Effect of flooding and draw‐down disturbance on germination from a seashore meadow seed bank

Abstract. The objective of this study was to investigate the effects of flooding and draw‐down on the germination from the coastal grassland seed banks and to determine whether the effect of flooding varies between the delta and the seashore. Seed bank samples were collected from three shore transects in SW Finland, two on the shore of the Baltic Sea and one on the delta of River Kokemäenjoki. Samples were germinated in non‐flooded and flooded conditions for over a month, after which both treatments were maintained in non‐flooded conditions. A total of 9267 seedlings of 47 species germinated and mean density of seeds in the soil was ca. 84 000/m². Most of the seedlings were monocots (98%) and perennials (98%). Ca. 30–40% of the species found in the above‐ground vegetation had a seed bank including the majority of the most abundant species. The number of seeds and species richness increased as the organic layer became thicker. The organic layer was thicker in the seashore samples and the seed bank was significantly larger than in the delta. The flooding and draw‐down treatment significantly increased the number of germinating seedlings in the seashore and also increased species richness in two transects, one in the delta and the other in the seashore. Two species, Schoenoplectus tabernaemontani and Typha latifolia, had significantly higher germination in the flooded treatment than in the non‐flooded. Apparently, many species in these coastal grasslands have adapted to flood disturbance and for seeds of some species flooding may work as a positive signal, possibly breaking dormancy.     

新疆葡萄新害虫——绿长突叶蝉主要生物学特性

【目的】绿长突叶蝉是中国新纪录种,是危害新疆葡萄生产的新害虫,为明确其生物学特性,进行了调查研究。【方法】田间定点调查,悬挂粘虫板、糖醋液诱集,结合室内饲养观察等方法。【结果】室内饲养表明,若虫共5龄,各龄期的平均发育历期分别为3.88、6.31、5.16、5.28、7.00 d;雌、雄成虫平均寿命分别为9.5和6.4 d。田间观察表明,绿长突叶蝉以卵在寄主葡萄上越冬,在新疆玛纳斯一年发生3代,越冬代卵于4月底开始孵化,5月下旬越冬代开始孵化为成虫;第1代卵从6月中旬开始孵化,7月中旬若虫开始羽化;第2代从8月初开始,一直持续到10月底;成虫主要在夜晚21点至23点及凌晨6点至8点活动。【结论】绿长突叶蝉一年发生3代,以卵越冬;若虫共5龄,具有较强的趋嫩性;成虫有较强的趋黄性,一定的趋光性,趋蓝性较弱,对糖醋液无趋性。试验结果可为葡萄安全生产,防治绿长突叶蝉提供理论依据。     

A comparison of unheated loose housing with stables on the respiratory health of weaned-foals in cold winter conditions: an observational field-study

Background

Newly weaned horses in Finland are often moved to unheated loose housing systems in which the weanlings have free access to a paddock and a shelter. This practice is considered to be good for the development of young horses. The daily temperatures can stay below ? 20 °C in Finland for several consecutive weeks during the winter season. However, the effect of unheated housing in a cold climatic environment on the respiratory health of weanlings under field conditions has not been studied before. This investigation was an observational field-study comprising 60 weanlings among 11 different voluntary participant rearing farms in Finland. Weanlings were either kept in unheated loose housing systems (n = 36) or in stables (n = 24) and were clinically examined on two separate occasions 58 days apart in cold winter conditions.

Results

The odds of clinical respiratory disease were lower in the older foals (log_e days); OR = 0.009, P = 0.044). The plasma fibrinogen concentration was higher when the available space (m²/weanling) in the sleeping hall was smaller (P = 0.014) and it was lower when the sleeping hall was not insulated (P = 0.010). The plasma fibrinogen concentrations at the second examination were lower with a body condition score above 3 (P = 0.070). Standardbreds kept in loose housing systems had a lower body condition score than Finnhorses or Standardbreds kept in stables at both examinations (P = 0.026 and P = 0.007, respectively). Haemoglobin level was lower in weanlings in loose housing systems compared to their counterparts at the first examination (P = 0.037). Finnhorses had higher white blood cell count than Standardbreds at first (P = 0.002) and at the second examination (P = 0.001).

Conclusions

Keeping weanling horses in cold loose housing systems does not seem to increase the occurrence of respiratory disease, but special attention should be focused on ventilation, air quality and feeding-practices. Our field study data suggest it might be advantageous to keep Standardbred foals born late in the season in a stable over the Finnish winter.

     

Maturation at a young age and small size of European smelt (<Emphasis Type="Italic">Osmerus eperlanus</Emphasis>): A consequence of population overexploitation or climate change?

