Scratching the Surface and Digging Deeper: Exploring Ecological Theories in Urban Soils

Humans have altered the Earth more extensively during the past 50 years than at any other time in history (Millennium Assessment 2003). A significant part of this global change is the conversion of land covers from native ecosystems to those dominated by human activities (Kareiva et al. 2007; Ellis and Ramankutty 2008). Although agricultural needs have historicall

The Conceptual Utility of Models in Human Ecology

Anthropology and bioecology are currently at a point in their development where researchers in both fields are working towards an integration, which can be described as a form of human ecology. Integration of such disparate disciplines is not easily achieved. Important steps which facilitate integration are the clear definition of terms relevant to the disciplines, and the development of a common framework which would allow the overlapping of domains of the disciplines. The objective of this paper is to contribute to an understanding of human ecosystems by discussing (1) the definition of human ecosystems, and (2) the use of models in illustrating the integration of bio-physical and socio-cultural components of human ecosystems. Icons from the systems modeling languages of H.T. Odum and J.M. Forrester are applied to the modeling of human ecosystems. Specifically, models of R.A. Rappaport\u27s work with the Tsembaga Maring are discussed in terms of their depiction of the components of human ecosystems. Modeling allows one to conceptualize the complexity of human ecosystems, and is an important step towards a human ecology

Decomposition of chestnut oak (Quercus prinus) leaves and nitrogen mineralization in an urban environment

Abstract We studied soil processes along an urban to rural gradient. To determine the ecosystem response to the urban soil environment, we measured (1) leaf litter decomposition rates using a reference leaf litter, and (2) net Nmineralization and net nitrification rates using paired in situ soil cores. A significant trend toward slower litter decomposition rates toward the urban end of the gradient was observed. In addition, percent ash-free dry mass remaining of the litter was significantly higher during the course of the study but was not statistically significant at the final sampling date. Litter C:N ratio had a complex response with respect to degree of urban land use, and litter % N did not differ between land-use types. Litter decomposition rates were not significantly correlated with observed soil physicochemical and biological characteristics but were influenced by soil moisture and soil organic matter. Net N-mineralization rates were higher in urban soils. Net nitrification rates did not differ with land-use type. Net Nmineralization rates were positively correlated with soil temperature, indicating a response to the urban heat island effect. Net N-mineralization rates were negatively correlated with the numbers of higher trophic level nematodes

Connecting plant traits and social perceptions in riparian systems: Ecosystem services as indicators of thresholds in social-ecohydrological systems

A major challenge in predicting the response of both social-hydrological and social-ecological systems to environmental change is the lack of a causal framework for predicting thresholds of change between the linked social and natural components. Here we propose a social-ecohydrological thresholds (SEHT) framework that integrates social-hydrological, trait-based ecological, and ecosystem services concepts. This approach facilitates the identification of thresholds by treating ecosystem services as indicators of the coupling of social and natural components of the system. Using the San Pedro riparian corridor in Arizona as a case study, we implemented the SEHT framework using ecological research and stakeholder perspectives to identify key drivers and thresholds in the social-ecohydrological system. In this way, we were able to describe expected outcomes of different hydrological change scenarios on the system. Stakeholders provided input on the utility of this information to inform management decisions aimed at mitigating the impacts of environmental change. The SEHT framework provides insight on dynamics of ecosystem services. This paper demonstrates that application of the framework enables the identification of several critical drivers of potential thresholds in ecosystem services that derive from either natural or social components of the overall system. These potential thresholds can guide ecosystem service assessment and monitoring and provide a roadmap for environmental management and the development of management scenarios.USA National Science Foundation (NSF) [DEB-1010495]; Inter-American Institute for Global Change Research (IAI) [CRN3056, GEO-1128040]; Morris K. and Stewart L. Udall Foundation; USDA NIFA Hatch project through the Maryland Agricultural Experimentation Station24 month embargo; published online: 12 August 2018This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Transpiration rates of red maple (Acer rubrum L.) differ between management contexts in urban forests of Maryland, USA

