180 research outputs found
Rethinking tipping points in spatial ecosystems
The theory of alternative stable states and tipping points has garnered a lot
of attention in the last decades. It predicts potential critical transitions
from one ecosystem state to a completely different state under increasing
environmental stress. However, typically ecosystem models that predict tipping
do not resolve space explicitly. As ecosystems are inherently spatial, it is
important to understand the effects of incorporating spatial processes in
models, and how those insights translate to the real world. Moreover, spatial
ecosystem structures, such as vegetation patterns, are important in the
prediction of ecosystem response in the face of environmental change. Models
and observations from real savanna ecosystems and drylands have suggested that
they may exhibit both tipping behavior as well as spatial pattern formation.
Hence, in this paper, we use mathematical models of humid savannas and drylands
to illustrate several pattern formation phenomena that may arise when
incorporating spatial dynamics in models that exhibit tipping without resolving
space. We argue that such mechanisms challenge the notion of large scale
critical transitions in response to global change and reveal a more resilient
nature of spatial ecosystems
ΠΠ°ΠΊΠΎΠ½ΠΎΠΌΠ΅ΡΠ½ΠΎΡΡΠΈ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ½ΠΎΡΡΠΈ Π² Π»ΠΈΠ½ΠΈΠΈ ΠΏΡΠΈΠ²ΠΎΠ΄Π° ΠΏΡΠΎΠΊΠ°ΡΠ½ΠΎΠΉ ΠΊΠ»Π΅ΡΠΈ Π² ΠΏΡΠΎΡΠ΅ΡΡΠ΅ Π΅Ρ ΡΠ°Π±ΠΎΡΡ
ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΡΠ°Π±ΠΎΡΡ ΠΊΠ»Π΅ΡΠΈ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½Ρ Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ½ΠΎΡΡΠΈ Π½Π° ΡΠΏΠΈΠ½Π΄Π΅Π»ΡΠ½ΠΎΠΌ ΠΈ ΠΌΠΎΡΠΎΡΠ½ΠΎΠΌ ΡΡΠ°ΡΡΠΊΠ°Ρ
ΠΏΠ΅ΡΠΈΠΎΠ΄ΠΈΡΠ΅ΡΠΊΠΈ ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎ ΠΈΠ·ΠΌΠ΅Π½ΡΠ΅ΡΡΡ Π·Π° ΡΡΠ΅Ρ ΠΈΠ·Π½ΠΎΡΠ° ΡΠΎΡΠ»Π΅Π½ΡΠ΅ΠΌΡΡ
ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ Π·Π°Π·ΠΎΡΠΎΠ². Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π½ΡΠ΅ Π·Π°ΠΊΠΎΠ½ΠΎΠΌΠ΅ΡΠ½ΠΎΡΡΠΈ
ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΠΏΡΠΎΠ³Π½ΠΎΠ·ΠΈΡΠΎΠ²Π°ΡΡ ΠΌΠ°ΠΊΡΠΈΠΌΠ°Π»ΡΠ½ΡΠ΅ Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ Π½Π°Π³ΡΡΠ·ΠΊΠΈ Π² Π»ΠΈΠ½ΠΈΠΈ
ΠΏΡΠΈΠ²ΠΎΠ΄Π°
Evasion of tipping in complex systems through spatial pattern formation
The concept of tipping points and critical transitions helps inform our understanding of the catastrophic effects that global change may have on ecosystems, Earth system components, and the whole Earth system. The search for early warning indicators is ongoing, and spatial self-organization has been interpreted as one such signal. Here, we review how spatial self-organization can aid complex systems to evade tipping points and can therefore be a signal of resilience instead. Evading tipping points through various pathways of spatial pattern formation may be relevant for many ecosystems and Earth system components that hitherto have been identified as tipping prone, including for the entire Earth system. We propose a systematic analysis that may reveal the broad range of conditions under which tipping is evaded and resilience emerges
Π‘ΡΡΡΠΊΡΡΡΠ½ΠΎ-Π³ΡΠ°ΠΌΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΎΡΠΎΡΠΌΠ»Π΅Π½ΠΈΠ΅ Π»ΠΈΠ½Π³Π²ΠΈΡΡΠΈΡΠ΅ΡΠΊΠΈΡ ΡΠ΅ΡΠΌΠΈΠ½ΠΎΠ² Π² ΠΊΡΡΠΌΡΠΊΠΎΡΠ°ΡΠ°ΡΡΠΊΠΎΠΌ ΡΠ·ΡΠΊΠ΅
Π ΡΡΠ°ΡΡΠ΅ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΡΡΠ° ΠΏΠΎΠΏΡΡΠΊΠ° ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΡΡΡΠΊΡΡΡΠ½ΡΡ
ΠΈ ΡΠ°ΡΡΠ΅ΡΠ΅ΡΠ½ΡΡ
ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠ΅ΠΉ Π»ΠΈΠ½Π³Π²ΠΈΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ΅ΡΠΌΠΈΠ½ΠΎΠ² ΠΊΡΡΠΌΡΠΊΠΎΡΠ°ΡΠ°ΡΡΠΊΠΎΠ³ΠΎ ΡΠ·ΡΠΊΠ°. ΠΠΎΠ΄ΡΠΎΠ±Π½ΠΎ Π°Π½Π°Π»ΠΈΠ·ΠΈΡΡΠ΅ΡΡΡ ΡΠΎΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ ΠΎΠ΄Π½ΠΎΡΠ»ΠΎΠ²Π½ΡΡ
ΠΈ ΠΌΠ½ΠΎΠ³ΠΎΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠ½ΡΡ
ΡΠ΅ΡΠΌΠΈΠ½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
Π΅Π΄ΠΈΠ½ΠΈΡ. Π Π°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΡΠΈΠΏΠΎΠ»ΠΎΠ³ΠΈΡ ΡΡΡΡΠΊΡΡΡΠ½ΡΡ
ΠΌΠΎΠ΄Π΅Π»Π΅ΠΉ Π΄Π²ΡΡ
ΡΠ»ΠΎΠ²Π½ΡΡ
ΡΠ΅ΡΠΌΠΈΠ½ΠΎΠ²-ΡΠ»ΠΎΠ²ΠΎΡΠΎΡΠ΅ΡΠ°Π½ΠΈΠΉ.Π£ ΡΡΠ°ΡΡΡ Π·Π΄ΡΠΉΡΠ½Π΅Π½Π° ΡΠΏΡΠΎΠ±Π° Π΄ΠΎΡΠ»ΡΠ΄ΠΆΠ΅Π½Π½Ρ ΡΡΡΡΠΊΡΡΡΠ½ΠΈΡ
ΠΎΡΠΎΠ±Π»ΠΈΠ²ΠΎΡΡΠ΅ΠΉ Π»ΡΠ½Π³Π²ΡΡΡΠΈΡΠ½ΠΈΡ
ΡΠ΅ΡΠΌΡΠ½ΡΠ² ΠΊΡΠΈΠΌΡΡΠΊΠΎΡΠ°ΡΠ°ΡΡΡΠΊΠΎΡ ΠΌΠΎΠ²ΠΈ ΡΠ° ΡΡ
Π½Π°Π»Π΅ΠΆΠ½ΡΡΡΡ Π΄ΠΎ ΡΠ°ΡΡΠΈΠ½ ΠΌΠΎΠ²ΠΈ. ΠΠΎΠΊΠ»Π°Π΄Π½ΠΎ Π°Π½Π°Π»ΡΠ·ΡΡΡΡΡΡ ΡΠΏΡΠ²Π²ΡΠ΄Π½ΠΎΡΠ΅Π½Π½Ρ ΠΎΠ΄Π½ΠΎΡΠ»ΡΠ²Π½ΠΈΡ
Ρ Π±Π°Π³Π°ΡΠΎΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠ½ΠΈΡ
ΡΠ΅ΡΡΠ½ΠΎΠ»ΠΎΠ³ΡΡΠ½ΠΈΡ
ΠΎΠ΄ΠΈΠ½ΠΈΡΡ. Π ΠΎΠ·Π³Π»ΡΠ΄Π°ΡΡΡΡΡ ΡΠΈΠΏΠΎΠ»ΠΎΠ³ΡΡ ΡΡΡΡΠΊΡΡΡΠ½ΠΈΡ
ΠΌΠΎΠ΄Π΅Π»Π΅ΠΉ Π΄Π²ΠΎΡΠ»ΡΠ²Π½ΠΈΡ
ΡΠ΅ΡΠΌΡΠ½ΡΠ²-ΡΠ»ΠΎΠ²ΠΎΡΠΏΠΎΠ»ΡΡΠ΅Π½Ρ.The author of the article makes an effort to research into structural and parts-of-speech peculiarities of Crimean Tatar linguistic terminology. The correlation of one-word and multi-componential terminological units is analyzed in detail. The article also deals with the structural types of the two-word term combinations
Grazing away the resilience of patterned ecosystems
Ecosystemsβ responses to changing environmental conditions can be modulated by spatial self-organization. A prominent example of this can be found in drylands, where formation of vegetation patterns attenuates the magnitude of degradation events in response to decreasing rainfall. In model studies, the pattern wavelength responds to changing conditions, which is reflected by a rather gradual decline in biomass in response to decreasing rainfall. Although these models are spatially explicit, they have adopted a mean-field approach to grazing. By taking into account spatial variability when modeling grazing, we find that (over)grazing can lead to a dramatic shift in biomass, so that degradation occurs at rainfall rates that would otherwise still maintain a relatively productive ecosystem. Moreover, grazing increases the resilience of degraded ecosystem states. Consequently, restoration of degraded ecosystems could benefit from the introduction of temporary small-scale exclosures to escape from the basin of attraction of degraded states.</p
Facilitation and competition deconstructed: a mechanistic modelling approach to the stress gradient hypothesis applied to drylands
Facilitative interactions among species are key in plant communities. While experimental tests support the Stress Gradient Hypothesis (SGH) as an association between facilitation and stress, whether the shape of net effects along stress gradients can be predicted is controversial, with no available mathematical modelling approaches. We proposed a novel test, using a modification of the R* model to study how negative and positive partial effects of plant interactions in drylands combine along two common stress gradients. We modelled different interactions: competition for water and light, amelioration of soil infiltration and/or grazing protection, obtaining that intensity and importance of facilitation did not generally increase along stress gradients, being dependent on the interaction type. While along the water stress gradient net interactions became more positive, reaching a maximum and then waning again, various outcomes were observed along the grazing gradient. Shape variety was mainly driven by the various shapes of the partial positive effects. Under resource stress, additive interaction effects can be expected, whereas when including grazing, the effects were non-additive. In the context of the SGH, deconstructing the effect of positive and negative interaction in a pairwise mechanistic models of drylands does not show a unique shape along stress gradients
