-
The movement ecology and dynamics of plant communities in fragmented landscapes
-
A conceptual model of movement ecology has recently been advanced to explain all movement by considering the interaction of four elements: internal state, motion capacity, navigation capacities, and external factors. We modified this framework to generate predictions for species richness dynamics of fragmented plant communities and tested them in experimental landscapes across a 7-year time series. We found that two external factors, dispersal vectors and habitat features, affected species coloniza- tion and recolonization in habitat fragments and their effects varied and depended on motion capacity. Bird-dispersed species richness showed connectivity effects that reached an asymptote over time, but no edge effects, whereas wind-dispersed species richness showed steadily accumulating edge and connectivity effects, with no indication of an asymptote. Unassisted species also showed increasing differences caused by connectivity over time, whereas edges had no effect. Our limited use of proxies for movement ecology (e.g., dispersal mode as a proxy for motion capacity) resulted in moderate predictive power for communities and, in some cases, highlighted the importance of a more complete understanding of movement ecology for predicting how landscape conservation actions affect plant community dynamics.
corridors dispersal diversity life-history traits species richness
Located in
Resources
/
Climate Science Documents
-
Multiple movement modes by large herbivores at multiple spatiotemporal scales
-
Recent theory suggests that animals should switch facultatively among canonical movement modes as a complex function of internal state, landscape characteristics, motion capacity, and navigational capacity. We tested the generality of this paradigm for free-ranging elk (Cervus elaphus) over 5 orders of magnitude in time (minutes to years) and space (meters to 100 km). At the coarsest spatiotemporal scale, elk shifted from a dispersive to a home-ranging phase over the course of 1–3 years after introduc- tion into a novel environment. At intermediate spatiotemporal scales, elk continued to alternate between movement modes. During the dispersive phase, elk alternated between encamped and exploratory modes, possibly linked to changes in motivational goals from foraging to social bonding. During the home-ranging phase, elk movements were characterized by a complex interplay between attraction to preferred habitat types and memory of previous movements across the home-range. At the finest tempo- ral and spatial scale, elk used area-restricted search while brows- ing, interspersed with less sinuous paths when not browsing. Encountering a patch of high-quality food plants triggered the switch from one mode to the next, creating biphasic movement dynamics that were reinforced by local resource heterogeneity. These patterns suggest that multiphasic structure is fundamental to the movement patterns of elk at all temporal and spatial scales tested.
elk foraging group formation motivation
Located in
Resources
/
Climate Science Documents
-
Southern Ocean acidification: A tipping point at 450-ppm atmospheric CO2
-
Southern Ocean acidification via anthropogenic CO2 uptake is expected to be detrimental to multiple calcifying plankton species by lowering the concentration of carbonate ion (CO32) to levels where calcium carbonate (both aragonite and calcite) shells begin to dissolve. Natural seasonal variations in carbonate ion concentrations could either hasten or dampen the future onset of this undersaturation of calcium carbonate. We present a large-scale Southern Ocean observational analysis that examines the seasonal magnitude and variability of CO32 and pH. Our analysis shows an intense wintertime minimum in CO32 south of the Antarctic Polar Front and when combined with anthropogenic CO2 uptake is likely to induce aragonite undersaturation when atmospheric CO2 levels reach 450 ppm. Under the IPCC IS92a scenario, Southern Ocean wintertime aragonite undersaturation is projected to occur by the year 2030 and no later than 2038. Some prominent calcifying plankton, in particular the Pteropod species Limacina helicina, have important veliger larval development during winter and will have to experience detrimental carbonate conditions much earlier than previously thought, with possible deleterious flow-on impacts for the wider Southern Ocean marine ecosystem. Our results highlight the critical importance of understanding seasonal carbon dynamics within all calcifying marine ecosystems such as continental shelves and coral reefs, because natural variability may potentially hasten the onset of future ocean acidification.
