James R. Grove

Strawberry fields forever? Urban agriculture in developed countries: a review

Food production in cities has long been a tradition in many countries around the world and a mainstream activity for many developed countries. While urban agriculture plays an important role in increasing food security and social well-being, it comes with significant costs and constraints. Here, we review the growth of urban agriculture throughout the developed world in order to clarify the different benefits, risks, and hindrances associated with the practice. Through this analysis, we identify the need for better understanding of the following five aspects if urban agriculture is to make a meaningful contribution to food security and social well-being in the future: (1) the impacts of continued urban sprawl and loss of peri-urban agricultural land; (2) appropriate government and institutional support at local, regional, and country levels; (3) the role of urban agriculture in self-sufficiency of cities; (4) the risks posed by pollutants from agriculture to urban ecosystems and from urban ecosystems to agriculture; and (5) the carbon footprint of urban agriculture and use of “food miles.” If urban agriculture is to have a legitimate place in resolving the global food crisis as advocates claim, then it is time to take urban agriculture seriously and assess more rigorously both the positive and negative impacts, especially carbon emissions. Only then can the world’s limited resources be properly allocated to the development of urban agriculture.

Give peas a chance? Urban agriculture in developing countries. A review

Urban agriculture is receiving increasing attention throughout the developing world, but debate rages as to whether it is a blessing or a curse. Some see it as savior for the poor, providing food, and livelihoods, yet to others it is responsible for harboring and vectoring pathogenic diseases and is an archaic practice that has no place along the path toward development. Consequently, the activity receives a mixed reception, and despite much support in many instances, it certainly does not enjoy universal unimpeded progress. Here, we undertake a global tour of urban agriculture throughout the developing world in an attempt to elucidate the various benefits, costs, and hindrances associated with the practice. Through this analysis we identify the need for better understanding of the following six aspects if urban agriculture is to make a meaningful contribution to food security and sustenance of livelihoods in the future: (1) the global and regional extent of urban agriculture; (2) the contribution of urban agriculture to communicable diseases, especially malaria but also diarrheal disease; (3) the role that urban agriculture does and/or could play in abating both malnutrition and obesity; (4) the impacts of urban agriculture on women; (5) appropriate methods of achieving governance and institutional support; and (6) the risks posed by chemical pollutants, particularly as Africa becomes increasingly industrialized. Overlaying these, we suggest that the time is ripe to extend the debate about urban agriculture’s positive and negative environmental impacts—especially in relation to carbon emissions—from primarily a developed world concern to the developing world, particularly since it is the developing world where population growth and consequent resource use is increasing most rapidly.

High and Dry: Comparing Literature Review Approaches to Reveal the Data that Informs the Geomorphic Management of Regulated River Floodplains

While the impacts of regulation on river systems have been investigated, the main focus of the research has been on ecological and in-channel impacts. An understanding of the impacts of regulation on floodplain geomorphology is needed in order to inform management actions, in particular environmental flows. Concurrently with a traditional literature review on the effects of river regulation on floodplain geomorphology, we undertook a systematic review of the evidence using causal criteria analysis. The causal criteria approach tested evidence from multiple studies against a ‘checklist’ of criteria, constructing an argument for causality by combining a number of pieces of evidence into a single coherent argument. The causal criteria analysis only found support for one hypothesized cause-effect linkage in the conceptual model. In contrast, after discussing many of the conceptual model linkages, the traditional review provided a series of eight hypothesised scenarios to highlight the different possibilities for floodplain geomorphic change resulting from regulation. The difference was partly as a result of the time taken to enter studies into the Eco Evidence Database, but mainly because of the quality of evidence from geomorphic studies. Low statistical rigour in study designs meant that many papers were inadmissible as evidence. Thus, the causal criteria analysis made transparent the quality of data used in a traditional literature review that might subsequently be used to justify costly management recommendations.

