Abstract Climate change has been linked to the intensification of forest pest outbreaks, posing a serious threat to non‐coevolved tree species because of their potentially weak defensive capabilities. However, unlike broad‐scale climatic disturbances such as drought and heatwaves, insect outbreaks are highly heterogeneous in space and among host species, and the response of occurring conifers to such outbreaks remains poorly understood. The core area of the Changbai Mountain Nature Reserve in northeastern China was severely defoliated in 2019 by larch caterpillars ( Dendrolimus superans Butler)—a conifer‐feeding defoliator that prefers larch but also attacks other conifers. In this region, a vegetation transition zone between the broadleaf‐Korean pine and spruce–fir forests hosts multiple conifer species co‐existing within short distances under similar defoliation intensities. We monitored 1,837 trees in 2019 (pre‐disturbance), 2021 and 2024, and sampled needles of healthy individuals of each species in 2024 to obtain species‐level proxies of intrinsic foliar traits. Results revealed that: (i) mortality of attacked Korean pine peaked within 2 years, with little subsequent increase, resulting in a cumulative mortality rate of 31.3%; in contrast, mortality of spruce and fir continued to increase until the fifth year, reaching a combined cumulative rate of 78.6%, while larch exhibited nearly 100% survival. (ii) a deciduous habit, low needle biomass allocation and low carbohydrate concentrations enhanced survival by reducing canopy regeneration costs. (iii) regarding radial growth responses, spruce showed stronger compensatory growth but weaker recovery ability than fir and Korean pine, likely due to its limited carbon and nutrient reserves. Considering these findings, prioritizing the protection of non‐coevolved conifers is recommended to minimize biomass loss during pest outbreaks. This study also provides important insights for temperate and boreal conifer forest conservation, highlighting the high vulnerability of spruce–fir forests to larch caterpillar outbreaks.
Abstract Sexually deceptive orchids mimic female mating signals of their pollinators to achieve pollination. In Australia, multiple orchid genera exploit male thynnine wasps as pollinators, raising the possibility of convergent evolution of floral traits. This study investigates the chemical basis of attraction in Spiculaea ciliata and its pollinator Thynnoturneria abspiculus , uncovering the use of shared chemical attractants. Flowers of S. ciliata were collected in the field and extracted in dichloromethane and methanol. Gas chromatography–mass spectrometry (GC–MS) and field bioassays were used to identify and test candidate floral semiochemicals. Compound identity was confirmed through co‐injection and peak enhancement with a synthetic standard, and behavioural responses of pollinators to candidate compounds were assessed with the aid of dummies loaded with candidate compounds. Spiculea ciliata attracts male T. abspiculus using a single semiochemical emitted from its labellum, identified as 4‐hydroxy‐3‐(methylthio)benzaldehyde. This compound alone elicited sexual behaviours in male wasps comparable to those triggered by whole floral extracts. 4‐Hydroxy‐3‐(methylthio)benzaldehyde is also known from distantly related Caladenia orchids and their pollinators, indicating repeated evolution of this unusual aromatic sulfurous semiochemical. These findings demonstrate convergent evolution of chemical signalling systems in sexually deceptive orchids and their thynnine wasp pollinators.
Abstract Pronounced seasonal fluctuations in Central Asian temperate deserts, where annual temperature variations can exceed 80 °C, have shaped unique environmental adaptation strategies in regional vegetation. However, it remains unclear how biological soil crusts (BSCs), a dominant desert land cover, respond to inter‐seasonal hydrothermal fluctuations and whether these adaptive strategies are consistent across different crust types. This study investigated cyanobacterial, lichen and moss crusts in the Gurbantunggut Desert to explore their seasonal adaptive strategies from the perspectives of biomass dynamics and non‐structural carbohydrate (NSC) allocation patterns. The results indicated that biomass in cyanobacterial and lichen crusts increased progressively from spring to the following spring, whereas moss crusts showed no significant variation. Regarding resource allocation, cyanobacterial crusts showed a steady increase in soluble sugars and the soluble sugar‐to‐starch ratio, suggesting they effectively utilize seasonal precipitation pulses to sequester carbon (C) for growth. In contrast, lichen and moss crusts exhibited an inverse relationship between soluble sugars and starch; specifically, during stress periods, they remobilize starch into soluble sugars to maintain cellular osmotic homeostasis. Notably, their environmental tolerances diverged: lichen crusts exhibited high thermal tolerance but were sensitive to low‐temperature stress, whereas moss crusts demonstrated robust chilling tolerance but were vulnerable to heat stress. In conclusion, our findings confirm that different BSC types employ distinctive survival strategies and stress‐tolerance mechanisms, suggesting a potential for seasonal ecological niche complementarity. This study provides novel insights into the physiological adaptation strategies of desert cryptogams in response to extreme environmental variability.
Abstract Global food systems are under pressure to remain stable amidst increasing uncertainty. Plant epicuticular waxes play vital roles in mitigating a range of environmental stressors, hence understanding their diversity can inform practices that sustain the large‐scale production of grain crops that underpin human nutrition. This study employs a combination of gas chromatography–mass spectrometry and scanning electron microscopy to chemically and morphologically characterise the foliar epicuticular waxes from economically important monocot and dicot species. Principal component analyses are also performed to identify key wax components that distinguish species apart. Monocot epicuticular waxes were uniform in platelet morphologies and were generally richer in primary alcohols, while dicots were morphologically diverse and were generally richer in alkanes. A clear disconnect between chemical composition and morphology suggests that individual wax components cannot be used to predict leaf surface properties. The wax composition data presented here also suggests that cuticular aldehydes are not exclusive to the decarbonylation pathway, depicting a more complex regulatory framework for cuticular wax biosynthesis. This study offers a broader inter‐ and intra‐species view of foliar wax chemistry, emphasising differences in cuticular wax biosynthetic strategies and their implications for plant–pathogen interactions. The data collected in this study provide a valuable baseline for future studies that link epicuticular wax physicochemical properties to their biological implications.
Abstract To alleviate negative effects of genetic drift on rare plants, it has been suggested to artificially increase gene flow between isolated populations and create new populations by mixing different provenances to maximize genetic variation. However, there is also a risk of outbreeding depression. We studied the effects of cross type on components of fitness in two closely related taxa, the rare rock plants Saxifraga rosacea ssp. rosacea (octoploid) and S. rosacea ssp. sponhemica (hexaploid), a Central European endemic. Using plants from 30 populations, we carried out within‐population crosses (WPC), between‐population crosses (BPC) and between‐taxon crosses (BTC), and measured performance over two generations in a common garden. We also studied backcrosses (BTC × WPC). Seed yield of BPC and survival of offspring were higher than that of both WPC and BTC, indicating genetic load in the isolated rock populations of both taxa. However, BPC offspring showed outbreeding depression for reproduction, while BTC offspring was nearly completely sterile, and backcrosses hardly produced any seeds. The mass and germination of the seeds produced by the F 1 and the F 2 , and survival of the F 2 were not negatively affected by BPC and BTC. Our results suggest caution in increasing gene flow between long‐term isolated populations or mixing seeds for restoration projects. The nearly complete infertility of the F 1 ‐plants resulting from BTC strongly supports the notion that management measures resulting in heteroploid crosses should be avoided. Moreover, the sterility of the hybrids suggests that the two taxa should be treated as separate species.
