{"title":"Variation in insect herbivory across an urbanization gradient: The role of abiotic factors and leaf secondary metabolites","authors":"","doi":"10.1016/j.plaphy.2024.109056","DOIUrl":null,"url":null,"abstract":"<div><p>Urbanization impacts plant-herbivore interactions, which are crucial for ecosystem functions such as carbon sequestration and nutrient cycling. While some studies have reported reductions in insect herbivory in urban areas (relative to rural or natural forests), this trend is not consistent and the underlying causes for such variation remain unclear. We conducted a continental-scale study on insect herbivory along urbanization gradients for three European tree species: <em>Quercus robur, Tilia cordata,</em> and <em>Fraxinus excelsior,</em> and further investigated their biotic and abiotic correlates to get at mechanisms. To this end, we quantified insect leaf herbivory and foliar secondary metabolites (phenolics, terpenoids, alkaloids) for 176 trees across eight European cities. Additionally, we collected data on microclimate (air temperature) and soil characteristics (pH, carbon, nutrients) to test for abiotic correlates of urbanization effects directly or indirectly (through changes in plant secondary chemistry) linked to herbivory. Our results showed that urbanization was negatively associated with herbivory for <em>Q. robur</em> and <em>F. excelsior</em>, but not for <em>T. cordata</em>. In addition, urbanization was positively associated with secondary metabolite concentrations, but only for <em>Q. robur</em>. Urbanization was positively associated with air temperature for <em>Q. robur</em> and <em>F. excelsior</em>, and negatively with soil nutrients (magnesium) in the case of <em>F. excelsior</em>, but these abiotic variables were not associated with herbivory. Contrary to expectations, we found no evidence for indirect effects of abiotic factors via plant defences on herbivory for either <em>Q. robur</em> or <em>F. excelsior</em>. Additional biotic or abiotic drivers must therefore be accounted for to explain observed urbanization gradients in herbivory and their interspecific variation.</p></div>","PeriodicalId":20234,"journal":{"name":"Plant Physiology and Biochemistry","volume":null,"pages":null},"PeriodicalIF":6.1000,"publicationDate":"2024-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0981942824007241/pdfft?md5=10a83c92c68377d730858a940501babd&pid=1-s2.0-S0981942824007241-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Plant Physiology and Biochemistry","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0981942824007241","RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PLANT SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Urbanization impacts plant-herbivore interactions, which are crucial for ecosystem functions such as carbon sequestration and nutrient cycling. While some studies have reported reductions in insect herbivory in urban areas (relative to rural or natural forests), this trend is not consistent and the underlying causes for such variation remain unclear. We conducted a continental-scale study on insect herbivory along urbanization gradients for three European tree species: Quercus robur, Tilia cordata, and Fraxinus excelsior, and further investigated their biotic and abiotic correlates to get at mechanisms. To this end, we quantified insect leaf herbivory and foliar secondary metabolites (phenolics, terpenoids, alkaloids) for 176 trees across eight European cities. Additionally, we collected data on microclimate (air temperature) and soil characteristics (pH, carbon, nutrients) to test for abiotic correlates of urbanization effects directly or indirectly (through changes in plant secondary chemistry) linked to herbivory. Our results showed that urbanization was negatively associated with herbivory for Q. robur and F. excelsior, but not for T. cordata. In addition, urbanization was positively associated with secondary metabolite concentrations, but only for Q. robur. Urbanization was positively associated with air temperature for Q. robur and F. excelsior, and negatively with soil nutrients (magnesium) in the case of F. excelsior, but these abiotic variables were not associated with herbivory. Contrary to expectations, we found no evidence for indirect effects of abiotic factors via plant defences on herbivory for either Q. robur or F. excelsior. Additional biotic or abiotic drivers must therefore be accounted for to explain observed urbanization gradients in herbivory and their interspecific variation.
期刊介绍:
Plant Physiology and Biochemistry publishes original theoretical, experimental and technical contributions in the various fields of plant physiology (biochemistry, physiology, structure, genetics, plant-microbe interactions, etc.) at diverse levels of integration (molecular, subcellular, cellular, organ, whole plant, environmental). Opinions expressed in the journal are the sole responsibility of the authors and publication does not imply the editors'' agreement.
Manuscripts describing molecular-genetic and/or gene expression data that are not integrated with biochemical analysis and/or actual measurements of plant physiological processes are not suitable for PPB. Also "Omics" studies (transcriptomics, proteomics, metabolomics, etc.) reporting descriptive analysis without an element of functional validation assays, will not be considered. Similarly, applied agronomic or phytochemical studies that generate no new, fundamental insights in plant physiological and/or biochemical processes are not suitable for publication in PPB.
Plant Physiology and Biochemistry publishes several types of articles: Reviews, Papers and Short Papers. Articles for Reviews are either invited by the editor or proposed by the authors for the editor''s prior agreement. Reviews should not exceed 40 typewritten pages and Short Papers no more than approximately 8 typewritten pages. The fundamental character of Plant Physiology and Biochemistry remains that of a journal for original results.