Formulating allometric equations for estimating biomass and carbon stock in small diameter trees

Biomass and carbon sequestration rate of a young (four year old) mixed plantation of Dalbergia sissoo Roxb., Acacia catechu Willd., and Albizia lebbeck Benth. growing in Terai region (a level area of superabundant water) of central Himalaya was estimated. The plantation is seed sown in the rainy season of year 2004 and spread over an area of 44 ha. Allometric equations for both above and below ground components were developed for three tree species. The density of trees in the plantation was 1322 trees ha⁻¹ The diameters of trees were below 10 cm. Five diameter classes were defined for D. sissoo and A. catechu and 3 for A. lebbeck. 5 trees were harvested in each diameter class. Individual tree allometry was exercised for developing the allometric equations relating tree component (low and above ground) biomass to d.b.h. Post analysis equations were highly significant (P > 0.001) for each component of all species. In the plantation Holoptelia integrifolia Roxb. (Family Ulmaceae) has been reduced to shrub form because of frost. Only the aboveground biomass of H. integrifolia and other shrubs were estimated by destructive harvesting method. Herbaceous forest floor biomass and leaf litter fall were also estimated. The total forest vegetation biomass was 10.86 Mg ha⁻¹ in 2008 which increased to 19.49 Mg ha⁻¹ in 2009. The forest is sequestering carbon at the rate of 4.32 Mg ha⁻¹ yr⁻¹.     

CSN3、CSN1S2和β-1g基因多态与西农萨能奶山羊产羔数的相关性研究

 首次利用PCR-RFLP技术探讨κ酪蛋白(CSN3)、αs 2酪蛋白(CSN1S2)和β-乳球蛋白（β-lg）基因多态与69只西农萨能奶山羊产羔数的相关性。结果表明：CSN3-TaqI位点与产羔数之间存在显著相关(P<0.05或P<0.01)，如TC基因型个体第1胎产羔数高于CC型（P<0.01），CC基因型个体第2胎产羔数高于CC型（P < 0.05）；CSN3-HindIII位点与产羔数之间不存在关联（P>0.05）；CSN1S2-Alw26I位点与产羔数间存在显著的相关性(P<0.05或P<0.01)，如NF基因型个体第1胎产羔高于NN型（P<0.05），NN基因型个体第4胎产羔数高于NF型(P<0.01)；β-lg-smaI位点与产羔数间不存在显著相关（P > 0.05）。结果提示CSN3和CSN1S2基因对奶山羊产羔数有显著影响, 从而推测酪蛋白基因可能与FecB基因连锁。因此，认为CSN3-TaqI和CSN1S2-Alw26I位点可作为奶山羊高产羔数标记辅助选择（MAS）的有效分子标记。     

三江平原小叶章枯落物分解及硫素释放动态

利用分解袋法研究了三江平原小叶章湿地枯落物在两个生长季的分解动态和硫素释放规律。结果表明：小叶章枯落物的分解模式为快一慢交替的变化模式。残留率随着时间逐渐降低，分解480d后小叶章典型草甸枯落物的残留率为70．87％，小叶章沼泽化草甸枯落物的残留率为66．28％，其二者相应的分解速率分别为0．0006117d^-1和0．0006745d^-1，二者的质量损失没有显著差异。二者枯落物中硫素的浓度在分解过程中均呈波动变化，并和干物质残留率存在线性关系，硫素释放模式为：淋溶一固持一释放，C：S是决定其释放模式的主要因素，当C：S降至908．59时小叶章典型草甸枯落物中硫素开始迅速释放，而小叶章沼泽化草甸枯落物硫素开始释放的C：S是1451．41。     

Organic farming fosters agroecosystem functioning in Argentinian temperate soils: Evidence from litter decomposition and soil fauna

Benefits of organic farming on soil fauna have been widely observed and this has led to consider organic farming as a potential approach to reduce the environmental impact of conventional agriculture. However, there is still little evidence from field conditions about direct benefits of organic agriculture on soil ecosystem functioning. Hence, the aims of this study were to compare the effect of organic farming versus conventional farming on litter decomposition and to study how this process is affected by soil meso- and macrofauna abundances. Systems studied were: (1) organic farming with conventional tillage (ORG), (2) conventional farming with conventional tillage (CT), (3) conventional farming under no-tillage (NT), and (4) natural grassland as control system (GR). Decomposition was determined under field conditions by measuring weight loss in litterbags. Soil meso- and macrofauna contribution on decomposition was evaluated both by different mesh sizes and by assessing their abundances in the soil. Litter decomposition was always significantly higher after 9 and 12 months in ORG than in CT and NT (from 2 to 5 times in average), regardless decomposer community composition and litter type. Besides, mesofauna, macrofauna and earthworm abundances were significantly higher in ORG than in NT and CT (from 1.6 to 3.8, 1.7 to 2.3 and 16 to 25 times in average, respectively for each group). These results are especially relevant firstly because the positive effect of ORG in a key soil process has been proved under field conditions, being the first direct evidence that organic farming enhances the decomposition process. And secondly because the extensive organic system analyzed here did not include several practices which have been recognized as particularly positive for soil biota (e.g. manure use, low tillage intensity and high crop diversity). So, this research suggests that even when those practices are not applied, the non-use of agrochemicals is enough to produce positive changes in soil fauna and so in decomposition dynamics. Therefore, the adoption of organic system in an extensive way can also be suggested to farmers in order to improve ecosystem functioning and consequently to achieve better soil conditions for crop production.     

