Chlorophyll index and photosynthetic carbon sequestration in Northern Eurasia

Based on physiological and biochemical evidence, the chlorophyll index of terrestrial vegetation cover of Northern Eurasia was proved a reliable tool for quantitative estimates of photosynthetic sequestration of atmospheric carbon. The photosynthetic carbon sequestration in the vegetation cover of Northern Eurasia, corrected for emissive carbon losses in the wood pool, was estimated at 4.7 Gt C/year. Accordingly, the refined estimate for net production in the vegetation ecosystem of Northern Eurasia approaches 1.3 Gt C/year.     

Innovation and technological knowledge in the Upper Paleolithic of Northern Eurasia

The technology of modern humans is unique in the animal kingdom with respect to its complexity and capacity for innovation. Evidence of technological complexity and creativity in the archeological record is broadly coincident with and presumably related to traces of creativity in art, music, ritual, and other forms of symbolism. The pattern of modern human technology is part of a larger package of behavior (sometimes referred to as “behavioral modernity”) that emerges with the appearance of industries in Eurasia classified as Upper Paleolithic, but has deeper roots in the African Middle Stone Age. 1 - 5 .     

Chlorophyll Photosynthetic Potential in Wheat Stands in Dry and Humid Years

Influence of climatic conditions (total precipitation and sunshine duration) on the dynamics of chlorophyll photosynthetic potential (CPSP) and its relation to productivity of crop stands was studied with long- and short-stalked cultivars of winter wheat (Triticum aestivum L.). The reduction of the total exposure time to solar photosynthetically active radiation by 100 h per growing season (humid year) was shown to decrease CPSP by a factor of 1.3 and 1.5 in long-stalked and short-stalked cultivars, respectively. The decrease was mainly related to the suppression of biomass production, one of the main constituents of photosynthetic potential. Retardation of growth processes was manifested in a twofold decrease in the shoot number per m² on average; furthermore, morphological stages were delayed during early development. Suppression of growth processes by the shortened sunshine time was not compensated for by a 30% increase in specific chlorophyll content (as distinct from shade leaves), the other component of CPSP. It was shown that growth conditions have an effect on the correlation coefficient between CPSP and productivity.     

Comparison of living-tree and subfossil ringwidths with summer temperatures from 18, 19 and 20 centuries in Northern Finland

This work seeks to analyse the importance of summer-temperatures an the tree-ring growth of Scots pine (Pinus sylvestris L.) during the past three centuries. Three living-tree chronologies, subfossil pine chronology and one composite tree-ring chronology were constructed from latitudinal and altitudinal forest-limits of pine in northern Finland and compared with meteorological data comes from three localities. These data include early instrumental temperature observations from 18^th and 19^th centuries. The modern meteorological data covers the period from 1860 to present. Response functions were derived by means of Pearson correlations using five subperiods as follows: 1738–1748, 1802–1822, 1825–1835, 1861–1926 and 1927–1992. It was demonstrated that the correlations between ringwidths and mid-summer (July) temperatures did not vary significantly as a function of time. Early(June) and late-summer (August) mean temperatures were secondary in relation to mid-summer temperatures in controlling the radial growth. Early-summer temperatures governed pine radial growth most clearly during the 19^th century, whereas late-summer temperatures had strongest influence an ring-widths during the 18^th century and later part of the 20^th century. There was no clear signature of temporally reduced sensitivity of Scots pine ring-widths to mid-summer temperatures over the periods of early meteorological observations. Subfossil pine chronology, constructed using pines recovered from small Jakes along the forest-limit zone, showed a consistent pattern of response to summer-temperatures in relation to living-tree chronologies.     

