There is an urgent need for woodland expansion to help mitigate climate change and biodiversity loss. However, the process of natural regeneration of forest ecosystems is often slow, requiring active reforestation approaches. Factors limiting regeneration are complex, but there is increasing evidence that natural expansion of woodlands onto sites that have been treeless for a long period of time may be limited by the loss of microbial woodland-soil properties. This study explored the potential role of mycorrhizal associations in facilitating obligate ectomycorrhizal (ECM) tree establishment. We determined the spatial distribution patterns of ECM tree seedlings – Pinus sylvestris and Betula spp. - outwith the existing woodlands, in relation to established dual-mycorrhizal Salix. There was very strong evidence that ECM tree seedlings were more likely to be found growing within groups around dual-mycorrhizal Salix than as isolated individuals, supporting the view that Salix drives the current spatial distribution patterns by supporting tree establishment. We suggest that the ability of Salix to form dual-mycorrhizal associations with both arbuscular (AM) and ECM fungi allows these plants to become established across the open AM dominated vegetation. Over time these plants can become colonised by ECM fungi via aerial spores and then act as a source of inoculum for obligate ECM tree seedlings, which land as seeds in the vicinity of Salix. This study highlights the potential role of dual-mycorrhizal Salix as a nurse plant in supporting secondary forest succession of obligate ECM boreal/temperate woodland species onto adjacent open areas through nucleation. Overall, we concluded that there is potential for existing ECM networks to aid tree establishment and propose a nature-based approach to maximize reforestation efforts by targeting existing symbiotic fungal networks as nucleation points for tree planting. Our findings contribute to understanding the ecological dynamics involved in woodland expansion and restoration.

To produce viable seeds, plants must simultaneously allocate mass to other reproductive tissues; however, it remains unclear how big these investments are, relative to seeds, and how much the balance of investment across diverse species reflects broader variation in their life history strategies. In particular, species are known to vary in their seed mass, and the amount they invest in pollen attraction versus seed provisioning. We quantified overall reproductive investment and its partitioning among different reproductive tissues for 14 perennial species in a recurrent-fire heath community. Integrating two lineages of evolutionary theory led to the prediction that relative investment in different reproductive tissues would be correlated with a species’ seed size, and the data supported this. Species with larger seeds were found to mature a smaller proportion of ovules, to expend more of pre-zygotic investment on discarded tissues, and to invest more in seed provisioning compared to pollen attraction. A little more than half of this correlation is phylogenetically conservative, reflecting the tendency for many species in Proteaceae to have large seeds, low seed set and relatively lower investment in pollen attraction. The total cost of accessory tissues – reproduction-related mass not directly invested in the seed – ranged from 95.8% to 99.8% of total investment for species in this study. Counting only seeds thus substantially underestimates total reproductive investment. Many studies have established that the seed size of a species positions it along a colonization-competition life-history spectrum. Here we have shown that relative investment in pollen-attraction versus provisioning tissues and in successful versus discarded ovules are also associated with seed size. The seed size spectrum among angiosperms is therefore connected with a spectrum of reproductive allocation strategies.

Straw return into the field reduces the reliance on chemical fertilisers, promoting sustainable straw utilisation, and mitigating soil nodulation associated with excessive chemical fertiliser application. In this study, we investigated the effects of straw return on soil carbon and nitrogen fractions and the structural and functional diversity of soil microbial communities. We set up four treatments: S0 (0% straw returned to the field), S1/2 (50% straw returned), S1 (100% straw returned to the field), and S2 (200% straw returned to the field). The results revealed that most carbon and nitrogen fractions increased with increased amounts of straw returned into the field (soil organic carbon and total nitrogen: 6.4–39.8 % and 2.9–15.1 %, dissolved organic carbon and nitrogen: 1.4–37.9 % and 20.2–33.1 %, microbial biomass carbon and nitrogen: 26.3–129.3 % and 4.7–62.6 %, and light organic carbon and nitrogen: 52.4–155.9 % and 72.6–166.7 %). High-throughput sequencing and Biolog-ECO revealed that straw return significantly altered the relative abundance of bacterial and fungal communities and enhanced soil carbon metabolism. Redundancy and correlation analyses and partial least squares path modelling revealed that Proteobacteria (P = 0.002), Acidobacteriota (P = 0.004), Mortierellomycota (P < 0.05), and amino acid carbon sources (P < 0.01) were correlated with the changes in soil carbon and nitrogen fractions. Returning straw to the field significantly boosted the soil carbon and nitrogen fractions and affected soil carbon pools, particularly the active ones, by markedly influencing soil bacterial activity and consequently altering the soil carbon pool content. Our results provide a scientific and theoretical basis for enhancing nutrient content in dryland wheat calcareous brown soil, establishing a healthy soil ecological environment, and improving quality and efficiency in wheat production.

