Plant Ecology最新文献

As climate change continues and the frequency and intensity of droughts become more prevalent in some regions, plant populations are facing greater ecological pressures. The objective of this study was to observe the response of a rare plant species to an extreme drought event associated with climate change. To study this response, we collected seeds from three populations of Collinsia multicolor (San Francisco collinsia, Plantaginaceae) found in central California both before and after the state's historic 2012-2016 drought. We conducted a greenhouse study to examine contemporary evolution between the collection years, and included a drought treatment to study plasticity. We measured three traits that indicate life history, morphological, and physiological responses to drought, including flowering time, stomatal density, and chlorophyll fluorescence. In the two coastal populations, where interannual moisture variation is greatest, we observed evolution only in stomatal density, while we observed plasticity in all measured traits. In contrast, the driest inland population showed no response to the drought or to the watering treatments, which is consistent with other studies that have found less response to drought in pre-adapted populations. Overall, our results suggest that plasticity is favored in variable environments. However, they also highlight that the pace of evolution may be insufficient to respond to current environmental change.

Climate changes in temperate regions are expected to result in warmer, shorter winters in temperate latitudes. These changes may have consequences for germination of plant species that require a period of physiological dormancy. The effect of cold duration on seed germination has been investigated in a number of plant taxa, but has not been well studied in wetland and bottomland forest tree species, an ecosystem that is threatened by habitat homogenization. Our work sought to test the role of changing winter temperatures on seed germination in specialist (Nyssa aquatica and Taxodium distichum) and generalist (Acer rubrum and Liquidambar styraciflua) tree species within forested wetlands throughout the eastern U.S. The experiment was conducted in an environmental chamber in Norfolk, VA, USA. Seeds of T. distichum, N. aquatica, A. rubrum, and L. styraciflua were exposed to each of seven pre-germination cold exposure durations (0, 15, 30, 45, 60, 75, and 90 days) and observed for germination for 30 days. Cold stratification duration positively impacted total percent germination in N. aquatica (p < 0.0001) as well as A. rubrum (p = 0.0008) and T. distichum (p = 0.05). Liquidambar styraciflua seeds exhibited more rapid rates of germination with increasing cold exposure duration and greater percent germination compared to the others regardless of cold stratification duration. Our results provide insight into how community dynamics and biodiversity of wetland and bottomland trees may shift with a changing climate. Further, this work emphasizes the importance of understanding the role of plant functional traits in early life stages in community dynamics and has implications for management practices.

Fine root stoichiometry characterizes nutrient cycling in terrestrial ecosystems. Mycorrhizae are major regulators of plant carbon (C), nitrogen (N) and phosphorus (P) nutrients. However, our understanding of the fine root stoichiometry at the global scale and their driving role by mycorrhizae is extremely limited. This study used global data to explore the stoichiometry of fine root C, N, P and their relationships with climatic factors across different mycorrhizal statuses and types. The results showed that obligately mycorrhizal (OM) species (always form mycorrhizae) had significantly higher fine root N contents (12.66 mg/g), while non-mycorrhizal (NM) species had significantly higher fine root P contents (1.50 mg/g). Arbuscular mycorrhizal (AM) plants had significantly lower fine root C contents (443.11 mg/g) and higher fine root N contents (13.55 mg/g). AM + ECM plants had significantly higher fine root C/N, root C/P, and root N/P. Mycorrhiza had a positive effect on fine roots N, with AM having the most pronounced positive effect. The correlation between the elements of fine roots was more pronounced among OM and AM plants. Mean annual precipitation (MAP) and mean annual temperature (MAT) had positive effects on C in OM plants, with the most pronounced positive effects on C in ECM plants. MAP and MAT had negative effects on C in FM plants. MAT had a positive effect on N in NM plants, but a negative effect on P in OM plants. Our study revealed biogeographic patterns of global fine root C:N:P stoichiometry and advanced our understanding of fine root biogeochemical cycling.

