountain taiga of the western Khentey in northernmost Mongolia, the other in the forest-steppe at the southern distribution limit of L. sibirica on Mt. Bogd Uul, southern Khentey. Larix sibirica growing in riverine taiga with contact to the groundwater table was better water-supplied than the larch trees growing at the forest line to the steppe. Larch trees from the interior of light taiga forests on north-facing slopes, however, exhibited more critical water relations than the trees at the forest line. Frequent drought stress in mature trees and even more in young larch trees at the forest-steppe borderline suggests that L. sibirica does not have the potential to encroach on the steppe under the present climate, except in a sequence of exceptionally moist and cool years. A regression of the present borderline between forest and steppe is likely to occur, as average temperatures are increasing everywhere and precipitation is decreasing regionally in Mongolia's taiga forest region. Higher stomatal conductance concomitant to lower Psi(m) in trees of northern-slope forests compared to trees from the forest line to the steppe may be the result of a recent increase in drought intensity that affects better drought-adapted trees at the forest edge less than the trees in the forest interior. We conclude that drought is a key factor explaining the forest-steppe borderline in northern Mongolia. The proportion of forests within the present vegetation pattern of forests on north-facing slopes and the grasslands on south-facing slopes in Mongolia's forest-steppe ecotone is not likely to increase under the present climate, but may decrease with increasing aridity due to global warming.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Wiley
Date: 16-01-2023
DOI: 10.1111/GCB.16585
Abstract: Responses of the terrestrial biosphere to rapidly changing environmental conditions are a major source of uncertainty in climate projections. In an effort to reduce this uncertainty, a wide range of global change experiments have been conducted that mimic future conditions in terrestrial ecosystems, manipulating CO 2 , temperature, and nutrient and water availability. Syntheses of results across experiments provide a more general sense of ecosystem responses to global change, and help to discern the influence of background conditions such as climate and vegetation type in determining global change responses. Several independent syntheses of published data have yielded distinct databases for specific objectives. Such parallel, uncoordinated initiatives carry the risk of producing redundant data collection efforts and have led to contrasting outcomes without clarifying the underlying reason for ergence. These problems could be avoided by creating a publicly available, updatable, curated database. Here, we report on a global effort to collect and curate 57,089 treatment responses across 3644 manipulation experiments at 1145 sites, simulating elevated CO 2 , warming, nutrient addition, and precipitation changes. In the resulting Manipulation Experiments Synthesis Initiative (MESI) database, effects of experimental global change drivers on carbon and nutrient cycles are included, as well as ancillary data such as background climate, vegetation type, treatment magnitude, duration, and, unique to our database, measured soil properties. Our analysis of the database indicates that most experiments are short term (one or few growing seasons), conducted in the USA, Europe, or China, and that the most abundantly reported variable is aboveground biomass. We provide the most comprehensive multifactor global change database to date, enabling the research community to tackle open research questions, vital to global policymaking. The MESI database, freely accessible at 0.5281/zenodo.7153253 , opens new avenues for model evaluation and synthesis‐based understanding of how global change affects terrestrial biomes. We welcome contributions to the database on GitHub.
Publisher: Springer Science and Business Media LLC
Date: 20-07-2018
Publisher: Wiley
Date: 25-11-2014
Publisher: Springer Science and Business Media LLC
Date: 08-10-2020
DOI: 10.1038/S41598-020-73527-W
Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Publisher: Wiley
Date: 09-02-2017
DOI: 10.1111/EFP.12327
Publisher: Scion
Date: 12-11-2015
Publisher: Canadian Science Publishing
Date: 12-2009
DOI: 10.1139/X09-156
Abstract: Pinus sylvesteris L. is locally common at the lower forest line to the steppe in Mongolia’s taiga forests, which are otherwise dominated by Larix sibirica Ledeb. The factors responsible for the occurrence of pine patches in the forest–steppe ecotone are insufficiently studied. We analyzed the response of P. sylvestris to summer drought in the western Khentey Mountains, northern Mongolia, by measuring shoot water potentials and exemplary measurements of δ 13 C signatures, CO 2 –H 2 O gas exchange, chlorophyll fluorescence yield, and concentrations of nonstructural carbohydrates. Pine trees growing in the forest–steppe ecotone show conservative water consumption with a sensitive stomatal regulation and relatively constant shoot water potentials under dry conditions. This might be a selective advantage for P. sylvestris against increasing aridity driven by global warming, since the main competitor, L. sibirica, often suffers from drought stress even under the current climate in the study area.