The Potential for Dams to Impact Lowland Meandering River Floodplain Geomorphology

The majority of the worlds floodplains are dammed. Although some implications of dams for riverine ecology and for river channel morphology are well understood, there is less research on the impacts of dams on floodplain geomorphology. We review studies from dammed and undammed rivers and include influences on vertical and lateral accretion, meander migration and cutoff formation, avulsion, and interactions with floodplain vegetation. The results are synthesized into a conceptual model of the effects of dams on the major geomorphic influences on floodplain development. This model is used to assess the likely consequences of eight dam and flow regulation scenarios for floodplain geomorphology. Sediment starvation downstream of dams has perhaps the greatest potential to impact on floodplain development. Such effects will persist further downstream where tributary sediment inputs are relatively low and there is minimal buffering by alluvial sediment stores. We can identify several ways in which floodplains might potentially be affected by dams, with varying degrees of confidence, including a distinction between passive impacts (floodplain disconnection) and active impacts (changes in geomorphological processes and functioning). These active processes are likely to have more serious implications for floodplain function and emphasize both the need for future research and the need for an “environmental sediment regime” to operate alongside environmental flows.

Iwao’s patchiness regression through the origin: biological importance and efficiency of sampling applications

Iwao’s mean crowding-mean density relation can be treated both as a linear function describing the biological characteristics of a species at a population level, or a regression model fitted to empirical data (Iwao’s patchiness regression). In this latter form its parameters are commonly used to construct sampling plans for insect pests, which are characteristically patchily distributed or overdispersed. It is shown in this paper that modifying both the linear function and statistical model to force the intercept or lower functional limit through the origin results in more intuitive biological interpretation of parameters and better sampling economy. Firstly, forcing the function through the origin has the effect of ensuring that zero crowding occurs when zero individuals occupy a patch. Secondly, it ensures that negative values of the intercept, which do not yield an intuitive biological interpretation, will not arise. It is shown analytically that sequential sampling plans based on regression through the origin should be more efficient compared to plans based on conventional regression. For two overdispersed data sets, through-origin based plans collected a significantly lower sample size during validation than plans based on conventional regression, but the improvement in sampling efficiency was not large enough to be of practical benefit. No difference in sample size was observed when through-origin and conventional regression based plans were validated using underdispersed data. A field researcher wishing to adopt a through-origin form of Iwao’s regression for the biological reasons outlined above can therefore be confident that their sampling strategies will not be affected by doing so.

Assessing stream bank condition using airborne LiDAR and high spatial resolution image data in temperate semirural areas in Victoria, Australia

Abstract Stream bank condition is an important physical form indicator for streams related to the environmental condition of riparian corridors. This research developed and applied an approach for mapping bank condition from airborne light detection and ranging (LiDAR) and high-spatial resolution optical image data in a temperate forest/woodland/urban environment. Field observations of bank condition were related to LiDAR and optical image-derived variables, including bank slope, plant projective cover, bank-full width, valley confinement, bank height, bank top crenulation, and ground vegetation cover. Image-based variables, showing correlation with the field measurements of stream bank condition, were used as input to a cumulative logistic regression model to estimate and map bank condition. The highest correlation was achieved between field-assessed bank condition and image-derived average bank slope ( R 2 = 0.60 , n = 41 ), ground vegetation cover ( R 2 = 0.43 , n = 41 ), bank width/height ratio ( R 2 = 0.41 , n = 41 ), and valley confinement (producer’s accuracy = 100 % , n = 9 ). Cross-validation showed an average misclassification error of 0.95 from an ordinal scale from 0 to 4 using the developed model. This approach was developed to support the remotely sensed mapping of stream bank condition for 26,000 km of streams in Victoria, Australia, from 2010 to 2012.

Using the Weibull distribution to improve the description of riverine wood loads

Abstract Reporting uncertainty in environmental measurements and estimates is important for cross‐comparison and inter‐comparison of sites and other spatial units. One such measure is the load of large in‐stream wood in river systems. In this paper we propose the use of the Weibull distribution to describe the central tendency and variability of wood loads along a river reach. We illustrate the link between the average wood load and the central tendency or scale parameter of the Weibull distribution. The shape of the Weibull distribution is strongly related to the ability of rivers to transport and rearrange the wood in a reach. We use six Victorian rivers to test the fit of the Weibull distribution, showing that the Weibull is a useful and flexible distribution that provides common reporting metrics useful for future studies. Using common reporting metrics provides a stronger tool for comparisons of wood loads between rivers and with reaches. Copyright