carbon cycle climate change
Located in
Resources
/
Climate Science Documents
-
Movement ecology of migration in turkey vultures
-
We develop individual-based movement ecology models (MEM) to explore turkey vulture (Cathartes aura) migration decisions at both hourly and daily scales. Vulture movements in 10 migration events were recorded with satellite-reporting GPS sensors, and flight behavior was observed visually, aided by on-the-ground VHF radio-track- ing. We used the North American Regional Reanalysis dataset to obtain values for wind speed, turbulent kinetic energy (TKE), and cloud height and used a digital elevation model for a measure of terrain ruggedness. A turkey vulture fitted with a heart-rate logger during 124 h of flight during 38 contiguous days showed only a small increase in mean heart rate as distance traveled per day increased, which suggests that, unlike flapping, soaring flight does not lead to greatly increased metabolic costs. Data from 10 migrations for 724 hourly segments and 152 daily segments showed that vultures depended heavily upon high levels of TKE in the atmospheric bound- ary layer to increase flight distances and maintain preferred bearings at both hourly and daily scales. We suggest how the MEM can be extended to other spatial and temporal scales of avian migration. Our success in relating model-derived atmospheric variables to migration indicates the potential of using regional reanalysis data, as here, and potentially other regional, higher-resolution, atmospheric models in predicting changing movement patterns of soaring birds under var- ious scenarios of climate and land use change.
energetics flight meteorology
Located in
Resources
/
Climate Science Documents
-
Understanding strategies for seed dispersal by wind under contrasting atmospheric conditions
-
Traits associated with seed dispersal vary tremendously among sympatric wind-dispersed plants. We used two contrasting tropical tree species, seed traps, micrometeorology, and a mechanistic model to evaluate how variation in four key traits affects seed dispersal by wind. The conceptual framework of movement ecology, wherein external factors (wind) interact with internal factors (plant traits) that enable movement and determine when and where movement occurs, fully captures the variable inputs and outputs of wind dispersal models and informs their interpretation. We used model calculations to evaluate the spatial pattern of dispersed seeds for the 16 factorial combinations of four traits. The study species differed dramatically in traits related to the timing of seed release, and a strong species by season interaction affected most aspects of the spatial pattern of dispersed seeds. A rich interplay among plant traits and seasonal differences in atmo- spheric conditions caused this interaction. Several of the same plant traits are crucial for both seed dispersal and other aspects of life history variation. Observed traits that limit dispersal are likely to be constrained by their life history consequences.
atmospheric turbulence conditional seed release Coupled Eulerian-Lagrangian closure (CELC) model long distance dispersal tropical forest
Located in
Resources
/
Climate Science Documents
-
Individual movement behavior, matrix heterogeneity, and the dynamics of spatially structured populations
-
The dynamics of spatially structured populations is characterized by within- and between-patch processes. The available theory describes the latter with simple distance-dependent functions that depend on landscape properties such as interpatch distance or patch size. Despite its potential role, we lack a good mechanistic understanding of how the movement of individuals between patches affects the dynamics of these populations. We used the theoretical framework provided by movement ecology to make a direct representation of the processes determining how individuals connect local populations in a spatially structured population of Iberian lynx. Interpatch processes depended on the heterogeneity of the matrix where patches are embedded and the parameters defining individual movement behavior. They were also very sensitive to the dynamic demographic variables limiting the time moving, the within-patch dynamics of available settlement sites (both spatiotemporally heterogeneous) and the response of indi- viduals to the perceived risk while moving. These context- dependent dynamic factors are an inherent part of the movement process, producing connectivities and dispersal kernels whose variability is affected by other demographic processes. Mechanistic representations of interpatch movements, such as the one pro- vided by the movement-ecology framework, permit the dynamic interaction of birth–death processes and individual movement behavior, thus improving our understanding of stochastic spatially structured populations.
demography Iberian lynx metapopulation population dynamics source-sink
Located in
Resources
/
Climate Science Documents
-
Populations of migratory bird species that did not show a phenological response to climate change are declining
-
Recent rapid climatic changes are associated with dramatic changes in phenology of plants and animals, with optimal timing of reproduction advancing considerably in the northern hemisphere. Some species may not have advanced their timing of breeding suffi- ciently to continue reproducing optimally relative to the occur- rence of peak food availability, thus becoming mismatched com- pared with their food sources. The degree of mismatch may differ among species, and species with greater mismatch may be char- acterized by declining populations. Here we relate changes in spring migration timing by 100 European bird species since 1960, considered as an index of the phenological response of bird species to recent climate change, to their population trends. Species that declined in the period 1990–2000 did not advance their spring migration, whereas those with stable or increasing populations advanced their migration considerably. On the other hand, popu- lation trends during 1970–1990 were predicted by breeding hab- itat type, northernmost breeding latitude, and winter range (with species of agricultural habitat, breeding at northern latitudes, and wintering in Africa showing an unfavorable conservation status), but not by change in migration timing. The association between population trend in 1990 –2000 and change in migration phenology was not confounded by any of the previously identified predictors of population trends in birds, or by similarity in phenotype among taxa due to common descent. Our findings imply that ecological factors affecting population trends can change over time and suggest that ongoing climatic changes will increasingly threaten vulnerable migratory bird species, augmenting their extinction risk.
