灵山湾国家森林公园垂序商陆土壤种子库时空动态及其对防除措施的响应

土壤种子库是植物潜在的种群,对生态系统稳定和未来植被的结构、功能有着举足轻重的影响。垂序商陆(Phytolacca americana)的入侵已对山东省胶南市灵山湾国家森林公园的森林生态系统构成严重危害。为调查该物种在公园内的潜在扩散能力,于2009—2014年调查了刺槐(Robinia pseudoacacia)林、黑松(Pinus thunbergii)林、刺槐黑松混交林和紫穗槐(Amorpha fruticosa)林(灌丛)4种林分类型,以及2009年采用物理和化学控制入侵危害严重的刺槐林内的土壤种子库。结果表明:垂序商陆种子在4种林分中均有发现,在刺槐、黑松林内表现为由林缘至林内逐步降低的趋势。垂序商陆种子只存在于枯落物层和5 cm以上的土壤中,随土层深度的增加而减少,枯落物层土壤种子库由林缘到林内呈递减趋势。与2009年相比,2014年黑松林和灌丛中平均种子库密度分别降低46%和44%,刺槐林和混交林分别增加299%和355%。垂序商陆种子发芽率在10%以下,随土层深度的增加而依次降低。采用物理、化学控制措施的刺槐林内垂序商陆的更新量、结实量、种子库含量均明显高于紫穗槐林的。调查结果表明垂序商陆土壤种子库具有明显的空间异质性,并且保持了较强的繁殖潜力,营造紫穗槐灌丛可以有效控制垂序商陆的扩散,可为经营沿海防护林提供理论指导。     

刈割加遮荫综合治理互花米草(Spartina alterniflora)

互花米草(Spartina alterniflora)是我国危害最严重的外来入侵植物之一,探索经济有效的控制治理技术对保护我国海滩生态环境具有重要意义。本研究集成了刈割与遮荫2种物理控制方法综合治理互花米草,并与单一刈割的治理效果进行对比。结果表明:单一刈割虽然显著降低了互花米草植株的节数、株高和地上生物量等个体生长特征(P0.05),但对互花米草植株的节长、基茎、种群密度、结穗率和穗长等特征没有显著影响(P0.05),6个月后互花米草刈割种群的无性生长和有性生殖特征与对照种群已无显著差别。而刈割加遮荫综合处理不仅显著抑制了互花米草节数、节长、基茎、株高、生物量等生长指标(P0.05),而且有效抑制了幼苗形成,完全抑制互花米草的有性繁殖,显著降低种群密度(P0.05),最后导致植株地上部分全部死亡,其控制效果远优于单一刈割处理。刈割与遮荫综合控制的方法主要适用于去除入侵早期、小面积分布的单一互花米草种群并恢复为沙滩,也可以作为生物替代方法的前期处理。     

光照，施肥及刈割对垂穗披碱草生长的影响

以甘南高寒草甸常见牧草垂穗披碱草（Elymus nutans）为研究对象,比较不同光照、肥力条件下,垂穗披碱草对刈割的生长和补偿反应。研究发现,光照和肥力存在交互作用。施肥、中度光照下,未刈割单株垂穗披碱草地上生物量最大,为3．239g。施肥、中度光照下,比较刈割植株地上生物量补偿发现：晚期刈割单株地上生物量的补偿大于早期刈割;刈割强度无显著影响;刈割两次单株地上生物量的补偿最大。施肥、中度光照、晚期、轻度、一次刈割时,单株垂穗披碱草地上生物量累积最大,为4．500g。全光照、未施肥条件下,刈割对单株地上生物量的补偿无影响。就补偿机制而言,植株地上生物量的增加以地下生物量为代价。     

锰胁迫对垂序商陆生长发育的影响

以垂序商陆为试验材料,采用温室溶液培养方法,在生长介质中添加不同浓度(1、5、8、12和15mmol·L-1)的锰离子,研究锰胁迫对垂序商陆生长发育的影响。结果表明:随着生长介质中锰含量的升高,垂序商陆种子的发芽率、发芽势和有丝分裂指数逐渐降低,幼苗根的生长逐渐受到抑制,根系活力呈下降趋势,植物体各器官的生物量减少。当锰胁迫浓度≥12mmol·L-1时,锰对垂序商陆的生长发育产生非常明显的毒害效应,导致种子的发芽、根尖有丝分裂和幼苗根的生长受到严重抑制,生物量显著减少。锰胁迫对垂序商陆幼苗的芽影响较小,而对生殖器官影响较大,严重降低了垂序商陆的结实数量与质量。     

刈割加遮荫对互花米草生长和存活的影响

该研究比较了在5月份实施刈割加不同程度遮荫处理后,互花米草地上部分和地下根茎6个月内的生长与死亡状况。结果表明:(1)单纯刈割处理在前2个月显著降低互花米草株高和生物量等生长指标(P0.05),随后地上部分生长和开花特征逐渐恢复并接近对照水平;而地下根茎存活率一直呈下降趋势;(2)刈割后加不同程度遮荫处理均可以有效抑制互花米草的生长并导致植株死亡,抑制效果显著高于单纯刈割的处理(P0.05),且遮荫程度越高抑制作用越明显。(3)刈割后加1层遮荫、2层遮荫和3层遮荫处理的平均透光率分别为15.27%、2.29%和0.31%,分别于11月份、7月份和7月份时导致互花米草地上部分全部死亡,至11月份时地下根茎存活率分别为3.68%、2.09%和1.70%,接近全部死亡。综合考虑治理费用、治理所需时间和治理效果,刈割后加1层遮荫是经济、有效的控制互花米草的方法。     

