Southern California: Engineering an Urban Landscape patterned after the blueprint found in Nature

Some interesting facts about Laurel Sumac and it's ability as an ideal nurse plant which utilizes Hydraulic Lift & Redistribution of sub-soil water which facilitated this Torrey Pine to thrive

I've written previously about this specific location in El Cajon California on the famous Rattlesnake Mountain regarding the Torrey Pines planted there over 30+ years ago and the emotional response by many folks over the irresponsible actions by Sky Ranch Housing  residents who cut them down with chainsaws and the blind eye stance by Center for Natural Lands Management to what took place even though the conservation area has a plethora of threatening signage around this mountain about the consequences of trepass into this conservation area (I would presume this also means Sky Ranch residents). I did contact someone at the CNLM (Ecologist Markus Spiegelberg), but he said there was nothing they could do. He claimed he never saw the trees, which wasn't true because he did initial plant inventory and did notice the San Diego Coastal Cholla Colony which I also established 30 + years ago along with one Saguaro I had and didn't know what t do with because my father did not want it in his yard. Yet Markus found it's presence way back when interating. The 30' tall Torrey Pines were all next to this colony, so he new, plus he said they did not belong there anyway. They were non-native. The irony is the restoration work of all Coastal Sage Scrub habitat ruined by Sky Ranch construction which he over saw contains non-natives like Mediterranean Rockrose, etc. However this post isn't about them or the negative actions they undertook. This is for people who wish to understand why these trees succeeded in such an inhospitable environment for trees where failure should have been the norm. The practical applications I used so many years ago which were inspired of biomimicry (strictly replicating how Nature works) is even more important now in view of the major declines of Torrey Pines at their native habitat in La Jolla and Del Mar along the coast which I just now wrote about in this link below.

Earth's Internet: "Major decline in Torrey Pines & SoCal Forests in general"

My photograph from 2011

This Torrey Pine tree above was one of many planted during the winter rainy season of 1980/81 after a wildfire had raged all across the Rattlesnake Mountain range between the cities of El Cajon, Santee and Lakeside that previous hot summer of 1980. I had planted other Torrey Pines during the 1977, but the wildfire of 1980 consumed all of them. It was in the middle 1970s when I was taking Ornamental Horticulture that some research was just coming out about the idea of nature having some plants which acted as nurse plants for tree seedlings. That intrigued me and my first experiments with testing for the best nurse plants were with California Buckwheat shrubs. While they worked okay, many plants failed after a couple of years and I eventually settled on Laurel Sumac which I found far more successful. I eventually chose the location I did because it was remote and rarely had visitors. It was on the direct south facing slopes of Rattlesnake Mountain towards direct sunlight. Not exactly an ideal location for trees in the dry west. Very little trails or reasons for people to hike around there. The tree in the photo above was over 25' in height when this photo was taken in 2011. It grew slowly at first, then started shooting up more as it matured. Under more ideal conditions it would be almost double that height like my 4 Torrey Pines I planted at my home in Anza California at elevation 4,500' (Table Mountain) back in 1986. Those trees are about 50', but the San Jacinto Mountains also get far more measurable rainfall per year compared to the interior hot valleys east of San Diego. An important part of that rain also comes in the form of Summer monsoonal thunderstorms from Mexico, something El Cajon never sees. This tree below is the smallest of the two Torrey Pines mainly because it became overwhelmed by it's nurse plant's foliage until it much later found a way out from the Laural Sumac's canopy. Hence you can see the crocked picturesque angle it had to take much like the Torrey Pines along the Sea cliffs. 

