DOI: 10.5061/dryad.f4qrfj72j
title: Latitudinal gradient, MEND experiment, and BioGen experiment relating species richness and net primary productivity (NPP)

description: Experiments often find that net primary productivity (NPP) increases with
 species richness when native species are considered.  However,
 relationships may be altered by exotic (non-nattive) species, which are
 hypothesized to reduce richness but increase productivity
 (invasion-diversity-productivity' paradox).  We compared
 richness-NPP relationships using a comparison of exotic vs.
 native-dominated sites across the central USA, and two epxeriments under
 common enviornments.  ANPP was measured using peak biomasss
 clipping in all three studies.  In all studies, there was a
 signfiicantly positive relationship between NPP and richness across
 native-species doimnated sites and plots, but no relatoinship across
 exotic-dominated ones.  The results indicatte that relationships
 between NPP and richness depend on whether natieve or exotic species are
 dominant, and that exotic species are 'breaking the rules'.
description: Peak biomass to estimated aboveground net primary productivity
 (ANPP) in three studies: a paired latitudinal study of native and exotic
 dominated sites from Minnesota to Texas (Latitudinal), an experiment in
 central Texas (MEND) and an experiment in western Iowa (BioGen). 
 Belowground net primary productivity (BNPP) was estimated in the MEND site
 with root ingrowth cores using root free field soil.  NPP was ANPP + BNPP
 for the MEND site.  Data were analyzed with ANCOVA to test whether NPP -
 richness slopes differed between native dominated sites or plots, and
 exotic (non-native) dominated sites or plots.
description: # Latitudinal Gradient, MEND experiment, BioGen experiment relating
 species richness and NPP
 [https://doi.org/10.5061/dryad.f4qrfj72j](https://doi.org/10.5061/dryad.f4qrfj72j) Data includes estimates of aboveground productivity in g/m2 from clip plots. Belowground productivity in g/m2 is from root ingrowth cores. Species richness is the number of plant species at the site (Latitudinal) or of plots (MEND, BioGen). Origin is whether the site or plots were dominated by native species or exotic (non-native) species of plants. Please see paper for more details, and github for code (github.com/wilsey-code/Richness-Productivity). #### CSV File Name: Latitude.csv Variables: * Region: Central, Northern or Southern Plains * Site: Site names * Native: E for exotic (non-native) and N for native species dominance * LatDecDeg: Latitude * mBioSDm2: Aboveground primary productivity in g/m2 * lmBioSD: ln ANPP * S: Plant species richness of the site #### CSV File Name: BioGen.csv Variables: * Plot: Plot number * Rich: Species Richness at planting of the plot * Origin: E for exotic, and N for native species * Grazing: Plot was grazed in the previous year or not * Pair: Species pairing * ANPP: Aboveground net primary productivity (peak biomass) in g/m2 * Simp4: Realized Simpson's 1/D * rich4: Realized species richness * lrich: ln (Richness) * lANPP: ln(ANPP). #### CSV File Name: MENDB.csv Variables: * Column: Plot location * Row: Plot location * Block: Established in Oct. 2007 or Mar 2008 * Rep: Replicate * Draw: Species pairing random draw * Origin: E for exotic species, N for native species * Irrigation: N for controls, Y for summer irrigation of 128 mm to plots * Richness: Realized species richness in the year of sampling (2015) * ANPP: Aboveground net primary productivity (peak biomass) estimated with clip plots in units of g/m2 * BNPP: belowground net primary productivity in g/m2 (mixtures, "n/a" in monocultures), * NPP: total net primary productivity in g/m2 (mixtures, "n/a" in monocultures) * Diversity: Simpson's diversity (realized) * lRichness: ln(Richness) * lANPP: ln(ANPP) * lBNPP: ln(BNPP) * lNPP: ln(NPP) ## Code/Software R code is included in GitHub.