Light and temperature dependent inhibition of photosynthesis in frost-hardened and un-hardened seedlings of pine

Needles of un-hardened and frost-hardended seedlings of Pinus sylvestris and Pinus contorta were exposed to photoinhibitory photon flux densities at temperatures between 0 and 35°C under laboratory conditions. Photoinhibition of photosynthesis was assayed by measuring oxygen evolution under saturating CO₂ in a leaf disc oxygen electrode or by recording of photosystem II fluorescence induction kinetics at 77 K. It was demonstrated that frost hardening of pine did not affect the susceptibility of photosynthesis to short time (2 h) photoinhibition at 15°C. The two pine species irrespective of acclimative state were equally sensitive to photoinhibition as assayed by apparent photon yield analyses of photosynthetic oxygen evolution. Plots of the apparent photon yield of oxygen evolution vs. F _v /F _m revealed a non-linear relationship.In the temperature range of 15–20°C short term photoinhibition caused a loss of F _v without effect on F ₀ . However, photoinhibition at temperatures lower or higher caused F ₀ to increase and decrease, respectively. In fact the decrease of F _v v _/F upon lowering the temperature was mainly caused by the temperature effect on F ₀ . Besides photoinhibition causing the well established quenching of F _v by increased radiationless decay somewhere in the reaction center-antenna complex, it is suggested that F ₀ generally increases as a result of loss of functional reaction centers causing decreased trapping of excitation energy. However, the high temperature induced quenching of F ₀ suggests that the quenching process (or processes) induced under photoinhibitory conditions is temperature dependent; i.e. it increases with the increase of temperature.In pine the photon yield of photosynthesis was much more sensitive to short term photoinhibition than was the rate of light saturated photosynthesis. This difference is explained by photosystem II and electron transport having surplus capacity relative to that of reductive carbon metabolism.     

Fire and site type effects on the long-term carbon and nitrogen balance in pristine Siberian Scots pine forests

Effects of fire and site type on carbon (C) and nitrogen (N) balances were determined by following the change of total and component C and N pools along four chronosequences of fire-prone Siberian Scots pine ecosystems. These differed in the mean return interval of surface fires (unburned – moderately burned, 40 years – heavily burned, 25 years) and site quality (lichen versus Vaccinium site type). Of the Vaccinium site type (higher site quality) only a moderately burned chronosequence was studied. A total of 22 even-aged stands were investigated with stand ages ranging from 2 to 383 years. The C balance was dominated by the opposing dynamics of coarse woody debris (CWD) and biomass and could be divided into three phases: (1) Young stands (up to 40 years)acted as a net source for C of 6-10 mol C m-2 year-1 because the previous generation CWD pool originating from stand-replacing crown fires decayed much faster than biomass increased. During this period the C pool in the unburned lichen type chronosequence decreased from 807 to 480 mol C m-2. (2) Middle aged stands (40-100 years) being in a stage of maximum biomass accumulation were a net sink of 8-10 mol C m-2 year-1. (3)Maturestands (100 to > 350 years) continued to sequester C at a lower rate (0.8-2.5mol C m-2 year-1). Differences in the rates of C sequestration during the two later phases could be explained by the complex interaction between surface fire regime and site type. Recurrent surface fires resulted in enhanced mortality and regularly redistributed C from the living to the CWD pool thereby lowering the rate of C sequestration. Site quality determined the potential to recover from disturbance by fire events. Differences in site type did not correlate with soil and total ecosystem N pool size. However, the N status of needles as well as the N pool of physiologically active tissue was highest in the stands of the Vaccinium type. The woody C pool (biomass + CWD) was sensitive to differences in surface fire regime and site type. It was lowest in the heavily burned lichen type chronosequence (297 ± 108 mol C m-2), intermediate in the unburned and moderately burned lichen type chronosequence (571 ± 179 mol C m-2) and highest in the moderately burned Vaccinium type chronosequence (810 ± 334 mol C m-2). In contrast, the total soil C pool (organic plus mineral layer down to a depth of 25 cm) was independent of stand age, surface fire regimeand site type and fluctuated around a value of 250 mol C m-2. The organic layer C pool oscillated in response to recurring surface fires and its C pool was dependent on time since fire increasing at a rate of about 1.5 mol C m-2 year-during the first 40 years and then reaching a plateau of 170 mol C m-2. The total ecosystem N pool was 7.4 ± 1.5 mol N m-2 on average of which only 25 % were stored in biomass or coarse woody debris. Total ecosystem N was independent of stand age, surface fire regime and site type. No correlation was found between total ecosystem C and N pools. Average total ecosystem C:N ratio was 114 ± 35 mol C mol N-1. A conceptual model illustrating how changes in the regime of stand-replacing crown fires and recurrent surface fires and changes in site quality interact in determining the long-term C balance in Siberian Scots pine forests is presented.     

