Impacts of ontogenetic and altitudinal changes on morphological traits and biomass allocation patterns of Fritillaria unibracteata

Environmental variations and ontogeny may affect plant morphological traits and biomass allocation patterns that are related to the adjustments of plant ecological strategies. We selected 2-, 3-and 4-year-old Fritillaria unibracteata plants to explore the ontogenetic and altitudinal changes that impact their morphological traits(i.e., plant height, single leaf area,and specific leaf area) and biomass allocations [i.e.,biomass allocations of roots, bulbs, leaves, stems, and flowers] at relatively low altitudinal ranges(3400 m to 3600 m asl) and high altitudinal ranges(3600 m to4000 m asl). Our results indicated that plant height,root biomass allocation, and stem biomass allocation significantly increased during the process of individual growth and development, but single leaf area, specific leaf area, bulb biomass allocation, and leaf biomass allocation showed opposite trends.Furthermore, the impacts of altitudinal changes on morphological traits and biomass allocations had no significant differences at low altitude, except for single leaf area of 2-year-old plants. At high altitude,significantly reduced plant height, single leaf area and leaf biomass allocation for the 2-year-old plants,specific leaf area for the 2-and 4-year-old plants, and stem biomass allocation were found along altitudinal gradients. Significantly increased sexual reproductive allocation and relatively stable single leaf area and leaf biomass allocation were also observed for the 3-and 4-year-old plants. In addition, stable specific leaf area for the 3-year-old plants and root biomass allocation were recorded. These results suggested that the adaptive adjustments of alpine plants, in particular F. unibracteata were simultaneously influenced by altitudinal gradients and ontogeny.

Symbiotic mycorrhizal types affect patterns of tree aboveground and belowground C allocation in Northeast China

Background Given the ubiquitous nature of mycorrhizal symbioses,different symbiotic fungi have obvious differences in structure and function,which may affect associated tree aboveground and belowground C allocation dynamics.However,the mechanisms underlying tree aboveground and belowground C allocation and its response to symbiotic mycorrhizal types and other factors(e.g.,resource availability)remain poorly understood.Results We used forest inventory data to explore the potential mechanism of tree aboveground and belowground C allocation patterns in Northeast China.Our results showed that tree-fungal symbioses were related to the patterns of tree C allocation.The ratio of aboveground to belowground C pool was significantly higher in ectomycorrhizal(EM)-associated trees than that in arbuscular mycorrhizal(AM)-associated trees.Symbiotic mycorrhizal types were associ-ated with the responses of tree aboveground and belowground C allocation to different factors,such as mean annual precipitation(MAP)and mean annual temperature(MAT).Almost all factors significantly increased aboveground C allocation in AM-associated trees but significantly decreased it in EM-associated trees.Moreover,after controlling the other factors,the effects of climate factors(MAT and MAP)on the C allocation of AM-and EM-associated trees were similar.Increases in MAT and MAP significantly increased belowground and aboveground C allocation,respectively.Conclusions Our results demonstrate symbiotic mycorrhizal types play an important role in controlling tree aboveground and belowground C allocation and dynamics.

Comparisons of carbon storages in Cunninghamia lanceolata and Michelia macclurei plantations during a 22-year period in southern China

Tree species composition was important for carbon storage within the same climate range.To quantify the dynamics of ecosystem carbon allocation as affected by different tree species,we measured the above-and below-ground biomass accumulation in 22 years,as well as the tissue carbon concentrations of trees in Cunninghamia lanceolata plantation and Michelia macclurei plantation.Results indicated that M.macclurei plantation significantly stored more carbon（174.8 tons/hm2） than C.lanceolata plantation（154.3 tons/hm2）.Most of the carbon was found in the soil pool（57.1% in M.macclurei plantation,55.2% in C.lanceolata plantation）.Tree and soil component of M.macclurei plantation possessed significantly higher carbon storage than that of C.lanceolata plantation（p 〈 0.05）.No significant difference was found in the carbon storage of understory and forest floor.These results suggest that the broadleaved species（M.macclurei） possesses greater carbon sequestration potential than the coniferous species（C.lanceolata） in southern China.

