Provenance selection and site conditions determine growth performance of pedunculate oak

Forests of the future need to cope with adverse climatic conditions, in particular drought, to ensure forest stability and productivity. Given the usually long rotation period of forests, forest managers need to select appropriate, i.e. productive and climate-change resilient tree species and/or provenances, to lower tree-mortality risks and sustain current wood production rates at the end of the 21^st century. A frequent means of assessing which provenances of a given species are adapted to anticipated climate conditions is common garden experiments, where trees from different provenances are planted under similar climate conditions. However, in this context soil conditions also play an important role, since they govern how climate translates into plant-available water and hence plant’s ability to cope with extreme drought events. Here, we examine the effects of soil conditions on pedunculate oak (Quercus robur L.), by studying 10 different Dutch oak provenances that were planted in three provenance trials on different soil types in 1988 in the Netherlands. Using dendroecological methods, we quantified provenance-specific productivity and assessed provenance- and site-specific growth patterns. Our results indicated clear differences in productivity among provenances as well as soil-type specific growth patterns. Consequently, our study highlights the importance of incorporating soil characteristics when evaluating the growth performance of provenances within common garden experiments.     

Phenology responses of temperate butterflies to latitude depend on ecological traits

Global change influences species’ seasonal occurrence, or phenology. In cold‐adapted insects, the activity is expected to start earlier with a warming climate, but contradictory evidence exists, and the reactions may be linked to species‐specific traits. Using data from the GBIF database, we selected 105 single‐brooded Holarctic butterflies inhabiting broad latitudinal ranges. We regressed patterns of an adult flight against latitudes of the records, controlling for altitude and year effects. Species with delayed flight periods towards the high latitudes, or stable flight periods across latitudes, prevailed over those that advanced their flight towards the high latitudes. The responses corresponded with the species’ seasonality (flight of early season species was delayed and flight of summer species was advanced at high latitudes) and oceanic vs. continental climatic niches (delays in oceanic, stability in continental species). Future restructuring of butterfly seasonal patterns in high latitudes will reflect climatic niches, and hence the evolutionary history of participating species.     

Tsuga seed cones from the late Paleogene of southwestern China and their biogeographical and paleoenvironmental implications

Six Tsuga ovuliferous/seed cone impression fossils were discovered from the late Eocene (34.6 ± 0.8 Ma) Lawula Formation in Mangkang County, eastern Tibet and the early Oligocene (32 ± 1 Ma) lacustrine deposits in Lühe Basin, Nanhua County, Yunnan Province. These two fossil sites are both located in southwestern China, ∼800 km apart from each other. These fossils represent the oldest records of this genus in southwestern China, even earliest reliable macrofossil records of this genus in the world. These well-preserved seed cones provide sufficient materials for the establishment of Tsuga asiatica Wu et Zhou n. sp. to accommodate five specimens, leaving one to be assigned to T. cf. dumosa Eichler (cf. Wu et Zhou). Both qualitative and quantitative comparisons with other cone fossils and cones of all living species of the genus suggested that T. asiatica shares more similarities with one of the basal species of the genus T. heterophylla. The discovery of late Paleogene macrofossil records of Tsuga in southwestern China supports the previous hypothesis of the early disposal routes of this coniferous genus predicted by phylogenetic analysis. The elevation ranges and the climate requirements of living species that are closely related to our fossils suggest that the southeastern edge of the Qinghai-Tibetan Plateau should be much warmer, and wetter in late Paleogene than nowadays.     