Infection with Phloem Limited Abutilon Mosaic Virus Causes Localized Carbohydrate Accumulation in Leaves of Abutilon striatum: Relationships to Symptom Development and Effects on Chlorophyll Fluorescence Quenching During Photosynthetic Induction

Abstract: Infection with phloem limited Abutilon Mosaic Virus caused localized carbohydrate accumulation (high levels of starch, sucrose, and hexoses) in leaves of Abutilon striatum during early symptom development. In mature leaves with attenuated symptoms, tissues showing faint vein-clearing had markedly higher carbohydrate contents than uniformly green areas of the same leaf. A similar pattern of carbohydrate accumulation was found in pale-green mosaics in mature leaves with overt symptoms when compared to green-islands of the same leaf, but overnight carbohydrate loses were comparable to controls. Because leaves with attenuated symptoms showed no further symptom development whereas the pale-green mosaics became yellow and eventually necrotic in leaves with overt symptoms, it seems unlikely that carbohydrate accumulation following impaired translocation was responsible for symptom expression. High carbohydrate status in leaves with attenuated symptoms had little effect on nonphotochemical quenching during early stages of photosynthetic induction. In leaves with overt symptoms, areas of high carbohydrate status with pale-green mosaics showed markedly slower nonphotochemical quenching. Early symptom areas of young leaves, and advanced symptom areas of mature leaves had low starch contents but were otherwise similar to controls in carbohydrate status. Impaired nonphotochemical quenching in these tissues tended to reflect the state of symptom development, rather than carbohydrate status. Plants with overt symptoms grew about half as fast as plants with attenuated symptoms.     

黄土高原丘陵区退耕还林地油松人工林碳储量及分配特征研究

以黄土高原丘陵区主要退耕还林树种油松为研究对象,对甘肃省庆阳市合水县采用样地调查与生物量实测方法,分析不同坡向（阳坡、阴坡）及退耕年限（退耕6年、9年和12年）油松人工林的乔木不同器官、灌草层、枯落物层和土壤层的碳含量,以及油松人工林乔木层、灌草层、枯落物层和土壤层碳储量及其分配特征,探讨甘肃黄土高原丘陵区生态林的固碳作用。结果表明:（1）油松不同器官碳含量为48.15%~53.90%,各器官碳含量大小为树干>叶>细枝>粗枝>根桩>粗根>树皮>大根>中根>小根>细根>球果;灌木层碳含量为茎>叶>根;草本层碳含量为地上部分>地下部分。（2）油松人工林的枯落物层碳含量为未分解层大于半分解层。（3）0~100 cm土壤层的碳含量随退耕年限增加而增大,随土壤深度的增加而下降;0~10 cm、10~20 cm土壤层不同坡向间碳含量差异显著。（4）阳坡和阴坡退耕6年、9年和12年油松林总碳储量分别为42.90、50.50、59.22 t·hm^-2和45.08、53.77、65.70 t·hm^-2。研究认为,黄土高原丘陵区阳坡和阴坡均适宜油松林发挥固碳效益,且阴坡要优于阳坡,是甘肃黄土高原丘陵区的理想树种。     

Nutrient Addition Differentially Affects Soil Carbon Sequestration in Secondary Tropical Dry Forests: Early‐ versus Late‐Succession Stages

