Fog drip maintains dry season ecological function in a California coastal pine forest

Abstract

Fog drip is recognized as an important source of water for many ecosystems that often harbor a disproportionate fraction of endemic species. Characterizing and quantifying the ecological importance of fog drip in these ecosystems requires a range of approaches. We report on a multi‐faceted study of Bishop pine (Pinus muricata D. Don) along a coastal‐inland transect on an island off Southern California. Hourly sampling included micrometeorology, sap flux, and soil moisture. Monthly measurements included changes in tree girth, plant water stress, and isotopic values of fogwater, rainwater, and xylem water. These data show that summertime fog drip clearly affected soil moisture and maintained aspects of tree function, including leaf water relations, sap flux dynamics, and growth rates. Although water from fog drip to the soil surface was occasionally taken up by pine trees, as quantified with isotopic measurements and a Bayesian mixing model, this utilization of fog drip was highly variable in space and time. The proportion of fogwater inferred to have been used is also much less than has been demonstrated in more mesic coastal forest ecosystems using isotopic methods. These results thus suggest high ecosystem sensitivity to even moderate amounts of fog drip, a finding with important implications as climate change differentially affects fog and rain patterns.

Parched pines: a quantitative comparison of two multi‐year droughts and associated mass mortalities of bishop pine (Pinus muricata) on Santa Cruz Island, California

“…; Fischer et al. ). CLCF contributes both fog drip and shading which serve to reduce water deficits for bishop pines during the summer months on the island (Carbone et al.…”

Oak habitat recovery on California's largest islands: Scenarios for the role of corvid seed dispersal

“…Located 40 km south of Santa Barbara, California, the Santa Cruz Island (34.02° N, 119.76° W) and neighbouring Santa Rosa Island (33.98° N, 120.09° W) are part of the northern Channel Islands archipelago of four islands aligned along an east–west axis (Figure ). The islands have a mediterranean climate with cool, wet winters and hot, dry summers, and receive considerable moisture input from fog (Fischer, Still, Ebert, Baguskas, & Park Williams, ). The vegetation is characterized by coastal sage scrub, oak‐dominated chaparral and woodlands, and non‐native grasslands (Junak et al., ; Cohen, Cory, Menke, & Hepburn, ).…”

“…The islands have a mediterranean climate with cool, wet winters and hot, dry summers, and receive considerable moisture input from fog (Fischer, Still, Ebert, Baguskas, & Park Williams, 2016). The vegetation is characterized by coastal sage scrub, oak-dominated chaparral and woodlands, and non-native grasslands (Junak et al, 1995;Cohen, Cory, Menke, & Hepburn, 2009).…”

Water availability limits tree productivity, carbon stocks, and carbon residence time in mature forests across the western US

“…This might explain some of the variation in NPP and BIO among areas with similar CMI wy ; however, quantifying soil water storage capacity even at individual sites is challenging given uncertainty in soil structure and plant rooting capacity (Running, 1994). The index also does not account for water added via fog drip, which has been shown to supply 13-45 % of the water transpired by redwood forests (Sequoia sempervirens) (Dawson, 1998) and sustain other forest ecosystems along the California coast (Johnstone and Dawson, 2010;Fischer et al, 2016). This potentially explains why there were areas with low CMI wy along the central and northern coast of California that supported forests with higher NPP and BIO than other forests with similar CMI wy .…”