Global Analysis of Human Population Density and Blue Carbon Stocks in Mangrove Soils

Recent research highlights the decline in blue carbon within mangrove ecosystems due to anthropogenic pressures. We investigate the impact of human population density on soil carbon stocks in urban mangrove forests to assess their contribution to the global carbon budget. Conducting a global analysis, we compile mangrove soil carbon data and calculate population density using European Commission records. Findings reveal a negative correlation between population density and mangrove soil carbon stocks. Specifically, when population density exceeds 300 people km−2, soil carbon decreases by 37% compared to isolated mangrove forests. However, accounting for climatic variables diminishes this negative relationship, rendering it insignificant in mixed effects models. This suggests population density alone may not accurately reflect human impacts on mangrove ecosystems, indicating that even in densely populated areas, mangrove forests can retain significant carbon stocks. Our study underscores the importance of conserving existing mangroves, especially in high-density urban areas, and advocates for further research on the relationship between human activities and mangrove carbon stocks

Characterization of Coal Particles in the Soil of a Former Rail Yard and Urban Brownfield: Liberty State Park, Jersey City (NJ), USA

From the 1850\u27s until the 1960\u27s, the Central Railroad of New Jersey was among several major railways shipping anthracite and bituminous coal to the New York City area, transferring coal from railcar to barge at its extensive rail yard and port facility in Jersey City. The 490 ha Liberty State Park was developed on the site after the rail yard closed, but a ca. 100 ha brownfield zone within the park remains off limits to visitors pending future remediation. As part of an environmental forensic and industrial archeological investigation of this zone, the present study characterizes anthracite and bituminous coal particles present in abundance in the soil by scanning electron microscopy (SEM) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). A simple pretreatment procedure employing density separation improved the analytical results. This detailed information about the nature of contaminants at the site will help to inform the remediation effort in the public interest

Urban Re-Greening: A Case Study in Multi-Trophic Biodiversity and Ecosystem Functioning in a Post-Industrial Landscape

The biodiversity of urban and post-industrial ecosystems is a highly relevant and growing new frontier in ecological research. Even so, the functionality of these ecosystems may not always be successfully predicted based on prior biodiversity and ecosystem functioning theory. Indeed, evidence suggests that the general biological impoverishment within the urban context envisioned thirty years ago was overstated. Many of the world’s urban centers support some degree of biodiversity that is indigenous, as well as a complex array of non-native species, resulting in highly functional, and often, novel communities. For over two decades, a multi-disciplinary team has examined the sub-lethal impact of soil metal contamination on the multi-trophic biodiversity and ecosystem functioning of a post-industrial brownfield in the New York City metropolitan area. We do this through examinations of photosynthesis, carbon allocation, and soil enzyme activity as well as multi-trophic metal translocation via the plant and rhizosphere. In this paper, we synthesize the findings of our research network and apply the results to a framework of functional diversity. Due to the unique constraints many post-industrial lands impose on communities, functional diversity may be more meaningful to ecosystem health than species richness

Fire and herbivory shape soil arthropod communities through habitat heterogeneity and nutrient cycling in savannas

Soil arthropods are important components of savannas, contributing to nutrient cycling and thus primary productivity. To investigate how fire and mammalian herbivores influ- ence arthropod food webs, we used two long term herbivore exclosures (ca. 20 y) and burning trials (ca. 5-y return) located along rivers in Kruger National Park, South Africa. Herbivory and fire will usually have negative effects on soil arthropods although this can be variable, and dependent on multiple aspects of habitat structure and nutrient cycling. We hypothesised that in our sites, the more chronic herbivory disturbance would have stronger and more effects than fire, and that both fire and herbivory would decrease arthropod abundance, biomass and diversity via changes to habitat structure and nutrient cycling. We used a structural equation model to investigate these mechanisms, and to compare these drivers. This model supported our hypothesis that herbivory had more and stronger effects than fire, largely through indirect flow-on effects. We also found evidence to support a ‘tolerance/avoidance’ hypothesis, in that herbivory increased soil arthropod diversity by decreasing soil nutrients. Herbivores also decreased arthropod biomass and abundance in total and in all trophic groups excluding omnivores. Fire and herbivory are closely linked, careful consideration should be made when making decisions in the management of either. In some areas either driver may be more dominant, as was the case in our research. Further studies should incorporate a range of fire fre- quencies and intensities, as well as herbivore types, densities and abundances. Disturbance Exclosures Fire Herbivory Path analysis Savannas Soil arthropods Soil food webspublishedVersio