conservation extinction risk migration phenology population trends
Located in
Resources
/
Climate Science Documents
-
Sharply increased insect herbivory during the Paleocene–Eocene Thermal Maximum
-
The Paleocene–Eocene Thermal Maximum (PETM, 55.8 Ma), an abrupt global warming event linked to a transient increase in pCO2, was comparable in rate and magnitude to modern anthropogenic climate change. Here we use plant fossils from the Bighorn Basin of Wyoming to document the combined effects of temperature and pCO2 on insect herbivory. We examined 5,062 fossil leaves from five sites positioned before, during, and after the PETM (59–55.2 Ma). The amount and diversity of insect damage on angiosperm leaves, as well as the relative abundance of specialized damage, correlate with rising and falling temperature. All reach distinct maxima during the PETM, and every PETM plant species is exten- sively damaged and colonized by specialized herbivores. Our study suggests that increased insect herbivory is likely to be a net long-term effect of anthropogenic pCO2 increase and warming temperatures.
Bighorn Basin paleobotany plant–insect interactions rapid climate change
Located in
Resources
/
Climate Science Documents
-
Global declines in oceanic nitrification rates as a consequence of ocean acidification
-
Ocean acidification produced by dissolution of anthropogenic carbon dioxide (CO2) emissions in seawater has profound conse- quences for marine ecology and biogeochemistry. The oceans have absorbed one-third of CO2 emissions over the past two centuries, altering ocean chemistry, reducing seawater pH, and affecting marine animals and phytoplankton in multiple ways. Microbially mediated ocean biogeochemical processes will be pivotal in deter- mining how the earth system responds to global environmental change; however, how they may be altered by ocean acidification is largely unknown. We show here that microbial nitrification rates decreased in every instance when pH was experimentally reduced (by 0.05–0.14) at multiple locations in the Atlantic and Pacific Oceans. Nitrification is a central process in the nitrogen cycle that produces both the greenhouse gas nitrous oxide and oxidized forms of nitrogen used by phytoplankton and other microorgan- isms in the sea; at the Bermuda Atlantic Time Series and Hawaii Ocean Time-series sites, experimental acidification decreased am- monia oxidation rates by 38% and 36%. Ammonia oxidation rates were also strongly and inversely correlated with pH along a gradi- ent produced in the oligotrophic Sargasso Sea (r2 = 0.87, P < 0.05). Across all experiments, rates declined by 8–38% in low pH treat- ments, and the greatest absolute decrease occurred where rates were highest off the California coast. Collectively our results sug- gest that ocean acidification could reduce nitrification rates by 3–44% within the next few decades, affecting oceanic nitrous oxide production, reducing supplies of oxidized nitrogen in the upper layers of the ocean, and fundamentally altering nitrogen cycling in the sea.
Located in
Resources
/
Climate Science Documents
-
Insects take a bigger bite out of plants in a warmer, higher carbon dioxide world
-
Excerpt from text : Because of the direct effect of CO2 and temperature on global food supplies, the influence of these changes on plant physiology and ecology is being actively studied (4–7). How these elements of global change may alter the interactions between plants and the insects that feed on them is relatively unknown. By bringing to light secrets contained in the fossil record, Currano et al. (8), published in this issue of PNAS, found that the amount and diversity of insect damage to plants increased in association with an abrupt rise in atmospheric CO2 and global temperature that occurred 55 million years ago. If the past is indeed a window to the future, their findings sug- gest that increased insect herbivory will be one more unpleasant surprise arising from anthropogenic climate change.
Located in
Resources
/
Climate Science Documents
