DOI: 10.5061/dryad.5x69p8d35
title: Data from: Restoration of native saltmarshes can reverse arthropod assemblages and trophic interactions changed by a plant invasion

description: Plant invasions profoundly impact both natural and managed ecosystems, and
 removal of the invasive plants addresses only part of the problem of
 restoring impacted areas. The rehabilitation of diverse communities and
 their ecosystem functions following removal of invasive plants is an
 important goal of ecological restoration. Arthropod assemblages and
 trophic interactions are important indicators of the success of
 restoration, but have largely been overlooked in saltmarshes. We
 determined how arthropod assemblages and trophic interactions changed with
 the invasion of the exotic plant Spartina alterniflora and with the
 restoration of the native plant Phragmites australis following Spartina
 removal in a Chinese saltmarsh. We investigated multiple biotic and
 abiotic variables to gain insight into the factors underlying the changes
 in arthropod assemblages and trophic structure. We found that although
 Spartina invasion had changed arthropod diversity, community structure,
 feeding-guild composition, and the diets of arthropod natural enemies in
 the saltmarsh, these changes could be reversed by the restoration of
 native Phragmites vegetation following removal of the invader. The
 variation in arthropod assemblages and trophic structure were critically
 associated with four biotic and abiotic variables (aboveground biomass,
 plant density, leaf N, and soil salinity). Our findings demonstrate the
 positive effects of controlling invasive plants on biodiversity and
 nutrient cycling, and provide a foundation for assessing the efficacy of
 ecological restoration projects in saltmarshes.
description: <strong>Study site and plant
 communities</strong> We collected
 this dataset in Dongtan wetlands on Chongming Island (31°27′–31°5l′ N,
 121°09′–121°54′ E) in the Yangtze estuary. We sampled replicate transects
 of five types of plant communities in the Dongtan wetlands: 1) the
 original reference<em> Phragmites</em> monoculture that had
 never been affected by <em>Spartina</em>; 2) the
 <em>Phragmites</em> monoculture that had not yet been invaded
 by but was being threatened by <em>Spartina </em>(i.e, on
 periphery of the plant community where <em>Spartina</em> was
 encroaching with some number of meters); 3) the
 <em>Phragmites–Spartina</em> mixture in which
 <em>Spartina</em> was gradually displacing
 <em>Phragmites</em>; 4) the <em>Spartina</em>
 monoculture in which <em>Spartina</em> had completely
 displaced <em>Phragmites</em>; and 5) the restored<em>
 Phragmites</em> monoculture following <em>Spartina</em>
 removal. <strong>Arthropod
 sampling</strong> In each type of plant community, we randomly
 designated 15 replicate transects along the main creek channel. We used a
 vacuum suctioning method to collect arthropods on each transect on 22–25
 June, 24–27 July, and 23–26 August in 2018. All arthropods were identified
 to the lowest taxonomic category possible and the number of individuals of
 each species on transects was counted. We followed several references to identify the arthropod
 taxa (Xin et al., 1985; Zhong, 1990; Zheng & Gui,
 1999; Zhang & Li,
 2011; Zhang & Wang, 2017). We also assigned these arthropods
 to trophic groups and feeding guilds according to Gratton and Denno
 (2005). <strong>Arthropod natural enemy
 diets</strong> We used stable isotopes to determine the diets
 of arthropod natural enemies collected from different types of plant
 communities. All arthropod and plant samples were dried, ground into
 powders and then subjected to the analysis using an isotope ratio mass
 spectrometer (DELTA V Advantage, Thermo, USA). <strong>Environmental
 variables</strong> We randomly
 designated five quadrats (0.5 m ´ 0.5 m) along each transect and extracted
 a soil core in each quadrat on 23–26 August 2018. All soil samples were
 weighted and then dried. Soil water was estimated from the weight of a
 soil core before and after drying. Soil pH and salinity were determined
 using a multi-function tester (S975-uMix SevenExcellence, Mettler-Toledo,
 Switzerland). Soil C and N were analyzed with an element analyzer
 (FlashEA1112 Series, Thermo, USA). Soil P was measured by
 molybdenum-antimony colorimetry using a microplate reader (Synergy 2,
 BioTek, USA). We counted plant (stem) density in each quadrat. All
 aboveground plant tissues in each quadrat were then dried and weighed to
 obtain their aboveground biomass. We measured leaf C, N, and P contents
 according to the same methods as used for soil samples. For each
 environmental variable, we used the average value in the five quadrats
 from one transect to represent the transect replicate. <strong>Reference</strong>
     Gratton, C. & Denno R. F.
 Restoration of arthropod assemblages in a Spartina salt marsh following
 removal of the invasive plant Phragmites australis. Restoration Ecology
 13, 358–372 (2005).     Xin,
 J.L., Q.S. Yang, C.Y. Hu. 1985. Insect morphology taxonomy. Shanghai:
 Fudan University Press.     Zhang, W.W., and Y.S. Li. 2011. Chinese
 insects illustrated. Chongqing: Chongqing University
 Press.     Zhang, Z.S., and L.Y. Wang. 2017. Chinese
 spiders illustrated. Chongqing: Chongqing University
 Press.     Zheng, L.Y., and H. Gui. 1999. Insect
 classification. Nanjing: Nanjing Normal University Press.
     Zhong, J.M. 1990. Taxonomy of insect larva.
 Beijing: Agriculture Press.
description: Please see
 README_Metadata.docx for details.