Partial funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.The hydrological functioning of urban trees can reduce stormwater runoff, mitigate the risk of flood, and improve water quality in developed areas. Tree canopies intercept rainfall and return water to the atmosphere through transpiration, while roots increase infiltration and storage in the soil. Despite this, the amount of stormwater that trees remove through these functions in urban settings is not well characterized, limiting the use of urban forests as practical stormwater management strategies. To address this gap, we use ecohydrological approaches to assess the transpiration rates of urban trees in different management settings. Our research questions are: Do transpiration rates of trees of the same species vary among different management contexts? Do relationships between environmental drivers and transpiration change among management contexts? These management settings included single trees over turfgrass and a cluster of trees over turfgrass in Montgomery County, MD, and closed canopy forest with a leaf litter layer in Baltimore, MD. We used sap flux sensors installed in 18 mature red maple (Acer rubrum L.) trees to characterize transpiration rates during the growing season. We also measured soil volumetric water content, air temperature, relative humidity, and precipitation at each site. In agreement with our initial hypothesis, we found that single trees had nearly three times the daily sum of sap flux density (JS) of closed canopy trees. When averaged over the entire measurement period, JS was approximately 260, 195, and 91 g H2O cm−2 day−1 for single trees, cluster trees and closed canopy trees, respectively. Additionally, single trees were more responsive to VPD than closed canopy and cluster trees. These results provide a better understanding of the influence of management context on urban tree transpiration and can help to identify targets to better manage urban forest settings to reduce urban stormwater runoff.https://doi.org/10.1038/s41598-021-01804-

The Photovoltaic Heat Island Effect: Larger solar power plants increase local temperatures

While photovoltaic (PV) renewable energy production has surged, concerns remain about whether or not PV power plants induce a "heat island" (PVHI) effect, much like the increase in ambient temperatures relative to wildlands generates an Urban Heat Island effect in cities. Transitions to PV plants alter the way that incoming energy is reflected back to the atmosphere or absorbed, stored, and reradiated because PV plants change the albedo, vegetation, and structure of the terrain. Prior work on the PVHI has been mostly theoretical or based upon simulated models. Furthermore, past empirical work has been limited in scope to a single biome. Because there are still large uncertainties surrounding the potential for a PHVI effect, we examined the PVHI empirically with experiments that spanned three biomes. We found temperatures over a PV plant were regularly 3-4 degrees C warmer than wildlands at night, which is in direct contrast to other studies based on models that suggested that PV systems should decrease ambient temperatures. Deducing the underlying cause and scale of the PVHI effect and identifying mitigation strategies are key in supporting decision-making regarding PV development, particularly in semiarid landscapes, which are among the most likely for large-scale PV installations.University of Arizona Institute of the Environment; Office of Research & Development through the TRIFThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Urban ecology: advancing science and society

Urban ecology has quickly become established as a central part of ecological thinking. As cities continue to grow in size and number, two questions serve to unify this broad and multidisciplinary research landscape: (1) how can urban ecology contribute to the science of ecology, and (2) how can urban ecology be applied to make cities more livable and sustainable? In spite of the advances made thus far, there are many unexplored ways of integrating the science and application of urban ecology. Although scientists assess and make predictions regarding the connections between environmental and socioeconomic processes, practitioners involved in real-world application deal with urban planning and with designing ecosystem services to improve living conditions for all urban inhabitants and to make cities more sustainable. Research in urban ecosystems can be developed from many different perspectives, and we suggest that each perspective has something to offer both society and the science of ecology. We present several research perspectives and describe how these can integrate conceptual and applied aspects to bridge the figurative gaps between trees, buildings, and people

Spatial aspects of food webs

Spatial distributions of trophic interactions define the spatial heterogeneity of food webs and differences between local and macroecological food webs. The concept of co-occurrence has to be given up when larger spatial scales are considered that integrate different local community food webs into a metacommunity food web. This chapter provides two examples. First, some large-bodied predators are too low in numerical abundance to invade all local community food webs simultaneously. Second, not all potential resource species in a metacommunity can persist under strong top-down pressure by their consumer species and thus avoid coexistence in the same local communities. Food webs consist of organisms that vary in their taxonomic identity, body size, trophic interactions, and trophic position and thus might have very different spatial scales of interactions. Recognition of the importance of spatial scale in food web studies has several implications for food web theory. In particular, the potential food webs that are frequently described by ecologists will often differ from how food webs are realized in actual space and time. Clearly, choosing the right spatio-temporal scale for a food web study depends on the species studied and the study objective. Integrating spatial processes such as extinction and colonization by dispersal in food web models is an important step towards understanding population dynamics in complex communities, and understanding the consequences of habitat loss for the community structure and food web dynamics.</p