Higher climate warming sensitivity of Siberian larch in small than large forest islands in the fragmented Mongolian forest steppe

Forest fragmentation has been found to affect biodiversity and ecosystem functioning in multiple ways. We asked whether forest size and isolation in fragmented woodlands influences the climate warming sensitivity of tree growth in the southern boreal forest of the Mongolian Larix sibirica forest steppe, a naturally fragmented woodland embedded in grassland, which is highly affected by warming, drought, and increasing anthropogenic forest destruction in recent time. We examined the influence of stand size and stand isolation on the growth performance of larch in forests of four different size classes located in a woodland‐dominated forest‐steppe area and small forest patches in a grassland‐dominated area. We found increasing climate sensitivity and decreasing first‐order autocorrelation of annual stemwood increment with decreasing stand size. Stemwood increment increased with previous year's June and August precipitation in the three smallest forest size classes, but not in the largest forests. In the grassland‐dominated area, the tree growth dependence on summer rainfall was highest. Missing ring frequency has strongly increased since the 1970s in small, but not in large forests. In the grassland‐dominated area, the increase was much greater than in the forest‐dominated landscape. Forest regeneration decreased with decreasing stand size and was scarce or absent in the smallest forests. Our results suggest that the larch trees in small and isolated forest patches are far more susceptible to climate warming than in large continuous forests pointing to a grim future for the forests in this strongly warming region of the boreal forest that is also under high land use pressure.     

Fruit production in Sorbus aucuparia L. (Rosaceae) and pre-dispersal seed predation by the apple fruit moth (Argyresthia conjugella Zell.)

Variation in fruit production and pre-dispersal seed predation by Argyresthia conjugella was studied in␣four populations of Sorbus aucuparia in northern Sweden.␣The number of infructescences, fruits per infructescence, consumed seeds and developed unattacked seeds per fruit were scored in marked trees from 1984 to 1990. The results showed that the number of fruits produced in each population determined the number of seed predators occurring in the host population, as the yearly number of seed predators was significantly and positively correlated with yearly number of fruits, in all but one population. The seed predators showed a delay in response to variation in number of fruits produced. This lag in response resulted in a large proportion of fruits being attacked and seeds consumed in a bad fruiting year that followed a good fruiting year, and vice versa. The proportion of fruits attacked and seeds consumed was largest in the population showing the greatest between-year variation in fruit production and lowest in the population showing the lowest between-year variation in fruit production. Furthermore, the individuals within the former population were synchronised, while they were not in the latter population. These results contradict one of the possible explanations of mast-seeding, where large synchronised between-year variation is supposed to reduce pre-dispersal seed predation. Instead, differences in attraction of the seed predator to differences in fruit crop size could explain the observed difference in seed predation between the two populations with opposite fruiting patterns. Within each population, irrespective of year, the proportion of fruits attacked and seeds consumed was independent of a tree's fruiting display. Therefore, trees with high fruit production, despite harbouring the largest number of seed predators, produced the largest number of developed seeds in absolute numbers, compared to trees that produced few fruits. Received: 25 February 1996 / Accepted: 30 November 1996     

蒙古旱獭体重体长变化及其年龄划分的研究

本文报告了645只蒙古旱獭体重体长变化与年龄的关系。结果表明:体重体长随年龄增长而递增,但体重和体长的增长速度和幅度不同。体重增长速度较快,幅度较大;体长增长速度较慢,幅度较小。经相关分析证明:体重体长与年龄呈正相关,相关系数和回归方程为: Y_w=1377.16x~(O.7729),R_w=0.9970; Y_L=33.95x~(0.2529),R_L=0.9947。 并根据相邻两个年龄组间体重均数有显著性差异(P<0.01),频数分布重叠不明显;组内变异具有一致性等特征,参考各年龄组蒙古早獭体重标准值(Mean ±Sx),划分了各年龄组早獭的体重范围。     

花楸腋芽增殖途径快繁技术研究

选用花楸茎节为外植体进行组培腋芽增殖途径研究,结果表明：利于花楸生长的最适宜基本培养基为MS培养基;芽诱导培养基为1/2MS+6-BA 2.5 mg·L^-1+2.4-D 0.5 mg·L^-1;增殖培养基为MS+6-BA（1.600~2.100）mg·L^-1+NAA（0.140~0.230） mg·L^-1,平均繁殖系数达到13倍以上;继代壮苗培养的最佳培养基为MS+6-BA 0.2 mg·L^-1+IBA 0.2 mg·L^-1;在1/2MS+IBA 0.3 mg·L^-1培养基上,平均生根数为5.96,生根率达90.20%。将生根后的组培苗移栽至腐殖土：泥炭土：河沙（比例为3：2：1）的基质中,成活率达95.55%。     

Chemical Composition of Pinus sibirica (Pinaceae)

Siberian pine (Pinus sibirica), also known as Siberian cedar pine and Siberian cedar, is an important plant that has been long used as a source of natural compounds and materials (wood, needles, soft resin, turpentine, colophony). Its chemical composition has been studied well enough; however, to our surprise, no articles that compile the phytochemical data have been published so far. Presumably, this is due to the fact that most of the studies were published in journals difficult to access and not indexed by search systems. This review, for the first time, presents a systematic compilation of available data of secondary metabolites occurring in the needles, shoots, bark, wood, seeds, and oleoresin of Pinus sibirica.     

