Effects of different site preparation methods on the root development of planted Quercus petraea and Pinus nigra

New Forests - Mechanical site preparation (MSP) is often performed prior to planting to improve the growth and survival of planted seedlings. In this study, we compared root development of...     

Reproductive performance and offspring quality in mud crab (Scylla paramamosain) broodstock fed different diets

A 2-month feeding trial was conducted toevaluate the reproductive performance andoffspring quality of mud crab (Scyllaparamamosain) females fed either a mixture offresh food items (squid, shrimp, trash fish andArtemia biomass) or two experimentaldiets developed for penaeids. Before testinitiation, mud crab females with an averageindividual wet weight of 200–300 g wereacclimated for 2–3 days and reared together inone concrete tank of 2.0 × 0.5 × 8 m untilspawning. After spawning, the spent spawnerswere unilaterally eyestalk ablated and randomlydivided (20 animals/treatment) over three tanksof the same size and subjected to the dietarytreatments. Spent spawners were used toeliminate the effect of feeding history.There were only minor differences inreproductive performance between dietarytreatments. No differences were observed in theduration of the latency period from eyestalkablation to spawning. Fecundity was onlymarginally higher for the broodstock fed thecontrol diet. Also egg quality seemed onlyslightly affected by the treatments. Egghatching rates were slightly higher in crabsfed the formulated diets compared to thosecrabs fed the fresh diet. The onlystatistically significant difference (p < 0.05) observed however was in egg hatchingrate between the control diet and diet A2. Incontrast, the crabs fed the fresh diet producedstronger larvae as determined by a starvationtest.We therefore conclude that artificial dietsresulted in reproduction success comparable tothe use of fresh food. The nutritionalcomposition of the artificial diets couldhowever be improved in order to produce larvaeof optimal quality. Based on our researchfindings, the protein level and n-3 HUFA levelin the diet warrants further investigation inthis respect.     

Optimal first feed organism for South African mud crab <Emphasis Type="Italic">Scylla serrata</Emphasis> (Forskål) larvae

It is not known whether rotifers or Artemia nauplii are the best first food for South African mud crab Scylla serrata larvae. In order to test this, larvae were fed with five different test diets. These were rotifers for the first 8 days and newly hatched EG^® type Artemia nauplii (San Francisco Bay) from day 6 onwards (treatment R6A); newly hatched EG^® type Artemia nauplii throughout the rearing period (treatment EG); newly hatched Vinh-Chau strain (Vietnam) Artemia nauplii throughout the rearing period (treatment VC); decapsulated cysts of EG^® type Artemia throughout the rearing period (treatment DECAP); or decapsulated cysts supplemented with low densities of Artemia EG type Artemia nauplii (treatment MIX). Two experiments were conducted approximately 1 month apart using larvae from two different female crabs. Although results showed it is possible to rear S. serrata larvae through metamorphosis on Artemia nauplii exclusively, larval performance (development, survival and successful metamorphosis) was enhanced by the inclusion of rotifers as a first feed.No significant difference in performance was recorded between larvae fed on the two strains of Artemia nauplii. Larvae fed on decapsulated cysts in treatments DECAP and MIX performed poorly, but there were indications that decapsulated cysts and other inert diets may have potential as supplements to live food in the rearing of S. serrata larvae.     

