DOI: 10.5061/dryad.rfj6q57p1
title: Data from: Long-term nutrient addition and grazing exclusion determine flower abundance, diversity and community composition in high-latitude grasslands

description: The abundance and composition of flowers within plant communities shape
 the resources available to flower-visiting insects. However, it remains
 unclear how nutrient enrichment and changes in grazing impact plant
 communities and their floral resources, and whether these effects
 contribute to ongoing pollinator decline. We investigated how the
 abundance, diversity, and species composition of flowers (excluding
 graminoids) respond to long-term nutrient additions and grazing exclusion
 in two high-latitude grasslands (tundra and montane). We used two
 factorial experimental designs: 1) a nutrient experiment with additions of
 nitrogen (N), phosphorus (P), and potassium (K with micronutrients, and 2)
 a grazing experiment that included combined NPK addition with and without
 grazing exclusion. Flower abundance was assessed in 5 × 5 m experimental
 plots after 6–10 years of treatments. N and P interactively affected
 flower abundance, with N counteracting the positive effects of P. N
 reduced flower abundance in the montane grassland, whereas P and K
 increased it. Grazing exclusion increased flower abundance, with its
 effect amplified under NPK addition, but this joint treatment reduced
 flower species richness. Grazing exclusion reduced flower species
 diversity, with contrasting site-specific effects depending on NPK. N, P,
 and K addition, as well as grazing exclusion and NPK addition, changed the
 composition of flower assemblages. At the montane grassland, joint NPK
 addition and grazing exclusion led to strong dominance of forbs, such as
 Anthriscus sylvestris and Geranium sylvaticum, and grazing exclusion led
 to homogenisation of the flower community at the montane grassland. Our
 study demonstrates the importance of grazing and nutrients as key
 determinants of floral resources, which are vital for flower-visiting
 insects. We suggest that quantifying floral resources could contribute to
 ecosystem status assessment. Our findings offer insights for managing and
 conserving pollinator habitats in the face of environmental change.
description: # Long-term nutrient addition and grazing exclusion determine flower
 abundance, diversity, and community composition in high-latitude
 grasslands **Metadata of flower_unit_data.csv:** * Site = factor with two
 levels: the tundra (kilp.fi) and the montane (saana.fi) site - Block =
 factor with four levels: the number of the block * Blocks = factor with
 four levels: the number of the block separated for kilp.fi (k) and
 saana.fi(s) sites - Block_Plot = plot code * Plot_nr = plot number within
 the site - N = factor of addition, levels '1=yes' or
 '0=no' * P = factor of P addition, levels '1=yes' or
 '0=no' - K = factor of K addition with micronutrients, levels
 '1=yes' or '0=no' * Fence = factor grazing exclusion,
 levels '1=yes' or '0=no' - NPK = factor NPK addition,
 levels '1=yes' or '0=no' * treatm = treatment code -
 treatm4 = factor to subset data with NPK-Fence treatments * treatm8 =
 factor to subset data with N, P, K addition treatments - species columns
 (N-BL) mean flower abundance per 1 sq. m (mean of 2020 and 2023) * family
 columns (BM - BU) family-wise sums of flower abundance per 1 sq. m (2020
 and 2023) - other = collected values for the other families * invsimp
 inverse Simpson's index values - fu.tot = total of flower units (sum
 of all species) * fu.rich = flower species richness (flower species per 25
 sq. m) **Metadata of flower_units_2020_2023_corrected.csv:** As above but
 additionally; * nr = a sequential number - Site = factor with two levels:
 the tundra (kilp.fi) and the montane (saana.fi) site * Year = sampling
 year, levels 2020 or 2023 - trts.started = year when experimental
 treatments started * columns E-CC correspond to C-BZ in flower_unit_data