Photo is mine from 2011

Image - AZ Plant Lady

Again this photo above is the smaller of the Torrey Pine which like the larger one was planted within the influence of a large Laurel Sumac chaparral shrub, but at time of planting after wildfire was burnt to the ground. The shrub resprouted and grew rapidly. Eventually enveloping both trees, but the upper tree had managed to have it's central leader always protruding through the Laurel Sumac's canopy. While this lower tree's foliage struggled with not only the larger Sumac's foliage, but also from competition from another Laurel Sumac on the other  side as there was a second shrub. I watered them once a week during the first Summer by carrying milk jugs full of water, three in each hand. It was tough going and generally 100+ Fahrenheit in summer. Later I switched to very early mornings or evenings after sunset, but still light outside. I had to also be careful so as not to drawn any suspicion from neighbours. And of course you know the reason why. My method of using the milk jugs was not like the one in the picture above, but rather I would turn them upside down partially burried and water would percolate slowly straight down into the soil directly next to the seedling. But after a year, this method was no longer needed.

Photo is mine from 

The following two years after that first hot summer the trees were doing excellent under their nurse chaparral shrubs (Laurel Sumacs and California Buckwheat), but something more was needed because I was not going to pack mule water up that mountainside forever which would force the seedlings to remain on life-support. Eventually they had to mature and stand on their own in the wild. For about eight good years the trees grwe slowly, but remained healthy. Something more was needed and again there was newer research coming out in some Ag & Forestry Journals about numerous symbiotic fungi which lived on plant roots and kept their hosts alive in the wild. 

(Research was tougher come by back in the 1970s as access was limited to conventional brick & Mortar libraries, school textbook references and subscriptions to journals. Today we have the internet which provides mountains of research on how nature works. And yet amazingly biomimicry still doesn't represent mainstream science.

Human understanding of plant ecosystem mechanisms in the wild was improving in the late 70s - early 80s. I found the research of US Forest Service Biologist, Dr Donald Marx (former senior scientist for PHC), who was studying which was the best species of ectomycorrhzal fungi that would benefit new pine and oak seedlings for survival. His conclusion was Pisolithus tinctorius like the one I collected here in the photo above from the San Diego County backcountry just south of the gold mining town of Julian. So I figured why not. The dried puffball truffles which looked like dog turds had the dark brown powdery substance (spores) I needed to make this work. So almost a decade after planting in 1980, I dug small three inch deep holes (about four) around all sides of the Torrey Pine seedlings with my finger and drop in some of the chocolate coloured spore powder into the holes, then back fill it in with soil and watered. I made about a dozen holes and inoculation points far enough away from the tree trunks where I thought the root hair feeder roots would be. It was crude in comparision to what I use now because many of the commercially prepared mixes today come with root growth stimulators like humic acid, etc. These are important because they encourage new root hair growth which is necessary for the fungi to begin to colonize. The fungi will only colonize the root hair tips or cap when it comes into contact with the spore. I worked quickly because in 1982 I was moving to Idyllwild California up in the San Jacinto Mountains. Take note below of the benefits of fungi and plant root interactions.

You can see clearly the colonized roots on the pine seeding at right. The image on the left has been digitally altered to remove the fungal web so that the actual pine seedling root system are exposed. As you can see, pines without fungal colonization are at a huge disadvantage from a water distribution area point of view. Frankly it was still some years later that I became more familiar with the value in nutrient uptake as well. For me, access to water was the more important factor at that time. It wasn't till the middle 1990s I found out that this particular fungi increases both water and nutrient absorption from 200% to 800%. Some of the central leader stems on the trees were now growing more than a foot high in a season and producing next years leader with numerous branch buds six more inches in length. That explained to me even further why I always had success with pines and oaks on my acreage up in Anza, California, when I mostly attributed the healthy vigorous growth to better access to more water availability because of higher geographical rainfall totals. This particular fungi is an ectomycorrhizal fungi symbiotic companion which generally prefers trees, but the nurse shrubs I used in El Cajon were endomycorrhizal. So no real connective interactions between pines and shrub. However, the PT mycorrhizae will travel underground 200' away from it's host looking for water and nutrients, so any water acquired by the nurse plant shrub from deeper sub-soil will be released in the top surface layers of soil and picked up be the ecto-fungi. More on that function and phenomena we call hydraulic lift below.

