Plant Succession on the Sand Dunes of the Monterey Peninsula, California

Abstract

The sequence of successional stages occurring on the sand dunes along the western edge of the Monterey Peninsula was inferred through an evaluation of total plant cover, plant height, cover of dominiant plant species and the age structure of stands when trees were present. The degree of soil development was determined beneath each successional stage by measurement of particle size distribution, organic carbon, water-holding capacity, cation exchange capacity, and pH. The sequence identified was supported by the soil analyses which demonstrated a close correlation between plant succession and soil development. Sand dune succession has been studied and reported by many ecologists. Warming (1891) was the first to describe and explain effectively the successional processes responsible for species replacement on dunes in northern Europe and this pioneer effort still serves as a model for such studies. Cowles (1899) published his now classical study of plant succession on dunes bordering Lake Michigan, and Harshberger (1900, 1902) published descriptions of dune succession along the New Jersey coast. All of these studies reported that dune development adjacent to large bodies of water depended on various beach grasses that were able to trap the moving sand and stabilize it by forming a tough, strongly rooted sod. They also reported that these stabilizing grasses were generally invaded by shrubs which in turn were invaded and replaced by trees. One important characteristic of these successional sequences was an increase in plant stature and cover in each succeeding stage. Sand dunes have also served as a focal point for basic studies dealing with soil formation as well as plant succession. Salisbury (1925) measured changes in pH, carbonates and organic matter throughout the Southport dune system in England. Olson (1958) measured changes in these as well as in several other soil characteristics on the Lake Michigan dunes on which Cowles had earlier traced the path of plant succession. Both Salisbury and Olson reported a progressive leaching of carbonates accompanied by an increase in acidity and a progressive increase in organic matter as the dune increased in age and as plant succession progressed through a characteristic sequence of species replacements. The processes of plant succession and soil formation on dunes along the California coast have been referred to by several investigators. Couch (1914) described plant succession at Manhattan Beach, Los Angeles Co. He reported that Gaertneria bipennatifida and Abronia umbellata were the most important pioneer species on the dunes. These succulent species were replaced by a low shrub cover dominated