san dimas experimental forest map

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San Dimas Experimental Forest

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Introduction

Established in 1933, the San Dimas Experimental Forest is the only such forest in southern California. It covers 6,945 ha in the front range of the San Gabriel Mountains, located about 50 km northeast of Los Angeles. Originally established as an outdoor hydrologic laboratory to document and quantify the water cycle in semi-arid steeplands, most of the facilities were constructed by the depression-era Civilian Conservation Corps and Work Projects Administration labor programs. San Dimas has a long history as a research site in the fields of hydrology and ecology and is recognized as a Biosphere Reserve by UNESCO's Man and the Biosphere program. San Dimas also contains the Fern Canyon Research Natural Area.

San Dimas experiences a Mediterranean-type climate, with cool wet winters and hot dry summers.

Soils are characterized by steep topography, semi-arid climate, and crystalline bedrock (Precambrian metamorphics and Mesozoic granitics), which produce shallow, azonal, coarse-textured soils with numerous rock outcrops and low fertility.

San Dimas is covered primarily with mixed chaparral brushfields but also includes areas of coastal sage scrub, oak woodland, and mixed conifers. Some areas were type-converted from native chaparral to grassland during the 1960s.

Long-Term Databases

Long-term databases include precipitation, streamflow, stream nitrate, temperature, relative humidity, and solar radiation. Also, since 1982 San Dimas has been an air quality monitoring site for the National Atmospheric Deposition Program/National Trends Network.

Research, Past and Present

Research has included watershed hydrology, chaparral ecology, water yield, precipitation monitoring, post-fire erosion control treatments, soil non-wetability, hillslope erosion and watershed sediment fluxes, soil nutrient cycling, and bird habitat use.

Major Research Accomplishments and Effects on Management

Major accomplishments and effects of research at San Dimas include the development of rain gauges and raingauge networks to accurately measure precipitation in steep terrain, the development of flumes to measure and withstand debris-laden flows, and the identification of post-fire soil non-wetability.

Collaborators

Collaborators include professors of hydrology, soil science, environmental science, ecology, biology, geography, and geology from University of California- Riverside, University of Georgia, University of Iowa, California Polytechnic University-Pomona, Pomona College, and California State University-Long Beach.

Research Opportunities

Research opportunities include a broad spectrum of studies in the general fields of watershed hydrology, ecology, biogeochemical cycling, and fire effects.

Facilities at the Tanbark Flat community near San Dimas include a laboratory/office, residences, a mess hall/ conference room, and several storage/utility buildings. Infrastructure includes water, electricity, propane heating, and phone service. Research/monitoring equipment includes rain gauges, stream gauges, debris dams, water-quality samplers, a weather station, and a historical lysimeter complex.

Lat. 34°12´ N, long. 117°45´ W

Contact Information

San Dimas Experimental Forest Manager USDA Forest Service Pacific Southwest Research Station 4955 Canyon Crest Drive Riverside, CA 92507 Tel: (951) 680-1538

Adams, Mary Beth; Loughry, Linda; Plaugher, Linda, comps. 2004. Experimental Forests and Ranges of the USDA Forest Service. Gen. Tech. Rep. NE-321. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 178 p.

1 Information has been updated since original publication.

A little-known treasure in our mountains: The San Dimas Experimental Forest

Look northward from the center of Claremont and the closest mountain you’ll see, just above the Claremont Hills Wilderness Park, is Sunset Ridge. This is the southern boundary of the San Dimas Experimental Forest, managed by the U.S. Forest Service. The SDEF covers 17,000 acres of rugged territory bounded on the north by Glendora Ridge Road, on the east by Sunset Ridge, above Mt. Baldy Road, and on the west by Little Dalton Canyon, above Glendora. Few Claremonters are aware of this place; fewer still have been there.

The SDEF is closed to the public except by prior arrangement for research or educational purposes. It was established in 1933 as a field laboratory for studies on chaparral and related ecosystems. It is called San Dimas after its main watershed, San Dimas Creek. Elevations range from 1,500 to 5,500 feet. Vegetation is typical of Southern California mountains: chaparral and coastal sage scrub in lower reaches, streamside woodland in the canyons, and conifers on higher ridges.

