Analysis of the Vigor of Pinus hartwegii Lindl. along an Altitudinal Gradient Using UAV Multispectral Images: Evidence of Forest Decline Possibly Associated with Climatic Change
Por:
Gallardo-Salazar, Jose Luis, Lindig-Cisneros, Roberto A., Lopez-Toledo, Leonel, Endara-Agramont, Angel R., Blanco-Garcia, Arnulfo, Saenz-Romero, Cuauhtemoc
Publicada:
1 jun 2023
Categoría:
Forestry
Resumen:
Future climate forecasts predict major changes that will have negative
impacts on the distribution, abundance, and dynamics of forest
ecosystems. In Mexico, there is evidence of symptoms of massive forest
decline; however, there is no consensus in terms of attributing these
symptoms to climate change. This study aimed to provide evidence of
forest decline possibly associated with climatic change in the highland
pine (Pinus hartwegii Lindl.) populations of the Nevado de Toluca Flora
and Fauna Protection Area. Using unmanned aerial vehicles (UAV) equipped
with multispectral sensors, the study applied digital photogrammetry
techniques, automated tree crown detection algorithms, and calculation
of the normalized difference vegetation index (NDVI) and leaf
chlorophyll index (LCI) to assess forest health across an altitudinal
transect (from 3300 m to the timberline at 4040 m elevation). Climate
analysis was conducted with TerraClimate data using mean annual
temperature (MAT), April temperature, and Palmer Drought Severity Index
(PDSI) from the studied altitudinal transect and its xeric limit. We
found that lower altitude populations had significantly higher stress
levels, indicating forest decline phenomena, while intermediate altitude
populations showed greater vigor of the detected trees. Statistically
significant differences in the NDVI and LCI values along the altitudinal
gradient provided evidence of forest decline in terms of forest vigor
and productivity, with the greatest disturbance found at the lower
altitude of the examined forest species. The analysis of the climatic
data revealed an increase in April temperature +1.4 & DEG;C of the
xeric limit of the transect (low altitude) when comparing the reference
period, 1961-1990 (mean: 12.17 & DEG;C), with the decade prior to our
study (2011-2020; mean: 13.57 & DEG;C). This would be equivalent to an
upward shift in elevation of 280 m of the xeric limit. In addition, the
PDSI analysis revealed that droughts are becoming increasingly intense
at a rate of 0.06 PDSI units per decade, with greater intensity in the
last five years. These findings highlight the negative impacts of
climate change on forest ecosystems and the urgent need for alternative
forest management and conservation practices to increase resilience and
adaptation in the temperate forests of Mexico. This study sets a
precedent for further research to improve our understanding of the
impacts of climate change on forest ecosystems and the development of
sustainable management practices.
Filiaciones:
Univ Michoacana San Nicolas Hidalgo UMSNH, Inst Invest Agr & Forestales, Morelia 58330, Michoacan, Mexico
Univ Nacl Autonoma Mexico, Inst Invest Ecosistemas & Sustentabil, Morelia 58190, Michoacan, Mexico
Univ Michoacana San Nicolas Hidalgo UMSNH, Inst Invest sobre los Recursos Nat, Morelia 58330, Michoacan, Mexico
Univ Autonoma Estado Mexico, Inst Ciencias Agr & Rurales ICAR, Inst Literario 100 Col Ctr, Toluca 50000, Estado De Mexic, Mexico
Univ Michoacana San Nicolas Hidalgo UMSNH, Fac Biol, Morelia 58030, Michoacan, Mexico
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