Using reciprocal leaf litter transplants, we investigated the effects of contrasting environments... more Using reciprocal leaf litter transplants, we investigated the effects of contrasting environments (urban vs. rural) and intraspecific variations in oak leaf litter quality on mass loss rates and nitrogen (N) dynamics along an urban-rural gradient in the New York City metropolitan area. Differences in earthworm abundances and temperature had previously been documented in the stands along this gradient. Red oak leaf litter was collected and returned to its original source stand as native litter to measure decay rates along the gradient. To separate site effects from litter quality effects on decay, reciprocal transplants of litter were also made between stands at the extremes of the environmental gradient (urban and rural stands). Land-use had no effect on mass loss and N dynamics of native litter by the end of the 22-month incubation period. The lack of differences in native litter suggests the factors affecting decay were similar across the stands in this study. However, in the tran...
The structure and function of soil communities in an area with a wide range of concentrations of ... more The structure and function of soil communities in an area with a wide range of concentrations of heavy metals was studied in portions of the U.S. Army`s Aberdeen Proving Ground, Maryland. The study included survey of soil macro- and microinvertebrate communities, soil microorganisms, enzyme activities and the rates of nutrient dynamics in soil. Soil macroinvertebrate communities showed significant reductions in
Soil enzyme activities and microbial biomass were measured in a grassland ecosystem with a wide r... more Soil enzyme activities and microbial biomass were measured in a grassland ecosystem with a wide range of heavy metal concentrations ranging from 7.2 to 48.1 mmol kg−1 (As, Cd, Cr, Cu, Ni, Pb and Zn) in portions of the U.S. Army's Aberdeen Proving Ground, Maryland, U.S.A. Total and fluorescein diacetate active (FDA) fungal biomass, FDA-active bacterial biomass, substrate-induced respiration (SIR),
Ecosystem processes such as N transformations have seldom been studied in urban and suburban area... more Ecosystem processes such as N transformations have seldom been studied in urban and suburban areas. Here we report the temporal and spatial variations in soil N measured continuously over 16 months in remnant forests dominated by northern red oak (Quercus ...
Soluble organic N and microbial N pools in terrestrial ecosystems have been less studied than tho... more Soluble organic N and microbial N pools in terrestrial ecosystems have been less studied than those of inorganic N. Therefore, cross-system variation in their pool sizes and seasonal dynamics, both absolute and relative to inorganic N pools, needs to be quantified so that their ecological importance in different ecosystems can be evaluated. We measured extractable soil organic N (ESON), microbial biomass N (MBN), and the net production rates of ESON in red oak-dominated remnant forests, along an urban–rural gradient in the New York City metropolitan area. We were interested in (1) determining the seasonal dynamics of ESON and MBN, and (2) examining whether the contrasts in land use (urban, suburban, rural) surrounding these forest remnants were associated with different amounts of ESON and MBN. This field-based study was conducted continuously for 16 months. Yearly average ESON concentrations ranged from 60 to 140 mg kg−1 soil organic matter (SOM), 3–4 times those of inorganic N, and average MBN ranged from 600 to 1100 mg kg−1 SOM. There was a considerable MBN increase in spring in all plots across the gradient. The average increase expressed on an areal basis (to a depth of 7.5 cm) ranged from 1.75 to 4.19 g Nm−2. The N incorporated into the microbial biomass in spring was gradually released later in the growing season (the mean MBN decrease ranged from 1.11 to 3.82 g Nm−2). The spring MBN increase could be an important retention mechanism for conserving soil inorganic N when plant N uptake may be low. The amplitude in the seasonal dynamics of ESON was far less than that of inorganic N, as was that of net ESON production rates when compared to net N mineralization. These suggest a closer coupling of plant N uptake with inorganic N, much more than with ESON. Both ESON and MBN were significantly higher in rural soils than in urban soils, and both concentrations were positively correlated with SOM content. The variation in ESON, MBN, or SOM associated with this urbanization gradient suggests that the form of N exported, the plant N budget and soil N retention mechanisms may be differentially affected by urban, suburban and rural land uses.
To determine the patterns of atmospheric deposition and throughfall in the vicinity of a large ci... more To determine the patterns of atmospheric deposition and throughfall in the vicinity of a large city, bulk deposition, oak forest throughfall, and particulate dust deposition were measured at sites along a transect within and to the north of New York City. Concentrations and fluxes ...
Over the next century, ecosystems throughout the world will be responding to rapid changes in cli... more Over the next century, ecosystems throughout the world will be responding to rapid changes in climate and rising levels of carbon dioxide, inorganic N and ozone. Because people depend on biological systems for water, food and other ecosystem services, predicting the range of responses to global change for various ecosystem types in different geographic locations is a high priority. Modeling
The leaves of plants in nature are commonly subjected to damage from a wide variety of agents, in... more The leaves of plants in nature are commonly subjected to damage from a wide variety of agents, including herbivory, air pollutants, and simple physical damage. Despite the attention paid to damage effects on living plants, the potential effects on the quality of litter ...
We compared the ectomycorrhizal community structure of oak forest stands located in either an urb... more We compared the ectomycorrhizal community structure of oak forest stands located in either an urban or a rural area. Urban stands had higher N deposition rates, soil heavy metal levels, and earthworm counts than rural stands. Ectomycorrhizal types were quantified on ...