Recently I organized the second in a series of field trips to the SDEF for Claremont Colleges faculty and leaders of local civic groups. Those on both trips were impressed by its mainly unrealized potential for research and learning in a setting that is nearby but seems a world apart. Our Forest Service hosts are eager to cooperate with us.

This is a special place from the standpoint of scientific research. Because of its protected status and ruggedness, most of the SDEF has a relatively high degree of ecological integrity for an area next to a metropolitan region. And it is a laboratory for understanding and managing the “wildland-urban interface” in Mediterranean-type climates such as ours, including dealing with the extreme heat, wildfires, heavy rainstorms, and flooding expected to increase with climate change.

Another thing makes it special, really a treasure. The SDEF has extensive files going back over 80 years. These include results of studies carried out by government and academic researchers, as well as detailed records on weather, erosion, native and invasive plants, resident and migratory birdlife, air pollution, and behavior and effects of wildfire. Researchers can draw on this information, build on it, and contribute to long-term studies.

The SDEF’s current administrative situation offers challenges as well as opportunities. It has been included within the new 346,000-acre San Gabriel Mountains National Monument, which is superimposed on part of the 700,000-acre Angeles National Forest. This is probably not a good idea, because it implies that the SDEF could be opened to recreational use, something that shouldn’t happen. In addition, although it has always been within the boundaries of Angeles National Forest, the SDEF is managed not by the national forest, headquartered in Arcadia, but by the research arm of the U.S. Forest Service, specifically the Pacific Southwest Research Station based in Albany, in the San Francisco Bay Area.

Finally, the SDEF is a Biosphere Reserve. Biosphere Reserves are set up by governments of countries and recognized by UNESCO, the United Nations Educational, Scientific, and Cultural Organization. They are meant to be sites of excellence where innovative ways of managing natural resources and promoting sustainability can be tested and demonstrated, with results shared through a network that now includes 632 locations in 119 countries. (Biosphere Reserves shouldn’t be confused with World Heritage Sites, another UNESCO program that designates cultural or natural places for their “outstanding universal value.”)

The SDEF is one of 47 Biosphere Reserves in the United States. However, the U.S. program has been dormant since the late 1990s as the result of a well-organized campaign that promoted the nonsensical notion that the United Nations was using Biosphere Reserves to take control of public and private lands in the United States. I’m part of a group working with federal officials to revive the U.S. program. If this happens, as I expect it will, it will add to the SDEF’s value.

Right now, the SDEF gets limited use. Better ways are needed to make it available for college-level courses and research projects, as well as group visits for high school students and the public. (A permit is needed to enter the SDEF and these are generally issued only for research and educational purposes. Contact information is listed at  www.fs.fed.us/psw/ef/san_dimas .)

Our mountains are part of Claremont’s heritage. We certainly need to protect natural areas within the city, including the Wilderness Park and the Bernard Field Station, but our concern should extend to places beyond the city limits, including the San Dimas Experimental Forest. Decisions are being made that will affect them for many years to come.

Demystifying Sustainability is an initiative of Sustainable Claremont ( sustainableclaremont.org ).

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The San Dimas experimental forest: 50 years of research

Authors:	, , Wade G. II.Wells, Mark A Poth, , Charles G. Colver
Year:	1988
Type:	General Technical Report
Station:	Pacific Southwest Research Station
DOI:
Source:	General Technical Report PSW-104. Berkeley, CA: U.S. Department of Agriculture, Pacific Southwest Forest and Range Experiment Station. 49 p

Michael Kauffmann

Educator • Author • Ecologist

San Dimas Experimental Forest

Bigcone douglas-fir ( pseudotsuga macrocarpa ) in the san gabriel mountain national monument  —  part one.

