Leaf habit affects the distribution of drought sensitivity but not water transport efficiency in the tropicsVargas G., German; Kunert, Norbert; Hammond, William M.; Berry, Z. Carter; Werden, Leland K.; Smith‐Martin, Chris M.; Wolfe, Brett T.; Toro, Laura; Mondragón‐Botero, Ariadna; Pinto‐Ledezma, Jesús N.; Schwartz, Naomi B.; Uriarte, María; Sack, Lawren; Anderson‐Teixeira, Kristina J.; Powers, Jennifer S.
doi: 10.1111/ele.14128pmid: 36257904
Considering the global intensification of aridity in tropical biomes due to climate change, we need to understand what shapes the distribution of drought sensitivity in tropical plants. We conducted a pantropical data synthesis representing 1117 species to test whether xylem‐specific hydraulic conductivity (KS), water potential at leaf turgor loss (ΨTLP) and water potential at 50% loss of KS (ΨP50) varied along climate gradients. The ΨTLP and ΨP50 increased with climatic moisture only for evergreen species, but KS did not. Species with high ΨTLP and ΨP50 values were associated with both dry and wet environments. However, drought‐deciduous species showed high ΨTLP and ΨP50 values regardless of water availability, whereas evergreen species only in wet environments. All three traits showed a weak phylogenetic signal and a short half‐life. These results suggest strong environmental controls on trait variance, which in turn is modulated by leaf habit along climatic moisture gradients in the tropics.
Nitrogen enrichment alters multiple dimensions of grassland functional stability via changing compositional stabilityXu, Qianna; Yang, Xian; Song, Jian; Ru, Jingyi; Xia, Jianyang; Wang, Shaopeng; Wan, Shiqiang; Jiang, Lin
doi: 10.1111/ele.14119pmid: 36308012
Anthropogenic nutrient enrichment is known to alter the composition and functioning of plant communities. However, how nutrient enrichment influences multiple dimensions of community‐ and ecosystem‐level stability remains poorly understood. Using data from a nitrogen (N) and phosphorus (P) addition experiment in a temperate semi‐arid grassland that experienced a natural drought, we show that N enrichment, not P enrichment, decreased grassland functional and compositional temporal stability, resistance and recovery but increased functional and compositional resilience. Compositional stability and species asynchrony, rather than species diversity, were identified as key determinants of all dimensions of grassland functional stability, except for recovery. Whereas grassland functional recovery was decoupled from compositional recovery, N enrichment altered other dimensions of functional stability primarily through changing their corresponding compositional stability dimensions. Our findings highlight the need to examine ecological stability at the community level for a more mechanistic understanding of ecosystem dynamics in the face of environmental change.
Inferring spatially varying animal movement characteristics using a hierarchical continuous‐time velocity modelPaun, Ionut; Husmeier, Dirk; Hopcraft, J. Grant C.; Masolele, Majaliwa M.; Torney, Colin J.
doi: 10.1111/ele.14117pmid: 36256526
Understanding the spatial dynamics of animal movement is an essential component of maintaining ecological connectivity, conserving key habitats, and mitigating the impacts of anthropogenic disturbance. Altered movement and migratory patterns are often an early warning sign of the effects of environmental disturbance, and a precursor to population declines. Here, we present a hierarchical Bayesian framework based on Gaussian processes for analysing the spatial characteristics of animal movement. At the heart of our approach is a novel covariance kernel that links the spatially varying parameters of a continuous‐time velocity model with GPS locations from multiple individuals. We demonstrate the effectiveness of our framework by first applying it to a synthetic data set and then by analysing telemetry data from the Serengeti wildebeest migration. Through application of our approach, we are able to identify the key pathways of the wildebeest migration as well as revealing the impacts of environmental features on movement behaviour.
