Piñon Pine (Pinus edulis) Age Influences on Development of Microenvironments with Respect to Basal Area, Crown
Base Height, and Crown Closure in North Central New Mexico Stands
Erik Casados, Ruben Trujillo, & Joaquin Gallegos, Environmental Science
Northern New Mexico College, Española, NM
Abstract
Results
The results indicate a possible pattern for the development of a
micro-environment as trees increase in age.
All of the results presented in the graphs showed the same
general trend. Crown Base Hieght (R2= 0.088) and crown
closure (R2= 0.017) increased significantly as age progressed.
Both would eventually level out shortly after one hundred
years of age. This is due to lower branches being shaded out
as crown closure increased over time. Basal Area also shows
a patterns as the trees progressed in age but no significant
data was produced. Our graphs showed very low statistical
significance though. Stronger patterns would probably be
visible if historical fire regimes still occurred in these stands.
The lack of fire in these forests has presented a problem with
our analysis on their growth physiology (Huffman et al. 2008).
A less noisy pattern would be visible during the piñon’s early
serial stage (trees less than 50 years of age) if natural fire regimes still occurred in these landscapes.
Natural fire regimes would sharply decrease basal area as the stand progressed in age. Similar
Crown Base Height should had a stronger less noisy regression. Crown closure at an early age of
tree and stand would be very closed and as the stand matured it would open up more and more.
This is the transition of a young stand towards a more savannah like ecosystem. More data will be
needed in the future for this study. Piñon stands that have frequent prescribed burns and thinning
operations would be highly valuable for this study.
A. Basal Area
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Basal Area (ft^2/ac)
Piñon and Juniper woodlands are among some of the least studied forest types in North
America. Due to the lack of research during the mid-20th century, these woodlands were deemed
a nuisance and were subject to intense destruction. More than 3 million acres of piñon forests
were converted to grasslands, generally under the auspices of "invading piñon" myth - a theory
developed to support the creation of grasslands for the cattle industry at tax payer expense
(Pinyon Penny’s 2011). The destruction of these areas negatively affected species of wildlife and
other vegetation that relied on their presence for survival (Short et al. 1977). One of the major
complications that arises when studying these species is determining age. This factor also
makes it difficult to study other parameters including: height, DBH (Diameter Base Height), basal
area, crown ratio, crown class, disease and pest outbreak, etc. By gathering age on these
stands, there will be a better overall understanding of their complex growth physiology. Data from
this study shows a relationship between age, crown base height (R2= 0.088), and crown closure
(R2=0.017), and suggests a relationship with basal area.
Discussion
Introduction
Dendrochronology (dendron = tree, chronos = time, logos = the science of) is the study of
age, past precipitation, and climate change as recorded by tree growth rings (Grissino-Mayer
2016). The layer, or ring seen in cross section, can be wide (which pertains to a wet season with
an average or above average amount of moisture) or narrow (which pertains to a dry growing
season with below average moisture). The rings are essentially recording a good growing
season or a bad growing season; therefore, they are indirectly recording more than just moisture.
They also document temperature and cloud cover as they impact tree growth as well. This
information is very important when you consider that certain types of trees grow slowly over
hundreds and hundreds of years. They contain a record of climate, precipitation, and climate
changes. In the analyzation of tree rings, you can also observe if there were any natural or
anthropogenic disturbances, such as fire, thinning, etc. Information about the past climate,
abnormal weather conditions, stages of succession, periods of climate change, and future
impacts of climate change can be determined by doing studies like this (Williams et al. 2010).
