Species Structure, Dry Matter Dynamics and Carbon Flux of a Dry Tropical Forest in India

Species composition, plant biomass and net primary productivitywere studied on three sites of a dry tropical forest The forestwas characterized by small structure with 38–10.4 m2 ha^–1tree and 3 1–7 8 m² ha^–1 shrub basal cover Speciesdiversity was highest for the mid-slope site while the concentrationof dominance was greatest for the hill-top stand The beta diversitywas 3 1 Total standing crop of vegetation averaged 66 98 t ha^–1with 46 70 t ha^–1 in the tree layer, 13.97 t ha^–1in the shrub layer, 0.35 t ha^–1 in the herb layer, 2 83t ha^–1 in the litter layer and 3 13 t ha^–1 in fineroots Of the total annual litterfall (4 88–6.71 t ha^–1),69% was accounted for by leaves and 31% by non-leaf matter Netprimary production (NPP) ranged between 11 3 and 19 2 t ha^–1year^–1, to which the contributions of trees, shrubs andherbs averaged 72, 22 and 6%, respectively Contribution of rootsto NPP was substantial and ranged from 2 9 to 5 3 t ha^–1year^–1 A total of 83% of vegetation carbon was storedin the above-ground plant parts while the above-ground NPP wasresponsible for 72% of the total carbon input into the systemThe contribution of foliage, herbaceous vegetation and fineroots to carbon turnover was disproportionately larger comparedto their share in the total standing crop Carbon budgeting indicatedthat the forest was an accumulating system, over at least theshort term Dry tropical forest, biomass, litterfall, net primary production, carbon budget, carbon flux     

The Effect of Different Root Temperatures on Dry Matter and Carbohydrate Changes in Rooted Leaves of Phaseolus Spp.

Weekly estimates of dry matter in rooted dwarf-bean leaves (Phaseolusvulgaris) and rooted runner-bean leaves (Phaseolus multiflorus)were made with roots held at 13°, 17°, 21°, or 25°C. Most dry matter accumulated in the lamina of both speciesat the coldest root temperature. Roots of runner bean grew morethan dwarf bean at all temperatures compared, especially at13° and 17° C and the greater net assimilation rate,i.e. dry matter increase per dm1 per week, of runner-bean leavesat cold temperatures, is attributed to faster root growth. Shading lessened accumulation in the lamina, especially at coldroot temperatures, because a greater proportion of assimilatewas transferred to roots. Rates of root growth are mainly influenced by temperature, andno effect could be detected of carbohydrate accumulation inthe lamina at cold temperatures on root growth after the rootswere kept warmer. Water content of the lamina per unit areaincreased as dry matter increased. For any particular dry-mattercontent, the water content was greater with roots at 20°than at 13°, i.e. the leaves were more succulent with warmerroots. When roots first formed on the petioles the lamina lost sugarand subsequently regained it, faster when roots were cold. Whentransferred from warm to cold root temperature, sugars accumulatedin the lamina. Starch changed more than sugars in response tochanging root temperatures. Starch in the lamina progressivelydeclined when roots were warm, but increased when they werecold. The starch content of the lamina was rapidly influencedby root temperature. Sugars and starch together account forless than half of the dry-matter increase in the lamina. Theunidentified fraction is little influenced by changes of roottemperature; it may be largely structural because the palisadecells continued to grow after the leaves were excised, althoughthe lamina was fully expanded before the leaves were rooted.Palisade cells were larger with roots at 20° than at 13°C.     