A Perfectly Natural Phenomena of Older Needle Drop in Evergreens like Pines

Image - affordabletrees.com

Photo: Ladd Livingston,
Idaho Department of Lands, Bugwood.org

Some people become alarmed when they see yellow dead and dying needles within their urban landscape pines or other evergreens. No worries, if the older, interior needles of your evergreen pine trees or even shrubs are yellowing and dropping, rest assured it is probably not a disease or an insect infestation. It is the normal fall needle drop, sometimes referred to as seasonal needle drop. All conifers loose at least some of their needles every year. Most conifers (Pines) will retain needles through several growing seasons as indicated by the branch whorls which count as a years growth in a season. But think of the foliage of a Pine tree or any other tree or shrub as a living biological manufacturing plant. They will shed and remove any of their older, less efficient needles each fall. Generally these are the oldest needles from past years. Prior to shedding these needles they will change color from their healthy green to yellow, orange and brownish-red like both photos above and to the right. Early in the shedding process, while the needles are still attached to the branches, these trees may appear to have an unhealthy appearance which can cause unnecessary concern. In urban landscapes people generally want everything to be perfect. Below is a beautiful illustrative graphic from Michigan State University which helps you to understand the process.

MSU Graphic

Take note in the graphic above, it indicates two and a half years growth is still going strong. However, about three and a quarter years growth is being shed. In some cases this could also be due to drier, maybe even drought conditions. Hence the elimination of older needles may help limit transpiration surface to help the tree survive.

References on Dead or Dying seasonal Pine Needle Drop

http://msue.anr.msu.edu/news/dying_and_falling_needles_on_evergreens_is_a_natural_process_in_the_fall

http://byf.unl.edu/natural-needle-drop

http://msue.anr.msu.edu/news/fall_needle_drop_a_natural_phenomenon_in_conifers

https://www.thespruce.com/fall-needle-drop-1403324

Why the ability of Pine Trees to hold many growth years of their needles is important

My last photograph taken 2013
 Tree was diliberately destroyed the following year 2014

Colorado State University

One of the more remarkable things I noticed when I took this last photo in 2014 of the largest Torrey Pine on Rattlesnake Mountain in El Cajon, California, was the fact that the tree was still carrying all it's needles on every branch and the central leader on all it's growth whorls six years back. Same was true of the Torrey pine that was half this size. Keep in mind these trees were 30+ years old and survived only on the meager rainfall averages (many of which were drought years) within an interior environment where the temperatures soared to 100+ Fahrenheit which is common. The photo at right is of a drought stressed Ponderosa Pine which has all it's needles turned brown with the exception of that present year's growth. This is also often common scene in Southern California urban landscapes where much of the trees and shrubs are on some sort of irrigation life-support infrastructure. When water rates soar sky-high, then the householder cuts back. Unfortunately the underground root structure has not developed naturally to where sub-soil moisture cannot be reached and all supporting cast members present in a wild setting like deeply rooted shrubs and mycorrhizal fungi are greatly reduced or more than likely completely absent. Often the root water transportation infrastructure and it's landscaping will suffer the most. Take this example below.

Image Google Earth (2914)
 Interchange between Freeway 52 & I-15

These pines are actually Torrey Pines planted along the western side of Interstate 15 heading south to San Diego just before the Freeway 52 interchange. Take close note of the extreme stress they are in holding only present years growth of pine needles and tiny needles at that. Torreys have some of the largest and longest needles of most pines. These are also natives and not that far from the coastline where they are native. This location also experiences a strong marine air influence of daily cloud cover, especially in May-Gray & June-Gloom periods. Still they are stressed more so than those Torrey Pines further east in the much hotter inland interior valleys of Santee, Lakeside & El Cajon. Not to mention the location on a southern slope face of Rattlesnake Mountain in direct intense sunlight. I should say that some of the Torrey Pine seedlings I did plant within the shelter of California Sagebrush and California Buckwheat did well for a few years, but at about 10 years they looked much like these example you see here above and below. Eventually they died or were vandalized by idiots with guns for target practice. Only the trees planted within Laurel Sumac fared exceptionally well. The installation plan and maintenance techniques are clear, Nature needs to be replicated through biomimicry. Now look at this same location below with a Google Earth shot in 2017.

