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\"As World War II threatens the United States in 1941, fourteen-year-old Junior Bledsoe fights his own battles at home. Junior struggles with school and with anger--at his father, his insufferable granddaddy, his neighbors, and himself--as he desperately tries to understand himself and find his own aim in life. But he finds relief in escaping to the quiet of the nearby woods and tinkering with cars, something he learned from his Pop, and a fatherly neighbor provides much-needed guidance\"--Amazon.com.
Book
Disturbance alters beta‐diversity but not the relative importance of community assembly mechanisms
Ecological disturbances are often hypothesized to alter community assembly processes that influence variation in community composition (β‐diversity). Disturbance can cause convergence in community composition (low β‐diversity) by increasing niche selection of disturbance‐tolerant species. Alternatively, disturbance can cause divergence in community composition (high β‐diversity) by increasing habitat filtering across environmental gradients. However, because disturbance may also influence β‐diversity through random sampling effects owing to changes in the number of individuals in local communities (community size) or abundances in the regional species pool, observed patterns of β‐diversity alone cannot be used to unambiguously discern the relative importance of community assembly mechanisms. We compared β‐diversity of woody plants and inferred assembly mechanisms among unburned forests and forests managed with prescribed fires in the Missouri Ozarks, USA. Using a null‐model approach, we compared how environmental gradients influenced β‐diversity after controlling for differences in local community size and regional species abundances between unburned and burned landscapes. Observed β‐diversity was higher in burned landscapes. However, this pattern disappeared or reversed after controlling for smaller community size in burned landscapes. β‐diversity was higher than expected by chance in both landscapes, indicating an important role for processes that create clumped species distributions. Moreover, fire appeared to decrease clumping of species at broader spatial scales, suggesting homogenization of community composition through niche selection of disturbance‐tolerant species. Environmental variables, however, explained similar amounts of variation in β‐diversity in both landscapes, suggesting that disturbance did not alter the relative importance of habitat filtering. Our results indicate that contingent responses of communities to fire reflect a combination of fire‐induced changes in local community size and scale‐dependent effects of fire on species clumping across landscapes. Synthesis. Although niche‐based mechanisms of community assembly are often invoked to explain changes in community composition following disturbance, our results suggest that these changes also arise through random sampling effects owing to the influence of disturbance on community size. Comparative studies of these processes across disturbed ecosystems will provide important insights into the ecological conditions that determine when disturbance alters the interplay of deterministic and stochastic processes in natural and human‐modified landscapes.
Journal Article
Mesophytic litter dampens flammability in fire‐excluded pyrophytic oak–hickory woodlands
Fire exclusion in eastern North American Quercus–Carya woodlands has resulted in overstory compositional changes, linked to altered fuel composition, structure, and ultimately, altered fire regimes. These compositional changes have been implicated in a dampening effect on fire behavior in formerly fire‐prone ecosystems, the positive feedback termed “mesophication.” Several proposed mechanisms are likely involved in this process; however, few have been examined. We evaluated the potential mechanism of dampened forest floor flammability through changes in litter composition in a southeastern U.S. oak–hickory forest undergoing mesophication. Laboratory drying and burning experiments revealed that increasing the relative contribution of litter from fire‐sensitive mesophytic tree species (Liquidambar styraciflua, Ulmus alata, and Cornus florida) increased moisture retention and diminished litter flammability. Litterbeds composed of ≥66% mesophyte litter gained the most moisture following fuelbed saturation and were consistently wetter than pyrophyte litter following 12 and 24 h of drying. Flammability metrics decreased with increasing contribution of mesophyte litter with reductions most pronounced under more moist conditions. Under dry conditions, where litter moisture did not differ across compositional treatments, mesophyte litter was less flammable than fuelbeds that contained any pyrophyte litter. The combined effects of moisture retention and less flammable litter reveal an important synergistic impact that may result with increased dominance of fire‐sensitive mesophytic species. Restoration efforts in long‐unburned eastern hardwood forests may require altering stand composition to limit mesophytic litter input or developing burn prescriptions that intensify surface fire behavior in less flammable fuels.
Journal Article
When does intraspecific trait variation contribute to functional beta‐diversity?