中国黄土高原北部地区新石器-青铜时代农业结构演变及其对区域生态环境的适应

本文分析并测定了从15个位于黄土高原北部的遗址中浮选的炭化植物遗存的年代及数量,讨论了该地区新石器-青铜时代农业结构的变化、发展及自适应。研究表明,该地区粟的占比随着遗址年代的推移呈现出上升趋势,证明了先民的农业技术随时间变化而发展;受季风降水特征影响,东南部灌丛草原区粟的占比随时间变化上升趋势明显,西北部干草原区则变化较弱,证明环境的差异也造成了农业模式的不同;在干旱气候条件限制下,自中全新世以来黄土高原北部地区的主要作物始终为粟和黍,粟作农业奠定了黄土高原乃至中国北方的文明基础。     

A review of mycotoxin biosynthetic pathways: associated genes and their expressions under the influence of climatic factors

Fungal contamination of agricultural commodities, particularly by mycotoxigenic fungi, represents an enormous concern for global food security in terms of feeding the world's growing population with sufficient and safe food. Not only do they reduce crop yield and quality, but they also produce substantial numbers of mycotoxins, which pose serious adverse health effects in human and animals. As the genome of most mycotoxigenic species have been sequenced, the gene clusters involved in the biosynthesis of agriculturally important mycotoxins including aflatoxins, fumonisins, ochratoxins, zearalenone and trichothecenes, have been largely identified and characterised, with their roles elucidated by researchers. This review provides a comprehensive overview of the current knowledge of genes involved in the biosynthetic pathways of mycotoxins. In addition, the influence of climatic factors including water, temperature and carbon dioxide on differential mycotoxin gene expressions have been highlighted. Overall, the relationship between the relative expression of key regulatory and structural genes under different environmental conditions is significantly correlated with mycotoxins production. This indicates that mycotoxin gene induction can be used as a reliable indicator or marker to monitor mycotoxin production pre-and-post harvest. Furthermore, current strategies to manage mycotoxin risks still require improvement. Thus, an accurate understanding of the molecular mechanisms of mycotoxin biosynthesis in mycotoxigenic species could help to develop an innovative, robust targeted control strategy. This could include the exploitation of novel compounds, which can inhibit biosynthetic genes, to minimise mycotoxin risks.     

Grazing-induced legacy effects enhance plant adaption to drought by larger root allocation plasticity

放牧诱导的植物遗留效应可以通过较大的根系分配可塑性增强其干旱适应性 为探索植物的放牧遗留效应是否有利于天然草原生态系统应对干旱环境,我们采集了 内蒙古典型草原自由放牧和多年围封样地内的冰草(Agropyron cristatum)和黄囊苔草(Carex korshinskyi)幼苗 进行了温室控水试验。研究结果表明,干旱处理对自由放牧样地采集的冰草和黄囊苔草子株生物量、子株数量和总生物量的影响较小;自由放牧区的冰草与黄囊苔草较强的干旱适应性可部分由干旱处理下较大的根系分配可塑性来解释。本研究结果表明合理放牧是天然草原适应气候变化的潜在管理办法之一。     

Fire and local factors shape ectomycorrhizal fungal communities associated with Pinus ponderosa in mountains of the Madrean Sky Island Archipelago

With a warming and drying climate, coniferous forests worldwide are increasingly threatened by wildfires. We examined how fire impacts ectomycorrhizal (EM) fungi associated with Pinus ponderosa, an important tree species in western North America. In the biodiverse Madrean Sky Islands, P. ponderosa forests exist on insular mountains separated by arid lands. How do EM fungi in these isolated ranges respond to fire, and can data from individual ranges predict community shifts after fire at a regional scale? By comparing areas in two ranges that experienced moderate fires 12–16 y earlier, and proximate areas in each range without recent fire, we reveal pervasive effects on diversity and composition of EM communities more than a decade after moderate fires occurred. Post-fire differences in EM communities in different ranges highlight the challenge of predicting fungal community shifts in these isolated forests, despite similarities of climate, plant communities, and fire severity.     