Google earth Same location along Interstate 15 (2017) 

Take note of the lusher greener plants in the foreground. In San Diego this past rainfall season they had much heavier rainfall records, but also an irrigation system and plants have been installed in the foreground. The trees are still in an incrediblly stressed out state with only present growth barely hanging on. Water is not the only key here, but rather colonization of Pisolithus tinctorius mycorrhizal fungi. PT mycorrhizal fungi is the best fungi for plants growing in hot dry areas. Yes, species does matter in this case. But so does a supprting cast of native deep rooted chaparral shrubs in the right strategic placements in this industrial landscape.

Supporting Cast Members in the Landscape, includes various species of Chaparral

Photograph by David Magney (2005)

San Alijo Lagoon Conservancy

This is the nurse plant chaparral shrub above and to the right called Laurel sumac (Malosma laurina) which has outstanding bright green foliage all year. These large clusters of cream flowers appear in the summer. Later the dried flowers and seed heads turn a rusty red-brown. The leaves tend to fold up along the midrib, especially during dry weather whuch apparently helps reduce exposure to the dry hot summer sun of the coastal sage scrub plant community, especially in the hotter interior valleys and mountains nearer to the coast. This gives the plant another common name reference, the taco shell plant. This along with a colony of very old, almost ancient, looking Lemonade Berry which are at the top of this mountain at the head of this normally dry wash (sometimes perennial stream) are the largest shrubs on this hill. Everything else is California Buckwheat, California Sagebrush, White Sage, Gold Yarrow, Monkeyflower, Deer Weed, Coastal Prickly Pear Cactus, Coastal Cholla Cactus, Coastal San Diego Barrel Cactus, etc. My choice for nurse plant was Laurel Sumac in 1980 which turned out to be a great choice and here's why:

"Laurel sumac roots are deep and extensive; vertical root depth of one individual in the Santa Monica Mountains exceeded 43.6 feet (13.2 m)"

US Forest Service - Malmosa laurina

One of the most amazing phenomena of a good nurse plant is it's deep root system ability to extract water from very deep subsoil layers and bring it to the surface. This process is known as Hydraulic Lift & Redistribution. Not only for itself, but also the more shallow rooted shrubs and perennials around it. But it's also beneficial for tree seedlings like oak or pine which would otherwise fail and not make it to the sapling stage of life and beyond towards being a fully mature tree. Especially at night will nurse plants like Laurel Sumac pull up incredible amounts of moisture for themselves and other plants as you see here on the left in the illustration. In places like Africa, plants like grasses and other forbes on the Savanna benefit by growing closest to those giant picturesque Acacia trees like Acacia tortilis. Young tree seedlings also benefit as a tiny emergent seedling from the nurse plant's shade before it pushes through the shrub's foliage when reaching for the sky on it's own. But there is so much more to this hydraulic movement of water.

There is yet another reverse type of phenomena known as Hydraulic Descent where in winter rainy season when the shrub or tree is dormant and not actively growing above ground, the root system is still active underground taking surface soils saturated with rainwater and sucking in and pumping that water into deeper sub-soil layers. If an ecosystem is healthy enough, this collective action by trees and shrubs can recharge acquifers. Many soils are to tough for water to percolate on it's own, so a healthy vegetated ecosystem like an old growth forest or even an old growth Chaparral Plant Community of Southern California will saturate the deeper layers of sub-soils for later usage during the hot summer months. Now even though this shrub is endomycorrhizal and will not form interconnected relationships with pines, oaks, etc, they will still release water from their lateral roots at the surface which can then be accessed by the ecto mycelium or fungal strands. When I lived at elevation 4,500' I used the chaparral shrub called Redshank or Ribbonwood as a nurse plant. Take a look at this gallery of trees below from my former acreage in Anza California.