Species alliances and hidden niche dimensions drive species clustering along a hydric gradient in a semiarid grasslandMartínez‐Blancas, Alejandra; Belaustegui, Ian Xul; Martorell, Carlos
doi: 10.1111/ele.14122pmid: 36217951
Clustering of species with similar niches or traits occurs in communities, but the mechanisms behind this pattern are still unclear. In the emergent neutrality model, species with similar niches and competitive ability self‐organise into clusters. In the hidden‐niche model, unaccounted‐for niche differences stabilise coexistence within clusters. Finally, clustering may occur through alliances of species that facilitate each other. We tested these hypotheses using population‐growth models that consider interspecific interactions parameterised for 35 species using field data. We simulated the expected community dynamics under different species‐interaction scenarios. Interspecific competition was weaker within rather than between clusters, suggesting that differences in unmeasured niche axes stabilise coexistence within clusters. Direct facilitation did not drive clustering. In contrast, indirect facilitation seemingly promoted species alliances in clusters whose members suppressed common competitors in other clusters. Such alliances have been overlooked in the literature on clustering, but may arise easily when within cluster competition is weak.
Fluctuating fortunes: Stressor synchronicity and fluctuating intensity influence biological impactsOstrowski, Andria; Connolly, Rod M.; Brown, Christopher J.; Sievers, Michael
doi: 10.1111/ele.14120pmid: 36217804
Ecosystems remain under enormous pressure from multiple anthropogenic stressors. Manipulative experiments evaluating stressor interactions and impacts mostly apply stressors under static conditions without considering how variable stressor intensity (i.e. fluctuations) and synchronicity (i.e. timing of fluctuations) affect biological responses. We ask how variable stressor intensity and synchronicity, and interaction type, can influence how multiple stressors affect seagrass. At the highest intensities, fluctuating stressors applied asynchronously reduced seagrass biomass 36% more than for static stressors, yet no such difference occurred for photosynthetic capacity. Testing three separate hypotheses to predict underlying drivers of differences in biological responses highlighted alternative modes of action dependent on how stressors fluctuated over time. Given that environmental conditions are constantly changing, assessing static stressors may lead to inaccurate predictions of cumulative effects. Translating multiple stressor experiments to the real world, therefore, requires considering variability in stressor intensity and the synchronicity of fluctuations.
Elemental and biochemical nutrient limitation of zooplankton: A meta‐analysisThomas, Patrick K.; Kunze, Charlotte; Van de Waal, Dedmer B.; Hillebrand, Helmut; Striebel, Maren
doi: 10.1111/ele.14125pmid: 36223425
Primary consumers in aquatic ecosystems are frequently limited by the quality of their food, often expressed as phytoplankton elemental and biochemical composition. However, the effects of these food quality indicators vary across studies, and we lack an integrated understanding of how elemental (e.g. nitrogen, phosphorus) and biochemical (e.g. fatty acid, sterol) limitations interactively influence aquatic food webs. Here, we present the results of a meta‐analysis using >100 experimental studies, confirming that limitation by N, P, fatty acids, and sterols all have significant negative effects on zooplankton performance. However, effects varied by grazer response (growth vs. reproduction), specific manipulation, and across taxa. While P limitation had greater effects on zooplankton growth than fatty acids overall, P and fatty acid limitation had equal effects on reproduction. Furthermore, we show that: nutrient co‐limitation in zooplankton is strong; effects of essential fatty acid limitation depend on P availability; indirect effects induced by P limitation exceed direct effects of mineral P limitation; and effects of nutrient amendments using laboratory phytoplankton isolates exceed those using natural field communities. Our meta‐analysis reconciles contrasting views about the role of various food quality indicators, and their interactions, for zooplankton performance, and provides a mechanistic understanding of trophic transfer in aquatic environments.
Effects of habitat destruction on coevolving metacommunitiesGawecka, Klementyna A.; Pedraza, Fernando; Bascompte, Jordi
doi: 10.1111/ele.14118pmid: 36223432
Habitat destruction is a growing threat to biodiversity and ecosystem services. The ecological consequences of habitat loss and fragmentation involve reductions in species abundance and even the extinction of species and their interactions. However, we do not yet understand how habitat loss alters the coevolutionary trajectories of the remaining species or how coevolution, in turn, affects their response to habitat loss. To investigate this, we develop a spatially explicit model which couples metacommunity and coevolutionary dynamics. We show that, by changing the size, composition and structure of local networks, habitat destruction increases the diversity of coevolutionary trajectories of mutualists across the landscape. Conversely, in antagonistic communities, some species increase while others reduce their spatial trait heterogeneity. Furthermore, we show that while coevolution dampens the negative effects of habitat destruction in mutualistic networks, its effects on the persistence of antagonistic communities tend to be smaller and less predictable.