The dendroclimatic value of oak stable isotopes

Tree-ring stable oxygen and carbon isotope ratios (δ¹⁸O and δ¹³C) are an important archive for climate reconstructions. However, it remains unclear whether the polyvinyl acetate emulsion, often used for the preservation and fixation of wood samples, influences δ¹⁸O and δ¹³C signals. Further uncertainties are associated with the possible effects of geographical origin and cambial age of historical samples. Here, we present annually-resolved and absolutely-dated δ¹⁸O and δ¹³C measurements of 21 living oaks (Quercus robur and Q. petraea) from the Czech Republic. We find that the δ¹⁸O and δ¹³C signals in the extracted alpha-cellulose are not affected by polyvinyl acetate treatment. Covering the entire 20^th century and reaching until 2018 CE, our dataset reveals spatial and temporal coherency within and between the individual δ¹⁸O and δ¹³C chronologies of different oak species, sample locations, and tree ages. Highly significant (p < 0.01) Pearson’s correlation coefficients of the site-specific δ¹³C and δ¹⁸O chronologies range from 0.48–0.77 and 0.36–0.56, respectively. The isotopic inter-series correlations of Q. robur and Q. petraea from the same site are 0.75 and 0.43 for the mean δ¹³C and δ¹⁸O values, respectively. Significant (p < 0.01) correlations of 0.49 and 0.84 are found for δ¹³C and δ¹⁸O, respectively, when all measurements from all sampling locations and tree ages are included. Our study shows that non-pooled oak δ¹⁸O and δ¹³C measurements from both species, different locations, and diverse tree ages can be combined into robust isotopic chronologies for climate reconstructions.     

Dynamics of solute/matric stress interactions with climate change abiotic factors on growth,gene expression and ochratoxin A production by Penicillium verrucosum on a wheat-based matrix

Penicillium verrucosum contaminates temperate cereals with ochratoxin A (OTA) during harvesting and storage. We examined the effect of temperature (25 vs 30 ^oC), CO₂ (400 vs 1000 ppm) and matric/solute stress (-2.8 vs -7.0 MPa) on (i) growth, (ii) key OTA biosynthetic genes and (iii) OTA production on a milled wheat substrate. Growth was generally faster under matric than solute stress at 25 ^oC, regardless of CO₂ concentrations. At 30 ^oC, growth of P. verrucosum was significantly reduced under solute stress in both CO₂ treatments, with no growth observed at -2.8 MPa (=0.98 water activity, a_w) and 1000 ppm CO₂. Overall, growth patterns under solute stress was slower in elevated CO₂ than under matric stress when compared with existing conditions. The otapksPV gene expression was increased under elevated CO₂ levels in matric stress treatments. There was fewer effects on the otanrpsPV biosynthetic gene. This pattern was paralleled with the production of OTA under these conditions. This suggest that P. verrucosum is able to actively grow and survive in both soil and on crop debris under three way interacting climate-related abiotic factors. This resilience suggests that they would still be able to pose an OTA contamination risk in temperate cereals post-harvest.     

Changes in haemolymph parameters and insect ability to respond to immune challenge during overwintering

Overwintering is a challenging period in the life of temperate insects. A limited energy budget characteristic of this period can result in reduced investment in immune system. Here, we investigated selected physiological and immunological parameters in laboratory‐reared and field‐collected harlequin ladybirds (Harmonia axyridis). For laboratory‐reared beetles, we focused on the effects of winter temperature regime (cold, average, or warm winter) on total haemocyte concentration aiming to investigate potential effects of ongoing climate change on immune system in overwintering insects. We recorded strong reduction in haemocyte concentration during winter; however, there were only limited effects of winter temperature regime on changes in haemocyte concentration in the course of overwintering. For field‐collected beetles, we measured additional parameters, specifically: total protein concentration, antimicrobial activity against Escherichia coli, and haemocyte concentration before and after overwintering. The field experiment did not investigate effects of winter temperature, but focused on changes in inducibility of insect immune system during overwintering, that is, measured parameters were compared between naïve beetles and those challenged by Escherichia coli. Haemocyte concentration decreased during overwintering, but only in individuals challenged by Escherichia coli. Prior to overwintering, the challenged beetles had a significantly higher haemocyte concentration compared to naïve beetles, whereas no difference was observed after overwintering. A similar pattern was observed also for antimicrobial activity against Escherichia coli as challenged beetles outperformed naïve beetles before overwintering, but not after winter. In both sexes, total protein concentration increased in the course of overwintering, but females had a significantly higher total protein concentration in their hemolymph compared to males. In general, our results revealed that insect’s ability to respond to an immune challenge is significantly reduced in the course of overwintering.