Photo Mine 2012

These to Coulter Pines above and below were planted across from one another. These trees were foot high bareroot trees I planted on a remote section of my acreage in Anza California. No irrigation. Although these were wild collected from along roadsides, I still inoculated them with Pisolithus tinctorius or P.T. Mycorrhizal Fungal spores. I also located them next to Scrub Oaks or Redshank Chaparral Shrubs. If Redshank was unavailable then I would use it's cousin Chamise or Greasewood (shrub gets blamed for intense wildfires), both of which are also ectomycorrhizal, but under only certain environmental conditions like times of heavy rainfall years. This is important to know because such knowledge allows for foresters to plant trees like Jeffrey, Coulter or Torrey Pines to pioneer into predominantly chaparral areas. Thus the shrubs and trees can interconnect through the mycorrhizal network and young trees throughout youth will be assured of being hydrated by their chaparral nurse plants. Up in Anza the Parry Pinyon will interconnect with Chamise and redshank during the wetter years. Sadly the present property owner removed some of the chaparral around the trees and built this shed between them. Still the healthy start for these trees has been a success. 

Photo is Mine 2012

The three trees below here are two Ponderosa and one Coulter Pine. The Coulter was actually a volunteer under a Redshank which was planted by a scrubjay from pine nuts taken from a large maturee tree next to my front porch. The two Ponderosas I planted within the same chaparral. At one time they were all surround by Redshank and Scrub Oaks, but the present owner wanted all brush removed. But notice on all my trees the five or six years growth of needles still on their whorls ? Very little leaf dander under these trees. This is a sign of very healthy trees. An odd side effect was that there was also an improvement in shrub vegetation and vigor after I inoculated with fungi, especially from the scrub oaks. Truffle formation was everywhere after that. The other fascinating thing here is that these trees are already baring pine cones.

Photo Mine 2012

Below are the three Torrey Pines I planted in Anza, California

Photo Mine 2012

These four Torrey Pines were planted on this bank behind the house in association with California Coffeeberry, San Gabriel Flannelbush and California Holly (Toyon). The year was 1985 where we has a couple of winters (3 in a row which had extremely low subzero temps from Arctic blasts from Canada and high wins at times from 50 to 60 mph. It was insane. The only problem for the Torreys were the very tips of all needles turned brown for about an inch in length. No problem, because after those three winters the central leader grew more than a meter or more in length, with often a secondary growth spurt after summer monsoonal thunderstorms which were intense with heavy rainfall. So no worries at high elevations and no supplementary watering after that.

Examples of Nurse Plant Mutualisms found in Nature within San Diego County

Photo is mine from 2013

The photo above shows a stand of Fremont Cottonwoods on the Henshaw Valley floor in northeast San Diego County. Take note that these large deeply rooted Cottonwood trees are able to support other smaller native plants like this wild native California Rose (Rosa californica) hedge. Other plants are also able to thrive under these trees like the native Snowberry (Symphoricarpos albus laevigatus) and Western Bracken Ferns. This location is amazing because of it's distance away from the forests on the mountainside and the fact that birds or animals originally brought the seeds of these plants to the trees through their feces droppings.

Photo is mine from 2013

Calflora

This photo is much further east in the backcountry community of Ranchita where my brother lives. This is a much hotter drier area just before the landscape drops down into the Anza Borrego Desert. The tree is an Interior Live Oak and the plant below which it is supporting is the native Honeysuckle. Take this Oak tree away and the honeysuckle dies. The area is just too harsh and dry for it to thrive without a companion nurse plant. No doubt a bird flew within the foliage of this Oak tree, pooped after eating the honeysuckle fruits somewhere else and poof, a honeysuckle seedling.

