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Geology topics

C. M. D’Antonio

Publications and source records attributed to C. M. D’Antonio.

5 recordsLinked to original sources
USGS2012

Sinks for nitrogen inputs in terrestrial ecosystems: a meta-analysis of 15 N tracer field studies

Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15 N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15 N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15 N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (<1 week after 15 N tracer application), total ecosystem 15 N recovery was negatively correlated with fine-root and soil 15 N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3&ndash;18 months after 15 N tracer application), total ecosystem 15 N retention was negatively correlated with foliar natural-abundance 15 N but was positively correlated with mineral soil C and N concentration and C: N, showing that plant and soil natural-abundance 15 N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15 N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15 N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15 N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N&middot;ha -1 &middot;yr -1 above which most ecosystems showed net losses of applied 15 N tracer in response to N fertilizer addition.

Ecology↗
USGS2010

Early impacts of biological control on canopy cover and water use of the invasive saltcedar tree (Tamarix spp.) in western Nevada, USA

D. carinulata defoliated the majority of trees within 25 and 9 km, respectively, of the release location within 3 years. At the Humboldt site, D. carinulata reduced the canopy cover of trees adjacent to the release location by >90%. At a location 4 km away during the first year of defoliation, D. carinulata reduced peak (August) stem water use by 50−70% and stand transpiration (July to late September) by 75% ( P = 0.052). There was, however, no reduction in stem water use and stand transpiration during the second year of defoliation due to reduced beetle abundances at that location. At the Walker site, we measured stand evapotranspiration (ET) in the center of a large saltcedar stand and found that ET was highest immediately prior to D. carinulata arrival, dropped dramatically with defoliation, and remained low through the subsequent 2 years of the study. In contrast, near the perimeter of the stand, D. carinulata did not reduce sap flow, partly because of low rates of defoliation but also because of increased water use per unit leaf area in response to defoliation. Taken together, our results provide evidence that in the early stages of population expansion D. carinulata can lead to substantial declines in saltcedar water use. The extent of these declines varies spatially and temporally and is dependent on saltcedar compensatory responses along with D. carinulata population dynamics and patterns of dispersal.

Nevada↗
USGS2004

Effects of invasive alien plants on fire regimes

Plant invasions are widely recognized as significant threats to biodiversity conservation worldwide. One way invasions can affect native ecosystems is by changing fuel properties, which can in turn affect fire behavior and, ultimately, alter fire regime characteristics such as frequency, intensity, extent, type, and seasonality of fire. If the regime changes subsequently promote the dominance of the invaders, then an invasive plant–fire regime cycle can be established. As more ecosystem components and interactions are altered, restoration of preinvasion conditions becomes more difficult. Restoration may require managing fuel conditions, fire regimes, native plant communities, and other ecosystem properties in addition to the invaders that caused the changes in the first place. We present a multiphase model describing the interrelationships between plant invaders and fire regimes, provide a system for evaluating the relative effects of invaders and prioritizing them for control, and recommend ways to restore pre-invasion fire regime properties.

BioScience↗