Tuesday, April 3, 2012

Networking With (New Mexico Locust)

New Mexico Locust (Robinia neomexicana)

This is really one of those interesting tough little trees and I mean little trees because as a single specimen they don't get more than 20-26 feet under ideal high forested mountain conditions where Aspen, Douglas Fir, Gambel Oak and Ponderosa Pine usually live up in the mountains. Yet, they can tolerate the nastiest and harshest dry hot conditions as long as they and their incredibly sophisticated and microbial colonized roots network have access to moisture somewhere. 

When I lived up in Anza, it was common to see many older Black Locust with their beautiful white flowers which smelled of Orange blossom fragrance. I was at Cahuilla Market one day talking with previous owner Chuck McKee about where his Orange tree were because the fragrance was so overpowering and he pointed out the Locust flowers. BTW, Oranges don't exactly grow up in Anza because the often bitter winter cold would fry them and that's why I was astonished by the familiar scent. The flowers grow in clusters and to me looked reminiscent of Wisteria flowers with the characteristic grape shaped cluster form that hangs down from the vines. Black Locust are native to areas back in the eastern USA and are usually the first tree to sprout back from a forest fire and the underground network has a lot to do with that. Later on (I think in the 1990s) some Anza folks later on brought up a variety called Idaho Locust which in many ways is a lot like Black Locust, but slower growing and the flower clusters as reddish purple.

Black Locust (Robinia pseudoacacia)

Idaho Locust (Robinia idahoensis)

My first encounter was on our annual Cline family reunion trip where we alternated each year for different locations between Lubbock TX, Sierra Vista AZ, Tijeras NM or sometimes we rented cabins at Ruidoso New Mexico.  While hiking up in the dense yet beautiful old growth forest I stumbled upon what I had often only seen and read about in numerous issues of Arizona Highways magazines where it was always in association with other larger trees in dense woods near a stream or some such other woodland setting. The trees here fursther up from where our cabins were located were higher up the mountain and closer to the ski resort. They grow in the high forest understory and can reach over 20' in height. Further on down they were growing with Gambel Oak (Quercus gambelii) which itself is another one of those interesting trees that spread and create small woodlands which contain what look to be numerous individuals but in reality are the same cloned genetic individual. Clearly networking works as a great survival strategy and I'll get to that further in the post as it serves multiple purposes and functions. 
 Gambel Oak (Qurecus gambelii) produces clones from an underground spreading root system which also serves to bind soils together and prevent erosion.

New Mexico Locust grows most commonly from it's underground spreading network of rhizomatous rooting systems which periodically send up sprouts to become new clones of the original parent. They can and do spread from seed as you can see they are in the pea family from the second from the top photo above, but once established in an area it seems the network is all that is necessary. Even after forest fires they are the first to sprout back and that's important for a number of reasons. New Mexico Locust is great for erosion control as the intricate complex network has long since been well established underground from previous decades. This network and regrowth covering  can have a Nurse Tree effect for the establishment of other later to be dominant trees like Ponderosa Pine, Douglas Fir, White Fir, other Oaks and even Maples. Here's what the US Federal Forest Service says about New Mexico Locust which some think needs to be controlled (no doubt by chemicals) for the re-establishment of forests after logging. (TYPICAL) Yet look what they reference about the benefits to Douglas Firs taken right from their own site:
"New Mexico locust competes with conifer seedlings and saplings for moisture and light.  Because of its rapid growth and prolific sprouting, efforts are made to suppress New Mexico locust, especially after timber harvest. Brush competition is usually detrimental to seedling or juvenile tree growth. However, Coffman  showed that under adverse planting conditions, the highest establishment rates of planted Douglas-fir (Pseudotsuga menziesii) seedlings occurred under moderate or heavy cover of New Mexico locust and Gambel oak."
So they can actually be of help and benefit towards re-establishment. Why ? First off,  after a catastrophic event such as a wildfire it should be noted that in almost all cases the natural "Earth Network" which not only contains the multi-species biodiverse Mycorrhizal Network & Beneficial Bacteria which for the most part were untouched by the event, but also both New Mexico Locust & Gambel Oaks have their own roots networks still intact for the benefit of not only themselves in resprouting, but the seed of other plants which will plug into the grid and be fed till they are once again established as adults. I refered to this plugging in from my illustrations of how a grid works in this post here:
How I First Became Addicted to the Internet 
This next piece comes right off Dr Dan Luoma's page where he works with the  mycorrhizas and Truffles industries as a business. He is also an active member of the Bashan Foundation of La Paz, Baja California. The link below of course is a science paper on the ability of already existing and established underground natural networked systems and their engineering ability to re-establish forest seedlings which becomes plugged into the network grid which fascillitates nutrient and water hydration to the young plants via this protected network. In one experiment they took a alcohol based blue die and saturated a large stump created by the strip logging. They saturated the stump which absorbed the die and transfered it into the roots eventually through the mycorrhzal grid only to be picked up by the young trees connected to the same grid even at great distances. Enjoy the read:
 Hydraulic redistribution of water from Pinus ponderosa trees to seedlings: evidence for an ectomycorrhizal pathway
"Here are some great photos of both New Mexico Locust & Gambel Oak show off their ability to resprout after a fire ravages an area. The first picture is where New Mexico locust dominates this slope along the Los Alamos ridge trail about a half-mile from the Mitchell Trail. It completely burned off above ground and will be back with a vengeance! Photo is from bike and hike NM Blog which monitors trail maintenance."

images: bikeandhike NM Blog

Another big important function that New Mexico Locust offers through it's extensive complex network in your landscape or forest ecology is it's ability as a member of the 'pea family' it's ability to feed the soil. It is among many plants in nature which is a Nitrogen-Fixing plant. Of course to help this along are beneficial bacteria which influence the process.

