Research Abstracts:

Soil Metal Contamination Influences the Vegetation Assemblage Development of an Urban Brownfield

Recognizing the growing importance of both structure (maintenance of biodiversity) and function (fostering natural cycles) of urban ecologies, we examine fine and coarse scale vegetation (alpha and beta guild) trajectories in an urban brownfield that had been undisturbed for almost forty years.  Our previous work had demonstrated that assemblage distribution and primary productivity could be correlated with total soil metal load.  Specifically that hardwood assemblage distribution was positively correlated with increasing soil metal load.  Using current vegetative assemblage distribution maps and digitized historic aerial photographs; we document distinct assemblage development trajectories above and below a critical soil metal load. 

These results indicate that hardwood assemblages, dominated by metal tolerant species, were early colonizers and became successfully established in areas of high total soil metal load.  Conversely shrub assemblages remain relatively absent from these areas for more than 25 years.  In addition, two scenarios for future assemblage trajectory, the first considering soil metal mitigation as the result of metal adsorption to or occlusion with organic matter, and a second considering a soil metal feedback loop via continuous cycling of metals in the leaf litter are proposed. These data indicate that assembly theory allowing alternate stable stages may provide a better model than traditional directed succession for the establishment of restoration objectives on degraded sites.

Ecological Applications, In review

Frank J. Gallagher (1) Ildiko Pechmann (2), and Claus Holzapfel (2)

1 Urban Forestry Program, Department of Ecology, Evolution and Natural Resources, Rutgers, The State University , 14 College Farm Road , New Brunswick, New Jersey 08901-8551

2 Rutgers University Newark, Dept. of Biological Sciences, Newark NJ 07102-1811, 

Heavy metal accumulation and growth performance of nestlings of passerine species at an urban brownfield site

The use of passerine species as biomonitors of heavy metal accumulation is often underutilized when examining the viability of polluted sites. In this study we used two common passerine species – house wrens (Troglodytes aedon) and American robins (Turdus migratorus) – as biomonitors of heavy metal accumulation at an urban brownfield site. We used breast feathers of nestling to test for heavy metal accumulation of Pb, Zn, Cr, Cu, Cr, Fe – metals that are known to persist in the study site’s soil. We compared a polluted brownfield site with a control site that has no known history of pollutants. Our intraspecific comparison between the two sites showed that house wren nestlings at the study site accumulated significantly greater concentrations of all target metals except, Cr and Zn. At the study site we found significant interspecific differences of metal concentrations in feathers, with house wrens accumulating greater concentrations of all metals except Cr. Although house wren nestlings demonstrated significant accumulation of metals, these concentrations showed little effect on growth rates or fledge rates during the breeding season compared with those data recovered from our control site. Among house wren nestlings we found greater interclutch variation of metal accumulation at the study site but greater intraclutch variation of metal accumulation at the control site.

 Environmental Pollution, In review

Charles Hofer(1), Claus Holzapfel(1), and Frank Gallagher(2)

1 Rutgers University Newark, Dept. of Biological Sciences, Newark NJ 07102-1811, 

2 Urban Forestry Program, Department of Ecology, Evolution and Natural Resources, Rutgers, The State University , 14 College Farm Road , New Brunswick, New Jersey 08901-8551

Morphological Variation in the Seed of Gray birch (Betula populifolia Marsh): The Effects of Soil Metal Contamination.

Seed dispersal effectiveness is an important factor that contributes to the success of plant migration and early assemblage development.  Variation in seed architecture determines the dispersal strategy employed and the distance the seed travels.  In addition, few species of trees are known to colonize disturbed sites that exhibit higher than normal concentrations of soil metals typical of urban brownfields. The patchy distribution and heterogeneous makeup of the soil contamination result in a strong abiotic filter, which limits recruitment from regional species pools. In the northeastern United States, one of the most successful species in these situations is gray birch (Betula populifolia Marsh).  Our previous work demonstrated that gray birch had dominated the study site and its distribution could be positively correlated with increasing soil metal loads. Hence, we questioned whether the size and weight of gray birch seeds collected from areas of various soil metal loads would differ, thereby impacting their dispersal effectiveness. We hypothesized that if seeds with a specific architecture were being selected for in these situations, it would rapidly alter genetic variation within the urban populations of this species. The results indicate that gray birch employs a strategy whereby different wing loading rates result from varying the size and weight of its seeds.  In addition, while a decrease in seed size correlated well with total soil metal load, the correlation with seed weight was marginal.  Wing loading rates (seed weight/seed surface area) however, exhibited no significant relationship with soil metal load, indicating that potential for seed distribution from areas of high soil metal load had not been impaired.  However, germination success exhibited a negative correlation with increasing metal load, indicating that metal tolerance is probably the result of genetic variation maintained within the metapopulation.