不同饵料对二次抱卵期间中华绒螯蟹生殖性能和HUFA组成的影响

中华绒螯蟹(Eriocheir sinensis)经一次受精便可多次产卵.与其他的虾类一样,在卵巢发育过程中,中华绒螯蟹的肝胰脏需从外界汲取许多能量和营养物质,通过血淋巴转移到卵巢以供胚胎发育和幼体孵化.亲蟹的营养需求可以通过第一次和第二次卵巢发育过程加以研究.第一次抱卵之后亲蟹消耗了大量的营养和能量物质,需要在二次抱卵前的短时间内得到及时补充.通常来说,二次抱卵蟹的产卵力低下,幼体质量差.因此研究饵料对二次抱卵期间中华绒螯蟹生殖性能和幼体质量的影响是很有意义的.本实验分4组,分别以3种天然饵料缢蛏(TC)、沙蚕(TS)、杂鱼(TT)和一种人工饵料(TA)投喂中华绒螯蟹亲蟹,投喂周期为2个月(从初始一次抱卵至二次抱卵结束).天然饵料和人工饵料的日投喂量分别为亲蟹体重的10%和1%～3%,每日下午4点投喂.用PVC板将8m2的玻璃纤维槽隔成4个单元作为试验槽.每个单元底面积为2m2,水深40 Cm.同一槽中的3个单元用做一个试验组的3个重复,每个重复为10只蟹.海水盐度为20 g·L,pH 8.20～8.30,溶解氧为8.40～8.90 mg·L-1,依据水中氨氮和亚硝酸氮的浓度(分别小于1 mg·L-1和0.2 mg·L-1),每2至3天换一次水,水温为15～17℃.实验结束后,对二次抱卵亲蟹的生殖性能(相对饱卵量、卵径和亲蟹成活率)、孵化出的幼体质量(蚤Ⅰ幼体在饥饿状态下的成活率)以及卵、卵巢和肝胰脏的脂肪酸组成进行了测定.结果表明,卵、卵巢和肝胰脏的高级不饱和脂肪酸(HUFA)组成与试验饵料的组成具有很好的相关性,其中卵的DHA与EPA水平、肝胰脏DHA水平与饵料中相应的HUFA水平成正相关(R2＞0.90),说明外界营养物质的吸收和转移对卵巢的二次发育相当重要.统计学分析表明,投喂杂鱼的亲蟹(TT)孵出的蚤Ⅰ幼体对饥饿的耐受力以及投喂缢蛏的亲蟹(TC)的卵径显著高于其他组,各组之间其他指标(相对抱卵量和成活率等)均无显著差异.二次抱卵的中华绒螯蟹的卵、卵巢和肝胰脏中HUFA的水平与试验饵料中HUFA水平具有很好的相关性,说明无论在第一次卵巢发育过程中积聚了多少营养物质,第一次抱卵后消耗殆尽的亲蟹需要从外界食物中汲取大量的能量和营养物质,通过肝胰脏转运到卵巢供二次发育之用.本研究结论与其他作者对其他甲壳类的研究结果是一致的.此外组织器官的HUFA水平不只局限于饵料HUFA水平,还受器官本身对这些脂肪酸特定需求的影响.肝胰脏作为甲壳类动物的脂肪存储器,在饵料中的脂类物质被吸收和利用之前首先将其存储起来.甲壳类动物具有合成更长链的脂肪酸能力,虽然这种能力很有限,但仍能重新合成一定数量的脂肪酸.由于卵巢和卵中的n-3 HUFA,尤其是EPA和DHA含量高于肝胰脏,因此有理由相信它们在中华绒螯蟹繁殖过程中起着非常重要的作用.用人工饵料投喂对中国对虾的研究表明,n-3 HUFA的水平与亲本的生殖性能有很大关系,其中EPA与产卵量有很大的关系,而DHA在胚胎发育早期和幼体孵化起着很大的作用.本实验结果可以推论,EPA和DHA对中华绒螯蟹的卵巢的发育和生殖性能具有相当重要的作用,其中EPA的作用更加明显.遗憾的是本实验没有得出非常明显的相关性结论.应该指出的是本实验所用的不同饵料,不但HUFA含量不同,而且在蛋白质、总脂和微量营养素(维他命、矿物质、胆固醇、磷脂、钙盐等)的组成上差异很大,因此不宜下确定的结论.     

From seedlings to trees: Using ontogenetic models of growth and survivorship to assess long-term (>100 years) dynamics of a neotropical dry forest

Long-term tree and seedling growth and survivorship data from permanent sample plots established in a neotropical dry forest in Jamaica from 1998 to 2008 were used to (1) model growth (periodic annual increment) and survivorship dynamics, (2) cluster structural and functional types, and (3) estimate the age of selected tropical dry forest tree species. A statistical comparison of parameter estimates derived from a generalized linear model (GLM) of each species to a reference species was used to group individuals based on size (DBH and height), and demographic dynamics (periodic annual increment and survivorship). We identified two groups of species based on structural types (canopy and sub-canopy species), three groups of species based on periodic annual increment (fast, intermediate, and slow growing) and four groups of species based on the probability of survivorship of seedlings and trees (very low probability of seedling survivorship but high tree survivorship (two groups); high survivorship throughout the DBH classes; very low survivorship, regardless of stem size). The composition of the groups was mixed, and included individuals of both structural types, and with different periodic annual increment and survival probabilities. The dichotomy of guilds found in tropical rainforests (pioneer and climax species) was not found in this forest. Individual and group GLMs incorporating empirical relationships between periodic annual increment and survivorship, across a spectrum of ontogenies and DBH’s, were also generated. The periodic annual increment models were then used to estimate the time taken by a newly germinated seedling to reach the largest recorded DBH. The fastest growing species was the hemi-cryptophyte Clusia flava which was estimated to take 74 years to reach its maximum recorded size (12.1 cm DBH), whereas the slowest growing species, Ziziphus sarcomphalus, was estimated to take 399 years to reach its maximum size (24.4 cm DBH). These dry forest trees were estimated to reach their maximum size (which was one-half or one-third of the largest DBH recorded for tropical rainforests) in a time similar to tropical rainforest trees. Some of the tree species are ubiquitous to other neotropical dry forests; therefore, our equations for periodic annual increment and survivorship can be applied elsewhere in the region.     