The relationship between arbuscular mycorrhizal fungi (AMF) and secondary vegetation (SV) species at early phenological stages is critical for the successful establishment of these plants on disturbance sites in temperate forests. The main objective of this research is to evaluate the effect of AMF colonization on the early phenological stages (germination and early growth) of three shrub species present in the SV of a temperate forest in central Mexico. We collected soil from different sites in the Abies religiosa forest in central Mexico. We collected seeds of Acaena elongata, Ageratina glabrata, and Solanum pubigerum. We used a controlled experimental design with pasteurized soil (-AMF treatments) and unpasteurized soil (+ AMF treatments). We monitored germination percentage, growth (shoot and root weight and total biomass), AMF root colonization, and the mycorrhizal response index (MRI) for each plant species. All three species tested benefited by AMF, showing higher germination rates. Shoot and root weight and total biomass were significantly higher in the + AMF treatment. Solanum pubigerum showed greater stem length and Ageratina glabrata showed greater root development due to AMF. Ageratina glabrata and Acaena elongata were the most responsive to AMF as indicated by MRI. This research underscores the critical role of AMF in the early phenological stages of SV and highlights the potential ecological benefits of AMF in supporting plant germination and plant growth. These results suggest that AMF enhance germination and early growth of secondary vegetation species, which can be considered in management plans for forest ecosystems.

Exposure to competition from invasive plants over multiple generations, or multigenerational invasive exposure can drive rapid native plant trait change. While invasive plant effects can be concentrated belowground, few studies consider native plant root trait responses to multigenerational invasive exposure. So, here we quantified root and shoot trait responses of the native grass Sporobolus airoides in response to multigenerational invasive exposure. S. airoides was sourced from invader-experienced subpopulations that co-occurred in the field for 58 years on average with invasive Russian knapweed (Rhaponticum repens) and from nearby invader-naïve plants that did not co-occur with the invasive. Maternal plants of these subpopulations were collected in the field, then transplanted to a greenhouse in Wyoming, USA. The first generation of seeds from these transplants were collected and grown for another round of seed collection (generation two). We grew invader-experienced and invader-naïve seedlings from both generations in a growth chamber in Illinois, USA. We found the largest shifts in root traits with invasive exposure status (e.g., for root mass fraction (standardized mean difference (SMD) = 0.5), primary root count (SMD) = 0.52), root length (SMD) = 0.44)); invader-experienced plants had significantly larger root traits in generation two, which was associated with greater survival, and thus may be adaptive. Since invader-experienced accessions have been evaluated as valuable restoration material in invaded sites, these findings highlight the need for continued root research in multigenerational invasive plant interactions and the need to evaluate more than one generation removed from a biotic influence.

Pollinators seek high quality nectar and pollen rewards critical for their growth and reproduction. Volatile emissions from inflorescences may signal plant health and floral resource quality to these flower-visiting insects. To understand the relationship between floral volatile emission and pollinator preference in a field setting, we conducted a replicated garden experiment consisting of 18 native perennial species from three different plant families with varying nutritional resource quality. We collected flower-visiting insects and floral volatile emissions over two field seasons, detecting over 60 volatile compounds and over 150 insect species. We collated trait data of visiting insects (bee or non-bee, body size, degree of sociality, nesting behavior, and whether the visitor was non-native) and evaluated interactions between these traits and volatile composition. Among the insect traits, bees and larger visitors had negative associations with sesquiterpenes, while in contrast visitors with complex nesting behaviors and social insects had positive associations. When comparing plant traits with bee traits, bee visitors had negative associations with purple inflorescences and larger insects and social insects both had positive associations with yellow inflorescences. We tested for direct associations between volatile class and insect taxa and found that sesquiterpenes had a strong positive relationship with hoverfly presence. This work demonstrates the complexity of floral volatiles as signals for pollinating insects and how floral scent composition allows individual compounds to act synergistically or antagonistically. These results can help us to better understand pollinator preferences and visitation patterns in the broad context of chemical ecology.

Understanding plant adaptive strategies to aridity is crucial for ecological research, particularly in the current context of climate change and increasing drought. This study focuses on the intraspecific phenotypic variation of the wild olive (Olea europaea subsp. europaea var. sylvestris), one of the most emblematic species of the Mediterranean Basin, widely distributed in Morocco. The research is based on measuring nine leaf and plant-size related traits in 130 trees across 13 populations under varying climate conditions and vegetation covers. The study explores the adaptive strategies of wild olive trees in response to increasing aridity and aridification. The results indicate that the nine traits exhibit significant covariation trends along environmental gradients, reflecting plant strategies related to resource acquisition, resource investment, and water use. Wild olive trees demonstrate substantial intraspecific variation both among and within populations in response to these environmental gradients. Climate, altitude, and vegetation cover together explain 93.8% of the trait covariations. The study elucidates the mechanisms underlying the adaptive strategies of wild olive trees to cope with stressful conditions. The findings suggest that wild olive trees adapt to stressful environments by adopting a conservative strategy, characterized by lower resource investment and higher water-use efficiency. This research underscores the importance of considering intraspecific variation in plant responses to environmental stressors and demonstrates the utility of trait-based approaches in understanding plant strategies under such conditions.