Carbohydrate, Nitrogen and Dry Matter Accumulation and Partitioning of Maize Hybrids Under Drought Stress

Maize (Zea mays L.) productivity under drought stress dependsto some extent upon a hybrid's capacity to produce and translocateassimilate to its developing kernels during the stress periodand/or after the stress is relieved. The objective of this studywas to evaluate differences in carbon and nitrogen accumulationand partitioning under drought stress among maize hybrids thatdiffer in yield potential and/or physiological metabolism duringreproductive development. The hybrids B73 x LH38, FS854, B73xMol7and US13 were subjected to drought stress from the 7th leafstage until pollination was completed, at which time the soilof the stressed plots was replenished with water. For d. wtand chemical constituent determinations, plants of each hybridwere harvested from the irrigated and drought stressed plotsat silking, mid-grain fill, and physiological maturity. Averagedover hybrids, vegetative biomass at silking was reduced 25%as a result of the drought stress treatment, with B73 x LH38and FS854 accumulating more total biomass during the later portionof grain fill than the other two hybrids under both soil moisturetreatments. At silking, the total non-structural carbohydratecontent of the hybrids' vegetative tissue was not changed asa result of drought stress, whereas their reduced nitrogen (N)contents were decreased by an average of 33%. B73 x LH38 andFS854 had greater grain carbohydrate and reduced N contentsunder irrigation and smaller decreases in those variables asa result of soil moisture deficit than did the other two hybrids.These results indicate that the greater drought tolerance ofB73 x LH38 and FS854 to stress imposed during vegetative andearly reproductive development resulted from their more activeN uptake and assimilation and sugar production during the laterportion of grain fill and from their more efficient partitioningof assimilate to the developing kernels. Zea mays L., maize, drought stress, nitrogen, carbohydrates, hybrids, partitioning     

江西省种子植物3种新记录

报道江西省种子植物3个新记录种(变种),即大别五针松Pinus fenzeliana Hand.-Mazz. var. dabeshanensis (C. Y. Cheng et Y. W. Law) L. K. Fu et Nan Li、浙江凤仙花Impatiens chekiangensis Y. L. Chen和浙江金线兰Anoectochilus zhejiangensis Z. Wei et Y. B. Chang。它们均发现于幕阜山脉中段江西省修水县和武宁县境内。文中简述各新记录种的区系地理学意义。     

Changes in Anuran Species Richness and Abundance Resulting from Hydroelectric Dam Flooding in Central Brazil

River damming causes ecosystem losses and habitat fragmentation. In the Cerrado, the flood affects mainly forested habitats in valleys. In 1996, the Tocantins River (Brazil) was dammed to create the Serra da Mesa hydroelectric plant, and 14 sites were monitored during flooding. Eight hills that formed islands were monitored with pitfall traps. Only one frog species was found on islands 3 yr after complete reservoir formation. Cerrado amphibians showed rapid decline during and after flooding.     

Species,Diaspore Volume and Body Mass Matter in Gastropod Seed Feeding Behavior

Background

Seed dispersal of ant-dispersed plants (myrmecochores) is a well studied ecosystem function. Recently, slugs have been found to act as seed dispersers of myrmecochores. The aim of our study was to (1) further generalize the finding that gastropods feed on seeds of myrmecochores and hence may act as seed dispersers, (2) to test whether gastropod body mass and the volume of diaspores have an influence on the seed dispersal potential.

Methodology and Principal Findings

We assessed the seed dispersal potential of four slug and snail species with a set of seven myrmecochorous plant species from seven different plant families common to Central European beech forests. Diaspores differed in shape and size. Gastropods differed in their readiness to feed on diaspores and in the proportion of seeds that were swallowed as a whole, and this readiness generally decreased with increasing diaspore size. Smaller Arionid slugs (58 mm body length; mean) mostly fed on the elaiosome but also swallowed small diaspores and therefore not only act as elaiosome consumers, a nutrient rich appendage on myrmecochorous diaspores, but may also disperse seeds. Large Arionid slugs (>100 mm body length) swallowed diaspores of all sizes. Diaspores swallowed by gastropods were defecated without damage. Within-species variability in body size also affect seed dispersal potential, as larger individuals of the red slug (Arion rufus) swallowed more diaspores of wood anemone (Anemone nemorosa) than smaller ones.

Conclusions and Significance

Our results help to generalize the finding that gastropods consume and potentially disperse seeds of myrmecochores. The dispersal potential of gastropods is strongly influenced by diaspore size in relation to gastropod size.     

