Fungal connections between plants and biocrusts

Treatments_180914 file:<br>2x2 experimental design with mesocosms with field-collected Bouteloua gracilis and associated rhizosphere soil and biocrusts. <br><br>Fungal connection treatment: For the intact fungal connections treatment, we used mesh with 50μm pores (Small Parts, Fort Meade, FL) to inhibit fine roots but allow fungal hyphae to pass through. For the impeded treatment, we used mesh with 0.45μm pores (GE Healthcare Life Science, Pittsburg, PA) to inhibit both roots and fungi. The mesh was placed horizontally under the biocrust (~0.5 – 1cm depth) with a small hole (~5 cm diameter) in the center to allow bunchgrass shoots to pass through. <br><br><br> Precipitation regime: We applied small,<b> </b>frequent events (100mL/pot once per week, a 2.5mm event) or large,<b> </b>infrequent<b> </b>events<b> </b>(400mL/pot once per month, a 10mm event) during August through October in 2013 and May through October in 2014 and 2015. <br><br>Response variables for each pot:- CN_r_ecol_180914 file: Percentage C and N by mass for crust and leaf from elemental analyzer.<br>- EEA_ecol_180914 file: Extracellular enzyme activity (nmol h^-1 g^-1) and organic matter percentage (Loss on ignition). β-1,4-glucosidase (BG), β-1,4- <i>N </i>-acetylglucosaminidase (NAG), and leucine aminopeptidase (LAP)<br>-PChSc_r_ecol_180914 file: Chlorophyll content for biocrust samples ("CHAugperg") and plant root crown dimensions ("shoot_largest_diameter_cm" and "shoot_perpendicular_diameter_cm") for each sampling period 2013-2015.<br>root_ecol_180914 file: Roots in 1.9cm diameter x 5cm deep soil core (g_root_intop5cm), in 19.cm diameter x .5cm deep crust sample, colonization of septate and aseptate hyphae in roots, and ergosterol content (ug g^-1) in bulk soil and crust.<br><br> seeds_ecol_180914 file: total mass of seed heads (g) at end of growing season (Oct) of 2014 and 2015. <br><br><br><br> 15N tracer experiment: To investigate N transfer from biocrust to plants, we added a total of 800μL of 0.86M ¹⁵N-NaNO₃ (8 mg N) to two points of biocrust on opposite sides of the plant (~6cm from root crown) during October 2015. <br><br>mass_balance_180914 file: sample type (crust, root, or leaf), time (h) since 15N tracer added (0=before label added), whether the pot had tracer added ("labeled15N"), the delta 15N value, the average mass percentage N, and the destructive harvest shoot and root values.<br><br>