Native Species Establishment on 

 an Oil Drill Pad Site in the Uintah 

 Mountains, Utah: Effects of 

 Introduced Grass Density and 

 Fertilizer 



Jeanne C. Chambers 



INTRODUCTION 



Native species are widely used in mined land reclama- 

 tion to meet legal requirements. The Surface Mining 

 Control and Reclamation Act (SMCRA) of 1977 requires 

 the use of native species for coal mine revegetation unless 

 introduced species are specifically approved by the regula- 

 tory authority. Individual State regulations for coal min- 

 ing operations must equal or exceed those of SMCRA. 

 Noncoal mining is governed solely by the States, and 

 large differences exist in the regulations. In Utah the 

 regulations for noncoal mines or other disturbances have 

 no requirements for native species. 



Ecologically, native species have many desirable attrib- 

 utes for disturbed land reclamation. In extreme environ- 

 ments such as harsh climates and toxic spoils, natives 

 may be the only species capable of surviving and repro- 

 ducing. Including native species in seeding mixtures can 

 enhance species diversity and may accelerate successional 

 processes. Diversity has been correlated with long-term 

 stability and productivity (Root 1973; Tahvanainen and 

 Root 1972), and ecosystems with several types of species 

 are more likely to persist following natural disturbances 

 such as grazing and fire (Harper 1977; McNaughton 1977; 

 Mellinger and McNaughton 1975). In addition, vegetation 

 diversity is frequently correlated with the diversity of 

 animal species (Southwood and others 1979). 



Knowledge of the establishment characteristics of na- 

 tive species is essential for the successful reclamation of 

 disturbed land with these species. When native species 

 are included in a seeding mixture, they are often sown 

 with rapidly growing introduced species. Studies that 

 have examined the interactions between natives and 

 introduced species indicate that seeding density, species 

 composition of the seeding mixture, and rate and fre- 

 quency of fertilization affect native species establishment 

 and ultimate stand composition (Brown and others 1984; 

 DePuit and Coenenberg 1979). 



Introduced and cultivated species frequently have 

 higher growth rates, lower root to plant ratios, and higher 

 nutrient uptake efficiency than native species (Chapin 

 1980). Given the proper growing conditions, these species 

 exhibit highly positive growth responses to N and P fer- 

 tilization (Aldon and others 1976; DePuit and others 

 1978; Hanson and others 1976; Hodder and others 1972; 



Houston and Hyder 1975). At high rates of fertilization 

 species that exhibit the greatest growth response, fre- 

 quently annuals and introduced grasses, tend to outcom- 

 pete slower growing natives (Berg 1980; DePuit and Coe- 

 nenberg 1979). In addition, N-fixing legumes often show 

 a negative response to high levels of N fertilization when 

 growing in mixtures with grasses (DePuit and 

 Coenenberg 1979). The frequency of fertilization also 

 affects individual species' responses and, ultimately, 

 stand composition (Brown and others 1984). Repeated 

 fertilizer application can stimulate introduced species 

 production over long periods. Native species development 

 in stands that include introduced species is often greatest 

 under no and first-year fertilization. 



This study addressed the question: What effects do 

 seeding density of introduced grasses and fertilization 

 have on establishment and growth of native grasses, 

 forbs, and shrubs? I tested three null hypotheses: (1) 

 increasing density of introduced grasses would not lower 

 establishment and growth of native grasses, forbs, and 

 shrubs; (2) fertilization would not have a larger positive 

 effect on the establishment and growth of introduced 

 grasses than on the establishment and growth of native 

 species; and (3) fertilization would not compound the 

 negative effects of increasing introduced grass density on 

 the establishment and growth of native species. I then 

 related the findings of this study to possible reclamation 

 strategies for this and similar sites. 



METHODS 



The study site is in the northeastern corner of Utah on 

 the north slope of the Uintah Mountains (S24, T3N, 

 R14E) at approximately 2,743 m. The site is in a small 

 basin, 1.2 to 1.6 ha, that was used as an oil drilling pad 

 site by Phillips Oil Company. The company recontoured 

 the basin leaving two sloping faces on the southern end, a 

 large mound on the east, and a small pond on the north. 

 The study plots are in the center of the basin on homoge- 

 neous (5 percent slope) terrain. 



The soil on the site is a well-drained sandy loam de- 

 rived from quartzite and sandstone. Average annual 

 precipitation is about 64 cm with April and May the wet- 

 test months and precipitation fairly evenly distributed 



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