Search Results (4)

Fine roots are essential for terrestrial biogeochemical cycles. Mycorrhizal fungi’s functions in regulating the uptake of carbon (C), nitrogen (N), and phosphorus (P) in plants are increasingly being recognized. However, the influence of mycorrhizae on Chinese plants’ fine-root stoichiometry has not been considered. Herein, 772 plants with identified mycorrhizal types were divided into arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) types to investigate the differences in their fine-root stoichiometry and their driving factors. The results showed that the AM and ECM fine-root stoichiometries were significantly different (p < 0.001; p < 0.05). The AM plants’ fine-root stoichiometry was mainly affected by the soil environment (8.76–90.12%), while ECM plants were more sensitive to climatic factors (23.51–52.41%). Further analysis showed that the mean annual temperature (MAT) was significantly correlated with AM plants’ fine-root C and P and ECM plants’ fine-root N and P. Mean annual precipitation (MAP) was significantly correlated with all AM plants’ fine-root elements (p < 0.01) but was only negatively correlated with ECM fine-root P. It was concluded that the mycorrhizal type affects the response of the fine-root stoichiometry to climate and soil variations. Therefore, the mycorrhizal effect deserves attention when studying the relationship between plant nutrient uptake and environmental changes. Full article

Senesced leaves play a vital role in nutrient cycles in the terrestrial ecosystem. The carbon (C), nitrogen (N) and phosphorus (P) stoichiometries in senesced leaves have been reported, which are influenced by biotic and abiotic factors, such as climate variables and plant functional groups. It is well known that mycorrhizal types are one of the most important functional characteristics of plants that affect leaf C:N:P stoichiometry. While green leaves’ traits have been widely reported based on the different mycorrhiza types, the senesced leaves’ C:N:P stoichiometries among mycorrhizal types are rarely investigated. Here, the patterns in senesced leaves’ C:N:P stoichiometry among plants associated with arbuscular mycorrhizal (AM), ectomycorrhizal (ECM), or AM + ECM fungi were explored. Overall, the senesced leaves’ C, with 446.8 mg/g in AM plants, was significantly lower than that in AM + ECM and ECM species, being 493.1 and 501.4 mg/g, respectively, which was mainly caused by boreal biomes. The 8.9 mg/g senesced leaves’ N in ECM plants was significantly lower than in AM (10.4 mg/g) or AM + ECM taxa (10.9 mg/g). Meanwhile, the senesced leaves’ P presented no difference in plant associations with AM, AM + ECM and ECM. The senesced leaves’ C and N presented contrary trends with the changes in mean annual temperature (MAT) and mean annual precipitation (MAP) in ECM or AM + ECM plants. The differences in senesced leaves’ C and N may be more easily influenced by the plant mycorrhizal types, but not P and stoichiometric ratios of C, N and P. Our results suggest that senesced leaves’ C:N:P stoichiometries depend on mycorrhizal types, which supports the hypothesis that mycorrhizal type is linked to the evolution of carbon–nutrient cycle interactions in the ecosystem. Full article

Designer niches in which environmental variables are controlled are useful in forest restoration to enhance survival of planted tree seedlings. Here, we evaluate particular manipulated habitats, on site variables, and pre-seedling conditions hypothesized to improve the survival rate of whitebark pine (Pinus albicaulis) seedlings out-planted in Waterton Lakes National Park. The tree species is in peril due to blister rust and mountain pine beetle infestations in its range; and is a restoration priority in Waterton Lakes because populations in the park are highly infected with blister rust (up to 90%). At Summit Lake, 21 plots were set up and half of each was terra-torched; 1000 seedlings were planted in clusters of three, under four conditions: on burned areas in burned beargrass mats, in burned areas where beargrass mats were not present, in unburned areas where beargrass was present, and in unburned areas without beargrass. This study reports data for the seventh year after planting, and overall, survival was 53% for individual seedlings and at least one seedling survived in 60.8% of clusters. Planting in burned areas increased cluster survival (by 34.3%, p ˂ 0.0001) and planting near microsites increased cluster survival (by 19.3%, p ˂ 0.0001); the type of microsite did not make a difference. Planting in beargrass mats decreased survival, but not significantly (8.9%, p = 0.11) and this was true for burns, not unburned areas. Inoculation with native ectomycorrhizal fungi did not enhance survival most likely because controls on lightly terra-torched and unburned areas had access to local native fungi. This is the first study to report statistics on the planting of seedlings in clusters; the results need to be compared with studies where seedlings are planted individually. Full article

In forest ecosystems, fungal mats are functionally important in nutrient and water uptake in litter and wood decomposition processes, in carbon resource allocation, soil weathering and in cycling of soil resources. Fungal mats can occur abundantly in forests and are widely distributed globally. We sampled ponderosa pine/white fir and mountain hemlock/noble fir communities at Crater Lake National Park for mat-forming soil fungi. Fungus collections were identified by DNA sequencing. Thirty-eight mat-forming genotypes were identified; members of the five most common genera (Gautieria, Lepiota, Piloderma, Ramaria, and Rhizopogon) comprised 67% of all collections. The mycorrhizal genera Alpova and Lactarius are newly identified as ectomycorrhizal mat-forming taxa, as are the saprotrophic genera Flavoscypha, Gastropila, Lepiota and Xenasmatella. Twelve typical mat forms are illustrated, representing both ectomycorrhizal and saprotrophic fungi that were found. Abundance of fungal mats was correlated with higher soil carbon to nitrogen ratios, fine woody debris and needle litter mass in both forest ecotypes. Definitions of fungal mats are discussed, along with some of the challenges in defining what comprises a fungal “mat”. Full article