I have always wanted to visit the San Dimas Experimental Forest and as part of a mapping and monitoring project for bigcone Douglas-fir, I finally had the opportunity. The “forest” descriptor in the area’s title is a bit misleading, as the majority of the vegetation is chaparral–but there are trees and it was our mission to find them (or at least what remains). Six major fires have been documented here since 1914, with the most recent occurring about 10 years ago. These fire events, along with climate change, are rapidly reshaping the remaining stands of trees. What follows is a photographic journey into the front range foothills of the eastern San Gabriel Mountains.

Fern Canyon Research Natural Area  – San Dimas Experimental Forest

From the RNA Report:

Low-Elevation Ponderosa Pine : Brown’s Flat, a shallow 80-acre (32-ha) bowl created by an ancient land slump, contains the lowest elevation stand of Pinus ponderosa in S. California (about 3900 ft, 1189 m). This relictual stand of 81 individuals is well-isolated from other ponderosa pine stands in the San Gabriel Mountains and strongly affected by air pollution. There is almost no recent reproduction.

We counted 27 individuals in September 2015.

Bigcone Douglas-fir : The stands of bigcone Douglas-fir at Fern Canyon have burned recently (1975). Poor reproduction suggests that the fire had a negative effect on seedling and sapling establishment. However, many of the larger trees, although scarred, survived the fire. The local stands should provide interesting comparisons with other stands in Millard Canyon and Falls Canyon RNAs, which have not been affected by fire for many years.

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12 replies to “san dimas experimental forest”.

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Hello, I am a enviornmental science major studying at Chaffey College. Is there any way I can help with this problem?

Aaron- Great question, but difficult to answer. First, I’m assuming your are asking about the Brown’s Flat ponderosa pines…I think the best approach is to get in touch with the Angeles National Forest botanist and encourage initiating a project that maps the remaining trees. We will then, at least, have a baseline moving forward.

Thank you. I just moved to San Dimas and just learned of the Expoerimental Forest. Currently I attempting to grow Live Oak from accorns i gathered from Walnut Creek. I hope we can do the same with Ponderosa and the Bigcone if they ever produce again. Is air polition and intense fires the main reason for their sterilization?

I am exploring the planting of the Big Cone Spruce/Douglas Fir macrocarpa on our property east of Clovis CA at about 3800Ft elevation. As you might know the Ponderosa Pine has been almost wiped out by the bark beetle. My friend that is the forester for Southern Ca. Edison has suggested using this tree for replanting, mixing it with pine and cedar. From the description of soil and other requirements the macrocarpa might grow perfectly, sheltered among the live and black oaks. The question is where is a source for purchase. I thank you in advance for your ideas and assistance.

Stanley- Sounds like a great idea! This is the time of year when the cones should be almost ready to drop seeds, so you might just want to go harvest some and put them in the ground before the rains come. Another idea is to use this resource: http://www.cnps.org/cnps/grownative/where_to_buy.php

Judging from the photos, I have a hard time believing the loss of trees is caused by air pollution. Air pollution has consistently improved in the LA basin for 60+ years. Has anyone looked closer at the bark beetle scenario? Any further info on this study?

Adam- That report was from 1971 and, to my knowledge, no one has looked at Brown’s Flat since because the area is more or less surrounded by impenetrable chaparral. My guess is you are right, decline is not as much attributable to pollution – instead aridification is the most likely culprit.

I find this fascinating.I am an Arborist specializing in bark beetles and can bushwack my way to Browns flat. Let me know how we can get an expedition going to research this unique microclimate and figure out what is causing the decline in this stand of Ponderosas.

Glad to see a few pines still remain at Browns Flat. I hiked in there twice in the early 1960s. I think that decreases in precipitation and the secondary effects it causes are the main factors in the decline. BTW: It’s a hell of a hike in there from Baldy Village or up from Evey Canyon.

Steve – thanks for the comment. I fear this stand of trees is not going to be around much longer based on what is happening to the bigcone Douglas-fir nearby. I was pushing the forest service to set up some long term monitoring here in 2015 but that has not happened…

I’m hoping that this year is El Nino will give enough rain to sprout some of those pine cones on the ground in Browns flat. I plan on checking it out sometime in late spring I will keep you updated

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