There is considerable interest in the potential use of soils to sequester carbon for climate change mitigation. As such, there is a need to evaluate the potential for carbon accumulation in tropical regions. We compared the effects of three annual additions of nitrogen and/or phosphorus on soil carbon and nitrogen contents and pools (bulk soil, macro‐, meso‐, and microaggregates) of two regenerating secondary tropical dry forest differing in nutrient status and succession stage (10‐year‐old early‐succession stage and approximately 60‐year‐old late‐succession stage). The selected forest sites were located on a shallow calcareous soil in the Yucatán Peninsula (Mexico). The primary production is limited by nitrogen and phosphorus in early‐succession stage and by phosphorus in late‐succession stage. In each forest site, four independent plots (12 × 12 m²) were established, the treatments being: controls and plots fertilized during three consecutive years with nitrogen, phosphorus, or nitrogen plus phosphorus. In both forests, soil carbon and nitrogen contents were consistently high, with soil carbon:nitrogen ratios generally greater than 10. Results indicate that usually there are no significant increases of soil carbon stock associated to late succession but can be increased to 3.7 Mg·ha^?1·yr^?1 with adoption of fertilizer practices. The potential soil carbon sequestration in early‐succession forest was estimated to be 2.7 Mg·ha^?1·yr^?1, and there is no indication that fertilization improves carbon sequestration. In short, results suggest that the soil potential for carbon sequestration in these ecosystems is high and depends on the specific nutrient status of the site.     

Evaporative enrichment and time lags between delta18O of leaf water and organic pools in a pine stand

Understanding ecosystem water fluxes has gained increasing attention, as climate scenarios predict a drier environment for many parts of the world. Evaporative enrichment of (18)O (Delta(18)O) of leaf water and subsequent enrichment of plant organic matter can be used to characterize environmental and physiological factors that control evaporation, based on a recently established mechanistic model. In a Pinus sylvestris forest, we measured the dynamics of oxygen isotopic composition (delta(18)O) every 6 h for 4 d in atmospheric water vapour, xylem sap, leaf water and water-soluble organic matter in current (N) and previous year (N-1) needles, phloem sap, together with leaf gas exchange for pooled N and N-1 needles, and relevant micrometeorological variables. Leaf water delta(18)O showed strong diel periodicity, while delta(18)O in atmospheric water vapour and in xylem sap showed little variation. The Delta(18)O was consistently lower for N than for N-1 needles, possibly related to phenological stage. Modelled leaf water Delta(18)O showed good agreement with measured values when applying a non-steady state evaporative enrichment model including a Péclet effect. We determined the time lags between delta(18)O signals from leaf water to water-soluble foliar organic matter and to phloem sap at different locations down the trunk, which clearly demonstrated the relevance of considering these time-lag effects for carbon transport, source-sink and carbon flux partitioning studies.     

秦岭北坡几种人工林根系及土壤有机碳剖面分布特征的研究

对秦岭北坡浅山区刺槐、油松、侧柏人工林根系生物量、土壤有机碳含量以及土壤氮素进行了测定分析.结果表明,3种人工林之间的根系生物量存在差异,变异系数达到27.75%;土壤有机碳含量差异不明显,变异系数只有3.36%;在土壤剖面上,3种人工林根系生物量的垂直分布有明显差异,但土壤有机碳含量的层次变化基本一致,土壤有机碳主要集中在0~10 cm土层中,其含量超过0~60 cm土层总量的40%;3种人工林土壤全氮与土壤有机碳含量之间都呈显著的线性正相关.     

Influence of Earthworm Invasion on Redistribution and Retention of Soil Carbon and Nitrogen in Northern Temperate Forests

We analyzed soil organic matter distribution and soil solution chemistry in plots with and without earthworms at two sugar maple (Acer saccharum)–dominated forests in New York State, USA, with differing land-use histories to assess the influence of earthworm invasion on the retention or loss of soil carbon (C) and nitrogen (N) in northern temperate forests. Our objectives were to assess the influence of exotic earthworm invasion on (a) the amount and depth distribution of soil C and N, (b) soil ¹³C and ¹⁵N, and (c) soil solution chemistry and leaching of C and N in forests with different land-use histories. At a relatively undisturbed forest site (Arnot Forest), earthworms eliminated the thick forest floor, decreased soil C storage in the upper 12 cm by 28%, and reduced soil C:N ratios from 19.2 to 15.3. At a previously cultivated forest site with little forest floor (Tompkins Farm), earthworms did not influence the storage of soil C or N or soil C:N ratios. Earthworms altered the stable isotopic signature of soil at Arnot Forest but not at Tompkins Farm; the alteration of stable isotopes indicated that earthworms significantly increased the loss of forest floor C but not N from the soil profile at Arnot Forest. Nitrate (NO₃^–) concentrations in tension and zero-tension lysimeters were much greater at Tompkins Farm than Arnot Forest, and earthworms increased NO₃^– leaching at Tompkins Farm. The results suggest that the effect of earthworm invasion on the distribution, retention, and solution chemistry of soil C and N in northern temperate forests may depend on the initial quantity and quality of soil organic matter at invaded sites.     