Productivity and Subordinate Species Response to Dominant Grass Species and Seed Source during Restoration

Grasses can be important regulators of species diversity and ecosystem processes in prairie systems. Although C₄ grasses are usually assumed to be ecologically similar because they are in the same functional group, there may be important differences among species or between seed sources that could impact restorations. I tested whether C₄ grass species identity, seed source, or grass species richness scales to influence aboveground net primary productivity (ANPP), resistance to weed invasion, or establishment of subordinate prairie species during restoration. Plots in western Iowa, United States, were planted with equal‐sized transplants of one of five common grass species (Panicum virgatum L., Sorghastrum nutans (L.) Nash, Andropogon gerardii Vitman, Schizachyrium scoparium (Michx.) Nash, and Bouteloua curtipendula (Michx.) Torrey) either from local seed or from cultivar seed sources. These plots were compared to plots containing all five species in mixture and to nonplanted plots. Differences in ANPP were found among species but not between cultivars and noncultivars or between monocultures and mixtures. Panicum virgatum, S. nutans, and S. scoparium were more productive than A. gerardii and B. curtipendula. Weed invasion was much higher when plots were not planted with grasses. Schizachyrium scoparium allowed greater establishment of subordinant prairie species than all other focal grass species. There were two separate mechanisms by which grasses suppressed prairie species establishment either (1) by growing tall and capturing light or (2) by quickly filling in bare space by spreading horizontally through rhizome growth in short species. These results suggest that high ANPP can be found with noncultivar plantings during the first 2 years after planting and that subordinate species establishment is most likely when shorter bunchgrasses such as S. scoparium are dominant.     

3种锦鸡儿种子萌发对温度和水分的响应

对本地种白毛锦鸡儿（Caragana licentiana）和甘蒙锦鸡儿(Caragana opulens)以及外来种中间锦鸡儿（Caragana intermedia）种子进行了室内和野外萌发试验。结果表明,白毛锦鸡儿种子最适萌发温度为20℃,5℃时种子不萌发,甘蒙锦鸡儿最适萌发温度为10-20℃,在5℃和30℃时萌发率显著低于其它温度下的萌发率,中间锦鸡儿种子最适萌发温度为15-30℃,5℃下的萌发率为8.5%。室内萌发试验和野外萌发试验都表明白毛锦鸡儿种子萌发的速度缓慢,这体现在达到最大萌发率需要的时间长,萌发速度慢,且有4.0%的硬实种子,甘蒙锦鸡儿种子萌发的速度快,无硬实种子,高温下萌发受到一定的抑制。中间锦鸡儿种子在高温下萌发率高,速度快。启运白毛锦鸡儿种子萌发的最低土壤含水量为1.25%,甘蒙锦鸡儿和中间锦鸡儿的分别为3.75%和2.50%。白毛锦鸡儿种子萌发需要的土壤含水量低,种子萌发慢,且有小部分硬实种子,这可能是白毛锦鸡儿适应特殊环境的对策之一。     

Seed Ecology of Woody Species in a Caribbean Dry Forest

Peak flowering activity among woody species in the tropical dry forests of St. John, U.S. Virgin Islands, coincided with the brief spring rainy season but continued at moderate levels for six months, abating with the autumn rains. Fruit maturation showed a major peak in the long winter dry season and a minor crest during the summer dry season. Seeds of wind-dispersed species disseminated mainly during the winter dry season, while animal dispersal of seeds (74% of all woody species) followed the bimodal pattern (for wet and dry seasons) described for the community as a whole. Under shadehouse conditions, most dry forest tree species germinated well (> 80%) and emerged promptly (within four weeks of planting) and synchronously (90% emergence within a four-week interval). Nine of 29 species tested in the shadehouse manifested dormancy of at least six weeks. Seed germinability varied among tree species, and the viability of most species began to decline following six months of dry storage. Few species retained high germinability after nine months of dry storage. The species composition of soil seed banks did not correspond closely with above-ground communities on three forested sites of varying stand age. In the youngest stand (35 years old), dominated by the weedy, arborescent legume Leucaena leucocephala, the soil seed bank was also dominated by this species, but no seeds of any other tree species were found in the soil samples. Seeds of native trees were scarcely encountered (only one indigenous species) in soil seed bank samples of three forest sites. Local seed rain from less disturbed forest may not be sufficient for prompt recovery of the dry forest community on degraded sites.     

