U53A-0709
High Elevation Monitoring in the North American Tropics: Ecosystem/Climate
Relationships on Nevado de Colima, Mexico
Graduate Program of Hydrologic Sciences, University of Nevada, Reno, phartsou@unr.nevada.edu, 2 Department of Geography, University of Nevada, Reno, fbiondi@unr.edu
Introduction
Results from Dendrometers
Parque National
Volcan Nevado de
Colima
12
PD 1 Tree 1
Soil Temp
10
18
8
16
6
4
14
2
12
05/24/03
0
09/01/03
12/10/03
03/19/04
06/27/04
10/05/04
Calendar Day
8000
30
7500
25
7000
20
6500
15
6000
10
precip
Tree1
5500
Tree2
Precip (mm)
Micrometers
The dendrometers and phytograms
show clear seasonal growth starting in April
coincident with increasing temperatures and
sustained growth with increased water
availability during the Monsoon. Cessation of
growth appears to be in October, coincident
with the end of the Monsoon and the beginning
of the tropical cyclone and winter precipitation
regime. We were able to get the better part of
three growing seasons of data from the site and
had the unforeseen opportunity to collect
dendrometer data of the growth suppression
and eventual death of the trees due to a bark
beetle (Dendroctonus adjunctus) infestation.
Due to park beetle control efforts, sensors at
Site 1, the infested site, were removed in
November 2003. Site 2 and the weather station
continue to collect data.
Stable isotopic analyses of the waters
show a clear signal of different waters being
used by the trees in cellulose formation. Early
spring (pre Monsoon) is characterized by a low
relative humidity and a high evaporation
regime at the leaf surface. Results also show
the trees using winter precipitation from
relatively deeper soils. Post Monsoon is
characterized by wet soils, high relative
humidity, and very little enrichment at the leaf
surface. Xylem samples show water use
consistent with shallower soils.
Tree5
Tree6 (north)
Tree3 (bark)
Tree7
5
5000
1/1/2002
0
1/6/2002
1/11/2002
1/16/2002
1/21/2002
1/26/2002
1/31/2002
Calendar Day
Site 1 Phytogram 1 July 2001
6100
4000
6080
3500
6060
3000
6040
2500
6020
2000
6000
1500
5980
1000
5960
Phytogram Potential
20
Cumulative Stem Increment (mm)
High elevation monitoring in the tropics is
uncommon. Presented here are the 2001-2004 results of
an intensive field study from Nevado de Colima,
Mexico. The site is at 3800 m at 19° 34’ N, a few
hundred meters below tree line. We have been comonitoring weather and tree growth at half-hour
intervals, as well as seasonally averaged stable isotopes
throughout the hydrologic/biologic cycle. The site is
under the influence of the North American monsoon,
which determines a wet-summer, dry-winter climatic
regime. Using point and band dendrometers, we have
shown the response of high elevation Pinus hartwegii
trees to changing weather patterns and attempted to
pinpoint factors related to onset and cessation of growth
in these high elevation tropical trees. Precipitation,
temperature and relative humidity are shown to
influence stem size at a range of timescales. Along with
the stable isotope data collected to date, we hope to
build a model of tree growth and stable isotope
incorporation into tree-ring cellulose. This will allow a
calibrated chemical reconstruction of seasonal growth
response to fluctuations in the monsoon over the length
of the tree ring record (>350yr). We also had the
unfortunate experience of monitoring several of our
instrumented trees during a round-headed pine beetle
(Dendroctonus adjunctus) infestation following an
exceptionally dry winter the year before. These data
may provide additional insight into tree response to
drought stress and physiological response to bark beetle
attacks. Long term monitoring provides insight into the
complex ecosystem response to global change.
Micrometers
1
Temp (C)
Peter Hartsough1, Franco Biondi1,2
500
5940
0
5920
5900
-500
7/18/01 12:00 AM
7/19/01 12:00 AM
7/20/01 12:00 AM
7/21/01 12:00 AM
7/22/01 12:00 AM
Calendar Date
Monitoring Network
Future Work and Implications
Baseline Isotopic Data
-40
-80
δD
Mexico's forests have shrunk to a quarter of the
size they were before the arrival of European colonists.