Plant–soil feedbacks of exotic plant species across life forms: a meta-analysis

Invasive exotic plant species effects on soil biota and processes in their new range can promote or counteract invasions via changed plant–soil feedback interactions to themselves or to native plant species. Recent meta-analyses reveale that soil influenced by native and exotic plant species is affecting growth and performance of natives more strongly than exotics. However, the question is how uniform these responses are across contrasting life forms. Here, we test the hypothesis that life form matters for effects on soil and plant–soil feedback. In a meta-analysis we show that exotics enhanced C cycling, numbers of meso-invertebrates and nematodes, while having variable effects on other soil biota and processes. Plant effects on soil biota and processes were not dependent on life form, but patterns in feedback effects of natives and exotics were dependent on life form. Native grasses and forbs caused changes in soil that subsequently negatively affected their biomass, whereas native trees caused changes in soil that subsequently positively affected their biomass. Most exotics had neutral feedback effects, although exotic forbs had positive feedback effects. Effects of exotics on natives differed among plant life forms. Native trees were inhibited in soils conditioned by exotics, whereas native grasses were positively influenced in soil conditioned by exotics. We conclude that plant life form matters when comparing plant–soil feedback effects both within and between natives and exotics. We propose that impact analyses of exotic plant species on the performance of native plant species can be improved by comparing responses within plant life form

The causes and consequences of biodiversity in multitrophic communities

The work described in this dissertation is linked by the common theme of biodiversity and its relationship to microbially-mediated functions in ecosystems. In the first chapter, I present results from a study where I evaluated the consequences of diversity by manipulating species richness in model aquatic communities. I showed that bacterial abundance remained constant with increasing eukaryotic species richness at low productivity, but significantly declined at high productivity. Furthermore, eukaryotic species richness together with productivity influenced the composition of the bacterial community, and food web diversity and productivity interact to influence bacterial community composition and function. In more diverse food webs, bacterial activity (decomposition) increased despite lower population abundance. In chapters two and three, I present results from one experiment in which I measured responses of microbial diversity and multiple trophic levels to an environmental perturbation in naturally occurring forest soil food webs from two geographically different locations. In the second chapter, I showed that diversity of the bacterial and fungal communities (measured by colony and ectomycorrhizal morphotype respectively) responded differently to nitrogen addition depending on geographic context. The composition of the bacterial community differed with nitrogen addition and geographic site, while the composition of the fungal community did not. In chapter three, I evaluated the relative importance of trophic control in the soil micro-food webs from the same two geographic sites (Florida and New Jersey). I found that the FL site supported greater biomass of bacteria and fungi than NJ, and the NJ site supported greater density of measured soil animal groups (collembola, oribatid mites and predatory mites) than FL. I found evidence for top down control by soil animals on microbial biomass, and at the same time, I also found evidence for bottom up control on microbial biomass through limitation of NO3 and PO4. This dissertation demonstrates that microbially mediated-ecosystem functions depend upon trophic interactions with producers, consumers and predators in food webs. Furthermore, it demonstrates that the response of these communities is context dependent. Biotic and abiotic factors play a critical role in shaping a community's diversity, composition and functioning.Ph.D.Includes bibliographical references

Interactions in Soil : Promoting Plant Growth

https://digitalcommons.montclair.edu/all_books/1201/thumbnail.jp

Human population density and blue carbon stocks in mangroves soils

Mangrove soils provide many important ecosystem services such as carbon sequestration, yet they are vulnerable to the negative impacts brought on by anthropogenic activities. Research in recent decades has shown a progressive loss of blue carbon in mangrove forests as they are converted to aquaculture, agriculture, and urban development. We seek to study the relationship between human population density and soil carbon stocks in urban mangrove forests to quantify their role in the global carbon budget. To this end, we conducted a global analysis, collecting mangrove soil carbon data from previous studies and calculating population density for each study location utilizing a recent database from the European Commission. Results indicate population density has a negative association with mangrove soil carbon stocks. When human population density reaches 300 people km ^−2 , which is defined as ‘urban domains’ in the European Commission database, mangrove soil carbon is estimated to be lower than isolated mangrove forests by 37%. Nonetheless, after accounting for climatic factors in the model, we see the negative relationship between population density and soil carbon is reduced and is even non-significant in mixed effects models. This suggests population density is not a good measure for the direct effects of humans on mangrove ecosystems and further implies mangrove ecosystems in close proximity to very high population density can still possess valuable carbon stocks. Our work provides a better understanding of how soil carbon stocks in existing mangrove forests correlate with different levels of population density, underscores the importance of protecting existing mangroves and especially those in areas with high human population density, and calls for further studies on the association between human activities and mangrove forest carbon stocks

Herbivory and Stoichiometric Feedbacks to Primary Production.

Established theory addresses the idea that herbivory can have positive feedbacks on nutrient flow to plants. Positive feedbacks likely emerge from a greater availability of organic carbon that primes the soil by supporting nutrient turnover through consumer and especially microbially-mediated metabolism in the detrital pool. We developed an entirely novel stoichiometric model that demonstrates the mechanism of a positive feedback. In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants. The model consists of differential equations coupling flows among pools of: plants, herbivores, detrital carbon and nitrogen, and inorganic nitrogen. We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant. Our model analyses show that partial feeding and plant C:N interact because when herbivores are sloppy and plant biomass is diverted to the detrital pool, more mineral nitrogen is available to plants because of the stoichiometric difference between the organisms in the detrital pool and the herbivore. This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production