Photo is mine from 2013

Photo is by Cody Bish

One of my favourite nurse plants is the Silver Sagebrush which thrives in the dry high mountain valleys and high deserts steppes of the western United States. The photo at the top is along Montezuma Road in Ranchita almost across from Old Mine Road turnoff. These Silver Sagebrush (Artemisia cana) are nursing along numerous Incense Cedar seedlings and Saplings. Older trees of Cedar were planted several decades ago along this road and San Felipe Road further west. In 2002 there was a wildfire that burned from Julian to the mountains north of Ranchita above Warner Springs. Many of the trees (Coulter Pine, Incense Cedar, etc) escaped the Pines Fire's fury and were years later producing seed which successfully germinated as you see in the top photo taken back in 2013. Another common association with Silver Sagebrush is the Indian Paintbrush seen in the photo here on the right. What many never realize is that Silver Sagebrush is an excellent facilitator of hydraulic lift and redistribution of water. While many will say that the Indian Paintbrush is partially parasitic to Silver Sagebrush, I imagine that this remarkable water hydraulics phenomena goes a long way in why Indian Paintbrush works out successsfully in growing in association with this Artesemia plant. Below are two other posts I've written more extensively on this mutualism with both plants & Artemesia.

An Icon of the Old West, Sagebrush (Atermisia tridentata) is Still Demonized as a Competing Invasive in it's Own Native Habitat

Lessons Observed From the Ranchita Hwy Beautification Project

Tragic End to one of the koolest 30+ year  Forestry Nurse Plant Experiments I've ever accomplished in 2014

Image taken from Google Earth

Image is mine from 2011

San Diego Coast Cholla

When the Sky Ranch Housing Development bulldozed it's way across the western part of the Rattlesnake Mountain range, they stopped short of the colony of Torrey Pines and Coastal Cholla colony. The San Diego Coast Cholla Cactus are also another endangered species from the coast sage scrub plant community. There never was Coast Cholla on Rattlesnake Mountain before, only San Diego Coast Barrel Cactus for which there were 1000s of them when I was a kid in the early 1960s and now only a handful, almost extinct. But I was excited to see that when they pre-stripped the land of all vegetation prior to bulldozing for roads and housing unit property pads, that they had roped off with special environmental sensitive area tape protecting the pines and cacti. Kool I thought. That was on an earlier visit in 2007 when I came back for a visit from my new home in Sweden. Above here you can see the construction and if you gaze up that rainwater runoff channel you can see one of the larger Torrey Pines just behind and to the left of the concrete roof tiles stacks. Unfortunately this did not last.

My photograph from 2011

This photo above shows a different viewpoint on how close the Sky Ranch Housing Development came to the Torrey Pine experiment. In fact this is the same smaller Torrey Pine I posted above, but out of view of the housing. Sadly in 2014 these Sky Ranch home owners and I'm guessing with the blessing of the Conservation Area Biologist (I only say I'm guessing because he was very vague on the telephone when I called to report the incident and was disinterested in doing anything about the trespass and destruction), cut down with chainsaws all of these Torrey Pines. They were in their backyards and the wives ran into the house to get their husbands because I was photographing the area. The husbands weren't exactly overly friendly. The reason these residents gave me was that they were a fire hazard. The biologist in Escondido said they were non-natives to the Coastal Sage Scrub within this designated California Gnat Catcher Conservation Area. This was bunk, almost a century prior to this Rattlesnake Mountain being considered as a conservation area, no one ever gave a rat's backside about Rattlesnake Mountain. In fact the very landscape company they hired to restore areas damaged or disturbed by the Sky Ranch contractors installed numerous exotic non-native Mediterranean plants like Rock Rose, some type of Iris and a variety of other non-native cactus to this mountain. Friends and neighbours were upset for me, but frankly while I was bummed in the beginning, I had always understood the property was never mine and the trees could succum to whatever disaster came along, be it wildfire or housing development. In any event what cannot be taken away is the valuable experience and knowledge I gained from these nurse plant experiments. So seriously, nobody should hold anything against these folks. That's just the way our world works.