Relationship between dew presence and Bassia dasyphylla plant growth

Dew has been recognized for its ecological significance and has also been identified as an additional source of water in arid zones. We used factorial control experiment, under dew presence in the field, to explore photosynthetic performance, water status and growth response of desert annual herbage. Bassia dasyphylla seedlings were grown in contrasting dew treatments （dew-absent and dew-present） and different watering regimes （normal and deficient）. The effects of dew on the water status and photosynthetic performance of Bassia dasyphylla grown in a desert area of the Hexi Corridor in Northwestern China, were evaluated. The results indicated the pres- ence of dew significantly increased relative water content （RWC） of shoots and total biomass of plants in both water regimes, and enhanced the diurnal shoot water potential and stomatal conductance in the early morning, as well as photosynthetic rate, which reached its maximum only in the water-stressed regime. The presence of dew increased aboveground growth of plants and photosynthate accumulation in leaves, but decreased the root-to-shoot ratio in both water regimes. Dew may have an important role in improving plant water status and ameliorating the adverse effects of plants exposed to prolonged drought.

Relationships among the Stem,Aboveground and Total Biomass across Chinese Forests

Forest biomass plays a key role in the global carbon cycle. In the present study, a general allometric model was derived to predict the relationships among the stem biomass Ms, aboveground biomass MA and total biomass MT, based on previously developed scaling relationships for leaf, stem and root standing biomass. The model predicted complex scaling exponents for MT and/or MA with respect to Ms. Because annual biomass accumulation in the stem, root and branch far exceeded the annual increase in standing leaf biomass, we can predict that MT ∝MA ∝ Ms as a simple result of the model. Although slight variations existed in different phyletic affiliations （i.e. conifers versus angiosperms）, empirical results using Model Type Ⅱ （reduced major axis） regression supported the model＇s predictions. The predictive formulas among stem, aboveground and total biomass were obtained using Model Type I （ordinary least squares） regression to estimate forest biomass. Given the low mean percentage prediction errors for aboveground （and total biomass） based on the stem biomass, the results provided a reasonable method to estimate the biomass of forests at the individual level, which was insensitive to the variation in local environmental conditions （e.g. precipitation, temperature, etc.）.

Assessment of above- and belowground carbon pools in a semi-arid forest ecosystem of Delhi, India

Background:Assessment of carbon pools in semi-arid forests of India is crucial in order to develop a better action plan for management of such ecosystems under global climate change and rapid urbanization.This study,therefore,aims to assess the above-and belowground carbon storage potential of a semi-arid forest ecosystem of Delhi.Methods:For the study,two forest sites were selected,i.e.,north ridge(NRF)and central ridge(CRF).Aboveground tree biomass was estimated by using growing stock volume equations developed by Forest Survey of India and specific wood density.Understory biomass was determined by harvest sampling method.Belowground(root)biomass was determined by using a developed equation.For soil organic carbon(SOC),soil samples were collected at 0–10-cm and 10–20-cm depth and carbon content was estimated.Results:The present study estimated 90.51 Mg ha−1 biomass and 63.49 Mg C ha−1 carbon in the semi-arid forest of Delhi,India.The lower diameter classes showed highest tree density,i.e.,240 and 328 individuals ha−1(11–20 cm),basal area,i.e.,8.7(31–40 cm)and 6.08m2 ha−1(11–20 cm),and biomass,i.e.,24.25 and 23.57 Mg ha−1(11–20 cm)in NRF and CRF,respectively.Furthermore,a significant contribution of biomass(7.8 Mg ha−1)in DBH class 81–90 cm in NRF suggested the importance of mature trees in biomass and carbon storage.The forests were predominantly occupied by Prosopis juliflora(Sw.)DC which also showed the highest contribution to the(approximately 40%)tree biomass.Carbon allocation was maximum in aboveground(40–49%),followed by soil(29.93–37.7%),belowground or root(20–22%),and litter(0.27–0.59%).Conclusion:Our study suggested plant biomass and soils are the potential pools of carbon storage in these forests.Furthermore,carbon storage in tree biomass was found to be mainly influenced by tree density,basal area,and species diversity.Trees belonging to lower DBH classes are the major carbon sinks in these forests.In the study,native trees contributed to the significant amount of carbon stored in their biomass and soils.The estimated data is important in framing forest management plans and strategies aimed at enhancing carbon sequestration potential of semi-arid forest ecosystems of India.

生产主义的产业政策观

配置主义的产业政策观是相关领域的主流研究范式。由于这种范式无法准确地把握成功的政策实践的关键,所以中国是否应该实行产业政策以及如何设计政策措施两大问题长期没有得到解决。为突破这一研究格局,本文提出生产主义的产业政策观。依据这种产业政策观,政策过程由政府分配状态依存租金和企业将其转化为熊彼特租金的两阶段过程构成,成功的政策实践的关键是在抑制寻租成本的同时,以推动企业提高技术和组织能力并形成技术—组织互补性的形式来提高租金转化效率。改进中国政策实践的要点在于以竞争力的形成机制为中心,结合当代生产组织方式的特点,为政策措施确立微观基础。