Identification of endogenous gibberellins, and metabolism of tritiated and deuterated GA4, GA9 and GA20, in Scots pine (Pinus sylvestris) shoots

The application of gibberellin A_4/7 (GA_4/7) to the stem of previous-year (1-year-old) terminal shoots of Scots pine (Pinus sylvestris) seedlings has been observed to stimulate cambial growth locally, as well as at a distance in the distal current-year terminal shoot, but the distribution and metabolic fate of the applied GA_4/7, as well as the pathway of endogenous GA biosynthesis in this species, has not been investigated. As a first step, we analysed for endogenous GAs and monitored the transport and metabolism of labelled GAs 4, 9 and 20. Endogenous GAs from the elongating current-year terminal shoot of 2-year-old seedlings were purified by column chromatography and high-performance liquid chromatography and analysed by combined gas chromatography-mass spectrometry (GC-MS). GAs 1, 3, 4, 9, 12 and 20 were identified in the stem, and GAs 1, 3 and 4 in the needles, by full-scan mass spectrometry (GAs 1, 3, 4, 9 and 12) or selected-ion monitoring (GA₂₀) and Kovats retention index. Tritiated and deuterated GA₄, GA₉ or GA₂₀ were applied around the circumference at the midpoint of the previous-year terminal shoot, and metabolites were extracted from the elongating current-year terminal shoot, the application point, and the 1-year-old needles and the cambial region above and below the application point. After purification, detection by liquid scintillation spectrometry and analysis by GC-MS, it was evident that, for each applied GA, unmetabolised [²H₂]GA and [³H]radioactivity were present in every seedling part analysed. Most of the radioactivity was retained at the application point when [³H]GA₉ and [³H]GA₂₀ were applied, whereas the largest percentage of radioactivity derived from [³H]GA₄ was recovered in the current-year terminal shoot. It was also found that [²H₂]GA₉ was converted to [²H₂]GA₂₀ and to both [²H₂]GA₄ and [²H₂]GA₁, [²H₂]GA₄ was metabolised to [²H₂]GA₁, and [²H₂]GA₂₀ was converted to [²H₂]GA₂₉. The data indicate that for Pinus sylvestris shoots (1) GAs applied laterally to the outside of the vascular system of previous-year shoots not only are absorbed and translocated extensively throughout the previous-year and current-year shoots, but also are readily metabolised, (2) the GA metabolic pathways found are closely related to the endogenous GAs identified, and (3) GA₉ metabolism follows two distinctly different routes: in one, GA₉ is converted to GA₁ through GA₄, and in the other it is converted to GA₂₀, which is then metabolised to GA₂₉. The results suggest that the late 13-hydroxylation pathway is an important route for GA biosynthesis in shoots of Pinus sylvestris, and that the stimulation of cambial growth in Scots pine by exogenous GA_4/7 may be due to its conversion to GA₁, rather than to it being active per se.     

Age-Dependent Changes in Ecosystem Carbon Fluxes in Managed Forests in Northern Wisconsin,USA

