Optimal siting, sizing, and enforcement of marine protected areas

The design of protected areas, whether marine or terrestrial, rarely considers how people respond to the imposition of no-take sites with complete or incomplete enforcement. Consequently, these protected areas may fail to achieve their intended goal. We present and solve a spatial bio-economic model in which a manager chooses the optimal location, size, and enforcement level of a marine protected area (MPA). This manager acts as a Stackelberg leader, and her choices consider villagers’ best response to the MPA in a spatial Nash equilibrium of fishing site and effort decisions. Relevant to lower income country settings but general to other settings, we incorporate limited enforcement budgets, distance costs of traveling to fishing sites, and labor allocation to onshore wage opportunities. The optimal MPA varies markedly across alternative manager goals and budget sizes, but always induce changes in villagers’ decisions as a function of distance, dispersal, and wage. We consider MPA managers with ecological conservation goals and with economic goals, and identify the shortcomings of several common manager decision rules, including those focused on: (1) fishery outcomes rather than broader economic goals, (2) fish stocks at MPA sites rather than across the full marinescape, (3) absolute levels rather than additional values, and (4) costless enforcement. Our results demonstrate that such naïve or overly narrow decision rules can lead to inefficient MPA designs that miss economic and conservation opportunities

A systematic review of drivers and constraints on agricultural expansion in sub-Saharan Africa

Understanding the dynamics of agricultural expansion, their drivers, and interactions is critical for biodiversity conservation, ecosystem-services provision, and the future sustainability of agricultural development in Sub-Saharan Africa (SSA). However, there is limited understanding of the drivers of agricultural expansion. A systematic review of the drivers of agricultural expansion was conducted from 1970 to 2020 using Web of Science, Elsevier Scopus and Google Scholar. Two researchers reviewed the papers separately based on inclusion and exclusion criteria. Fifteen papers were included in the final systematic review. The paper proposed expansion pathways in a conceptual framework and identified proximate and underlying drivers. Population dynamics and government policies were found to be key underlying drivers of agricultural expansion. The proximate drivers include economic opportunities such as agriculture mechanisation and cash crops production, and more troubling trends such as soil fertility decline and climate change and variability. This paper further explores the constraints that have been found to slow down agricultural expansion, including strong land institutions and good governance

Editorial: Economics of the Environment in the Shadow of Coronavirus

This is the author accepted manuscript. The final version is available from Springer via the DOI in this recor

Weed management implications of introducing dry-seeding of rice in the Barind Tract of Bangladesh

A single crop of transplanted rainfed rice each year provides a major component of livelihoods for farm families in the Barind Tract of Bangladesh. Variable rainfall, frequent drought during grain filling and limited irrigation constrain intensification of the cropping system in this region. Dry seeding allows earlier rice establishment, reduces the impact of late drought and allows timely planting of a subsequent chickpea crop to exploit residual soil moisture. Although the potential of this modified cropping system has been demonstrated in research trials, early season weed growth, which is suppressed by puddling and partially controlled by flooding in transplanted rice, remains a major constraint to farmer adoption. On-farm studies indicated that yield gap between production of transplanted rice under farmer management and the potential yield under weed free conditions in three villages in Rajshahi averaged from 0.29 to 0.47 t/ha, with 34% of farmers losing over 0.5 t/ha. Labour availability constrains timeliness of first weeding in this system. A range of weed management practices, including the integration of a pre-emergence herbicide with inter-row weeding with a hand-pushed weeder, resulted in similar yields of direct seeded rice to hand weeding. The use of these labour saving practices in relation to the potential adoption of dry seeding, maintaining rice yield and increasing the productivity of the cropping system is discussed

Harvesting a remote renewable resource

Upmann T, Behringer S. Harvesting a remote renewable resource. Theoretical Ecology. 2020;13(4):459-480.**Abstract** In standard models of spatial harvesting, a resource is distributed over a continuous domain with an agent who may harvest everywhere all the time. For some cases though (e.g., fruits, mushrooms, algae), it is more realistic to assume that the resource is located at a fixed point within that domain so that an agent has to travel in order to be able to harvest. This creates a combined travelling–and–harvesting problem where slower travel implies a lower travelling cost and, due to a later arrival, a higher abundance of the resource at the beginning of the harvesting period; this, though, has to be traded off against less time left for harvesting, given a fixed planning horizon. Possible bounds on the controls render the problem even more intricate. We scrutinise this bioeconomic setting using a two-stage optimal control approach, and find that the agent economises on the travelling cost and thus avoids to arrive at the location of the resource too early. More specifically, the agent adjusts the travelling time so as to be able to harvest with maximum intensity at the beginning and the end of the harvesting period, but may also find it optimal to harvest at a sustainable level, where the harvesting and the growth rate of the stock coincide, in an intermediate time interval