Linking characteristics of parasites to host diet-induced shifts in host-parasite interactions is a critical step in predicting the abundance of specific parasites within an ecosystem. A parasite’s infection route reflects a suite of parasite characteristics that could mediate the effects of host diet quality on host-parasite interactions, but the effect of infection route on the response of host-parasite interactions to host diet quality has not been quantified. We quantified these effects for the first time by experimentally manipulating a parasite capable of transmitting itself via multiple pathways utilized by a wide variety of parasites. We altered the diet phosphorus (P) content of Daphnia infected by the mixed mode transmitter Hamiltosporidian tvaerminnensis via one of two infection routes: horizontal, via the ingestion of spores from dead hosts, or vertical, via the infection of host offspring. Then, we quantified the effect of infection route on host diet-induced shifts in parasite load and virulence (i.e. host fecundity and survival). Overall, we found that horizontal infections were more sensitive to host diet than vertical infections. Low P diets decreased the parasite load and fecundity of all hosts, but had stronger negative effects on the loads of horizontally infected individuals than vertically infected ones. Likewise, horizontal infection reduced the survival of hosts fed low P (but not high P) diets while vertical infection did not affect survival. This increased sensitivity of horizontal infections to diet quality empirically supports the intuitive hypothesis that host diet quality exerts stronger effects on parasites that transmit via ingestion into a host’s gut than on parasites that transmit via routes less directly related to host nutrient uptake. Through these effects, host diet quality may shape the ecology and evolution of parasite communities.

Phenotypic plasticity is the key adaptive mechanism behind annual adjustment of breeding time in response to temperature. In nature, organisms are not only subjected to variation in temperature but encounter multiple fluctuating environmental factors that affect phenotypic expression, including conspecific density, which affects individual performances through resource competition. We examined the interactive effects of temperature and conspecific density at different spatial scales (territory and patch level) on breeding time and success utilizing data obtained from a long-term monitoring of a wild great tit (Parus major) population in a fragmented woodland. As expected, we detected earlier breeding in response to warmer spring temperatures but surprisingly, we report earlier laying at low local density, but no evidence of density effects at patch level. Birds experiencing low local density throughout their life bred on average earlier, but this response was also seen at the within-individual level showing earlier laying in years when individuals experienced a lower density than average. In terms of breeding success, earlier laying decreased the risk of brood failure and increased the number of fledglings. The number of fledglings was higher at low density at the territory level, while higher patch-level density increased the probability of brood failure. Altogether, these results support our hypothesis that density-related responses were likely mediated by food competition rather than increased numbers of low-quality birds or increased occupation of poorer territories at higher densities. This study highlights the importance of examining parameters at different spatial scales, along with the study of individual responses to multivariate cues for a comprehensive understanding of the variations in phenological plasticity.

Understanding the factors influencing how fast populations can spread across the landscape will be crucial as species ranges shift due to climate change. While the role of abiotic factors in determining expansion speed has been well studied in theory and empirical research, how interspecific interactions such as competition impact speed has received far less attention. Here, we investigated how seed dispersal distances change in response to competition and how these changes to seed distributions impact expansion speed. We dispersed four genotypes of the annual plant Arabidopsis thaliana with variation in life history traits into greenhouse mesocosms of either empty habitat or habitat containing the annual grass competitor, Lolium multiflorum. We found that competition decreased both mean and maximum dispersal distance. We then built a simulation model of range expansion with experimental data from this and a prior experiment to understand whether competition slows species expansions primarily through decreasing dispersal or fecundity. We found that competition primarily slows expansion speed through decreases in dispersal, but that when competition impacts both dispersal and fecundity, expansions slow more than with dispersal alone. The genotype with traits associated with longer distance dispersal was the most affected by competition in both experimental dispersal and simulations. This research suggests that not only does competition slow range expansions through decreases in both fecundity and dispersal, but that there may be consequences for evolutionary processes at the leading edge.

Deterministic and stochastic factors shape ecological communities. However, a quantitative synthesis of the factors underlying the balance among different assembly processes is lacking. Here, we synthesized data from 149 datasets covering major biotic groups and ecosystem types globally. We used a null model approach based on Raup-Crick dissimilarities and Bayesian meta-regression to analyze the data. We found that communities were more under homogeneous selection than heterogeneous selection across biotic taxa and ecosystems. Environment selected species homogeneously more often at small scales while heterogeneously more often at large scales. Stochasticity also showed scale-dependence as stochastic community assembly increased with study scale. Homogeneous and heterogeneous selection were strongest at high latitudes while stochastic factors were strongest in tropics. Marine systems had the highest degree of homogeneous selection and the lowest stochasticity. We provide the first analysis of community assembly across taxa and ecosystems which should be important for a better understanding of how communities respond to environmental change.