The age-dependent variability of ecosystem carbon (C) fluxes was assessed by measuring the net ecosystem exchange of C (NEE) in five managed forest stands in northern Wisconsin, USA. The study sites ranged in age from 3-year-old clearcut to mature stands (65 years). All stands, except the clearcut, accumulated C over the study period from May to October 2002. Seasonal NEE estimates were −655 ± 17.5 g C m^–2 in the mature hardwood (MHW), −648 ± 16.8 in the mature red pine (MRP), −195 ± 15.6 in the pine barrens (PB), +128 ± 17.1 in the young hardwood clearcut (YHW), and −313 ± 14.6 in the young red pine (YRP). The age-dependent differences were similar in the hardwood and conifer forests. Even though PB was not part of either the hardwood or conifer chronosequence, and had a different disturbance agent, it still fits the same general age relationship. Higher ecosystem respiration (ER) in the young than in the mature stands was the combined result of earlier soil warming in spring, and higher temperature and greater biological activity in summer, as indicated by temperature-normalized respiration rates. The fire-generated PB had lower ER than the harvest-generated YHW and YRP, where high ER was sustained partly on account of logging residue. During the main growing season, the equivalent of 31 (MHW), 48 (MRP), 68 (PB), 114 (YHW) and 71% (YRP) of daily gross ecosystem production (GEP) was released in ER during the same day. The lower ER:GEP ratio in the mature stands was driven by greater age-dependent changes in ER than GEP. The magnitude of the increase in ER:GEP ratio in spring and fall was interpreted as the extent of the decoupling of ER and GEP. Decoupling (sustained high ER despite decreasing GEP) was observed in YHW, PB and MHW, whereas in coniferous stands (MRP and YRP) the stable ER:GEP ratio suggested preferential use of new photosynthates in ER. The results indicate that a great part of the variation in landscape-level C fluxes can be accounted for by mean stand age and associated parameters, which highlights the need to consider this source of heterogeneity in regional C balance estimates.     

Defoliation,Photosynthetic Rates,and Assimilate Transport in Grapevine Plants

The source-sink relations in grapevine (Vitis vinifera L., var. Rkatsiteli) plants were disturbed by defoliation at different stages of vegetative growth in order to investigate changes in photosynthetic activity and assimilate partitioning. Defoliation was shown to stimulate photosynthesis in the remaining source leaves, enhance the assimilate export, and diminish the midday suppression of photosynthesis. Defoliation created a powerful sink for assimilates, and stimulated their delivery to the affected zone. It is hypothesized that defoliation-induced stress is accompanied by a substantial enhancement of photosynthetic activity and by redistribution of assimilate flows, which enables a sustained supply of assimilates to the sink organs of grapevine plants.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 507–512.Original Russian Text Copyright © 2005 by Chanishvili, Badridze, Barblishvili, Dolidze.     

The marketing ofLactarius deliciosus in Northern Spain

We report the harvesting of an average of 4,000 kg of saffron milk caps (Lactarius deliciosus Fr.) per day during four to six weeks between mid-October and mid-November in a village of 200 inhabitants in northern Spain. Nearly every inhabitant picks saffron milk caps, for which they receive an average of 2 ε/kg. A family of four could make a profit of 5,600–8,400 ε in a season (average annual income per family in the area is 18,727 ε). Pickers sell the harvested mushrooms either to a local middleman or directly to the buyer, who then takes the produce to the final point of sale, usually in Catalonia, where the demand for saffron milk caps is increasing yearly. This trade has occurred for 30 years, and began when saffron milk caps started to appear in the area after pine trees were introduced to replace the native oaks. This study provides evidence that the collection and marketing of wild edible fungi is a profitable task on a local and national scale.     

Photosynthetic acclimation to elevated atmospheric carbon dioxide and UV irradiation in Pinus banksiana

Pinus banksiana seedlings were grown for 9 months in enclosures in greenhouses at CO₂ concentrations of 350 or 750 μmol mol⁻¹ with either low (0.005 to 0. 3 W m⁻²) or high (0.25 to 0. 90 W m⁻²) ultraviolet-B (UV-B) irradiances. Total seedling dry weight decreased with high UV treatment but was unaffected by CO₂ enrichment. High UV treatment also shifted biomass partitioning in favor of leaf production. Both CO₂ and UV treatments decreased the dark respiration rate and light compensation point. High UV light inhibited photosynthesis at 350 but not at 750 μmol mol⁻¹ CO₂ due to a UV induced increase in ribulose-1, 5-bisphosphate carboxylase/oxygenase efficiency and ribulose-1, 5-bisphosphate regeneration. Stomatal density was increased by high UV irradiance but was unchanged by CO₂ enrichment.