Intraspecific trait variation (ITV) is hypothesized to play an important role in community assembly and the maintenance of biodiversity. However, fundamental gaps remain in our understanding of how ITV contributes to mechanisms that create spatial variation in the functional‐trait composition of communities (functional β‐diversity). Importantly, ITV may influence the perceived importance of environmental filtering across spatial scales. We examined how ITV contributes to functional β‐diversity and environmental filtering in woody plant communities in a temperate forest in the Ozark ecoregion, Missouri, USA. To test the hypothesis that ITV contributes to changes in the perceived importance of environmental filtering across scales, we compared patterns of functional β‐diversity across soil‐resource and topographic gradients at three spatial grains and three spatial extents. To quantify the contribution of ITV to functional β‐diversity, we compared patterns that included ITV in five traits (leaf area, specific leaf area, leaf water content, leaf toughness and chlorophyll content) to patterns based on species‐mean trait values. Functional β‐diversity that included ITV increased with spatial extent and decreased with spatial grain, suggesting stronger environmental filtering within spatially extensive landscapes that contain populations locally adapted to different habitats. In contrast, functional β‐diversity based on species‐mean trait values increased with spatial extent but did not change with spatial grain, suggesting weaker environmental filtering among larger communities which each contain a variety of habitats and locally adapted populations. Synthesis. Although studies typically infer community assembly mechanisms from species‐mean trait values, our study suggests that mean trait values may mask the strength of assembly mechanisms such as environmental filtering, especially in landscape‐scale studies that encompass strong environmental gradients and locally adapted populations. Our study highlights the utility of integrating ITV into studies of functional β‐diversity to better understand the ecological conditions under which trait variation within and among species contributes most strongly to patterns of biodiversity across spatial scales.
Journal Article
Analysis of transcriptome in hickory (Carya cathayensis), and uncover the dynamics in the hormonal signaling pathway during graft process
Background
Hickory (
Carya cathayensis
), a woody plant with high nutritional and economic value, is widely planted in China. Due to its long juvenile phase, grafting is a useful technique for large-scale cultivation of hickory. To reveal the molecular mechanism during the graft process, we sequenced the transcriptomes of graft union in hickory.
Results
In our study, six RNA-seq libraries yielded a total of 83,676,860 clean short reads comprising 4.19 Gb of sequence data. A large number of differentially expressed genes (DEGs) at three time points during the graft process were identified. In detail, 777 DEGs in the 7 d vs 0 d (day after grafting) comparison were classified into 11 enriched Gene Ontology (GO) categories, and 262 DEGs in the 14 d vs 0 d comparison were classified into 15 enriched GO categories. Furthermore, an overview of the PPI network was constructed by these DEGs. In addition, 20 genes related to the auxin-and cytokinin-signaling pathways were identified, and some were validated by qRT-PCR analysis.
Conclusions
Our comprehensive analysis provides basic information on the candidate genes and hormone signaling pathways involved in the graft process in hickory and other woody plants.
Journal Article
Functional diversity response to hardwood forest management varies across taxa and spatial scales
Contemporary forest management offers a trade-off between the potential positive effects of habitat heterogeneity on biodiversity, and the potential harm to mature forest communities caused by habitat loss and perforation of the forest canopy. While the response of taxonomic diversity to forest management has received a great deal of scrutiny, the response of functional diversity is largely unexplored. However, functional diversity may represent a more direct link between biodiversity and ecosystem function. To examine how forest management affects diversity at multiple spatial scales, we analyzed a long-term data set that captured changes in taxonomic and functional diversity of moths (Lepidoptera), longhorned beetles (Coleoptera: Cerambycidae), and breeding birds in response to contemporary silvicultural systems in oak–hickory hardwood forests. We used these data sets to address the following questions: how do even- and uneven-aged silvicultural systems affect taxonomic and functional diversity at the scale of managed landscapes compared to the individual harvested and unharvested forest patches that comprise the landscapes, and how do these silvicultural systems affect the functional similarity of assemblages at the scale of managed landscapes and patches? Due to increased heterogeneity within landscapes, we expected even-aged silviculture to increase and uneven-aged silviculture to decrease functional diversity at the landscape level regardless of impacts at the patch level. Functional diversity responses were taxon-specific with respect to the direction of change and time since harvest. Responses were also consistent across patch and landscape levels within each taxon. Moth assemblage species richness, functional richness, and functional divergence were negatively affected by harvesting, with stronger effects resulting from uneven-aged than even-aged management. Longhorned beetle assemblages exhibited a peak in species richness two years after harvesting, while functional diversity metrics did not differ between harvested and unharvested patches and managed landscapes. The species and functional richness of breeding bird assemblages increased in response to harvesting with more persistent effects in uneven- than in even-aged managed landscapes. For moth and bird assemblages, species turnover was driven by species with more extreme trait combinations. Our study highlights the variability of multi-taxon functional diversity in response to forest management across multiple spatial scales.
Journal Article
The mechanism of high contents of oil and oleic acid revealed by transcriptomic and lipidomic analysis during embryogenesis in Carya cathayensis Sarg
Background
Hickory (
Carya cathayensis
Sarg.) accumulates more than 70 % oil and 90 % unsaturated fatty acids with considerably high oleic acid in its mature embryo. The concurrent global trancriptomic and lipidomic analyses provided a framework for better understanding of glycerolipid biosynthesis and metabolism in the hickory nut.
