Oecologia最新文献

Globally, vegetation biodiversity is expected to decline as the rate of plant adaptation struggles to keep pace with rising temperatures. To support conservation efforts through remote sensing, we disentangled the nested effects of genetic and environmental influences on reflectance spectra, leveraging spectroscopy to assess plant adaptations to temperature. Specifically, we quantified the relative effect of plasticity and heritability on Populus fremontii (Fremont cottonwood) leaf reflectance using clonal replicates propagated from 16 populations and grown across three common gardens spanning a mean annual temperature gradient representing the thermal range of P. fremontii. We used variance partitioning to decompose phenotypic variation expressed in the leaf spectra into genotypic and environmental components to estimate broad-sense heritability. Heritability was strongly expressed in the spectral red edge (~ 680-750 nm) and shortwave infrared (~ 1400-3000 nm), though the heritability peak in the red edge was sensitive to extreme temperatures. By comparing distances of group centroids in principal component space, we determined that P. fremontii intraspecific spectral variation was shaped by the interaction between common garden site conditions and source population. Support vector machine models indicated pronounced environmental influence on spectral variation, as P. fremontii source population and garden location were classified at 71.8% and 92.6% accuracy, respectively. These findings emphasize the utility of reflectance data in separating genetic and environmental influences on plant phenotypes, offering a pathway to scale these insights across broader landscapes and aid in the conservation and management of vulnerable ecosystems in a warming climate.

Long-term information is crucial for enhancing our ability to predict ecosystem trajectories under adaptive management and climate change scenarios. In this study, we assessed how the systematic incorporation of information affects our predictive capacity regarding the response of a target variable, offering insights into ecosystem dynamics and highlighting the importance of long-term data. We analyzed over 20 years of aboveground net primary production (ANPP) data across three highly dynamic dryland ecosystems in a grassland-to-shrubland transition zone. Our approach, widely applicable for testing long-term observations, involved modeling probability distributions, temporal semivariograms, and copula-based dependency functions between annual precipitation and ANPP. Our results indicate non-linear trends in prediction capacity as more data are included, demonstrating emergent unexpected responses not evident in short-term observations. These dynamic and non-stationary responses pose significant challenges for prediction, even with over 20 years of data, underscoring the need for ongoing measurements. Our findings emphasize the importance of long-term temporal variability for understanding trends and resilience of ecosystem processes. Quantitative methodologies for assessing predictive capacity and identifying trends are essential for making informed decisions regarding the continuation or termination of long-term monitoring initiatives. We strongly advocate for the sustained support of long-term ecological research, as it is crucial for deepening our understanding of ecosystem responses and for guiding effective management and policy decisions.

Endozoochory is a type of mutualistic seed dispersal in which animals ingest seeds (usually contained in fruits) and then pass them in their feces, effectively distributing them to new locations. Some seed characteristics may be altered by the oral apparatus and digestive system of frugivores, resulting in physiological changes due to pulp removal or mechanical changes due to scarification of the testa, which affect seed integrity and germination. The cactus Pilosocereus leucocephalus produces fleshy fruits containing hundreds of seeds that are consumed by birds and mammals, which may differentially influence seed damage. Thus, we experimentally evaluated the proportion and germination of intact (whole) seeds found in the feces of representative species of these two frugivore groups. For this, at least two individuals per frugivore species (Psilorhinus morio, Campylorhynchus rufinucha, Artibeus jamaicensis, and Peromyscus mexicanus) were kept in captivity and fed with ripe P. leucocephalus fruits. Physical damage and germination under controlled conditions were compared between frugivore species and two control groups (non-ingested seeds with and without pulp). The proportion of intact seeds defecated, in descending order, was P. morio, C. rufinucha, and A. jamaicensis, while all the seeds found in the feces of P. mexicanus were destroyed. The germination percentages observed in the treatments, from higher to lower, were P. morio, control without pulp, A. jamaicensis, C. rufinucha, and control with pulp. These results suggest a gradient in seed dispersal quality, which is mutualistic in the birds and bats, and differentially affects seed integrity and germination, and antagonistic in rodents.

