66 research outputs found
Emigration rates and population turnover of teal Anas crecca in two major wetlands of western Europe
Consequences of wooded shrine rituals on vegetation conservation in West Africa: a case study from the Bwaba cultural area (West Burkina Faso)
Reproductive phenological pattern of Calotropis procera (Apocynaceae), an invasive species in Brazil: annual in native areas; continuous in invaded areas of caatinga
Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests
The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associate canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is < 2000 mm.yr−1 (water-limited forests) and to radiation otherwise (light-limited forests); on the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. Precipitation first-order control indicates an overall decrease in tropical forest productivity in a drier climate.Peer reviewe
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Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests
The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall < 2000 mm yr⁻¹
Surviving winter: Food, but not habitat structure, prevents crashes in cyclic vole populations
Vole
population
cycles
are a major
force
driving
boreal
ecosystem
dynamics
in north
-
western
Eurasia.
However,
our understanding
of the impact
of winter
on these
cycles
is increasingly
uncertain,
especially
because
climate
change
is affecting
snow
predict
-
ability,
quality,
and
abundance.
We
examined
the role
of winter
weather
and
snow
conditions,
the lack
of suitable
habitat
structure
during
freeze-
thaw
periods,
and
the
lack
of sufficient
food
as potential
causes
for winter
population
crashes.
We
live-
trapped
bank
voles
Myodes glareolus
on 26 plots
(0.36 ha
each)
at two
different
eleva
-
tions
(representing
different
winter
conditions)
in southeast
Norway
in the winters
2013/2014
and
2014/2015.
We
carried
out two
manipulations:
supplementing
six
plots
with
food
to eliminate
food
limitation
and six plots
with
straw
to improve
habitat
structure
and limit
the effect
of icing
in the subnivean
space.
In the first
winter,
all bank
voles
survived
well
on all plots,
whereas
in the second
winter
voles
on almost
all plots
went
extinct
except
for those
receiving
supplemental
food.
Survival
was
highest
on the
feeding
treatment
in both
winters,
whereas
improving
habitat
structure
had no effect.
We conclude
that
food
limitation
was a key factor
in causing
winter
population
crashes
Surviving winter: Food, but not habitat structure, prevents crashes in cyclic vole populations
Vole
population
cycles
are a major
force
driving
boreal
ecosystem
dynamics
in north
-
western
Eurasia.
However,
our understanding
of the impact
of winter
on these
cycles
is increasingly
uncertain,
especially
because
climate
change
is affecting
snow
predict
-
ability,
quality,
and
abundance.
We
examined
the role
of winter
weather
and
snow
conditions,
the lack
of suitable
habitat
structure
during
freeze-
thaw
periods,
and
the
lack
of sufficient
food
as potential
causes
for winter
population
crashes.
We
live-
trapped
bank
voles
Myodes glareolus
on 26 plots
(0.36 ha
each)
at two
different
eleva
-
tions
(representing
different
winter
conditions)
in southeast
Norway
in the winters
2013/2014
and
2014/2015.
We
carried
out two
manipulations:
supplementing
six
plots
with
food
to eliminate
food
limitation
and six plots
with
straw
to improve
habitat
structure
and limit
the effect
of icing
in the subnivean
space.
In the first
winter,
all bank
voles
survived
well
on all plots,
whereas
in the second
winter
voles
on almost
all plots
went
extinct
except
for those
receiving
supplemental
food.
Survival
was
highest
on the
feeding
treatment
in both
winters,
whereas
improving
habitat
structure
had no effect.
We conclude
that
food
limitation
was a key factor
in causing
winter
population
crashes
Surviving winter: Food, but not habitat structure, prevents crashes in cyclic vole populations
Vole
population
cycles
are a major
force
driving
boreal
ecosystem
dynamics
in north
-
western
Eurasia.
However,
our understanding
of the impact
of winter
on these
cycles
is increasingly
uncertain,
especially
because
climate
change
is affecting
snow
predict
-
ability,
quality,
and
abundance.
We
examined
the role
of winter
weather
and
snow
conditions,
the lack
of suitable
habitat
structure
during
freeze-
thaw
periods,
and
the
lack
of sufficient
food
as potential
causes
for winter
population
crashes.
We
live-
trapped
bank
voles
Myodes glareolus
on 26 plots
(0.36 ha
each)
at two
different
eleva
-
tions
(representing
different
winter
conditions)
in southeast
Norway
in the winters
2013/2014
and
2014/2015.
We
carried
out two
manipulations:
supplementing
six
plots
with
food
to eliminate
food
limitation
and six plots
with
straw
to improve
habitat
structure
and limit
the effect
of icing
in the subnivean
space.
In the first
winter,
all bank
voles
survived
well
on all plots,
whereas
in the second
winter
voles
on almost
all plots
went
extinct
except
for those
receiving
supplemental
food.
Survival
was
highest
on the
feeding
treatment
in both
winters,
whereas
improving
habitat
structure
had no effect.
We conclude
that
food
limitation
was a key factor
in causing
winter
population
crashes
Groupements floristiques et capacité de régénération des espèces ligneuses des sanctuaires boisés dans l’aire culturelle bwaba (département de Bondoukuy, Ouest Burkinabé)
What is the spatial unit for a wintering teal Anas crecca? Weekly day roost fidelity inferred from nasal saddles in the Camargue, southern France
Dabbling ducks generally use distinct day roost and nocturnal habitats, the set of which constitute their ’functional unit’. The rate at which these birds may switch between day roosts has never been quantified. Using resightings of nasal- saddled birds and capture-recapture modelling in the Camargue, southern France, we estimated the weekly probability that a teal Anas crecca switches from one day roost to another one nearby (transition probabilities). We also estimated the probability that a teal survives and remains in our study area, consisting of four neighbouring roosts (apparent survival). Birds were highly faithful to one specific water body if they remained in our study area (i.e. weekly rate of switching between roosts was only about 2-6%), but the probability that an individual remained within one of the four roosts from one week to the next (local weekly apparent survival rate) was only 60-70%. Intensive search efforts led to a
60% detection probability. Low local apparent survival coupled with very high site fidelity within the system suggests that two distinct strategies may coexist, i.e. frequent movement between distant winter quarters vs very high fidelity to the very same local wetland. Such strategies may be used successively by the same individuals, or may alternatively represent distinct bird categories (i.e. transients vs residents). In any case, these different strategies suggest that habitat management procedures need to be considered at both local and flyway scales simultaneously. The former may ensure that sites repeatedly used by the same individuals can provide adequate conditions to birds when they remain in a given winter quarter, while the latter will ensure transient birds find appropriate sites within the network of distant wetlands they may use as successive wintering quarters during a seasonPeer reviewe
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