DOI: 10.5061/dryad.ncjsxkst3
title: Data from: Plant quantity and quality regulate the diversity of arthropod communities in a semi-arid grassland

description:   The quantity (e.g. biomass production) and quality (e.g. leaf
 nutrient content) of plants can strongly influence arthropod diversity,
 but few studies have tried to disentangle such effects. In this study, we
 examined the independent effects of plant productivity and leaf traits on
 the taxon richness and abundance of entire arthropod communities and
 multiple arthropod orders in replicated monocultures of 15 herbaceous
 species in the Inner Mongolian grassland. Total taxon richness of
 arthropod communities increased with plant productivity and an increase in
 a high nutrient content indicator (PC1) of plant leaf traits (e.g. high
 leaf nitrogen, phosphorus and water contents), but decreased with an
 increase in a poor nutrient content indicator (PC2) of plant leaf traits
 (e.g. high leaf lignin content but low specific leaf area).
  Total abundance of arthropod communities increased with
 increasing plant productivity but decreased with increasing PC2. Many
 common, rather than rare arthropod orders, exhibited strong responses to
 the changes in plant quantity or quality.  Taxon richness of
 Diptera, Neuroptera and Coleoptera responded positively to the increase in
 plant productivity and PC1, while taxon richness of Hemiptera and
 Coleoptera responded negatively to the increase in PC2. Abundances of
 Diptera and Coleoptera responded positively to the increased plant
 productivity, whereas abundances of Hymenoptera and Hemiptera responded
 negatively to the increased PC2.  The order-specific responses of
 arthropod richness and abundance to plant quantity or quality reflected
 the different food requirements and feeding behaviors of arthropods. Our
 findings demonstrate that plant quantity and quality can independently
 control richness and abundance of arthropod communities.  The
 changes in plant productivity and nutrient content of different plant
 species may alter arthropod diversity and community structure, and these
 changes in turn may have strong cascading effects on multiple functions
 (e.g. prey, decomposers, pollinators and predators) in terrestrial
 ecosystems.  
description: Arthropod richness and abundance,
 plant leaf traits, and aboveground net primary productivity (ANPP) data
 used in the analyses are included in this file. <i>Arthropod richness and
 abundance</i> Arthropods were collected by using
 sweep net sampling between 10 a.m. and 4 p.m. on days with no rainfall in
 August 2018. For each monoculture plot, we conducted 50 sweeps using
 muslin net. We sampled arthropods by sweeping in 180° arcs through
 vegetation canopy, quickly turning and reversing direction at the end of
 each arc. At the end of each arc, a quick but fluid upturn of the
 sweep-net was used to prevent the escape of captured arthropods. The
 contents of the sweep net were preserved in bottles containing ethyl
 acetate. In the lab, all arthropod individuals were manually sorted into
 eight orders: Hymenoptera, Diptera, Hemiptera, Neuroptera, Coleoptera,
 Araneae, Lepidoptera and Orthoptera. Then, arthropods were identified by
 optical microscopy at the category of genus and species as far as
 possible. Finally, we summarized the information of arthropods in each
 plot and measured the total taxon richness and abundance of
 arthropods. <i>Plant leaf
 traits</i> Leaf area was calculated from
 photographs of fresh leaves using IMAGEJ software. The sampled leaves were
 then weighed and dried for 24 h at 65°C and the water content of leaf was
 expressed as the difference between fresh and dry weight, divided by dry
 weight. SLA was calculated as the ratio of total leaf area divided by
 total leaf dry mass per sample
 (cm<sup>2 </sup>g<sup>-1</sup>). Dry leaf material
 was then ground to a fine powder with a ball mill, and samples of 10 mg
 were analyzed for leaf N and P contents with an elemental analyzer
 (VarioEL Element Analyzer, Hanau, Germany). Leaf lignin content was
 measured following a sequential extraction analysis of acid detergent
 lignin. Finally, the data of each leaf trait was averaged for each plant
 species. <i>Aboveground net primary
 productivity (ANPP)</i> ANPP was calculated based
 on dry biomass measurement (g m<sup>-2</sup>) of each plot, as
 the standing aboveground biomass of these steppe communities reached the
 annual peak at middle August.