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Se prevé que el cambio climático global va a generar altos impactos en la precipitación pluvial en el Sur de México. Habrá cambios en la cantidad y en la distribución de las lluvias en el tiempo, lo cual puede tener un efecto en la viabilidad de los sistemas agrícolas de temporal, particular- mente en regiones marginales. Las comunidades campesinas en México poseen, por un lado, un acervo importante en cuanto a la agro-diversidad y al conocimiento indígena sobre el manejo del ambiente y la conservación de los recursos naturales; por el otro lado, registran experiencias de prácticas y tecnologías alternativas y novedosas que han sido adoptadas y adaptadas a lo largo de los años. Para poder evaluar la sustentabilidad, la resiliencia y adaptabilidad de estos sistemas en estas regiones del país se hicieron recorridos de campo y talleres participativos en la Comuni- dad de San Miguel Huautla en la Mixteca Alta Oaxaqueña, además de entrevistas a profundidad y muestreo en parcelas agrícolas en 10 unidades familiares. Se evaluaron en concreto los sistemas agrícolas frecuentemente practicados que son el cajete y el temporal. Los dos sistemas han sido históricamente complementarios en un contexto de alta agro-diversidad, pero el cajete se ha ido abandonando en estas últimas décadas. Se hizo una caracterización del paisaje de comunidad y de los sistemas productivos. Se demostraron: (a) los beneficios en las propiedades del suelo y la productividad del maíz obtenidos a través de la intensiva preparación del suelo que implica la práctica indígena del cajeteo; (b) que las unidades familiares con alta agro-diversidad, que practi- can el Cajete (C) y el temporal (T),cubren prácticamente el 80% de las necesidades alimentarias y de insumos, pero cuando abandonan el cajete la capacidad productiva y la resiliencia disminuyen drásticamente. Es imperativo mejorar e innovar el cajete para poder conservar sus beneficios y aumentar la eficiencia de la mano de obra invertida. Summary: It is predicted that global climate change will greatly impact precipitation in Southern Mexico. There will be changes in the quantity and distribution of rainfall in time, which may affect the viability of rainfed agricultural systems, particularly in marginal regions. Farming communities in Mexico posses, on one hand, important reserves of biodiversity and indigenous knowledge about environmental management and the conservation of natural resources. On the other hand, they have a long history of adopting alternative and innovative agricultural practices over the years. To evaluate the sustainability, resilience, and adaptability of farming systems in this region, field visits and participatory workshops were conducted in the territory of San Miguel Huautla in the Mixteca Alta Oaxaqueña. In addition, in-depth interviews and soil samples were made in 10 fam- ily units. We evaluated the common cultural practices associated with the cajete (C) and temporal (T) production systems. From a historical perspective, the two systems were complementary in the sense of high agricultural biodiversity, but the cajetesystem has undergone a process of abandonment in the last decades. Some families now only practice the temporal system. We also characterized the landscape characteristics of the community. Our analysis demonstrated (a) the benefits to soil property characteristics and productivity of maize obtained through an intensive preparation of the soil using indigenous practices; (b) that family units that maintain high levels of agricultural biodiversity through the practice of both cajeteand temporal systems meet practi- cally 80% of their needs for food and agricultural inputs, however when they abandon cajetethey suffer a dramatic loss in productive capacity and resilience. It is imperative to support the process of farmer-led innovations in the cajete system to increase its benefits and to increase its labor efficiency.

In 1991 Napa County adopted an erosion control ordinance that regulates alterations of landscapes with slopes greater than 5%. The objectives of the Hillside Ordinance are to reduce erosion from hillsides into streams and improve water quality. Vineyard development and management are regulated by this ordinance. Little research has directly addressed the effectiveness of erosion control strategies as recommended by the Hillside Ordinance. The Napa Conservation District (RCD) initiated the first monitoring that will compare management techniques for erosion control. They are recording suspended sediment concentrations (SSC) flowing from two vineyard plots under different management. The RCD will conduct further data analysis in May of 2004. Another study conducted by Lutrick (2000), a student in landscape Architecture 222, focused on the impacts of vineyard development to a stream in Napa. After the plots were cleared Lutrick (2000) conducted basic stream surveys and pebble counts pre and post rains. She chose an adjacent watershed as an analogous control. Her findings indicate that the grain size of the stream changed similarly to the control. In both streams, grain size decreased after one winter (Lutrick 2000). Lutrick (2000) concluded that the development had no significant measured effects on the test stream. In spring 2004 I resurveyed the streams. My objective was to analyze more longterm changes that might have occurred to Lutrick’s (2000) study sites. My findings indicate that the pebble size D50 for cumulative percent finer in both streams seems to be decreasing. Increased sedimentation in both streams may be due to upstream human activity or natural phenomena.

Local seed systems remain the fundamental source of seeds for many crops in developing countries. Climate resilience for small holder farmers continues to depend largely on locally available seeds of traditional crop varieties. High rainfall events can have as significant an impact on crop production as increased temperatures and drought. This article analyzes the dynamics of maize diversity over 3 years in a farming community of Yucatán state, Mexico, where elevated levels of precipitation forced farmers in 2012 to reduce maize diversity in their plots. We study how farmers maintained their agroecosystem resilience through seed networks, examining the drivers influencing maize diversity and seed provisioning in the year preceding and following the 2012 climatic disturbance (2011–2013). We found that, under these challenging circumstances, farmers focused their efforts on their most reliable landraces, disregarding hybrids. We show that farmers were able to recover and restore the diversity usually cultivated in the community in the year following the critical climate event. The maize dynamic assessed in this study demonstrates the importance of community level conservation of crop diversity. Understanding farmer management strategies of agrobiodiversity, especially during a challenging climatic period, is necessary to promote a more tailored response to climate change in traditional farming systems.