Impact of long-term N fertilization on the structural composition of spruce litter and mor humus

The aims of this study were to determine the degree of lignin degradation and to investigate changes in the chemical composition of the organic matter in the forest floor in an N fertilized Norway spruce forest soil. Needle litter and mor humus were collected from the field experiment at Skogaby in southern Sweden (56°33′N; 13°13′E). The spruce stand had been fertilized for 11 years with 100 kg N ha⁻¹ yr⁻¹ as (NH₄)₂SO₄. The degree of lignin degradation was determined with alkaline CuO oxidation followed by HPLC analysis. The chemical composition of the organic matter was characterized by CPMAS ¹³C NMR. Tannin was specifically analyzed using dipolar dephasing CPMAS ¹³C NMR and the N distribution was studied by CPMAS ¹⁵N NMR.The C-to-N ratios in the fertilized Oi and Oe layers were significantly lower than in the unfertilized layers (24 compared to 34 and 23 compared to 27, respectively). Neither the sum of the CuO oxidation products (Vanillyls+Syringyls+Cinnamyls expressed as VSC) nor the acid-to-aldehyde ratio ((Ac/Al)_V) showed any significant treatment effects. The content of aromatic C (including phenolic C) was significantly lower in the unfertilized than in the fertilized Oi layer (18 versus 21%). In the unfertilized soil, VSC was positively correlated (r=+0.63, p<0.05) with the C-to-N ratio, whereas the phenolic C content was negatively correlated (r=−0.61, p<0.05). The tannin index showed a tendency of increasing from Oi to Oe layers in both treatments. Most of the organic N was found as amide-N, whereas no heterocyclic N was detected. We have not been able to show any major C structural changes due to N fertilization. We suggest that the significantly higher content of aromatic and phenolic C in the fertilized Oi layer is due to an initial stimulation of the microbial community.     

Effects of fungal inocula on the decomposition of lignin and structural polysaccharides in Pinus sylvestris litter

 Litter bags containing sterile Scots pine (Pinus sylvestris) needles (19.8% lignin, 26.5% cellulose and 0.34% N) were inoculated with two species of fungi in the laboratory and then placed in the litter layer of a pine plantation. Marasmius androsaceus, which can degrade lignocellulose, was initially displaced by other fungal colonisers and was not detected in the litter after 2–3 months; but was re-isolated from the needles after 12 months. Trichoderma viride, which is a cellulolytic species and also antagonistic to other fungi, dominated the litter throughout the experiment. The control litter was naturally colonised by litter fungi. After 12 months, mass losses were similar at 52% for M. androsaceus and 48% for T. viride, compared with 36% for the control litter colonised by a more complex fungal community. Lignin concentrations increased with time in control litter and with T. viride because mass losses of carbohydrates were greater than those of lignin. Litter inoculated with M. androsaceus showed significant lignin decomposition throughout the experiment but cellulose concentrations showed a proportional increase in the first 6 months, suggesting that the fungus was preferentially exploiting hemicellulose and non-structural carbohydrates. Analysis of TFA-extractable sugars (mainly from hemicellulose) and CuO-derived phenylpropanoid moieties from lignin confirmed the differential patterns of resource decomposition which were not evident from total mass losses. During the initial stages of decomposition, T. viride was as effective in utilising structural polysaccharides as the complex fungal community in the control litter. Furthermore, M. androsaceus not only exhibited unexpectedly low cellulolytic activity but also facilitated lignin depolymerisation after the fungus was no longer detectable in the litter. The pre-inoculation of litter with these two fungal species therefore affected the overall dynamics of decomposition at a biochemical level. This study illustrates the importance of understanding the effects and interactions of specific fungi, rather than assumptions about the functional competence of diverse communities, on the processes of litter decomposition. Received: 5 July 2000     