Publisher: Springer Science and Business Media LLC
Date: 13-06-2016
DOI: 10.1038/NCLIMATE3054
Publisher: Wiley
Date: 11-03-2014
DOI: 10.1111/PPL.12170
Abstract: Southwest Australian Banksia woodlands are highly erse plant communities that are threatened by drought- or temperature-induced mortality due to the region's changing climate. We examined water relations in dominant Banksia menziesii R. Br. trees using magnetic leaf patch cl pressure (ZIM-) probes that allow continuous, real-time monitoring of leaf water status. Multiple ZIM-probes across the crown were complemented by traditional ecophysiological measurements. During summer, early stomatal downregulation of transpiration prevented midday balancing pressures from exceeding 2.5 MPa. Diurnal patterns of ZIM-probe and pressure chamber readings agreed reasonably well, however, ZIM-probes recorded short-term dynamics, which are impossible to capture using a pressure chamber. Simultaneous recordings of three ZIM-probes evenly spaced along leaf laminas revealed intrafoliar turgor gradients, which, however, did not develop in a strictly basi- or acropetal fashion and varied with cardinal direction. Drought stress manifested as increasing daily signal litude (low leaf water status) and occasionally as rising baseline at night (delayed rehydration). These symptoms occurred more often locally than across the entire crown. Microclimate effects on leaf water status were strongest in crown regions experiencing peak morning radiation (East and North). Extreme spring temperatures preceded the sudden death of B. menziesii trees, suggesting a temperature- or humidity-related tipping point causing rapid hydraulic failure as evidenced by collapsing ZIM-probe readings from an affected tree. In a warmer and drier future, increased frequency of B. menziesii mortality will result in significantly altered community structure and ecosystem function.
Publisher: Elsevier BV
Date: 05-2023
Publisher: Elsevier BV
Date: 04-2009
Publisher: Oxford University Press (OUP)
Date: 15-11-2022
DOI: 10.1093/EE/NVAC094
Abstract: Hylurgus ligniperda (F.) and Hylastes ater (Paykull) are secondary bark beetles that have successfully spread beyond their native range, particularly into Pinus spp. plantations in the Southern Hemisphere. They feed on the phloem and cambial regions of highly stressed and recently dead Pinus spp. Here H. ligniperda and H. ater egg, larval, and pupal survival and development rates were modeled. Survival was variably influenced by temperatures depending on the life stage, but general trends were for H. ligniperda to tolerate warmer temperatures in comparison to H. ater. Nonlinear models showed 26, 29, and 34°C are the optimal temperature (maximum development rates) for the development of eggs, larvae, and pupae of H. ligniperda. In contrast, optimal temperature predictions were lower for H. ater, with estimates of 26, 22, and 23°C for the development of eggs, larvae, and pupae, respectively. H. ligniperda pre-imaginal stages were more tolerant to high temperatures, and H. ater pre-imaginal stages were more tolerant to low temperatures. Understanding the thermal requirements and limits for development for these two pests can assist in modeling emergence times, their current and potential species distribution and have potential phytosanitary applications.
Publisher: Wiley
Date: 19-08-2010
Publisher: Elsevier BV
Date: 02-2023
Publisher: Wiley
Date: 02-03-2021
DOI: 10.1111/EFP.12680
Abstract: New Zealand kauri ( Agathis australis ) trees are culturally, socially and ecologically significant within northern New Zealand's nutrient‐poor podocarp forest ecosystems. Phytophthora agathidicida is an aggressive oomycete pathogen, capable of killing A . australis across its ecological range, causing the disease known as kauri dieback. The pathogen, like many other forest Phytophthora species, commences as a fine root rot which progresses to collar rot and resinous cankers on the lower trunk. In this study, we investigated the eco‐physiological and fine root responses of kauri to infection by P . agathidicida and tested whether the foliar application of micronutrients (manganese and zinc combined, iron alone, or a trace element mix) affects dieback disease expression. Fortnightly assessments of chlorophyll‐ a ‐fluorescence were conducted over 12 weeks, and fine root length and tip numbers were recorded at the end of the experiment. None of the micronutrient treatments had a significant physiological effect regardless of pathogen infection. However, contrary to expectations, pathogen infection caused a significant upregulation in photosynthetic activity over time, as the electron transport rate of infected plants was approximately 26% higher than that of control plants at the end of the trial. These results indicate that an increase in the strength of the below‐ground carbon sink through pathogen consumption of labile carbohydrates (sugars), together with pathogen‐induced root damage, triggered upregulation of photosynthesis in the seedlings. Understanding how P . agathidicida infection affects the physiology and resource allocation in kauri is critical to determining the disease aetiology and management options.
Publisher: Springer Science and Business Media LLC
Date: 21-02-2015
No related grants have been discovered for Martin Karl-Friedrich Bader.