不同温湿条件下贮藏的3种禾本科植物花粉的一些生理变化

测定了水稻、玉米和狼尾草花粉在低温(4℃),低湿(RH45％),低温(4℃)高湿(RH90％),高温(35℃),低湿(RH45％)和高温(35℃),高湿(RH90％)4种贮藏条件下的蛋白酶活性,蛋白质含量,游离氨基酸含量的变化,结果表明：在低温高湿条件下,蛋白质降解和游离氨基酸含量上升慢;在高温条件下蛋白质降解快,游离氨基酸含量迅速上升。3种植物花粉中,水稻花粉蛋白酶活性强,在贮藏过程中蛋白质降解速率和游离氨基酸含量上升快：狼尾草花粉蛋白酶活性低,在贮藏过程中蛋白质降解速率和游离氨基酸含量上升慢;玉米花粉的蛋白酶活性、蛋白质降解速率和游离氨基酸含量上升速率居两者之间。     

Dry Matter Yields and Photosynthetic Rates of Diploid and Hexaploid Triticum Species

The above ground dry matter yields of two wild diploid Triticumspecies averaged 76 per cent of that of two hexaploid breadwheat varieties in field trials carried out over five years.A cultivated diploid species, T. monococcum, gave similar drymatter yields to the bread wheat varieties but had a longergrowth cycle. The flag leaves of wild diploid species had higher rates ofphotosynthesis than those of the bread wheat varieties bothwhen expressed per unit area of leaf or per unit weight of chlorophyll.Photosynthetic rates of other organs, expressed per unit weightof chlorophyll were also greater for the wild diploids thanfor hexaploids. For snoots at the stage when their flag leaveswere fully expanded, the investment in photosynthetic machinery,as measured by chlorophyll concentration, was less in the twowild diploids than in the hexaploids. This compensated for thehigh photosynthetic rate of the former, such that the specificgrowth rates, assessed by carbon-14 fixation per unit shootdry matter, were similar. Triticum spp., wheat, dry matter yield, photosynthesis, carbon-14, ploidy     

A Comparison of the Seasonal Rates of Dry Matter Production of Three Coniferous Species with Contrasting Patterns of Growth

Seasonal rates of growth and dry-matter production were examinedin second-year seedlings of Larix leptolepis, Pinus contorta,and Pinus radiata grown in an unheated glasshouse. The deciduousLarix had a higher rate of production of dry matter than eitherof the two species of Pinus until the time of leaf fall, andthis was accompanied by a greater height and diameter increment.However, between the time of leaf fall in Larix and the endof the growing season, the species of Pinus increased in dryweight by more than 25 per cent, and in consequence Larix, becauseof its deciduous habit, lost much of the advantage of its fastgrowth-rate. Comparison of the two pine species showed thatP. radiata, while making nearly 3.5 times as much height incrementas P. contorta, had only a 45 per cent higher dry weight thanthat species at the end of the experiment. The dry-weight differenceswere due to differences in relative growth-rate (RGR). The RGR differences between the two pine species resulted fromdifferences in net assimilation rate (NAR) rather than differencesin the ratio of photosynthetic to non-photosynthetic tissue,and P. radiata gained most of its dry-weight advantage duringthe two months of October and November. It seems possible thatthe higher NAR of P. radiata at this time was a reflection ofthe difference in growth habit between the two pine species,and possible mechanisms by which growth may have affected NARin this experiment are briefly considered.     

