Plant interactions in redberry juniper-mixed communities

Date

1987-08

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Publisher

Texas Tech University

Abstract

Relationships between species in redberry juniper (Juniperus pinchotii)-mixed grass communities were studied. Investigations focused on 1) factors affecting reproductive maturity of juniper plants, 2) factors affecting establishment and invasion of juniper, 3) effect of juniper canopy cover on forage yield, 4) factors affecting survival and re-growth following top-removal, and 5) economic feasibility of control methods. Maturity occurred earlier on a lowland site with deep soil than on an upland site with shallow soil. Maturity was more highly correlated with juniper height than with other tree characteristics. Herbaceous vegetative cover was negatively correlated with maturity. Juniper seedling density was higher on a grazed upland site than ungrazed upland or grazed lowland sites. Honey mesquite (Prosopis qlandulosa) facilitated juniper establishment on upland sites. Forage production decreased with increasing juniper cover in years with below average, average, and above average growing-season precipitation. The relationship between juniper cover and grass yield was logarithmic on the grazed upland site and linear on the ungrazed upland site. Survival and subsequent re-growth of harvested trees were strongly influenced by pre-harvest juniper height. Increased herbaceous vegetation did not reduce survival or re-growth of harvested juniper plants. Competition from neighboring shrubs explained little variation in survival or re-growth. Economic feasibility of brush control was determined largely by calf prices. Optimal treatment regime for the grazed upland site was chaining at year 0 followed by burning every 20 years.

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