Riparian management affects instream habitat condition in a dairy stream catchment

Using a space-for-time substitution design, we investigated the response of structural instream habitat and fish populations to different riparian management practices throughout a Dairy Best Practice Catchment. We found a significant negative correlation between the upstream area of stock exclusion fencing and deposited instream fine sediment cover. Furthermore, we determined that this relationship emerges when ≥300?m lengths of upstream riparian area were included in the analysis, indicating the scale at which stock exclusion fencing results in a positive instream habitat response. Specifically, for this historically degraded spring-fed stream, our findings indicate that riparian segments with 5 m wide stock exclusion fences (both banks) are required to achieve instream fine sediment cover below 20% in downstream reaches. Fish were sparse and evenly spread throughout the catchment. Fish distributions were not correlated with reach-scale riparian or instream habitat variables, possibly because the available habitat quality gradient was too narrow.     

Large-scale features of Africa’s diurnal climate

This study explores the structure and modulation of the mean diurnal climate of Africa with a focus on satellite rainfall. Solar heating over tropical mountains and land-sea temperature gradients initiate moisture convergence in the afternoon-evening. The diurnal temperature range is from 5 °C along the coast to 20 °C in arid zones with low vegetation fraction. NCEP2 reanalysis reveals the diurnal circulation via continental-scale drainage and seabreeze flows. Factors modulating the diurnal cycle vary across four sub-regions: South Africa, East Congo, Ethiopia, and Guinea. In the Congo and Guinea coast the surface moisture and heat fluxes are important, while in South Africa convective available potential energy and vertical motion are influential. Ethiopia’s evening orographic convection is out of phase with surface fluxes. The diurnal residual calculated from NCEP2 fields exhibits a 2 km depth for thermal gradients and 200 km inland penetration of onshore flow by evening.     

Inserting scales of urban politics: the possibilities of meso-urban governance shims

This article explores the geographic literature on governance at smaller-than-urban but larger-than-household scales, identifying a relative inattention to neighborhood and other partial-city scales of governance. Hegemonic power relationships are institutionalized at particular scales of state government (e.g. national, regional, municipal) and state-sanctioned governing units (e.g. jurisdictional districts or supranational bodies), which in turn shapes urban research. We propose a new analytical term, governance shims, to describe the insertion of new scales of governance between those already reified and reproduced; institutions at such scales may be unusually grounded in authority beyond the state. Geographers seem well positioned to explore the characteristics of governance shims at the meso-urban scale. We illustrate this by briefly tracing how common interest communities (CICs), housing cooperatives, and community land trusts (CLTs) might be analyzed through a shims approach. Provocatively, emergent governance at the meso-urban scale often leverages idiosyncratic structures of property ownership to produce institutional authority.