Lawrence Walker

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Tropical storms are the principal cause of landslides in montane rainforests, such as the Luquillo Experimental Forest (LEF) of Puerto Rico. A storm in 2003 caused 30 new landslides in the LEF that we used to examine prior hypotheses that slope stability and organically enriched soils are prerequisites for plant colonization. We measured slope stability and(More)
Plants alter their environment in a number of ways. With correct management, plant communities can positively impact soil degradation processes such as surface erosion and shallow landslides. However, there are major gaps in our understanding of physical and ecological processes on hillslopes, and the application of research to restoration and engineering(More)
Landslides are excellent illustrations of the dynamic interplay of disturbance and succession. Restoration is difficult on landslide surfaces because of the high degree of spatial and temporal heterogeneity in soil stability and fertility. Principles derived from more than a century of study of ecological succession can guide efforts to reduce chronic(More)
There are potential operational and strategic benefits to implementing lecture-capture systems but the issues are much deeper than simply the question of which technology system to implement. This paper explores the lecturer and student perspectives by analysing survey data from a small scale time-terminated implementation. Results show that an automated(More)
Augmented Books show three-dimensional animated educational content and provide a means for students to interact with this content in an engaging learning experience. In this paper we present a framework for creating educational Augmented Reality (AR) books that overlay virtual content over real book pages. The framework features support for certain types(More)
Thermodynamic measurements of Fe(II) binding and activation of repressor function in the iron-dependent repressor from Mycobacterium tuberculosis (IdeR) are reported. IdeR, a member of the diphtheria toxin repressor family of proteins, regulates iron homeostasis and contributes to the virulence response in M. tuberculosis. Although iron is the physiological(More)
Tropical landslides are suitable locations to study short-term carbon (C) fluxes because of the rapid changes that occur for the first few years following initial disruption of the slope. Because of the high heterogeneity among landslide soils and plant re-colonization patterns, we measured C fluxes from 30 landslides in the Luquillo Experimental Forest in(More)
Landslides are a frequent disturbance in montane tropical rainforests that result in heterogeneous environments for plant and soil development. Natural inputs of organic matter and associated nutrients contribute to soil fertility patchiness within landslides. To test the importance of organic matter and nutrient addition to landslide soil fertility and(More)
Impoundments create unnatural shorelines that differ from lake shorelines in patterns of waterlevel fluctuations, flow, sediment transport, and shoreline vegetation dynamics. Shoreline plant communities of impoundments in the American Southwest often become dominated by mature, senescent Populus and Salix, with few if any seedlings. The failure of native(More)
Non-native species can alter patterns of species diversity at multiple spatial scales, but the processes that underlie multi-scale effects remain unclear. Here we show that non-native species reduce native diversity at multiple scales through simultaneous disruption of two processes of native community assembly: species immigration, which enhances alpha(More)