A dynamic model for uptake of pesticides in potatoes is presented and evaluated with measurements performed within a field trial in the region of Boyacá, Colombia. The model takes into account the time between pesticide applications and harvest, the time between harvest and consumption, the amount of spray deposition on soil surface, mobility and degradation of pesticide in soil, diffusive uptake and persistence due to crop growth and metabolism in plant material, and loss due to food processing. Food processing steps included were cleaning, washing, storing, and cooking. Pesticide concentrations were measured periodically in soil and potato samples from the beginning of tuber formation until harvest. The model was able to predict the magnitude and temporal profile of the experimentally derived pesticide concentrations well, with all measurements falling within the 90% confidence interval. The fraction of chlorpyrifos applied on the field during plant cultivation that eventually is ingested by the consumer is on average 10(-4)-10(-7), depending on the time between pesticide application and ingestion and the processing step considered.

Aims: Bryophytes can cover three quarters of the ground surface, play key ecological functions, and increase biodiversity in mesic high-elevation conifer forests of the temperate zone. Forest gaps affect species coexistence (and ecosystem functions) as suggested by the gap and gap-size partitioning hypotheses (GPH, G S PH). Here we test these hypotheses in the context of high-elevation forest bryophyte communities and their functional attributes.Study Site: Spruce-fir forests on Whiteface Mountain, NY, USA. Methods:We characterized canopy openness, microclimate, forest floor substrates, vascular vegetation cover, and moss layer (cover, common species, and functional attributes) in three canopy openness environments (gap, gap edge, forest canopy) across 20 gaps (fir waves) (n = 60); the functional attributes were based on 16 morphologic, reproductive, and ecological bryophyte plant functional traits (PFTs). We tested GPH and G S PH relative to bryophyte community metrics (cover, composition), traits, and trait functional sensitivity (functional dispersion; FDis) using indicator species analysis, ordination, and regression. Results: Canopy openness drove gradients in ground-level temperature, substrate abundance and heterogeneity (beta diversity), and understory vascular vegetation cover. The GPH was consistent with (a) the abundance patterns of forest canopy indicator species (Dicranum fuscescens, Hypnum imponens, and Tetraphis pellucida), and (b)FDis based on three PFTs (growth form, fertility, and acidity), both increasing with canopy cover. We did not find support for GPH in the remaining species or traits, or for G S PH in general; gap width (12-44 m) was not related to environmental or bryophyte community gradients. Conclusions:The observed lack of variation in most bryophyte metrics across canopy environments suggests high resistance of the bryophyte layer to natural canopy gaps in high-elevation forests. However, responses of forest canopy indicator species suggest that canopy mortality, potentially increased by changing climate or insect pests, may cause declines in some forest canopy species and consequently in the functional diversity of bryophyte communities. K E Y W O R D S Abies balsamea, bryophyte community, Ellenberg indicator values, environmental gradient, fir wave, forest gaps, functional dispersion, functional trait, gap partitioning hypothesis, indicator species, moss layer 236 | Additional supporting information may be found online in the Supporting Information section at the end of the article. Appendix S1 Whiteface Mountain characteristics: location and appearance of fir wave zone Appendix S2 Supplementary methods. Appendix S3 Supplementary results. How to cite this article: Berdugo MB, Dovciak M. Bryophytes in fir waves: Forest canopy indicator species and functional diversity decline in canopy gaps. J Veg Sci. 2019;30:235-246.