Using reciprocal leaf litter transplants, we investigated the effects of contrasting environments... more Using reciprocal leaf litter transplants, we investigated the effects of contrasting environments (urban vs. rural) and intraspecific variations in oak leaf litter quality on mass loss rates and nitrogen (N) dynamics along an urban-rural gradient in the New York City metropolitan area. Differences in earthworm abundances and temperature had previously been documented in the stands along this gradient. Red oak leaf litter was collected and returned to its original source stand as native litter to measure decay rates along the gradient. To separate site effects from litter quality effects on decay, reciprocal transplants of litter were also made between stands at the extremes of the environmental gradient (urban and rural stands). Land-use had no effect on mass loss and N dynamics of native litter by the end of the 22-month incubation period. The lack of differences in native litter suggests the factors affecting decay were similar across the stands in this study. However, in the tran...
The structure and function of soil communities in an area with a wide range of concentrations of ... more The structure and function of soil communities in an area with a wide range of concentrations of heavy metals was studied in portions of the U.S. Army`s Aberdeen Proving Ground, Maryland. The study included survey of soil macro- and microinvertebrate communities, soil microorganisms, enzyme activities and the rates of nutrient dynamics in soil. Soil macroinvertebrate communities showed significant reductions in
Soil enzyme activities and microbial biomass were measured in a grassland ecosystem with a wide r... more Soil enzyme activities and microbial biomass were measured in a grassland ecosystem with a wide range of heavy metal concentrations ranging from 7.2 to 48.1 mmol kg−1 (As, Cd, Cr, Cu, Ni, Pb and Zn) in portions of the U.S. Army's Aberdeen Proving Ground, Maryland, U.S.A. Total and fluorescein diacetate active (FDA) fungal biomass, FDA-active bacterial biomass, substrate-induced respiration (SIR),
Ecosystem processes such as N transformations have seldom been studied in urban and suburban area... more Ecosystem processes such as N transformations have seldom been studied in urban and suburban areas. Here we report the temporal and spatial variations in soil N measured continuously over 16 months in remnant forests dominated by northern red oak (Quercus ...
Soluble organic N and microbial N pools in terrestrial ecosystems have been less studied than tho... more Soluble organic N and microbial N pools in terrestrial ecosystems have been less studied than those of inorganic N. Therefore, cross-system variation in their pool sizes and seasonal dynamics, both absolute and relative to inorganic N pools, needs to be quantified so that their ecological importance in different ecosystems can be evaluated. We measured extractable soil organic N (ESON), microbial biomass N (MBN), and the net production rates of ESON in red oak-dominated remnant forests, along an urban–rural gradient in the New York City metropolitan area. We were interested in (1) determining the seasonal dynamics of ESON and MBN, and (2) examining whether the contrasts in land use (urban, suburban, rural) surrounding these forest remnants were associated with different amounts of ESON and MBN. This field-based study was conducted continuously for 16 months. Yearly average ESON concentrations ranged from 60 to 140 mg kg−1 soil organic matter (SOM), 3–4 times those of inorganic N, and average MBN ranged from 600 to 1100 mg kg−1 SOM. There was a considerable MBN increase in spring in all plots across the gradient. The average increase expressed on an areal basis (to a depth of 7.5 cm) ranged from 1.75 to 4.19 g Nm−2. The N incorporated into the microbial biomass in spring was gradually released later in the growing season (the mean MBN decrease ranged from 1.11 to 3.82 g Nm−2). The spring MBN increase could be an important retention mechanism for conserving soil inorganic N when plant N uptake may be low. The amplitude in the seasonal dynamics of ESON was far less than that of inorganic N, as was that of net ESON production rates when compared to net N mineralization. These suggest a closer coupling of plant N uptake with inorganic N, much more than with ESON. Both ESON and MBN were significantly higher in rural soils than in urban soils, and both concentrations were positively correlated with SOM content. The variation in ESON, MBN, or SOM associated with this urbanization gradient suggests that the form of N exported, the plant N budget and soil N retention mechanisms may be differentially affected by urban, suburban and rural land uses.
To determine the patterns of atmospheric deposition and throughfall in the vicinity of a large ci... more To determine the patterns of atmospheric deposition and throughfall in the vicinity of a large city, bulk deposition, oak forest throughfall, and particulate dust deposition were measured at sites along a transect within and to the north of New York City. Concentrations and fluxes ...
Over the next century, ecosystems throughout the world will be responding to rapid changes in cli... more Over the next century, ecosystems throughout the world will be responding to rapid changes in climate and rising levels of carbon dioxide, inorganic N and ozone. Because people depend on biological systems for water, food and other ecosystem services, predicting the range of responses to global change for various ecosystem types in different geographic locations is a high priority. Modeling
The leaves of plants in nature are commonly subjected to damage from a wide variety of agents, in... more The leaves of plants in nature are commonly subjected to damage from a wide variety of agents, including herbivory, air pollutants, and simple physical damage. Despite the attention paid to damage effects on living plants, the potential effects on the quality of litter ...
We compared the ectomycorrhizal community structure of oak forest stands located in either an urb... more We compared the ectomycorrhizal community structure of oak forest stands located in either an urban or a rural area. Urban stands had higher N deposition rates, soil heavy metal levels, and earthworm counts than rural stands. Ectomycorrhizal types were quantified on ...
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Papers by Margaret Carreiro