Antigonon leptopus invasion is associated with plant community disassembly in a Caribbean island ecosystem
Invasions by non-native plant species are widely recognized as a major driver of biodiversity loss. Globally, (sub-)tropical islands form important components of biodiversity hotspots, while being particularly susceptible to invasions by plants in general and vines in particular. We studied the impact of the invasive vine A. leptopus on the diversity and structure of recipient plant communities on the northern Caribbean island St. Eustatius. We used a paired-plot design to study differences in species richness, evenness and community structure under A. leptopus-invaded and uninvaded conditions. Community structure was studied through species co-occurrence patterns. We found that in plots invaded by A. leptopus, species richness was 40β50% lower, and these plots also exhibited lower evenness. The magnitude of these negative impacts increased with increasing cover of A. leptopus. Invaded plots also showed higher degrees of homogeneity in species composition. Species co-occurrence patterns indicated that plant communities in uninvaded plots were characterized by segregation, whereas recipient plant communities in invaded plots exhibited random co-occurrence patterns. These observations suggest that invasion of A. leptopus is not only associated with reduced species richness and evenness of recipient communities in invaded sites, but also with a community disassembly process that may reduce diversity between sites. Given that A. leptopus is a successful invader of (sub-)tropical islands around the globe, these impacts on plant community structure highlight that this invasive species could be a particular conservation concern for these systems
Spatial self-organization as a new perspective on cold-water coral mound development
Cold-water corals build extensive reefs on the seafloor that are oases of biodiversity, biomass, and organic matter processing rates. The reefs baffle sediments, and when coral growth and sedimentation outweigh ambient sedimentation, carbonate mounds of tens to hundreds of meters high and several kilometers wide can form. Because coral mounds form over ten-thousands of years, their development process remains elusive. While several environmental factors influence mound development, the mounds also have a major impact on their environment. This feedback between environment and mounds, and how this drives mound development is the focus of this paper. Based on the similarity of spatial coral mound patterns and patterns in self-organized ecosystems, we provide a new perspective on coral mound development. In accordance with the theory of self-organization through scale-dependent feedbacks, we first elicit the processes that are known to affect mound development, and might cause scale-dependent feedbacks. Then we demonstrate this concept with model output from a study on the Logachev area, SW Rockall Trough margin. Spatial patterns in mound provinces are the result of a complex set of interacting processes. Spatial self-organization provides a framework in which to place and compare these processes, so as to assess if and how they contribute to pattern formation in coral mounds