The country has one of the highest deforestation rates in
the world, losing about 1.5 percent of its forests and
jungles -about 1.7 million acres- every year. The forests
that remain are vulnerable to drought and insect attacks.
Along with the loss of forests comes a major threat to
catchments and watersheds. The protected area around
Nevado de Colima is in the headwaters for both the
Amería and Naranjo rivers, both important drinking and
agricultural water sources in the states of Jalisco, Colima
and Michoacán.
Further characterization of the monsoon history
will lead to more skillful forecasts of future climate
scenarios and the associated ecosystem response. A better
understanding of plant water relations will allow for the
establishment of rainfall records which go beyond the
historic record, using xylem anatomy, dendrochronology,
and stable isotopes. The combination of different source
waters and different evaporation regimes will clearly lead
to different cellulose isotopic values at the sub annual
level. The ring structure, clear early and latewood bands,
will allow seasonal to sub seasonal division of the rings for
chemical characterization. Cores will be subdivided into
increments representing pre and post monsoon growth.
Cellulose will be extracted from ring sub samples and
analyzed for 13C, 18O and 2H variations within the yearly
growth. It may be possible to reconstruct valuable
information such as moisture sourcing and relative
humidity. A better understanding of the Monsoon system both temporal and physical- will be of great value for
understanding hydrologic dynamics in the vast region
watered by the North American Monsoon.
-120
y = 7.0183x - 0.8374
2
R = 0.9768
y = 7.302x + 0.7007
R2 = 0.9696
Post Monsoon
Pre Monsoon
-160
-200
-30.0
-25.0
-20.0
-15.0
-10.0
-5.0
δ O
18
Variable Leaf Enrichment
-20
-40
-60
Premonsoon Leaf enrichment
δD
The core portion of the monitoring effort was
the installation of a weather station and a pair of
dendrometer networks just below tree line at 3770 m
(12,370 ft) on Nevado de Colima in May 2001. The
weather station is measuring soil and air temperature,
soil moisture content, RH, barometric pressure,
insolation, wind speed and two precipitation gauges.
The dendrometer networks consist of point and band
dendrometers,
phytograms
and
additional
environmental sensors measuring tree growth at the
same time scale. Each network consists of 7
instrumented trees in a fenced off plot. Replicate
sensors are measuring growth at multiple locations
on the same tree and inside and outside of the bark.
While the dendrometers have performed well, we
have had some problems with electrical activity
taking out the dataloggers, leading to their
replacement in June 2003.
To further characterize the hydrologic and
environmental regime the trees are growing under,
two additional collectors were installed for
precipitation chemistry in early 2003 and collection
of spring samples has been going on since 2002. We
have also carried out four isotopic characterization
events, sampling soil, xylem and leaf water from pre
and post Monsoon. Two of the sites are collocated
with the dendrometer sites while a third is a
comparison site on the west facing side of the
mountain. Waters were extracted from soils and
tissues using the toluene extraction method. We
have also collected weekly and event based
precipitation samples tracing the evolution of the
monsoon at the Universidad de Colima
Post Monsoon Leaf Enrichment
-80
-100
-120
-15.0
-10.0
-5.0
0.0
5.0
10.0
15.0
δ18Ο
Thanks To
•Our Mexican collaborators
–Ignacio Galindo Estrada (U of Colima)
–Carolina Cavazos Guerra (U of Colima)
–Ramon Diaz Aguayo (El Patronato del Nevado de
Colima y Cuencas Adyacentes, A.C)
•Ed Wright (Lamont-Doherty)
•Simon Poulson (UNR Stable Isotope Lab)
•Greg McCurdy (WRCC)
•NSF and NOAA for funding
•Agricultural Equipment Corporation
•IAI CRN 3
20.0