😲😭

Gallery of Photographs Documenting the Destruction of the Torrey Pines

Photo is mine 2014

Photo is mine 2014

Photo is mine 2014

Photo is mine from 2014

Above is the photo of the signage threatening anyone with trespass which can be found everywhere around the conservation area borders. Interestingly when I was confronted by the residents wondering why I was taking photographs by angry people in their backyards, I asked the reason for the Torrey Pines being cut down. The unbelievable excuse I was given was that these pines posed a wildfire hazzard and the larger trees were producing cones and seedlings were discovered along the bank behind the backyards. Seriously, seedlings ??? That would have meant if the cones were truly matured (I had previously seen cones, but didn't know if they were mature enough the previous year), that ScrubJays had been taking the heavy pine nuts and planting them somewhere, since the heavy Torrey Pine nuts are unable to sail away on wind currents like other pines. The Sky Ranch Housing development also has allowed invasive plants such as non-native weedy invasives like Mediterranean Wild Mustard, Yellow Star Thistle, European Wild Oats, Cheatgrass, and African Fountain Grass (commonly planted along freeway cutouts in Southern California). For example, in this photo on the right I brought in numerous Coastal Cholla sections and planted them within the coastal sage scrub. Previous Cholla colonies were never there and surprisingly Cactus Wren are present when they never were before. But African Fountain grass has made it's way here. I believe the Sky Ranch landscapers planted them along the road cutous like CalTrans has done along freeways. None of these invaders existed in mass qualities at this high of elevation on Rattlesnake Mountain prior to Sky Ranch Development.

List Image - Sky Ranch

These invasives have an epigenetic effect in the releasing of chemical root exudates which hinder the chemical signaling between the native shrubs and/or trees and their mycorrhizal partners. Eventually this coast sage scrub landscape will disappear and become like the shrubless hillsides of northern Santee and Fletcher Hills west of El Cajon which are now nothing more than non-native grasslands. But at least many reading who may live in this area will get a glimpse of how Nature of SoCal works and how they can replicate the mechanisms within their own landscapes. Seriously, anyone reading can easily replicate this within their own landscapes. The local area newspaper, El Cajon Californian (online), has a nice reecent article about the Rattlesnake Mountain Conservation Area and visiting certain portions of it which are open to public and the challenges of ridding that area of invasive non-native weeds. 

https://eccalifornian.com/exploring-the-breathtaking-beauty-of-rattlesnake-mountain-habitat-preserve/

Also another news source, inewsource.org, had an interesting article from September of 2016 about the dire situation of all forests within San Diego county disappearing for good.

http://inewsource.org: If San Diego County Lost it's Forests

And here is my own take on climate change's effect on San Diego County and how people can counter it's effects on a personal level.

Face of the Climate Change & Drought in San Diego County 

An Urban Landscape Success Story at the foot of Rattlesnake Mountain's Sky Ranch Housing Development

Image Mine in September 2015

California Fan Palm (Washingtonia filifera) growth explosion with Mycorrhizal Fungi

This is my mother's place above, the same place I grew up in from 1961 all the way through high school until I left home in 1977. It's at the foot of Rattlesnake Mountain across from Pepper Drive Elementary School in El Cajon. There is no irrigation infrastructure  here and the entire landscape is native plants with heavily inoculated mycorrhizal associations. Yearly applications of mulch is the only fertilizer they ever get. Annual weeds do not appear anymore. The only weeds are shrub and tree seedlings and these are easy to deal with once a year. You can read about this landscape from the link below the photograph.

Further Educational References on Practical Applications Biomimicing Nature

Chaparral Biome & it's Forest building abilities with or without Wildfire

My source for most mycorrhizal fungi mixes is out of Oregon http://mycorrhizae.com

Aside from that I have always wild collected specific truffle species with great success.