Response of leaf anatomical structure of to climate warming and provenance variation.

Exploring the response of leaf anatomical structure to climate warming is helpful for understanding the adaptive mechanisms of trees to climate change. We conducted a warming experiment by transplanting seedlings of from 11 provenances to two common gardens, and examined the response of leaf anatomical structure to climate warming. The results showed that warming significantly increased leaf thickness (T), upper epidermal mesophyll thickness (T), lower epidermal mesophyll thickness (T), endodermal thickness (T), vascular bundle diameter (D), transfer tissue thickness (T), and the percentage of mesophyll thickness to T(P), and significantly decreased the upper epidermal thickness (T) and the percentage of epidermal thickness to T (P).

New Intrinsic Ecological Mechanisms of Leaf Nutrient Resorption in Temperate Deciduous Trees.

Leaf nutrient resorption is a critical process in plant nutrient conservation during leaf senescence. However, the ecological mechanisms underlying the large variability in nitrogen (NRE) and phosphorous (PRE) resorption efficiencies among trees remain poorly understood. We conducted a comprehensive study on NRE and PRE variability using 61 tree individuals of 10 temperate broad-leaved tree species.

Provenance variation of root C, N, P, and K stoichiometric characteristics under different diameter classes of .

For exploring the difference of root stoichiometric characteristics among diameter classes and provenances, we examined the contents and stoichiometric ratios of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) in three diameter classes of roots (0-1, 1-2 and 2-5 mm, respectively) of 39-year-old grown in a common garden. The results showed that root element contents and their stoichiometric ratios had significant difference among three diameter classes of roots. C content, C:N, C:P, C:K were the lowest, and N, P, K contents, N:P, and N:K were the highest in 0-1 mm diameter class roots.

Trade-offs between leaf stoichiometric characteristics and photosynthetic traits of and its differences among provenances.

Variations and trade-offs between leaf stoichiometric characteristics and photosynthetic traits are indicative of ecological adaptation strategies of plants and their responses to environment changes. In a common garden of Maoershan, we measured leaf stoichiometric characteristics (carbon content (C), nitrogen content (N), phosphorus content (P), C/N, C/P, N/P) and photosynthetic traits (maximum net photosynthetic rate (), maximum electron transport rate (), maximum carboxylation rate ()) of from 17 geographical provenances. We examined the provenance differences in stoichiometric characteristics and photosynthetic traits, and analyzed their trade-offs and influencing factors.

Transplanting larch trees into warmer areas increases the photosynthesis and its temperature sensitivity.

To investigate the effects of climate warming on photosynthesis, Dahurian larch (Larix gmelinii Rupr.) trees from four sites (spanning ~ 5.5° in latitude and ~4 °C of warming) within the geographic range in China were transplanted into a common garden close to the warmer border in 2004.

[Transcriptome analysis on responses of leaf photosynthesis and nitrogen metabolism of to environmental change].

To reveal molecular mechanisms underlying photosynthesis responses of Dahurian larch () to environmental changes, we used the high-throughput sequencing technology to sequence the transcriptome of larch leaves from four latitudinal sites with different environmental conditions, and compared differential expression genes (DEGs). The four sites from high- to low-latitude were Tahe (52°52' N), Songling (50°72' N), Heihe (49°22' N), and Dailing (47°08' N). A total of 282428811 clean reads were sequenced out, among which the abundace of DEGs were 16915, 18812, 28536, 20635, 29957 and 23617 for the Tahe-Songling, Tahe-Heihe, Tahe-Dailing, Songling-Heihe, Songling-Dailing, and Heihe-Dailing comparisons, respectively.

Thermal acclimation of leaf dark respiration of Larix gmelinii: A latitudinal transplant experiment.

The response of tree leaf dark respiration (R) to temperature change is important in modeling and predicting forest carbon (C) cycling under climate change, but it has rarely been investigated in nature. We conducted a field experiment by transplanting the trees of Larix gmelinii - the dominant tree species in Chinese boreal forests from four latitudinal sites to a common garden near the warm border of its range. Our objective was to explore thermal acclimation of R and the underlying mechanisms by comparing the temperature-response curves of R and related leaf traits both in the common garden and at the original sites.

The transcriptional events and their relationship to physiological changes during poplar seed germination and post-germination.

Background: Seed germination, the foundation of plant propagation, involves a series of changes at the molecular level. Poplar is a model woody plant, but the molecular events occurring during seed germination in this species are unclear.

Results: In this study, we investigated changes in gene transcriptional levels during different germination periods in poplar by high-throughput sequencing technology.

[Effects of nitrogen fertilization on fine root lifespan of Fraxinus mandshurica and Larix gmelinii].

Root observation tubes (minirhizotrons) were used to study the effects of nitrogen addition on the fine root growth of Fraxinus mandshurica and Larix gmelinii, with the correlations between the fine root lifespan and nitrogen availability analyzed. After the nitrogen addition, the fine root number of F. mandshurica and L.

[Carbon and nitrogen storages and allocation in tree layers of Fraxinus mandshurica and Larix gmelinii plantations].

By the methods of wood analysis and sequential soil core, the biomass and productivity of the tree layers in 20-year old Fraxiuns mandshurica and Larix gmelinii plantations, as well as the carbon (C) and nitrogen (N) storages in the above- and below-ground organs of the stands, were estimated. The biomass of F. mandshurica and L.

[Effects of nitrogen fertilization on ectomycorrhizal infection of first order roots and root morphology of Larix gmelinii plantation].

In this paper, the first order roots of Larix gmelinii plantation under N fertilization were sampled from different soil depths in different seasons to study their morphology under effects of ectomycorrhizal fungi. The results showed that the infection rate of ectomycorrhizal fungi on the first order roots was significantly affected by soil N availability, soil depth, and season. N fertilization induced a decrease of the infection rate, and the decrement varied with soil depth and season.