Plant-herbivore interactions are important for almost all terrestrial ecosystems, but little is known about how herbivory and the specialization of these interactions change with the resource availability provided by host plant communities and time since disturbance. In fire-prone scrublands of the South African Cape Floristic Region, we studied interaction networks between 20 Protea shrub species and ten herbivorous insect species that consume seeds inside Protea cones during their larval stage. We studied these interactions at 18 sites that differed widely in plant resource availability (protea cone mass per hectare) and time since the last fire event. We sampled 1173 protea cones, identified the herbivores in each cone, and calculated herbivory rate (the proportion of infested cones), herbivore diversity (herbivore species richness and Shannon diversity), the number of host plant species per herbivore species (insect generality), the number of herbivore species per host plant species (plant vulnerability), as well as niche overlap among insect and plant species for each site. We found that most herbivore species interacted with the majority of Protea species. Herbivory rate and herbivore diversity were not affected by site-level resource availability or time since fire. Surprisingly, specialization of plant-herbivore interactions at the community level was independent of the environmental gradients studied, suggesting that the mechanisms structuring the interactions in this plant-herbivore system were independent of the environmental context. This finding suggests coupled community dynamics of protea plants and the insect herbivores feeding inside their cones in South African fynbos ecosystems.

Complex landscapes (i.e., those harboring multiple habitat types at immediate spatial proximity) are highly relevant to both applied and theoretical ecological research, yet the mechanisms shaping functional trait distributions and diversity metrics across trophic levels in these systems remain poorly understood. To address this knowledge gap, we used wood-pastures as a model system and focused on two prominent groups occupying different trophic levels: plants and ants. We sampled three Central-European wood-pastures, with all four encompassed habitat types (grasslands, solitary trees, forest edges, and forests; 48 sites in total). Our results revealed significant differences in taxonomic and functional composition for both groups among the different habitat types of wood-pastures. However, the underlying mechanisms driving these patterns differed between plants and ants. Based on RLQ and fourth-corner analyses, heterogeneity in environmental conditions mainly influenced plant functional trait distributions. In contrast, ant diversity metrics and trait distributions were strongly linked to vegetation characteristics and habitat structure, and were only indirectly influenced by local microclimate, as shown by path analyses. These highlight that while mapping the increased environmental heterogeneity of complex landscapes, the main mechanisms shaping functional composition and diversity metrics might differ for organisms at different trophic levels (i.e., predominantly environmental filtering for plants and interspecific competition for ants). Consequently, the patterns and peaks of taxonomic and functional diversity do not necessarily coincide for different organisms in complex landscapes, emphasizing that conservation initiatives should focus on the system as a whole, rather than individual habitat types, to maximize biodiversity conservation.

Biological invasions are a serious global issue, but invasions are relatively less common at high latitudes, likely due to harsh environmental conditions and limited accessibility. An exception to this is human-settled and disturbed towns that may promote invasions and risk acting as sources of non-native species into the surrounding natural areas. For instance, Churchill, Manitoba, Canada (58ºN), is a treeline subarctic town and port connected by a railway to temperate North America. More than a hundred non-native plant species have been recorded within the town footprint and associated areas. While some have persisted for decades in these areas, none has spread into nearby tundra or boreal forest ecosystems. We used a greenhouse warming experiment to investigate the importance of increased growing season temperatures on three perennial non-native species (Linaria vulgaris, Plantago major, Taraxacum officinale), and used a transplant experiment to investigate non-native survival and growth after manual translocation to tundra and boreal forest roadside over several full years. We found that non-native plants were able to survive temporarily after manual translocation to roadsides adjacent to natural areas, with higher survival in warmer boreal forest roadsides. When we experimentally increased temperature, non-native seed germination increased, and non-native transplants trended toward increased survival and growth, again suggesting that temperature is a limiting factor. However, survival and growth of these non-native species consistently declined over time. Future global and climate change that results in increased warming therefore may shift these non-native species from invasion failure to success.

The current increase in annual temperatures is altering the spatial distribution and timing of activity patterns, i.e. phenology, of many animal and plant species. Theory predicts such phenological plasticity to affect community composition and food web structure. We inferred temporal changes in Lepidoptera phenology in a mountainous region of northern Austria characterised by ongoing environmental and climate change. Long-term records (1960‒2022) representing 189,993 records of 2111 Lepidoptera species at two elevational belts served to assess phenology and species composition at a weekly resolution. Temporal trends towards earlier appearance in spring and prolonged activity in autumn altered short-term community composition at lower and higher elevations. Phenological plasticity was high throughout the study period and increased over the course of the years, becoming more and more fuzzy towards autumn. Variability in community composition decreased over the years. We found little evidence for synchronous phenological shifts at the community level. Species-specific phenological plasticity seems to prevail, causing constant changes in seasonal community composition. Long-term directional changes in community composition due to increasing temperature might change food webs and affect species interactions, particularly pollination, and possibly insect and plant diversity.

