The Bennett Juniper is the largest known juniper tree in the United States. It is located in Section 5, Township 5 North, Range 20 east of the Mount Diablo meridian, on an inholding in the Stanislaus National Forest in Tuolumne County, California. The tree is owned by the Mother Lode Land Trust, a regional land trust organization.
Species
Originally the Bennett was considered to be a western juniper (Juniperus occidentalis). Over time the differences between the northern and southern populations of western junipers justified dividing them into two subspecies and the Bennett is in the southern population which was named Juniperus occidentalis australis. A field guide published by UC Press in 2001 gives the common name Mountain Juniper for the australis population. DNA studies (2006) by Adams resulted in the southern population being raised to species status and it was given the common name “grand juniper” (Juniperus grandis). This name and status are recognized in the USDA Plant Database.
Age
The age of the Bennett has been an enigma and the subject of several attempts to determine the age. As reported in Madroño, the tree was cored in the 1930s by Glock and he estimated the age as about 3,000 years old. The tree was cored again in 1989 by Peter Brown from the University of Arizona Tree Ring Lab at the request of the current owners of the Bennett, Save the Redwoods League. His estimate based on a short sample was the age was also almost 3,000 years. During this coring it was discovered that rotten wood was reached about into the tree and that the tree was also partially hollow. As a result there will never be a definitive result from a complete core sample.
The naturalist Clarence K. Bennett for whom the tree is named believed the tree to be over 6,000 years old. His conclusion was based upon extrapolations of measurements taken either from core samples or cross-sections of nearby trees. An example is a cross-section from a downed juniper about away which was in diameter and 800 years old. About away is the Scofield Juniper stump which is about in diameter and 2700 years old by ring count. A major issue with the extrapolation method is that the Bennett has some access to water in a drainage which is unusual in this area for junipers.
Size
The Bennett Juniper's height is feet with an average crown spread of . The diameter at breast height ( above ground) is . This gives it a total of 573 points by the American Forests formula for measuring "Big Trees", and by that measure the Bennett is the largest juniper of any type listed in the National Register of Big Trees.
Location
The Bennett Juniper grows on Sardine Meadow, an open area at elevation just off the top of a ridgeline. The site was heavily glaciated during the last ice age stripping the site of any previous soils. Current soils vary between and thick and are derived from the underlying volcanic bedrock. While sitting in a dry spot, the roots on one side of the tree can reach a seasonal drainage. The area is dominated by low-growing () sagebrush (Artemisia tridentata) and scattered lodgepole pine (Pinus contorta murrayana) and a few juniper. Because of fire suppression since the 1950s there are more sagebrush and young trees (both lodgepole and juniper) than would be historically normal for the preserve. Once the sagebrush established its dominance very few young trees have started since 1960. There are a number of junipers within several miles whose heights, but not other dimensions, rival the Bennett. In each case they are growing on glacial till or, more commonly, a glacial moraine with much deeper soil and water availability.
Human history
The Native Americans certainly visited this area in the summer time, though no specific history regarding the tree is known. Within a half mile (.8 km) of the preserve are five locations with bedrock mortars and several spots where obsidian (often used for tools) was worked. The earliest known sighting, probably in the 1920s, of the Bennett was by Basque sheepherders who described a huge juniper to their employer, Ed Burgson, a local Tuolumne County sheep rancher. The naturalist Clarence Bennett, who had traveled throughout the Sierra studying junipers, connected with Burgson a few years later. This was the largest specimen that Bennett had ever seen. Bennett became a champion of getting the tree studied and protected. By the 1950s the Forest Service had named the tree after Bennett.