Age of fish at maturation depends on the species and environmental factors but, in general, investment in growth is prioritized until the first sexual maturity, after which a considerable and increasing proportion of resources are used for reproduction. The present study summarizes for the first the key elements of the maturation of European smelt (Osmerus eperlanus) young of the year (YoY) in the North-eastern Gulf of Riga (the Baltic Sea). Prior to the changes in climatic conditions and collapse of smelt fishery in the 1990s in the Gulf of Riga, smelt attained sexual maturity at the age of 3–4 years. We found a substantial share (22%) of YoY smelt with maturing gonads after the collapse of the smelt fisheries. Maturing individuals had a significantly higher weight, length and condition factor than immature YOY, indicating the importance of individual growth rates in the maturation process. The proportion of maturing YoY individuals increased with fish size. We discuss the factors behind prioritizing reproduction overgrowth in early life and its implications for the smelt population dynamics.     

Genome Scan for Predisposing Loci for Distal Interphalangeal Joint Osteoarthritis: Evidence for a Locus on 2q

The genetic contribution to common forms of osteoarthritis (OA) is well established but poorly understood. We performed a genome scan, using 302 markers for loci predisposing to distal interphalangeal joint (DIP) OA. To minimize genetic heterogeneity in our study sample, we identified siblings with a severe, radiologically defined phenotype from the nationwide registers of Finland. In the initial genome scan, linkage analysis in 27 sibships gave a pairwise LOD score (Z) >1.00 with nine of the screening markers. In the second stage, additional markers and family members were genotyped in these chromosomal regions. On 2q12-q13, IL1R1 resulted in Z=2.34 at recombination fraction (theta) 0, allowing a dominant mode of inheritance. Association analysis of markers D2S2264, IL1R1, D2S373, and D2S1789 jointly provided some evidence for a shared haplotype among the affected individuals (P value of.012). Also, multipoint nonparametric linkage analysis yielded a P value of.0001 near the locus IL1R1 and P=.0007 approximately 20 cM telomeric near marker D2S1399, which, in two-point analysis, gave Z=1.48 (straight theta=. 02). This chromosomal region on 2q harbors the interleukin 1 gene cluster and, thus, represents a good candidate region for inflammatory and autoimmune disorders. Three additional chromosomal regions-4q26-q27, 7p15-p21, and Xcen-also provided some evidence for linkage, and further analyses would be justified to clarify their potential involvement in the genetic predisposition to DIP OA.     

Accumulation of Single-Stranded DNA and Destabilization of Telomeric Repeats in Yeast Mutant Strains Carrying a Deletion of RAD27

The Saccharomyces cerevisiae RAD27 gene encodes the yeast homologue of the mammalian FEN-1 nuclease, a protein that is thought to be involved in the processing of Okazaki fragments during DNA lagging-strand synthesis. One of the predicted DNA lesions occurring in rad27 strains is the presence of single-stranded DNA of the template strand for lagging-strand synthesis. We examined this prediction by analyzing the terminal DNA structures generated during telomere replication in rad27 strains. The lengths of the telomeric repeat tracts were found to be destabilized in rad27 strains, indicating that naturally occurring direct repeats are subject to tract expansions and contractions in such strains. Furthermore, abnormally high levels of single-stranded DNA of the templating strand for lagging-strand synthesis were observed in rad27 cells. Overexpression of Dna2p in wild-type cells also yielded single-stranded DNA regions on telomeric DNA and caused a cell growth arrest phenotype virtually identical to that seen for rad27 cells grown at the restrictive temperature. Furthermore, overexpression of the yeast exonuclease Exo1p alleviated the growth arrest induced by both conditions, overexpression of Dna2p and incubation of rad27 cells at 37 degrees C. However, the telomere heterogeneity and the appearance of single-stranded DNA are not prevented by the overexpression of Exo1p in these strains, suggesting that this nuclease is not simply redundant with Rad27p. Our data thus provide in vivo evidence for the types of DNA lesions predicted to occur when lagging-strand synthesis is deficient and suggest that Dna2p and Rad27p collaborate in the processing of Okazaki fragments.     

松材线虫(Bursaphelenchus xylophilus)入侵对马尾松(Pinus massoniana)林分生长的影响及相关生长模型

松材线虫（Bursaphelenchus xylophilus）是一种松树上发生严重的有害生物,它不仅改变了生态系统的结构和功能,而且改变了系统内生物的原有特性和地理分布。松材线虫及其引起的松树萎蔫病已对中国马尾松林（Pinus massoniana）的树木成长产生了巨大影响。基于此,使用＂每木调查法＂和＂样方法＂,对松材线虫入侵后的马尾松林内松树的各项生长指标因子进行了调查分析,其结果表明：自松材线虫1996年入侵所调查地区的松林后,对于受害松树不管是伐倒木（被伐倒）还是倒木（自然倒地）,其对周围马尾松胸径生长的影响是显著的,而对树高生长的影响不显著。最后建立了一系列的灰色和灰色-马尔可夫链数学模型,其预测结果精度高,可用于今后受害和未受害区马尾松林分因子的生长预测。     