Results
The synthetical regulation of numerous leading lipid-related genes harmonized with the oil accumulation and fatty acid conversion in embryo development. The high level of
ACCase
correlated positively with fatty acids
de novo
synthesis, and the synergy of
DGAT2
and
PDAT
promoted the TAG assembly, and
oleosins
,
caleosins
and
steroleosins
were transcribed considerably high for timely energy reserve in oil body. Glycolysis possibly provided sufficient precursors and energy for lipid synthesis. The perfect harmonization of the high level of
SAD
with low level of
FAD2
facilitated the oleic acid accumulation. And the ratio of
FATA
/
FATB
or SAD/FATB was proposed for determining the saturated degree of oil. The gene multi-copy event was generated probably for accommodating various survival environments. A thermotolerant defense system including TAG hydrolysis determinants, heat shock proteins, and high ratio of MUFA to PUFA constrained the lipid degradation and provided a guarantee for high lipid content. A batch of potential genes recruited from the co-expression network helps us to understand the lipid synthesis and the response to high temperature better.
Conclusions
The high transcriptional levels of key genes in lipid synthesis promoted the oil accumulation, and the harmonious expression of key ones for unsaturated fatty acids led oleic acid to high levels.
Journal Article
The Effects of Different Management and Processing Methods on the Carbon Footprint of Chinese Hickory
Amidst the global shift towards a low-carbon development trajectory, the hickory industry in Lin’an District is progressively embracing green, low-carbon, and sustainable practices. This study, leveraging the life cycle assessment (LCA) methodology, meticulously scrutinizes the carbon footprint of the hickory industry by segmenting its life cycle into two distinct subsystems: the plantation and the factory. Through comprehensive, year-long monitoring of soil greenhouse gas (GHG) emissions in hickory plantations, our findings underscore that while total GHG emissions from eco-complex management (ECM) surpassed those of intensive management (IM) by 10.7% (p < 0.001), ECM significantly mitigated the carbon footprint per kilogram of hickory produced, achieving a reduction of 1.0495 kgCO2eq. This advantage is primarily attributable to ECM’s diminished reliance on chemical fertilizers. Within the factory subsystem, when processing 1 kg of hickory, the digital factory incurred a carbon footprint of 2.5923 kgCO2eq kg−1, whereas family workshops exhibited a lower footprint of 1.9544 kgCO2eq kg−1. Notably, the processing and packaging stages collectively accounted for over 90% of the factory subsystem’s carbon emissions, with natural gas being the primary contributor during processing. To estimate the carbon emission reduction potential within the hickory industry, this research draws parallels with emission reduction strategies employed by other industries and outlines tailored strategies to propel its low-carbon development. By advocating for the widespread adoption of ECM and enhancing the energy efficiency of processing enterprises, the hickory industry can effectively diminish its carbon footprint and steer towards a green, low-carbon, and high-quality development paradigm.
Journal Article
Valorization of Chinese hickory shell as novel sources for the efficient production of xylooligosaccharides
Chinese hickory shell, a by-product of the food industry, is still not utilized and urgent to develop sustainable technologies for its valorization. This research focuses on the systematical evaluation of degraded products and xylooligosaccharide production with high yield from the shell via hydrothermal process. The pretreatment was carried out in a bath pressurized reactor at 140–220 °C for 0.5–2 h. The results indicated that the pretreatment condition strongly affected the chemical structures and compositions of the liquid fraction. The maximum yield of XOS (55.3 wt%) with limitation of by-products formation was achieved at 160 °C for 2 h. High temperature (220 °C) and short time (0.5 h) contributed to hydrolysis of xylooligosaccharide with high DP to yield 37.5 wt% xylooligosaccharide with DP from 2 to 6. Xylooligosaccharide obtained mainly consisted of xylan with branches according to the HSQC NMR analysis. Overall, the production of XOS with a high yield from food waste will facilitate the valorization of food waste in the biorefinery industry.
Journal Article
Bats reduce insect density and defoliation in temperate forests
Bats suppress insect populations in agricultural ecosystems, yet the question of whether bats initiate trophic cascades in forests is mainly unexplored. We used a field experiment to test the hypothesis that insectivorous bats reduce defoliation through the top-down suppression of forest-defoliating insects. We excluded bats from 20 large, subcanopy forest plots (opened daily to allow birds access), each paired with an experimental control plot, during three summers between 2018 and 2020 in the central hardwood region of the United States. We monitored leaf area changes and insect density for nine to 10 oak or hickory seedlings per plot. Insect density was three times greater on seedlings in bat-excluded versus control plots. Additionally, seedling defoliation was five times greater with bats excluded, and bats’ impact on defoliation was three times greater for oaks than for hickories. We show that insectivorous bats drive top-down trophic cascades, play an integral role in forest ecosystems, and may ultimately influence forest health, structure, and composition. This work demonstrates insectivorous bats’ ecological and economic value and the importance of conserving this highly imperiled group of predators.
Journal Article