PubMed | The College of New Jersey, Bryn Mawr College, Eastern Illinois University, University of Mississippi and Rutgers Pinelands Field Station
Type: | Journal: Annals of botany | Year: 2017
Temperate deciduous forest understoreys are experiencing widespread changes in community composition, concurrent with increases in rates of nitrogen supply. These shifts in plant abundance may be driven by interspecific differences in nutrient foraging (i.e. conservative vs. acquisitive strategies) and, thus, adaptation to contemporary nutrient loading conditions. This study sought to determine if interspecific differences in nutrient foraging could help explain patterns of shrub success and decline in eastern North American forests.Using plants grown in a common garden, fine root traits associated with nutrient foraging were measured for six shrub species. Traits included the mean and skewness of the root diameter distribution, specific root length (SRL), C:N ratio, root tissue density, arbuscular mycorrhizal colonization and foraging precision. Above- and below-ground productivity were also determined for the same plants, and population growth rates were estimated using data from a long-term study of community dynamics. Root traits were compared among species and associations among root traits, measures of productivity and rates of population growth were evaluated.Species fell into groups having thick or thin root forms, which correspond to conservative vs. acquisitive nutrient foraging strategies. Interspecific variation in root morphology and tissue construction correlated with measures of productivity and rates of cover expansion. Of the four species with acquisitive traits, three were introduced species that have become invasive in recent decades, and the fourth was a weedy native. In contrast, the two species with conservative traits were historically dominant shrubs that have declined in abundance in eastern North American forests.In forest understoreys of eastern North America, elevated nutrient availability may impose a filter on species success in addition to above-ground processes such as herbivory and overstorey canopy conditions. Shrubs that have root traits associated with rapid uptake of soil nutrients may be more likely to increase in abundance, while species without such traits may be less likely to keep pace with more productive species.
DiLeo K.,Rutgers University |
Donat K.,Rutgers University |
Min-Venditti A.,Rice University |
Dighton J.,Rutgers Pinelands Field Station
Fungal Ecology | Year: 2010
Zoosporic fungi (chytrid) abundance, as captured on pollen bait, was significantly higher in pristine sites than impacted sites in a survey of six water bodies of varying ecological integrity (as categorized by the NJ Pinelands Commission) in the New Jersey pine barrens (USA). Using a series of laboratory manipulations of water from a pristine and an impacted site, altered pH appeared to be the primary driver of zoosporic fungi abundance in the field. Increasing pH of the naturally acid water of the pine barrens, significantly reduced zoosporic fungal populations and a reduction of pH of impacted water ameliorated conditions and increased abundance. The addition of nitrogen or phosphorus to, or an increase in specific conductance of, pristine water reduced zoosporic fungal abundance, but a reduction in these parameters in impacted water did not induce restoration of zoosporic fungi. These results show zoosporic fungi have potential as bioindicators of pollution. © 2009 Elsevier Ltd and The British Mycological Society.
Dighton J.,Rutgers Pinelands Field Station |
Helmisaari H.-S.,University of Helsinki |
Maghirang M.,Rutgers University |
Smith S.,Rutgers University |
And 9 more authors.
Applied Soil Ecology | Year: 2012
There is increasing interest in removing greater amounts of non-timber residues from forests for use in energy production. As part of a study aimed at elucidating the ecological impacts of these practices in Finland, piles of thinning residues of contrasting mass per unit area were established in 2004 around the base of individual Scots pine trees. As part of an NSF funded undergraduate training program, we have sampled the soil under these residue piles to evaluate the effect of leaving different amounts of residue on site to supply nutrients for remaining trees. Aboveground tree biomass production was significantly higher with higher levels of post-harvest residue retention. However, changes in soil chemistry were minimal and inconsistent with increasing residue amounts. Fine (<1. mm) tree root biomass showed little response to residue levels, but specific root length (length per unit mass) and ectomycorrhizal root tip abundance showed significant increases in the highest residue addition compared to the no-addition control. This may suggest a greater root searching strategy under high residue levels. There was no evidence of residue effect on soil nematodes but a consistent increase in abundance of 0-2. mm length enchytraeids with increased residue. This may be a result of higher rates of asexual reproduction under residues. Soil arthropod abundances did not correlate with residue levels. Even in this cold boreal forest ecosystem, it is possible that sampling 5. years after residue placement we may have missed some of the early influence of decomposition of more labile fractions of the residues on soil organisms and processes. It is likely that the current phase of woody material decomposition will have lesser effects on soil biology. © 2012 Elsevier B.V.
Wang Y.,Rutgers University |
Boyd E.,Montana State University |
Crane S.,Rutgers University |
Lu-Irving P.,Rutgers University |
And 7 more authors.
Microbial Ecology | Year: 2011
The distribution and phylogeny of extant protein-encoding genes recovered from geochemically diverse environments can provide insight into the physical and chemical parameters that led to the origin and which constrained the evolution of a functional process. Mercuric reductase (MerA) plays an integral role in mercury (Hg) biogeochemistry by catalyzing the transformation of Hg(II) to Hg(0). Putative merA sequences were amplified from DNA extracts of microbial communities associated with mats and sulfur precipitates from physicochemically diverse Hg-containing springs in Yellowstone National Park, Wyoming, using four PCR primer sets that were designed to capture the known diversity of merA. The recovery of novel and deeply rooted MerA lineages from these habitats supports previous evidence that indicates merA originated in a thermophilic environment. Generalized linear models indicate that the distribution of putative archaeal merA lineages was constrained by a combination of pH, dissolved organic carbon, dissolved total mercury and sulfide. The models failed to identify statistically well supported trends for the distribution of putative bacterial merA lineages as a function of these or other measured environmental variables, suggesting that these lineages were either influenced by environmental parameters not considered in the present study, or the bacterial primer sets were designed to target too broad of a class of genes which may have responded differently to environmental stimuli. The widespread occurrence of merA in the geothermal environments implies a prominent role for Hg detoxification in these environments. Moreover, the differences in the distribution of the merA genes amplified with the four merA primer sets suggests that the organisms putatively engaged in this activity have evolved to occupy different ecological niches within the geothermal gradient. © 2011 Springer Science+Business Media, LLC.