Plant-associated microbes play a key role in mediating the relationship between plant diversity and productivity. However, previous studies have generally focused on a sole microbial guild (i.e. plant-beneficial microbes or pathogens), and on either aboveground or belowground microbes. As a result, the interplay among different microbial guilds and the overall impact of above- and belowground microbes on plant diversity-productivity relationships have rarely been investigated. Here we carried out an experiment where we applied microbial inocula collected from leaves and soils in the field onto plant leaves and soil in a greenhouse experiment with a herbaceous plant community. We showed that microbial inoculation of leaves reduced plant productivity and this negative effect was weaker at higher plant diversity, which promoted positive diversity-productivity relationships through complementarity effects. In contrast, microbial inoculation of soil alone had no impact on plant diversity-productivity relationships, but it counteracted the negative effects of leaf inoculum on plant productivity and weakened the leaf microbe-induced positive diversity-productivity relationships. We found that the abundance of arbuscular mycorrhizal fungi increased when soil microbes were inoculated, and such increase was more significant at lower plant diversity, potentially explaining the effects of soil inoculation on plant productivity. These results suggest that the belowground plant beneficial microbes can counteract the effect of aboveground plant pathogens in mediating positive plant diversity-productivity relationships. Simultaneous study of plant-pathogenic and -beneficial microbes both above- and belowground is required to better understand the contributions of plant-associated microbes to biodiversity-ecosystem function relationships.

Dissolved organic matter and nutrients released from forest leaf litter are important cross-ecosystem resources that support freshwater ecosystems. Dissolved organic matter released from leaf litter is one of the allochthonous sources for heterotrophic organisms in freshwater communities. However, the role of macro- and micronutrients released from leaf litter in producing autochthonous organic matter in aquatic ecosystems is not necessarily well understood. In this study, therefore, we investigated how dissolved nutrients released from leaf litter affect the algal growth, biomass production, and cell elemental quotas. Specifically, we focused on the responses of the green algae to TDN, TDP, and micronutrients released from the leaf litter of 11 temperate tree species. We found that the algal growth rate increased with TDP when micronutrients were amended. In contrast, the algal biomass production increased with TDN, regardless of micronutrient amendment. Micronutrient limitation of algal growth rate was found in the leaf litter leachates from oak, Japanese elm, and Japanese hemlock. However, algal biomass production was limited by micronutrients only in the leaf litter leachate from Japanese hemlock. More importantly, leaf litter leachates from different tree species altered algal cell quotas and C:N:P ratios, which would affect secondary production. These results suggest that forest vegetation change or succession affect the quantity and quality of autochthonous organic matter and thus the mass transfer efficiency in the aquatic community by changing the stoichiometry of nutrient input from the leaf litter.

Declining enemy release predicts that invasive plants accumulated more soil natural enemies, and the increase in enemies may inhibit growth of invasive plants themselves. But most studies focus on historical time rather than short-term. We designed a fully crossed factorial experiment, we grew individuals of four congeneric pairs of invasive and native plant species in 2.5 L pots that contained live or sterilized field soil under two harvest time (first vs second). Results shows that soil microbes tended to have a slight positive effect on total biomass of the native plant species over time in short-term, while the effect of soil microbes on invasive plants as their total biomass tended to change from promotion to inhibition over time in short-term. Overall, these results suggest that regardless of the direction and strength of plant-soil feedback on invasive plant species, invasive plant species consistently may grow larger than co-occurring native plant species over time in short-term.

Disturbance and connectivity control biodiversity, ecosystem functioning and their interactions across connected aquatic and terrestrial ecosystems, that form a meta-ecosystem. In rivers, detrital organic matter (OM) is transported across terrestrial-aquatic boundaries and along the river network and decomposed on the way by diverse communities of organisms, including microorganisms and invertebrates. Drying naturally fragments most river networks and thereby modify organism dispersal and OM transfers across ecosystems. This may prevent organisms from reaching and consuming OM, generating mismatches between community composition and decomposition. However, little evidence of the effects of drying on river network-scale OM cycling exists. Here, we aim to examine the effects of fragmentation by drying on the structure of consumer communities and ecosystem functioning within interacting aquatic-terrestrial river ecosystems. We monitored leaf resource stocks, invertebrate communities and decomposition rates in the instream and riparian habitats of 20 sites in a river network naturally fragmented by drying. Although instream resource quantity and quality increased with drying severity, decomposition decreased due to changes in invertebrate communities and particularly leaf-decomposer abundance. Invertebrate-driven decomposition peaked at intermediate levels of upstream connectivity, suggesting that intermediate levels of fragmentation can promote the functioning of downstream ecosystems. We found that the variability in community composition was unrelated to variability in decomposition at sites with low connectivity and high drying severity, suggesting that such conditions can promote mismatches between community composition and decomposition. Decomposition instream was correlated to decomposition in the riparian area, revealing one of the first network-scale evidence of the links between ecosystem functions across terrestrial-aquatic boundaries. Our river network-scale study thus demonstrates the paramount effect of drying on the dynamics of resources, communities and ecosystem functioning in river networks, with crucial implications for the adaptive management of river networks and preservation of their functional integrity.