This study highlights the coupling effect of disturbance and Lantana camara invasion on vegetation and soil properties in the least disturbed (LD), moderately disturbed (MD) and highly disturbed (HD) sites in the semi-arid region of Aravalli Mountain, South Delhi. A total of 60 quadrats of 10 m × 10 m were laid for tree species and 5 m × 5 m for shrub species in the LD, MD and HD sites for phytosociological study. Soil samples were collected at three places: areas occupied by Lantana camara (LC) and Adhatoda vasica (AV), as well as areas of bare soil (no vegetation) at two different depths: the upper layer (0–10 cm) and the lower layer (10–20 cm). Results showed higher tree diversity in the LD site, whereas shrub diversity was high in HD site. The relative density (RD) of invasive L. camara and soil properties was maximum in MD (61.5%) and minimum (55.5%) in HD site, however low soil nutrients in HD site may be due to the lower RD of LC. Statistical analysis showed significant (p < 0.05) high soil moisture, soil organic carbon (SOC), microbial biomass carbon (MBC) and nitrogen (MBN) in MD site. SOC, TN, MBC and MBN were higher under LC-occupied regions compared to AV in LD and MD sites. In HD site, nutrient content was higher under AV region, reflecting that in nutrient-deficit soil, native species adapt and resist the invasion of LC. However, among the different biotic and abiotic factors, disturbance is one of the major drivers that promotes plant invasion.

The ability of non-native plant species to tolerate water scarcity and high temperatures, especially during the early stages of development, may influence their invasive potential. Ligustrum lucidum is a tree native to warm temperate areas of Asia. To understand the potential expansion of this non-native invasive species into more arid regions, we conducted an experiment in incubation chambers to evaluate seed germination under different water potentials and the response of its seedlings under different water availability and temperature scenarios. Seeds were collected from central Argentina and placed to germinate under four different water potentials (−0.2; −0.4; −0.7 and −1.2 MPa) created with polyethylene glycol 6000. Additionally, L. lucidum seedlings were subjected to contrasting levels of water availability combined with different periods of exposure to high temperatures. Germination measurements (germination percentage, velocity, and synchronicity) decreased at lower water potentials. No germination occurred at −0.7 and −1.2 MPa. The seedlings showed a slight increase in mortality and a significant reduction in most of the growth variables under low water availability, while exposure to high temperatures had significant effects only on chlorophyll estimate. The germination response of L. lucidum to water deficits could pose a significant constraint on its establishment in arid ecosystems. Nonetheless, this constraint may be alleviated by the species’ prolific propagule production, coupled with asynchronous seed germination, which may help it exploit more humid micro-sites or sporadic water events. Furthermore, the drought tolerance of its seedlings strongly warns against the use of this species as an ornamental plant in arid environments.

The impact of climate warming on the decomposition of wetland plant litter has received widespread attention. We used the litter bag method to compare and study the decomposition processes of three species of litter in the Nansi Lake wetland of China, Phragmites australis (Ph), Nelumbo nucifera (Ne) and Typha domingensis (Ty), and simulate the changes in the decomposition characteristics of litter and the structure of the fungal community under atmospheric warming (2.0 ± 0.5 °C ~ 4.0 ± 0.5 °C) using open-top chambers (OTCs). The results showed that increasing temperature significantly accelerated the decomposition process of the three species of litter and increased the beta and alpha diversities of the fungal communities at the class level. The fungal community co-occurrence network showed that the fungal community network associated with litter decomposition under warming conditions consisted mainly of symbiotic relationships, and the order of the average clustering coefficients of the three networks was 2.0 ± 0.5 °C (0.81) > 4.0 ± 0.5 °C (0.77) > control (0.57). Moderate warming increased the degree of positive correlation and clustering between fungi, thus accelerating the decomposition process of plant litter and affecting the carbon balance of wetland ecosystems.