[MCN] Forest conservation/sustainability in time of die-offs
Lance Olsen
lance at wildrockies.org
Wed Jul 27 14:19:56 EDT 2016
"Defining sustainability is like trying to define
justice or democracy. There are many definitions
and some consensus, but agreement over the
specifics is elusive."
Donald Floyd, author of Forest Sustainability:
The History, the Challenge, the Promise. © 2002
Forest History Society__80 pp.; 21 photos;_11
maps and figures. __Issues Series booklets are
$9.95 (plus $4.00 shipping). Discounts are
available if ordering 10 or more copies.
http://foresthistory.org/Publications/Issues/floyd.html
=========================================================================
On underestimation of global vulnerability to
tree mortality and forest die-off from hotter
drought in the Anthropocene.
Allen, C. D., D. D. Breshears, and N. G. McDowell. 2015.
Ecosphere 6(8):129.
http://dx.doi.org/10.1890/ ES15-00203.1
Abstract. [Bold added] Patterns, mechanisms,
projections, and consequences of tree mortality
and associated broad- scale forest die-off due to
drought accompanied by warmer
temperatures-''hotter drought'', an emerging
characteristic of the Anthropocene-are the focus
of rapidly expanding literature. Despite recent
observational, experimental, and modeling studies
suggesting increased vulnerability of trees to
hotter drought and associated pests and
pathogens, substantial debate remains among
research, management and policy-making
communities regarding future tree mortality
risks. We summarize key mortality- relevant
findings, differentiating between those implying
lesser versus greater levels of vulnerability.
Evidence suggesting lesser vulnerability includes
forest benefits of elevated [CO2] and increased
water-use efficiency; observed and modeled
increases in forest growth and canopy greening;
widespread increases in woody-plant biomass,
density, and extent; compensatory physiological,
morphological, and genetic mechanisms; dampening
ecological feedbacks; and potential mitigation by
forest management. In contrast, recent studies
document more rapid mortality under hotter
drought due to negative tree physiological
responses and accelerated biotic attacks.
Additional evidence suggesting greater
vulnerability includes rising background
mortality rates; projected increases in drought
frequency, intensity, and duration; limitations
of vegetation models such as inadequately
represented mortality processes; warming
feedbacks from die-off; and wildfire synergies.
Grouping these findings we identify ten
contrasting perspectives that shape the
vulnerability debate but have not been discussed
collectively. We also present a set of global
vulnerability drivers that are known with high
confidence: (1) droughts eventually occur
everywhere; (2) warming produces hotter droughts;
(3) atmospheric moisture demand increases
nonlinearly with temperature during drought; (4)
mortality can occur faster in hotter drought,
consistent with fundamental physiology; (5)
shorter droughts occur more frequently than
longer droughts and can become lethal under
warming, increasing the frequency of lethal
drought nonlinearly; and (6) mortality happens
rapidly relative to growth intervals needed for
forest recovery. These high-confidence drivers,
in concert with research supporting greater
vulnerability perspectives, support an overall
viewpoint of greater forest vulnerability
globally. We surmise that mortality vulnerability
is being discounted in part due to difficulties
in predicting threshold responses to extreme
climate events. Given the profound ecological and
societal implications of underestimating global
vulnerability to hotter drought, we highlight
urgent challenges for research, management, and
policy-making communities.
=========================================================
"We also infer stress incurred by shifting
climate should create an opening for the
establishment of forest types not currently seen
in the conterminous United States."
Jean Liénard, John Harrison, Nikolay Strigul. US
forest response to projected climate-related
stress: a tolerance perspective. Global Change
Biology August 2016
http://onlinelibrary.wiley.com/doi/10.1111/gcb.13291/full
=======================================================
'"Drought and heat-induced tree mortality is
accelerating in many forest biomes as a
consequence of a warming climate, resulting in a
threat to global forests unlike any in recorded
history (1-12)."
" Š. we conclude with high certainty that
today's forests are going to be subject to
continued increases in mortality rates that will
result in substantial reorganization of their
structure and carbon storage."
Nathan G. McDowell and Craig D. Allen. Darcy's
law predicts widespread forest mortality under
climate warming.
Nature Climate Change. Published online 18 MAY 2015
DOI: 10.1038/NCLIMATE2641
==========================================
"If the vapour-pressure deficit continues
increasing as projected by climate models, the
mean forest drought-stress by the 2050s will
exceed that of the most severe droughts in the
past 1,000 years. Collectively, the results
foreshadow twenty-first-century changes in forest
structures and compositions, with transition of
forests in the southwestern United States, and
perhaps water-limited forests globally, towards
distributions unfamiliar to modern civilization."