Changes in Toxicity and Mobility Resulting from Bioremediation Processes

Bioremediation is a commonly used process for the remediation of soils and sludges containing hydrocarbon compounds. The extent of chemical concentration reduction that occurs in bioremediation processes and the concentration of residual chemicals varies widely for different soils and sludges and for different processes. Along with changes in chemical concentration, measures of toxicity and chemical mobility are important information as site remediation decisions are increasingly being made within a risk-based corrective action framework.

This review article presents illustrative data from studies that evaluated the effectiveness of bioremediation processes and that contained information about changes in chemical mobility and soil or sludge toxicity. The weight-of-evidence data presented indicated that, as part of the bioremediation process, there is a reduction of the apparent toxicity of the soils and sludges that were treated. In addition, remaining chemical constituents generally were less mobile. The patterns were consistent for both laboratory and field-scale bioremediation studies.     

Analysis of Covariation of Grain Yield and Dry Matter Yield for Breeding Dual Use Hybrid Rye

Winter rye (Secale cereale L.) is becoming increasingly important as substrate for biogas production in Central Europe. Dry matter yield has evolved as a breeding goal comparably important to the traditional grain yield. We analyzed the covariation between both traits and tested other agronomic traits for their correlation to dry matter yield that could be used for prediction of biomass yield. A set of 258 experimental hybrids were tested for dry matter yield harvested at late milk stage and grain yield harvested at full ripening at three to four locations in Germany in 2011 and 2012. We observed a wide range of dry matter yield (10–24 Mg ha^?1) and grain yield (6–15 Mg ha^?1) among testcross progenies. Genetic variances were significantly (P?<?0.01) different from zero for all traits. High entry-mean heritabilities (0.92–0.94) were found for plant height measurements and moderate heritabilities for grain and dry matter yield (0.52 and 0.49, respectively). Relative efficiencies for selection of dry matter yield estimated by second (EC 51–55) and third (EC 73) measurements of plant height were 1.24 and 0.98 respectively, compared to 0.52 for grain yield. Indirect selection for high dry matter yield using late plant height measurements should be successful. Using grain yield for indirect selection was less effective. The observed broad genetic variation for biomass yield in elite hybrid rye gives good prospects for the use as a resource of renewable energy. Plant height is a good predictor of dry matter yield but should be selected together with improved lodging resistance.     

The Photosynthetic Net Carbon Dioxide Exchange Potential in Conventional and 'Leafless' Phenotypes of Pisum sativum L. in Relation to Foliage Area, Dry Matter Production and Seed Yield

The effect of the ‘leafless’ mutation (in whichtendrils replace leaflets and the stipules are reduced to avestigial form) upon foliage area, photosynthetic net CO₂ uptakepotential, dry matter production and seed yield in Pisum sativumwas studied by comparing two near-isogenic lines of genotypeafafstst and ++++. The mutation is of potential agronomic valuein that it offers improved lodging resistance, crop drying andharvester throughput. In the conventional phenotype the total foliage area of themain axis attained a plateau (456 cm²) at day 56 from seedlingemergence, whereas corresponding values for the ‘leafless’mutant showed a total area of 208 cm² at day 68 with no indicationof a plateau. The agronomic consequence of this is discussed.During the vegetative phase of the plant the maximum CO₂ uptakepotential in the fully expanded conventional leaf was 8·5mg CO₂ leaf^–1 h^–1 and in the ‘leafless’mutant this value was 7·0 mg CO₂ leaf^–1 h^–1.For most ‘leaves’ of the latter phenotype this valuewas between 30 and 60 per cent less than for their conventionalcounterpart. There was a consistently higher photosyntheticpotential per unit area in tendrils of the ‘leafless’mutant than in leaflets of the conventional phenotype. The respectivemean specific values for the two phenotypes were 53 and 37 mgCO₂ dm^–2 h^–1. The problem of obtaining a meaningfulsurface area value for tendrils is discussed and the cylindricalnature of tendrils is taken into account. The ‘leafless’ mutant consistently accumulated 50per cent less dry matter than did conventional plants in theperiod from seedling emergence to anthesis and yield of maturedry seed per plant showed a reduction of 50 per cent both inseed number and total seed weight. The implications for future breeding and selection programmesaimed at haulm reduction are discussed in relation to evaluatingthe ability of the background genotype to produce adequate tendrilsin the presence of afafstst. Triticum aestivum, wheat, callus culture, organogenesis     