猪催乳素受体(PRLR)基因AluⅠ多态性与产仔数关系的研究

研究采用PCR-RFLP方法检测了猪PRLR基因exon10多态性,结果显示,除马身猪中只有A基因存在外,其他品种中,均有A和B两个等位基因存在。利用最小二乘分析研究了该多态位点对猪初产和经产的总产仔数和活产仔数的影响,结果表明不同基因型母猪的总产仔数和活产仔数的差异均未达到显著水平,但呈现出AA>AB>BB的趋势。对于头胎总产仔数、经产总产仔数和活产仔数,A基因的加性效应分别为0 29头/胎、0 38头/胎和0 39头/胎,显性效应分别为0 21头/胎、0 19头/胎和0 19头/胎,对于头胎活产仔数来说,A基因的加性效应和显性效应分别为-0 4头/胎和0 2头/胎。     

Quantity and quality of organic inputs from coppicing leguminous trees influence abundance of soil macrofauna in maize crops in eastern Zambia

Soil invertebrates are the major determinants of soil processes such as organic matter decomposition and nutrient cycling. However, the effect of quantity and quality of organic inputs on soil biota has not been studied in agroforestry systems in southern Africa. Variations in soil macrofauna abundance under maize grown in fallows of Gliricidia sepium, Acacia anguistissima, Leucaena collinsii, Leucaena diversifolia, Leucaena esculenta, Leucaena pallida, Senna siamea, Calliandra calothyrsus and monoculture maize were assessed at three sites with contrasting agro-ecological conditions in eastern Zambia. It was hypothesised that spatial variations in soil macrofauna abundance under maize crops are mediated by heterogeneity in the quality and quantity of organic inputs produced by these legumes. The relationships between the abundance of macrofauna groups and litter, leaf, stump re-sprout and recycled biomass, stump survival and the quality index lignin (L)+polyphenol (P) to nitrogen (N) ratio were assessed using generalised linear models assuming spatial randomness (Poisson distribution) and aggregation (negative binomial distribution). Earthworms, beetles and millipedes showed spatial aggregation, which was partly explained by the heterogeneity in organic resource quantity and quality. Earthworms and beetles were more abundant under legumes that produced high quantities of biomass with low (L + P) to N ratios and species that have high stump survival after coppicing. Millipedes were favoured by species which produced high quantities of biomass with high (L + P) to N ratios. Although ants and termites showed spatial aggregation, their distributions were not influenced by the quantity or quality of biomass produced by the legumes. Centipedes and Arachnida showed spatial randomness, and their distribution was not influenced by any of the organic quality and quantity variables.     

An improved method for extraction of sorghum polymeric protein complexes

A method for fractionating sorghum proteins using extraction solvents and techniques designed to obtain polymeric protein structures (especially disulfide linked) was developed. Extraction and separation conditions were optimized in terms of completeness of protein extraction, sample stability, and analytical resolution. After pre-extraction of albumins and globulins, a 3-step sequential procedure involving no reducing agents was applied to ground whole sorghum flour. The three fractions obtained represented proportionally different protein polymer contents and molecular weight distribution as evidenced by comparative size exclusion chromatography. Protein composition also varied among the extracts with differences in kafirin composition and non-kafirin proteins detected in the fractions by RP-HPLC and SDS-PAGE analysis. The ability to quantify and further characterize sorghum polymeric protein complexes will be useful for additional studies linking protein structures with functionality and digestibility and variations for these properties within diverse sorghum germplasm.     

Litter-fall and litter decomposition in a low Mediterranean shrubland

Annual production of litter by Cistus incanus (L.) and Myrtus communis (L.) and decomposition dynamics of leaf litter of these species was studied in a Mediterranean shrubland. Myrtus and Cistus produced 472 and 429 g dry weight litter m^-2 year^-1, respectively. Leaves were the predominant litter component for both species. The average decay constant of Myrtus and Cistus litters enclosed in litter bags, calculated over the whole study period (38 months), was 0.71 year^-1 and 0.31 year^-1 respectively. In green leaves the N content differed during growth seasons for both species, whereas the content of Ca, Mg, P, K, and Na did not show significant changes. Abscised leaves had lower N, P and K contents than green leaves, evidencing that a nutrient translocation before abscission occurred from senescent leaves. The nutrient contents of the leaves at abscission time, generally higher in Cistus than in Myrtus, allowed us to estimate the annual nutrient input to the soil. Phosphorus and K more than N were rapidly released by the decomposing litters after exposure. Nutrient limitation, in particular P, might be considered the main growth limiting factor for Myrtus and Cistus. Both species were adapted to recovery and rapidly recycle P more than N and K in the living biomass through retranslocation from green leaves before abscission and/or a high release rate from the decomposing litter. The former strategy was better used by Cistus, the latter by Myrtus.