DOI: 10.5061/dryad.0j2q8
title: Data from: Fog as a source of nitrogen for redwood trees: evidence from fluxes and stable isotopes

description: A defining feature of the redwood forest in coastal California is the
 presence of fog in the summer months, a time when there is typically
 little rainfall. Our goal was to determine the role of summer fog in
 canopy transformation of nitrogen, nitrogen uptake by trees and
 photosynthesis within a coastal redwood forest ecosystem. We measured
 horizontal and vertical inputs of nitrogen, the isotopic composition of
 nitrogen in a variety of atmospheric sources (summer fog, winter rain and
 throughfall throughout the year), nitrogen pools (soil solution) and plant
 tissue (roots and foliage), as well as rates of photosynthesis and
 nitrogen uptake by trees. Throughfall nitrogen fluxes were greater at the
 forest edge compared to the interior both within the canopy (sampled 10 m
 above-ground) and onto the forest floor (sampled 1 m above-ground; P
 &lt; 0.05). Similarly, soil solution inline image and total inorganic
 nitrogen were greater at the forest edge compared to the interior (P =
 0.0014 and 0.009, respectively). Whereas natural abundance δ15NO3 values
 were not significantly different between winter rain (measured as bulk
 precipitation) and summer fog water (average δ15N = −1.2 ± 0.680/00),
 δ15NH4 values were significantly greater in fog water (11.4 ± 2.70/00)
 compared to rain (1.2 ± 0.90/00). We found no difference in δ15N in roots
 from forest edge trees compared to interior trees. In contrast, nitrogen
 concentrations and δ15N in foliage from forest edge trees were
 significantly greater compared to interior trees (P &lt; 0.0001),
 suggesting that the leaves of forest edge trees may be obtaining a greater
 proportion of their nitrogen from fog compared to those of the interior
 trees. Natural abundance 13C of leaf sugars and rates of photosynthesis
 were significantly higher at the forest edge compared to the interior
 during the fog season (P &lt; 0.05), but not different between
 locations in the rain season (P &gt; 0.05). Nitrification in the
 forest floor, rather than the canopy, is the primary source of inline
 image in these soils throughout the year. Synthesis. Summer fog provides
 nitrogen directly and indirectly to redwood trees, especially those at the
 forest edge, and affects the physiologic function of redwood trees.
description: 15N_DIN_WaterSamplesFile contains data for d15NH4 and d15NO3 (units = per mil) of water samples, including throughfall, fog, bulk collectors, gravimetric lysimeters, and tension lysimeters, collected in California redwood forest. This file includes data from Table 1 in associated manuscript.Roots&LeavesFile contains data for %N, d15N, %C, d13C and C:N of needles and roots collected from the redwood forest edge and interior. Units for d15N and d13C are per mil. This file includes data from Table 2 in associated manuscript.ResinBags&ColumnsFile contains data for fluxes of NH4 and NO3 in resin bags and resin columns collected in California redwood forest. Units are ug N/m2/d for throughfall and ug N/g resin/day for resin bags (soil solution). This file includes data from Figure 1 in associated manuscript.Isotopes_Water&ResinFile contains data for d15N and d18O (units = per mil) of water and resin samples collected in a California redwood forest. This file includes data from Figure 2 in associated manuscript.Photosyn&LeafSugarFile contains data for C assimilation (nmol C/g/sec) and d13C of leaf sugar (units = per mil) collected in a California redwood forest. This file includes data from Figure 3 in associated manuscript.RootUptakeFile contains data for nitrogen uptake by roots of trees in a California redwood forest (units = ug N/mg root/hr). This file includes data from Figure 4 in associated manuscript.