西双版纳地区森林变化碳效应与生态效益评估

减少发展中国家因森林砍伐与森林退化导致的碳排放和保持碳储量(REDD+),不仅能减少因森林砍伐和森林退化造成的碳排放,而且还可以带来其它生态效益,如减缓森林破碎化、保护生物多样性和增强水土保持功能等。以中国的西双版纳地区为研究区域,以毁林最严重的1976—2007年为REDD+基线,基于卫星影像,并结合植被指数,提取了研究区的土地利用变化信息。基于IPCC温室气体清单方法,计算了研究区的森林碳储量变化。在此基础上,对REDD+的碳汇效益和生态效益进行了系统综合评估。结果显示：(1)1976—2007年间天然林碳储量从占总碳储量的78.24%减少至50.52%,这是造成西双版纳地区碳储量减少的主要原因。(2)1976—2007年,天然林的斑块数量和平均最近邻距离分别增加了120.00%和25.21%,平均斑块面积下降了71.98%,说明天然林的破碎化程度加剧。从研究区整体景观格局来看,斑块数量、Shannon多样性指数和Shannon均一性指数分别增加了8.16%、51.39%和34.07%;与此同时,平均斑块面积和景观内聚力指数分别下降了26.26%和2.13%,表明研究区整体景观格局...     

不同配置模式林分中光肩星天牛空间格局的地统计研究

运用地统计学方法对光肩星天牛在新疆杨和复叶槭混交林（新复混交林）、合作杨纯林以及新疆杨与合作杨混交林（新合混交林）3种林分中的空间格局进行了研究.结果表明：刻槽、排粪孔和羽化孔在新复混交林和合作杨纯林中呈现较明显的空间聚集状态,而在新合混交林中则呈现完全的随机分布.新复混交林中,刻槽和排粪孔在林内的扩散趋势完全相反,即刻槽由林地周围向中心扩散,而排粪孔则由林地中心向四周扩散,这在一定程度上反映了光肩星天牛喜好产卵于刻槽较少,危害较轻的树上,而羽化孔在新复混交林中的分布数量较少,仅有几处聚集分布,由这些零星分布的聚集斑块向周围扩散;合作杨纯林中,由于林缘通风透光,合作杨生长状况较好,受害严重,从而导致枯死,最终失去对光肩星天牛的诱集作用,光肩星天牛刻槽、排粪孔和羽化孔由林地周围向中心扩散;而新合混交林中,刻槽、排粪孔和羽化孔在林内有多个聚集区域,并以此为中心向四周扩散,保持聚集和扩散平衡状态,从而表现为随机分布,这主要是由林内树种的配置情况所决定的.就不同配置树种的空间依赖性范围而言,刻槽和羽化孔在新复混交林内的空间依赖性范围要远远大于合作杨纯林,而排粪孔则远小于合作杨;就样方内的空间连续性强度而言,新复混交林中刻槽大于合作杨纯林,而排粪孔和羽化孔均小于合作杨纯林,这些均说明光肩星天牛危害在新复混交林内较集中,而在合作杨纯林内较分散.     

长江三峡库区蝶类群落的物种多样性

报道了多样性指数、丰富度和均匀度.各小生境物种丰富度的变化在0～28之间,其下限值的数理分布范围主要在0与5之间,而上限值的分布主要在9、11和12.物种多样性指数的变化范围是：样本间0～4.9285,小生境间0～2.1143,生境类型间0～1.7091和植被型0.9740～1.3143;而物种多样性指数最高的样本（4.9285）在1500～1500m针阔混交林的小生境中,物种多样性指数最高的小生境（2.1143）是1000～1500m阔叶林,物种多样性指数最高的生境类型是阔叶林灌丛（1.4373）,物种多样性指数最高的植被型是灌丛（1.3143）;而灌丛各生境类型的物种多样性指数最高,从1.2773到1.4373;草地居第二位1.0588～1.2402,森林最低,0.8088～0.9618（仅分布在一个海拔梯度的生境类型除外）;就整体有而言,物种多样性指数居前5位的生境类型都是灌丛.可见,三峡库区灌丛是最适宜于蝴蝶繁衍的植被型;完全成片的森林与纯粹的农田均不太适合蝴蝶生存.因环境的复杂性,物种多样性指数的最高值（4.9285）和最低值（0.0）均出现森林植被型,样本间物种多样性指数变异系数最大的也是森林植被型,表明它给蝴蝶生存的影响,也将是最复杂的.海拔高度对物种多样性指数的影响明显,最高的物种多样性指数出现在海拔1000～1500m（1.2363）,最低是2000m以上（0.2536）,但没有显著的规律性.灌丛和森林各个小生境的蝴蝶均匀度与物种多样性的变化趋势基本是一致的,表明这两种植被型内各小生境的物种多样性指数主要受物种均匀度变化的影响;农田和草地两种植被型的物种多样性指数的变化除受均匀度影响外,还较大程度地受物种丰富度的影响.在生境类型的水平上,蝴蝶均匀度与物种多样性指数、丰富度间有着比较复杂的关系.这些结果反映了三峡库区蝶类生存环境的多样性和破碎化,从而影响了蝴蝶分布的丰富度、多样性和均匀性.