A. Park Williams, Craig D. Allen, Alison K.
Macalady et al. Temperature as a potent driver of
regional forest drought stress and tree
mortality. Nature Climate Change PUBLISHED
ONLINE: 30 SEPTEMBER 2012 | DOI:
10.1038/NCLIMATE1693
=================================================
"From field measurements, aerial photos, and
Ikonos satellite images, we detected significant
1954-2002 tree density declines in the western
Sahel of 18 ` 14% (P 1Ž4 0.014, n 1Ž4 204) and 17
` 13% (P 1Ž4 0.0009, n 1Ž4 187). From field
observations, we detected a significant 1960-2000
species richness decline of 21 ` 11% (P 1Ž4
0.0028, n 1Ž4 14) across the Sahel and a
southward shift of the Sahel, Sudan, and Guinea
zones. Multivariate analyses of climate, soil,
and population showed that temperature most
significantly (P < 0.001) explained tree cover
changes. Multivariate and bivariate tests and
field observations indicated the dominance of
temperature and precipitation, supporting
attribution of tree cover changes to climate
variability. Climate change forcing of Sahel
climate variability, particularly the significant
(P < 0.05) 1901-2002 temperature increases and
precipitation decreases in the research areas,
connects Sahel tree cover changes to global
climate change. This suggests roles for global
action and local adaptation to address ecological
change in the Sahel."
P. Gonzalez, C.J. Tucker, H. Sy.Tree density and
species decline in the African Sahel attributable
to climate. Journal of Arid Environments 78
(2012) 55e64 17 November 2011
doi:10.1016/j.jaridenv.2011.11.001
========================================================
"We find that hydraulic damage persisted and
increased in dying trees over multiple years and
exhibited few signs of repair Š. Contrary to
the expectation that surviving trees have
weathered severe drought, the hydraulic
deterioration demonstrated here reveals that
surviving regions of these forests are actually
more vulnerable to future droughts due to
accumulated xylem damage."
WILLIAM R. L. ANDEREGG et al. Drought's legacy:
multiyear hydraulic deterioration underlies
widespread aspen forest die-off and portends
increased future risk. Global Change Biology
(2013) 19, 1188-1196,
doi: 10.1111/gcb.12100
================================================
"Climate-driven forest die-off from drought and
heat stress has occurred around the world, is
expected to increase with climate change and
probably has distinct consequences from those of
other forest disturbances."
William R. L. Anderegg et al. Consequences of
widespread tree mortality triggered by drought
and temperature stress. Nature Climate Change.
PUBLISHED ONLINE: 9 SEPTEMBER 2012 |
DOI: 10.1038/NCLIMATE1635
============================================
"Notably, the recent drought was warmer than the
previous sub-continental drought of the 1950s."
" Š nearly complete tree mortality across many
size and age classes was observed in response to
the recent drought."
David D. Breshears et al. Regional vegetation
die-off in response to global-change-type
drought. Proceedings National Academy of Sciences
October 18, 2005 _ vol. 102 _ no. 42
www.pnas.org_cgi_doi_10.1073_pnas.0505734102
© 2005 by The National Academy of Sciences of the USA
===================================================
"This review Š deals exclusively with observed
responses of wild biological species and systems
Š. "
"Climate change is not a new topic in biology.
The study of biological impacts of climate change
has a rich history in the scientific literature,
since long before there were political
ramifications. ..... Observations of range shifts
in parallel with climate change ... date back to
the mid-1700s."
"A surprising result is the high proportion of
species responding to recent, relatively mild
climate change (global average warming of 0.6
C)." The proportion of wild species impacted by
climate change was estimated at 41% of all
species (655 of 1598)."
Parmesan, Camille. "Ecological and Evolutionary
Responses to Recent Climate Change." Annual
Review of Ecology, Evolution, and Systematics.
2006. 37: 637-69
--
=====================================
"The individual scientist can survive for a long
time by lying low in the valley of specialized
intellectual interest ... We in science must get
up and face the wind, confront the future."
William Bevan, "The Sound of the Wind That's Blowing."
American Psychologist. July 1976
=================================================
" ... all of us, including scientists, will have
to give serious thought to the notion that
economic growth and true sustainable long-term
wealth may now be antithetical."
Kurt Cobb, "Should Scientists Embrace Economic Growth?" Scitizen, 16 Oct, 2007
http://www.scitizen.com/stories/Future-Energies/2007/10/Should-Scientists-Embrace-Economic-Growth/
=================================
"Because the decimating factor of economic growth
eliminates welfare factors for virtually all
imperiled species via the principle of
competitive exclusion, economic growth may be
classified as the limiting factor for wildlife
conservation. The wildlife profession has been
virtually silent about this limiting factor,
suggesting that the profession has been laboring
in futility. Š. The Wildlife Society should lead
the natural resources professions in developing a
position on economic growth."
Brian Czech. Economic growth as the limiting
factor for wildlife conservation. Wildlife
Society Bulletin 2000, 28(1):4-15
==================================================
"The Ecological Society of America (ESA) is a
professional organization with about 10,000
members .... As one might expect, it can be
difficult to produce position statements and
other documents that represent a consensus among
all members of such a diverse society. A case in
point is ESA's recent position statement on
economic growth
(www.esa.org/pao/ecogrowth_statement.php), which
has already elicited a broad spectrum of
passionate responses from members."
Alison Power "Ecology and economic growth: the
challenge of building consensus." Frontiers in
Ecology and the Environment: (2009) Vol. 7, No.
6, pp. 287-287.
------------------------------------------------------------
"Š energy consumption in 1960 was about half what
it is now [1970]Š. Surely we had a civilized
country then [1960], with roads, electricity,
entertainment, and so on. Š. Have we, by doubling
our energy consumption, doubled our happiness?"
Kimon Valaskakis, Peter S. Sindell, J. Graham
Smith, and Iris Fitzpatrick-Martin. The Conserver
Society. 1970. Harper & Row.
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