Urban Habitat, Vol. 6, In press

Frank J. Gallaghera (1), Ildiko Pechman (2), Bernard Isaacson (3), Jason Grabosky (1) 

(1) Urban Forestry Program, Department of Ecology, Evolution and Natural Resources, Rutgers, The State University , 14 College Farm Road , New Brunswick, New Jersey 08901-8551, Work Phone (609) 439-6527

(2) Department of Biological Sciences, Rutgers, The State University, 113 University Ave Newark, NJ 08-205-3619

Betula populifolia Marsh. Seed Samples

Soil Metal Concentrations and Plant Productivity in an Urban Brownfield

Anthropogenic sources of toxic elements have seriously compromised the ecological integrity of many green areas in urban landscapes.  Analysis of soil samples from a forested brownfield within Liberty State Park, Jersey City, New Jersey, USA, shows that arsenic, chromium, lead, zinc and vanadium exist at concentrations above those considered ambient for the area.  Using both satellite imagery and field spectral measurement we examined plant productivity at the assemblage and individual specimen level.  In addition, we studied longer term growth trends via tree core data (basal area increase).  Leaf chlorophyll content (calculated with NDVI) within the hardwood assemblage correlated with a threshold model for metal tolerance, decreasing significantly beyond a total soil metal index of 3.5.  Biomass production (calculated with RG – Red/Green ratio index) Betula populifolia, the co-dominant tree species, demonstrated an inverse relationship with the concentration of Zn in the leaf tissue during the growing season.  Incremental basal area growth in B. populifolia exhibited a statistically significant relationship to total soil metal load. 

Environmental Pollution 156 (Dec. 2008) 699–706

Frank J. Gallagher (1), Ildiko Pechmannb (2), John D. Bogden (3), Jason Grabosky (1) and Peddrick Weis (4)

(1) Urban Forestry Program, Department of Ecology, Evolution and Natural Resources, Rutgers, The State University , 14 College Farm Road , New Brunswick, New Jersey 08901-8551, Work Phone (609) 439-6527

(2) Dept of Biological Sciences, Rutgers University, Newark NJ 07102

(3) Dept. of Preventive Medicine and Community Health, University of Medicine and Dentistry of New Jersey – N. J. Medical School, P. O. Box 1709., Newark, NJ 07101-1709, work phone (973) 972-5432

(4) Dept. of Radiology, University of Medicine and Dentistry of New Jersey -  N. J. Medical School, P. O. Box 1709,  Newark, NJ 07101-1709, work phone (973) 972-4409

Soil Metal Concentrations and Vegetative Assemblages in an Urban Brownfield

Anthropogenic sources of toxic elements have had serious ecological and human health impacts. Analysis of the soil samples from a brownfieldwithin Liberty State Park, Jersey City, NJ, USA, showed that arsenic, chromium, lead, zinc and vanadium exist at concentrations above those considered ambient for the area. Accumulation and translocation features were characterized for the dominant plant species of four vegetativeassemblages. The trees Betula populifolia and Populus deltoides were found to be accumulating Zn in leaf tissue at extremely high levels.B. populifolia, P. deltoides and Rhus copallinum accumulated Cr primarily in the root tissue. A comparison of soil metal maps and vegetative
assemblage maps indicates that areas of increasing total soil metal load were dominated by successional northern hardwoods while semi-emergentmarshes consisting mostly of endemic species were restricted primarily to areas of low soil metal load.

Environmental Pollution 153 (May 2008) 351-361

Frank J. Gallagher (1), Ildiko Pechmannb (2), John D. Bogden (3), Jason Grabosky (1) and Peddrick Weis (4)

(1) Urban Forestry Program, Department of Ecology, Evolution and Natural Resources, Rutgers, The State University , 14 College Farm Road , New Brunswick, New Jersey 08901-8551, Work Phone (609) 439-6527

(2) Dept of Biological Sciences, Rutgers University, Newark NJ 07102

(3) Dept. of Preventive Medicine and Community Health, University of Medicine and Dentistry of New Jersey – N. J. Medical School, P. O. Box 1709., Newark, NJ 07101-1709, work phone (973) 972-5432

(4) Dept. of Radiology, University of Medicine and Dentistry of New Jersey -  N. J. Medical School, P. O. Box 1709,  Newark, NJ 07101-1709, work phone (973) 972-4409

Interaction of native and non-native plant species and the assembly and evolution of new plant communities: Fusion Ecology
        
Species that have common evolutionary background (i.e., are evolved in the same area: sympatric species) develop mechanisms that minimize competitive interaction (above and below ground) and form recognizable territories. Species that lack this common background (i.e., species that evolved in different areas and are brought together artificially: allopatric species) do this to much lesser extent.
        
The consequence of biological invasion is the process of bringing together organisms from different geographical areas that lack common evolutionary background. By comparing “old” and “new” plant assemblies in a variety of locations with different levels of human disturbance we propose to put above hypothesis to the test.
        
A preliminary empirical and modeling study (in cooperation with NJJT) in summer 2005 conducted in various sites in NJ (including Liberty State Park) demonstrated that in tendency sympatric had smaller above-ground overlap compared to allopatric species. A modeling approach has been developed that aims at explaining species specific overlap in terms of resource competition and other direct types of interaction (allelopathy, cooperation).

Investigator: Dr. Claus Holzapfel, Rutgers University, Newark