Plants That Feed The Soil? In one word - YES! 

Nitrogen is one of the most important elements required by growing plants. Some plants form symbiotic relationships with certain types of soil bacteria that live on the plants’ roots are able to “fix” atmospheric nitrogen and make it available to the plant for growth. This gives these plants a decided advantage over other plants, especially in nitrogen-poor soils. When the plant dies, this nitrogen is left in the soil and is available to other plants.

Most gardeners know about planting annual, nitrogen-fixing cover crops, such as peas, vetch or clover, as a way to improve the soil for the following food crop to be planted in their organically raised gardens . These cover crops are usually cut down and turned-in to the soil to release the nutrients. However, New Mexico Locust (Robinia neomexicana) is just one of many plants that can accomplish this in a wild landscape environment. This is exactly what I established on my property in Anza California on that trip back from Ruidosos, NM.

Perennial nitrogen fixers feed the soil without having to be cut down because all roots are in a constant state of growth and die-back. As bits of the roots of nitrogen-fixing perennials die, nitrogen is released and made available to surrounding plants. Spacing these plants regularly throughout the landscape will help reduce imported fertilizer needs while increasing productivity. 
Here is a great piece by a student presenting his thesis with some good reads, though the text is a bit rough on the PDF.
by Nabil Y. Khadduri (New Mexico State University - Las Cruces NM, 2003)
Some Pertinent Points extracted from "Introduction" of Nabil's Thesis
"New Mexico locust (Robinia neomexicana A. Gray), a small tree native to the southwestern United States, occurs at elevations from 1,200 to 2,800 meters. This species fills a successional role in post-disturbance situations. As a primary invader, New Mexico locust quickly establishes on burned areas arid flood banks, as well as road cuts (Wagner et aI. 1992). Rapid growth, crown sprouting and prolific root suckering favor the successful establishment ofNew Mexico locust on disturbed sites (Simpson 1988, Gottfried 1980). These attributes also may make New Mexico locust well suited for steep-slope revegetation where erosion is a problem."
"New Mexico locust is a nitrogen-fixing legume that tolerates and improves nutrient-poor soils. Stands ofNew Mexico locust increase Nitrogen (N) and Calcium (Ca) in the forest floor. Levels of Carbon (C), Phosphorous (P), Sulfur (8) and Potassium (K) aIso have been shown to increase in soil beneath New Mexico locust (Klemmedson 1994)."
"The ability to colonize rapidly and ameliorate harsh sites contributes to New Mexico locust's potential as a nurse plant. A nurse plant colonizes an inhospitable site and creates an environment suitable for successional plant establishment. New Mexico locust demonstrates this role in the ponderosa pine (Pinus ponderosa Douglas ex Lawson & C. Lawson)/Gambel oak (Quercus gambelii Nutt.) community. After a disturbance such as wildfire, New Mexico locust and Gambel oak colonize and dominate the site until shaded out by ponderosa pine. Once shaded, these species become understory shrubs, a process taking an average of 15-20 years (Dick-Peddie 1993, Hanks and Dick-Peddie 1974). New Mexico locust gradually declines, with small dense patches averaging about 0.05 ha beneath pine, until the next disturbance once again offers it a competitive advantage (Klemmedson 1994)." 
"Gottfried (1980), expecting ponderosa pine regeneration to be greater where New Mexico locust had been eradicated, found that survival of planted pine seedlings was greater where locust had not been removed. In a follow-up study, Gottfried (1980) noted that soil moisture in the top 57 cm was highest in 5-year old locust sites, as compared to grass or 20-year old locust sites. He concluded that managing an appropriate cover of New Mexico locust could help regenerate pine, the later successional species."
"The ability of New Mexico locust to improve harsh sites also makes it a candidate for reclaiming disturbances associated with mining. Black locust (Robinia pseudoacacia 1.) has been used for decades to reclaim mine spoils and other disturbed sites in the eastern US and around the world (Keresztesi 1988, Zimmerman and Carpenter 1980). Ashby et al. (1985) described similar positive attributes of black locust also mentioned previously for New Mexico locust: quick cover for stabilization, supply ofN and nutrient-rich litter to the soil, and site improvement for establishment oflater successional trees. Referring specifically to mine reclamation, the authors note the ability of black locust to grow on a wide range ofmine soil conditions, including extremely acid soils. Black locust also shows some tolerance to soils compacted by grading and topsoiling practices (Ashby et aL 1985)."
"New Mexico locust holds promise as a native southwe~tem counterpart to black locust in mine reclamation, but it has been used infrequently to date. Natural invasion and succession occur slowly on most mine sites (Monsen 1984). While New Mexico locust often colonizes sites naturally, there is no assurance a seed will reach a particular site and establish in a reasonable time frame. The challenge is to introduce New Mexico locust as mother plants to facilitate colonization. Seedling production for outplanting on disturbed sites has been hampered by poor germination (Lin et al. 1996). The goal, then, is to develop techniques to overcome poor germination in New, Mexico locust, thereby facilitating macropropagation." 
The above should at least illustrate to all the important ability of New Mexico Locust to be used as an establishment mother plant to be utilized in the beginning to be replaced naturally over time by more dominant and desirable plants in the landscape without itself totally disappearing from the ecosystem. 
Here is an updated Version of my experience with New Mexico Locust at my former property in Anza California
Revisiting Black Locust and Networks

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by scarification trea

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