Juniper (Juniperus spp.) encroachment in grasslands usually progresses toward a stable woody state of mature trees that requires a significant disturbance to shift succession in another direction. Fire alone is often inadequate to shift succession in dense stands of mature juniper and must be preceded by a mechanical treatment such as chaining to reduce juniper competition and increase herbaceous growth that fuels a subsequent fire. However, little long-term data are available that measure combined effects of mechanical and fire treatments on restoration of juniper-dominated grasslands. Here, on a degraded (40% bare ground) north Texas site dominated by redberry juniper (Juniperus pinchotii Sudw), we quantify long-term herbaceous responses to mechanical chaining followed by fire. Two types of chaining, ground-level and elevated, were evaluated and all chained plots were burned 4 years after chaining. Herbaceous and woody responses were measured for several years after both chaining and fire treatments and compared to untreated controls. At study termination, both of the chaining þ fire treatments reduced juniper cover from 32% to , 6%, but mortality was , 10%, because most plants basal-sprouted. Total grass production did not increase in chained treatments over the untreated until 3 growing seasons after chaining. Grass production declined the first growing season following the fire treatment, but increased in treated plots to 3 times the untreated the second and third year postfire. Total grass cover in treated plots did not increase over the untreated until the second year after the fire treatment. There was no difference in juniper or herbaceous responses between the 2 chain types. Results suggest increases in herbaceous production from chaining alone were due to increased growth of existing vegetation patches whereas the fire treatment appeared to stimulate herbaceous recruitment into bare soil areas.
ResumenLa invasió n de ''Juniper'' (Juniperus spp.) en los pastizales generalmente progresa hacia un estado estable de plantas leñ osas de árboles maduros que requieren de un disturbio significativo para desviar la sucesió n hacia otra direcció n. El fuego solo a menudo es inadecuado en poblaciones densas de ''Juniper'' maduros y debe ser precedido por un tratamiento mecánico, tal como el cadeneo, para reducir la competencia del ''Juniper'' e incrementar el crecimiento de las herbá ceas que servirá n de combustible para el fuego subsiguiente. Sin embargo, son pocos los datos de largo plazo disponibles que miden los efectos combinados de los tratamientos mecá nicos y fuego en la restauració n de pastizales dominados por ''Juniper''. Aquí, en un sito degradado (40% de suelo desnudo) del norte de Texas dominado por ''Redberry juniper'' (Juniperus pinchotii Sudw), cuantificamos la respuesta a largo plazo de las herbá ceas al cadeneo mecá nico seguido por fuego. Se evaluaron dos tipos de cadeneo, a nivel de suelo y elevado, y todas las parcelas cadeneadas fueron quemadas 4 añ os después del cadeneo. La respu...