六种藜科植物提取物对植物病原菌的抑制活性

研究了角果藜（ Ceratocarpus arenarius）、盐穗木（ Halostachys caspica）、里海盐爪爪（ Kalidium caspicum） 、叉毛蓬（ Petrosimonia sibirica ）、盐角草（ Salicornia europaea ）和小叶碱蓬 （ Suaeda microphylla ）等六种新疆藜科植物提取物及其不同极性萃取部分对根癌土壤杆菌（Agrobacterium tumefaciens ）、黄瓜角斑病菌（P Pseudomonas lachrymarts）、番茄疮痂病菌（ Xanthomonas vesicatoria ） 等植物病原细菌以及杨树溃疡病菌（ Botryosphaeria dothidea ）、棉花枯萎病菌（Fusarium oxysporum f. sp. vasinfectum ）、稻纹枯病菌（Rhizoctonia solani）等病原真菌的抑制活性。结果显示角果藜、叉毛蓬和盐角草乙醇粗提物表现出一定抗细菌活性,其中以叉毛蓬和盐角草提取物对黄瓜角斑病菌的抑制活性最强。多数植物提取物及其不同极性萃取部分对杨树溃疡病菌表现出强的抑制活性。抗真菌活性成分主要存在于供试植物的石油醚、氯仿和正丁醇萃取部分中,提示活性成分为极性中等的化合物。角果藜和盐角草乙醇粗提物及其不同极性萃取部分对供试真菌有较好的抑制活性。     

新疆阜康绿洲荒漠过渡带叉毛蓬种群遗传多样性及环境适应性研究

本文采用RAPD分子标记分析了新疆阜康绿洲荒漠过渡带叉毛蓬种群的遗传多样性;运用ORIGIN软件,对叉毛蓬种群的遗传多样性和土壤因子进行了回归相关分析。结果表明:叉毛蓬种群具有高的遗传多样性(P=98.7%)。亚种群的Nei基因多样性指数(H)与土壤中的钠离子、氯离子含量显著负相关(P=0.042、P=0.0408);遗传多样性指数与土壤中的电导率、含水量无显著相关关系;多态位点比率(P)与土壤中的全钾含量显著相关(P=0.011),Shannon多样性指数和Nei基因指数与有机质呈极显著负相关(P=0.0030、P=0.0015),与全磷、全氮负相关,但没有达到显著水平。叉毛蓬为旱生植物,利用有限的水分就可以完成生活史,水分没有成为一种限制性因子;土壤中的氯盐在维持叉毛蓬亚种群遗传多样性方面可能起着较为重要的作用,成为与遗传多样性显著相关的限制性因子,对叉毛蓬种群的遗传多样性具有一定的选择压力;同时处于贫瘠土壤上的叉毛蓬机体能够更加完全地利用土壤中的限制性养分,与土壤养分表现出负相关关系。另外,用随机引物检测到的叉毛蓬种群77个位点中有11个位点的基因频率与过渡带土壤因子存在着显著相关,表明这些位点对土壤因子具有特殊的敏感性。新疆阜康地区绿洲荒漠过渡带中叉毛蓬种群的遗传多样性特性可能是亚种群对所处微生境长期适应的结果。     

芦笋茎基部施药对芦笋木蠹蛾幼虫的防治试验

芦笋木蠹蛾Isoceras sibirica(Alpheraky)为芦笋(Asparagus officinalis(L.))上的一种蛀茎性害虫。试验结果表明,采用50%辛硫磷乳油300倍液在芦笋茎基部给药(5月中旬至6月中旬)为该虫的最佳化学防治方法,相对防治效果为92.5%,在所有处理中其加权Borda值最高(2.9)。调整芦笋播期,可使定植当年最易受害的笋苗免于虫害。     

Pollen- versus seed-mediated gene flow in a scattered forest tree species

We examined the spatial distribution of maternally inherited chloroplast DNA markers over the French part of the range of Sorbus torminalis, a scattered temperate forest tree native to most of Europe. The survey by restriction analysis of polymerase-chain-reaction amplified fragments for 880 individuals distributed among 55 populations allowed the detection of 25 haplotypes. The coefficient of differentiation among populations computed on the basis of haplotype frequency (G(STc) = 0.34) was one of the lowest found in forest trees so far, and the mean within-population diversity was relatively high, indicating multiple-mother foundation events. A significant but slight geographical pattern was observed, up to distances of about 100 km. This pattern of differentiation was compared to the genetic structure of the same populations revealed by biparentally inherited markers (isoenzymes), and a new method to quantify the relative importance of seed and pollen dispersal was derived, based on isolation-by-distance models. Neither pollen- nor seed-mediated gene flow was predominant in S. torminalis, a finding that differs from those for the majority of tree species studied so far. This result was most likely due to an extinction-recolonization dynamics based on efficient seed dispersal strategies. The joint screening of 31 individuals of the related Sorbus aria and of 163 hybrid individuals shows that hybridization occurs predominantly in one direction and is rarely followed by cytoplasmic introgression. As a consequence, interspecific gene flow should not significantly affect the diversity dynamics within S. torminalis.