Revealing patterns of local species richness along environmental gradients with a novel network tool
How species richness relates to environmental gradients at large extents is commonly investigated aggregating local site data to coarser grains. However, such relationships often change with the grain of analysis, potentially hiding the local signal. Here we show that a novel network technique, the βmethod of reflectionsβ, could unveil the relationships between species richness and climate without such drawbacks. We introduced a new index related to potential species richness, which revealed large scale patterns by including at the local community level information about species distribution throughout the dataset (i.e., the network). The method effectively removed noise, identifying how far site richness was from potential. When applying it to study woody species richness patterns in Spain, we observed that annual precipitation and mean annual temperature explained large parts of the variance of the newly defined species richness, highlighting that, at the local scale, communities in drier and warmer areas were potentially the species richest. Our method went far beyond what geographical upscaling of the data could unfold, and the insights obtained strongly suggested that it is a powerful instrument to detect key factors underlying species richness patterns, and that it could have numerous applications in ecology and other fields
Combined Grazing and Drought Stress Alter the Outcome of Nurse: Beneficiary Interactions in a Semi-arid Ecosystem
Positive interspecific plantβplant interactions in (semi-)arid ecosystems are crucial for supporting ecosystem diversity and stability, but how interactions respond to grazing combined with temporal variation in drought is poorly understood. In a semi-arid area in south-eastern Spain (Murcia region), we planted 1280 saplings of the palatable shrub Anthyllis cytisoides (beneficiary) under the canopy of the unpalatable shrub Artemisia herba-alba (nurse) or in open microsites between shrub patches. We applied four grazing treatments (no grazing, low goat grazing pressure, high goat grazing pressure and rabbit grazing) and two watering treatments. Sapling height and survival were followed for two consecutive years, during which one extreme drought event occurred. We analysed how grazing, watering and their combination affected nurse effects throughout the course of the study. Grazing and the drought event, but not watering, significantly altered the nurse effects. Under ungrazed conditions prior to the extreme drought event, nurse effects on sapling survival were neutral, whereas they were positive at rabbit-grazed plots. At low goat grazing, sapling growth was higher under nurse shrubs than in open microsites. However, after the extreme drought event, sapling survival was higher in open microsites at ungrazed plots, whereas at rabbit-grazed plots, nurse effects shifted from positive to neutral. Our findings highlight the importance of rabbit grazing in determining the direction of plantβplant interactions in arid ecosystems. Moreover, our findings support the idea that positive plantβplant interactions may wane under the combination of high grazing and drought stress.This study has been supported by a NWOβALW Open Program Grant (Netherlands Science Foundationβ Earth and Life Sciences, project number 820.01.020), the projects CASCADE (Grant Agreement 283068) funded by the Seventh Framework Programme FP7/2007e2013 and FEEDBACK (Grant #CGL2011-30515- C02-01) and DRYEX (Grant #CGL2014-59074-R) funded by the Spanish Ministry of Economy and Competitiveness
- β¦