In vertebrates, habitats differ in many biotic and abiotic factors with potential important consequences on fitness. Measuring phenotypic differences between habitats is a relevant approach to assess habitat quality for multiple categories of individuals such as males and females. Morphological traits have, for example, been used to successfully assess the impact of urbanization on birds. Surprisingly, this approach has rarely been used in farmlands, although it could be useful to assess the constraints of agricultural practices (i.e. habitat alteration, pesticides). We investigated the phenotypic differences between three habitats (forest, urban, vineyard) in male and female great tits (Parus major) to assess the constraints that occur in small cities and intensive vineyards, and to test if one sex may be more sensitive than the other to habitat-specific constraints. We measured three traits that integrate environmental constraints (body size, body condition, carotenoid-based plumage colouration). We found that urban great tits are of lower phenotypic quality (size, condition, plumage brightness) than their forest counterparts even when they live in small cities. Despite intensive agricultural practices, we found no difference in body size and plumage colouration between vineyard and forest birds, and vineyard birds were even in better condition than forest ones. We found that the differences in body condition between habitats were more pronounced for females relative to males. This supports the idea that females may be more sensitive to habitat-specific constraints than males. Our study suggests that food availability is probably not limited for this generalist species in vineyards, contrary to cities.

Aggregations of plants surrounded by sparsely vegetated areas in drylands can arise when larger plants facilitate the recruitment of smaller "protégé" plants-a phenomenon referred to as the "nurse plant" effect. Numerous drivers can generate a nurse plant effect; efforts to simultaneously quantify multiple drivers are rare. Given higher densities of protégés beneath the foundational shrubs Larrea tridentata and Neltuma glandulosa, multiple potential mechanisms underlying the nurse plant effect were quantified in the Chihuahuan Desert, New Mexico, USA. As expected, there was a greater concentration of soil nutrients and lower photosynthetically active radiation and soil temperatures beneath shrubs. Throughout the study, however, soil moisture was consistently higher in interspaces despite the greater water holding capacity of soils beneath shrubs. Nutrient concentrations were greater beneath N. glandulosa than L. tridentata, while protégé numbers did not significantly differ among the species. The canopy size of both species was positively related to understory shading, and the size of N. glandulosa was positively related to soil nitrogen and microbial biomass. The results of this study suggest that much of the abiotic nurse plant effect of this low-latitude system is explained by radiation interception and concomitant reductions in temperatures experienced by protégé plants as opposed to the direct effects of shrubs on soil water availability. As global change pressures intensify in drylands, a loss of perennial plant cover could have negative effects on soil biogeochemical pools and plant diversity. Quantification of the mechanisms driving the nurse plant effect across environmental and climatic gradients could improve our understanding of plant community dynamics in drylands.

The functional traits of angiosperm vessels influence water transport and, therefore, metabolism and performance. Among these traits is a trade-off between vessel diameter and number, known as the "packing rule", which has been abundantly confirmed. But how packing rule is connected to major dimensions of variation in hydraulic function remains unclear across and within diverse species. Using data from the primary literature spanning 3992 species for intraspecific data and 54 species for interspecific data, and newly acquired data from the branches of 80 tree species, we examine the ways that key xylem traits plus leaf mass covary with the packing rule for stems across and within species. We analyzed vessel diameter, individual vessel lumen area, vessel density (number of vessels per unit area), lumen fraction (the product of individual vessel lumen area and vessel density), non-vessel lumen fraction (total area minus total lumen area), specific stem conductivity, and wood density. Mean vessel lumen area scaled approximately as the - 1.0 power of vessel density across the pooled data. Little variation in the lumen fraction was attributable to total vessel lumen area, whereas the lumen fraction was positively correlated with vessel density in stems and branches across all species. Wood density was weakly negatively correlated with mean vessel lumen area, but was not correlated with either lumen or non-vessel lumen fractions in branches or stems across species. Vessel area scaled positive with leaf mass. Specific stem conductivity was correlated with mean vessel lumen area and wood density. These results validate and extend the implications of the packing rule, and identify and define the limits of hydraulic efficiency and safety strategies within and across angiosperm species.