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Tree Age (years)
B. Crown Base Height
y = 0.5291ln(x) + 0.5161
R² = 0.08789
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There seems to be a correlation on all three parameters that were looked at for this study. As age
increased, so did basal area, crown closure and crown base height. Basal area and crown closure
measurements began to plateau shortly after one hundred years of age though. All parameters
suggested that these piñon stands reached their climax at around 125 years of age and showed no
further growth in biomass. These preliminary studies do not provide sufficient evidence to prove this
theory though. As stated in the discussion, since Piñon Pine is a heavily fire adapted species,
without historical fire regimes, we cannot effectively make a final conclusion on Pinus edulis’ growth
physiology. Analyzing more piñon stands within northern New Mexico will be necessary for this study,
including piñon stands that have experienced prescribed burns and thinning operations, which mimic
the impacts of a natural fire regime, they will be valuable to the accuracy and success of future
studies. Future findings will provide valuable information for land managers to use in helping restore
piñon stands to optimal health. If fire suppression and interruption of natural fire regimes is to
continue research should be conducted to see what the impacts will be on Piñon health and
physiology.
Acknowledgments and References
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Special thanks to Kenny Lopez, Matthew Herrera, Brandon Fernandez, and Manny Vargas who all
performed field and lab work to compile this data.
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Tree Age (years)
*
• Tree Increment Borerto collect tree cores
from the trees
• Prism- to get a basal
area
• Spherical
Densiometer- to
measure crown cover
• Compass- to get
aspect
• Measuring Tape- to
measure CBH (Crown
Base Height)
• Level- to measure the
slope of the ground
• GPS- to get X and Y
coordinates of plot
(Zobrist et al. 2012)
Retrieved April 4, 2017, from http://www.pinenut.com/growing-pine-nuts/pinon-pinyonchaining.shtml
-Grissino-Mayer, H. D. (2016). Principles of Dendrochronology. Retrieved April 10, 2017,
from http://web.utk.edu/~grissino/principles.htm
-Huffman, D.W., P.Z. Fule, K.M. Pearson and J.E. Crouse. (2008). Fire history of pinyon–
juniper woodlands at upper ecotones with ponderosa pine forests in Arizona and New
Mexico. NRC Canada, 38(1), 2097-2107.
-Short, H.L., W. Evans and E.L. Boeker. (1977). The Use of Natural and Modified Pinyon
Pine-Juniper Woodlands by Deer and Elk. The Journal of Wildlife Management, 41(3),
543-559.
-Zobrist, K.W., D.P. Hanley, A.T Grotta and C. Schnepf. (2012). Basic Forest Inventory
Techniques for Family Forest Owners. Pacific Northwest Extension Publications, 1(1), 167.
-Williams, A.P., J. Michaelson, S.W. Leavitt and C.J. Still. (2010). Using Tree Rings to
Predict the Response of Tree Growth to Climate Change in the Continental United States
during the Twenty-First Century. Earth Interactions, 14(1), 1-17.
y = 61.489e0.0007x
R² = 0.01651
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Literature Cited
- Pinyon Penny’s. (2011). Destroying millions of acres of pine nut groves in the Great Basin.
C. Crown Closure
Crown Closure (%)
Research was conducted by
randomly selecting a plot within
five different piñon stands. An
indicator tag was placed at the
center of each plot for reference
point. Coordinates were also
acquired for each plot, along with
the date and time of the study. Any
tree that was within 23 feet from
each reference point was flagged
and analyzed for this experiment.
Tree height, basal area, diameter
of root collar, mistletoe sightings,
canopy cover, crown ratio, crown
base height, and tree core samples
were taken for each tree within the
plots (Zobrist et al. 2012). The
three factors that this study will be
focusing on consist of basal area,
crown base height, and crown
closure though. Tree core samples
were taken from piñon and pine
trees only. All other trees were
excluded. Tree samples were
analyzed by using low magnifying
microscopes to count tree rings.
Each sample was counted and
recorded on a data sheet with the
age of each tree. Statistical
analysis was used and best fit
regression analysis was used and
reported. Crown base height used
Logarithmic and Crown Closure
used Exponential Regression.
Crown Base Height (ft)
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Conclusion & Implications
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Tree Age
(years)
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