Year of Award

2007

Document Type

Professional Paper

Degree Type

Master of Science (MS)

Degree Name

Resource Conservation (International Conservation and Development)

Department or School/College

College of Forestry and Conservation

Committee Chair

Stephen Siebert

Commitee Members

Dan Spencer, Don Bedunah

Keywords

Colorado River Delta, habitat revegetation, Populus fremontii, Prosopis glandulosa, Prosopis pubescens, riparian restoration, Salix goodingii

Abstract

Sweeping changes across the Colorado River watershed in the 20th century resulted in near-complete collapse of the natural communities in the Colorado River Delta (CRD) in Mexico. A brief return of freshwater flows in the 1980s and 1990s showed the riparian corridor remains resilient to past damage, and the CRD remains a vital area for habitat conservation and restoration. This project aimed to test conclusions drawn from similar projects in the United States and show that revegetation projects are possible along the lower Colorado River in Mexico. From November 2006 to October 2007, we tested the effects of various treatments on the first-year growth and survival of irrigated mesquite seedlings (Prosopis glandulosa and P. pubescens) and rooted cuttings of cottonwood and willow (Populus fremontii and Salix goodingii). Mean first-year growth of seedlings planted from 2.8-L pots was comparable between fall-planted honey mesquite and spring-planted honey mesquite. Fall-planted screwbean mesquite were affected by a larval infection and grew far less than spring-planted screwbean mesquite. Slow-release fertilizer had no effect on mesquite seedlings planted in the fall. Seedlings planted in the spring from 2.8-L pots and 12-cm plugs had similar first-year growth for both mesquite species. Rooted cuttings of cottonwoods grew taller on average than cuttings of willow trees in the first growing season, and each species performed better from 2.8-L pots than 12-cm plugs. Within the time windows we tested, potting date and planting date did not measurably influence ending height for rooted cuttings. Survival was encouragingly high throughout this first season for mesquite seedlings as well as rooted cuttings, and the plantings ended the first growing season in good condition. Additionally, we ran pilot studies to test factors affecting the growth of cottonwood and willow pole plantings, the effect of watering regime on mesquite seedlings, and nursery preparation on the growth of mesquite seedlings. These tests were inconclusive, but I discuss the preliminary results. Our results support and expand upon many of the conclusions of similar restoration projects undertaken in the United States, and demonstrate that areas within the Colorado River riparian corridor in Mexico are suitable for habitat improvement.

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© Copyright 2007 Stephen Dwight Handler