Cross-evaluation of measurements of peatland methane emissions on microform and ecosystem scales using high-resolution landcover classification and source weight modelling

The methane exchange in an oligotrophic mire complex was measured on the ecosystem and microform scale with the eddy covariance (EC) and the closed chamber technique, respectively. Information about the distribution of three distinct microform types in the area of interest and in each 30 min EC flux source area was derived from a high-resolution (1 m²) landcover map in combination with an analytical source weight model (Kormann and Meixner, 2001). The mean weighted coverage of flark, lawn and hummock microforms in the EC source area (0.3% : 57% : 43%) closely mirrors the overall distribution in the area of interest (0.5% : 50.1% : 49.4%), despite great differences in microform coverage between individual 30 min EC source areas. The measured ecosystem flux was fitted to the sum of three microform flux models based on environmental variables and weighted by their fractional coverage in the EC source area. This method resulted in a better representation of the ecosystem flux compared to an approach based on only one flux model for the whole ecosystem (R² = 0.87, RMSE = 0.44 vs. R² = 0.74, RMSE = 0.61, n = 5181) and thus constitutes a successful down-scaling of measured ecosystem scale flux to the microform scale. A comparison of down-scaled and measured microform fluxes reveals a good agreement for lawn microforms and systematic differences for flark and hummock microforms. Reasons for the differences are thought to be the limited resolution of the landcover classification and the systematic underestimation of hummock fluxes by the closed chamber technique. As a result, hummock fluxes derived by down-scaling of EC fluxes are considered to be more dependable than closed chamber fluxes. The seasonal ecosystem methane budget from gap-filled EC measurements was 9.4 ± 0.2 g CH₄ m⁻²; the budget derived from up-scaled microform measurements was 8.0 ± 0.8 g CH₄ m⁻². The lower value of the latter budget is attributed to the underestimation of flark and hummock fluxes by closed chamber measurements and to the microform gap-filling procedure. Generally, estimates from up-scaled microform measurements are found to be less certain than estimates from EC measurements.     

Seed exchanges,a key to analyze crop diversity dynamics in farmer-led on-farm conservation

Sustainable management of genetic resources is a crucial issue in the global context of food security. On-farm conservation is now widely acknowledged as a relevant strategy to reach this goal because it maintains evolutionary forces within and between the different components of the agricultural system. Seed exchanges between farmers play a key role in this process but are complicated to study over different agricultural contexts. This review begins by illustrating how interdisciplinary approaches combining ethnobotany and genetics helps provide a detailed analysis of the role of social and genetic dynamic interactions related to seed exchanges in traditional farming systems with farmer-led on-farm conservation. Secondly, the evolution of crop genetic diversity management is described in the context of industrialized farming systems. We follow the evolution of crop biodiversity perception by involved actors using a socio-historical perspective. After the agricultural shift from a traditional to a productivist model, recent social developments such as citizen science and participatory research movements are emerging and are strongly concerned by the question of biodiversity. These emerging trends which recognize and value seed exchanges between farmers show similarities to farmer-to-farmer seed exchanges in traditional farming systems. To what extent are these systems comparable? To fully benefit from studies in both traditional and industrialized contexts, it will be critical to develop an interdisciplinary framework to rigorously compare seed exchange systems and more generally farmer-led on-farm conservation strategies in diverse agricultural systems.     

Determination of seven glycidyl esters in edible oils by gel permeation chromatography extraction and liquid chromatography coupled to mass spectrometry detection

A method based on a gel permeation chromatography (GPC) extraction procedure combined with an additional cleanup by solid-phase extraction (SPE) on silica gel and liquid chromatography-mass spectrometry (LC-MS) detection has been validated for the analysis of seven glycidyl esters (GEs) including glycidyl laurate, myristate, palmitate, stearate, oleate, linoleate, and linolenate in various edible oils. This method was conjointly developed and validated by two different laboratories, using two different detection systems, a LC time of flight MS (LC-ToF-MS) and a LC triple-quadrupole MS (LC-MS/MS). The extraction procedure allowed targeting low contamination levels due to a highly efficient matrix removal from the 400 mg oil sample loaded on the GPC column and is suitable for routine analysis as 24 samples can be extracted in an automated and reproducible way every 12 h. GPC extraction combined with SPE cleanup and LC-MS/MS detection leads to a limit of quantification in oil samples between 50 and 100 μg/kg depending on the type of glycidyl ester. Recoveries ranged from 68 to 111% (average = 93%). Quantification was performed by automated standard addition on extracts to compensate matrix effects artifacts. To control recoveries of each sample four isotopically labeled GEs ((13)C(3) or (13)C(4)) were included in the method.