Phenology and Seed Yield Performance of Determinate Soybean Cultivars Grown at Elevated Temperatures in a Temperate Region

Increased temperature means and fluctuations associated with climate change are predicted to exert profound effects on the seed yield of soybean. We conducted an experiment to evaluate the impacts of global warming on the phenology and yield of two determinate soybean cultivars in a temperate region (37.27°N, 126.99°E; Suwon, South Korea). These two soybean cultivars, Sinpaldalkong [maturity group (MG) IV] and Daewonkong (MG VI), were cultured on various sowing dates within a four-year period, under no water-stress conditions. Soybeans were kept in greenhouses controlled at the current ambient temperature (AT), AT+1.5°C, AT+3.0°C, and AT+5.0°C throughout the growth periods. Growth periods (VE–R7) were significantly prolonged by the elevated temperatures, especially the R1–R5 period. Cultivars exhibited no significant differences in seed yield at the AT+1.5°C and AT+3.0°C treatments, compared to AT, while a significant yield reduction was observed at the AT+5.0°C treatment. Yield reductions resulted from limited seed number, which was due to an overall low numbers of pods and seeds per pod. Heat stress conditions induced a decrease in pod number to a greater degree than in seed number per pod. Individual seed weight exhibited no significant variation among temperature elevation treatments; thus, seed weight likely had negligible impacts on overall seed yield. A boundary line analysis (using quantile regression) estimated optimum temperatures for seed number at 26.4 to 26.8°C (VE–R5) for both cultivars; the optimum temperatures (R5–R7) for single seed weight were estimated at 25.2°C for the Sinpaldalkong smaller-seeded cultivar, and at 22.3°C for the Daewonkong larger-seeded cultivar. The optimum growing season (VE–R7) temperatures for seed yield, which were estimated by combining the two boundary lines for seed number and seed weight, were 26.4 and 25.0°C for the Sinpaldalkong and Daewonkong cultivars, respectively. Considering the current soybean growing season temperature, which ranges from 21.7 (in the north) to 24.6°C (in the south) in South Korea, and the temperature response of potential soybean yields, further warming of less than approximately 1°C would not become a critical limiting factor for soybean production in South Korea.     

罗霄山脉西坡—湖南省种子植物三新记录种

报道发现于罗霄山脉西坡湖南省种子植物3种新记录:水晶兰Monotropa uniflora Linn.、江西蒲儿根Sinosenecio jiangxiensis Y.LiuQ.E.Yang、华西俞藤Yua thomsonii var.glaucescens(DielsGilg)C.L.Li,并探讨3新记录种的生物地理学意义。     

三种类型草地植物种间关联的测定与比较

植物种间关联的研究,对于进一步确定植物种间关系、揭示群落演替过程中植物种间替代关系的机制、草场退化和人工草地产量下降的原因都有重要意义。本文之所以选取三种类型的草地进行研究主要是考虑到由于一个群落从初期阶段到顶极阶段的演替需要十几年甚至几十年的时间,这样对于演替不同阶段植物种间关联的观测是困难的。故在本文中我们采用     

The Effects of Mineral Nutrition and Density on Root Interactions in Three Grass Species

Studies were made of competition between Dactylis glornerataL., Holcus lanatus L. and Anthoxanthum odoratum L. The competitiveability of the species depended on the density of planting.D. glomerata was more competitive when planted at high density,whereas H. lanatus was more competitive at low density. A. odoratumwas most competitive at the intermediate density.