盐碱条件下刈割干扰对羊草的氮素分配策略及补偿生长的影响

土地盐碱化和过度放牧是制约松嫩平原畜牧业发展的两大因素,羊草是松嫩平原上的优势种,被认为具有较强的耐牧及耐盐碱能力.本文通过田间原位试验,以叶面涂抹标记¹⁵N-尿素的方法,研究了不同盐碱条件下刈割干扰对羊草的氮素分配策略及补偿生长的影响.结果表明: 总体上叶面新吸收的氮60%以上保留在地上部分.与不施盐碱无刈割处理的对照相比,单纯的盐碱胁迫使新吸收的氮在细根中的分配率显著增加了5.1%;而盐碱胁迫下,中度刈割使叶面新吸收的氮在地上部分的分配率增加了11.6%,地上及总生物量发生超补偿生长,但是重度刈割使叶面新吸收的氮在茎基部的分配率显著增加了9.5%,地上、细根及总生物量均表现为欠补偿生长.上述结果表明盐碱胁迫下,中度刈割干扰时羊草采取积极的再生策略,促进其超补偿生长,但在重度刈割时羊草会采取增加氮素在茎基部存储的相对保守的氮素分配和生长策略.     

高寒矮嵩草草甸两种主要植物耐牧性的比较

通过野外控制实验,研究了刈割(留茬3 cm、留茬1 cm及不刈割)、施肥(施肥、不施肥)和浇水(浇水、不浇水)处理对高寒草甸矮嵩草(Kobresia humilis)和垂穗披碱草(Elymus nutans)补偿高度、株高相对生长率、比叶面积、叶片净光合速率和地上总生物量的影响.结果表明:2物种的株高和地上总生物量在刈割后均为低补偿响应,但其株高相对生长率显著提高,并均随年份而增加;垂穗披碱草比叶面积、叶片净光合速率和地上总生物量对刈割损伤更加敏感;尽管施肥能显著提高2物种上述各项指标,但在不同处理条件下矮嵩草的耐牧性指数均小于垂穗披碱草;浇水的作用不显著.说明2物种的耐牧性依赖于土壤养分资源获得性,矮嵩草的耐牧性强于垂穗披碱草.     

灵山湾国家森林公园刺槐林下垂序商陆种子雨时空动态

垂序商陆(Phytolacca americana)的入侵给山东省沿海防护林的生物多样性及乔木更新造成了严重的危害, 为揭示其繁殖特性和扩散机制, 在灵山湾国家森林公园刺槐(Robinia pseudoacacia)林下由林缘至林内60 m设置5个梯度, 采用机械布点法对垂序商陆的结实量、种子雨分布和扩散格局进行了调查。结果表明: 1)垂序商陆的结实量与种子雨量由林缘至林内逐渐减小, 分别为2 273-1 846和1 382-621粒·m^-2, 不同空间种子雨密度占结实密度的60.80%-33.64%, 平均为49.52%, 人为搂割及动物取食是种子雨量损失的主要原因; 2)种子雨始于9月中旬, 林缘种子雨的发生早于林内, 种子雨的平均强度由林缘至林内逐渐减小, 在10月下旬和12月中旬各有一次种子雨高峰, 最大强度分别为32-4和59-5粒·m^-2·d^-1; 3)种子雨由林缘至林内散布范围逐渐减小, 同时随距母株距离的增加而减小, 其中最大散布距离与加权平均距离分别为210-180 cm和94.32-63.03 cm, 整体加权平均距离为81.00 cm。表明垂序商陆种子雨具有明显的时空异质性, 对预测其扩散潜力及群落结构组成趋势有重要的意义。     

垂序商陆种子油与根皂苷微波辅助提取工艺及种子油理化性质与根皂苷杀虫活性研究

为更好地开发利用垂序商陆(Phytolacca americana L.),本文关注了垂序商陆种子油与根皂苷的微波辅助提取工艺,及种子油理化性质与根皂苷对农业害虫的灭杀效果。结果发现:(1)垂序商陆种子油的微波辅助最佳提取工艺为料液比1∶10(g/m L),微波时间70 min,微波功率300 W,微波温度50℃,种子油得率26.8%;(2)根中皂苷最佳提取工艺为料液比1∶25,微波时间80 min,微波功率500 W,微波温度70℃,根皂苷得率3.22%;(3)垂序商陆种子油密度、折光值、碘值、酸值、过氧化值、皂化值分别为0.887 g/m L、1.542 n_D~(20)、138.6 g I2/100g、0.89 mg KOH/g、28.25 meq/kg与185.7 mg KOH/g;(4)根皂苷对供试害虫小菜蛾具明显杀虫活性,小菜蛾死亡率随处理时间增加呈递增趋势,至第4 d时达84.4%。结果表明,微波在垂序商陆种子油与根皂苷提取中可起到很好的辅助效果,二者在粮油安全或生物农药领域具有较好的开发潜能。     

刈割加淹水对互花米草萌发和幼苗生长的影响

互花米草(Spartina alterniflora)是我国危害最严重的外来入侵植物之一,探索环保、经济、有效地防治互花米草的技术对保护我国海滩生态环境具有重要意义。本研究通过人工气候室(20~25℃)的盆栽实验,研究刈割与淹水对互花米草萌发和幼苗生长的影响。实验持续4个月,对互花米草地上部分进行了2次刈割,首次刈割是在互花米草生长季结束时,3个月后进行第二次刈割。首次刈割后持续淹水至实验结束,淹水处理设计0、5、10、20 cm四个淹水深度。首次刈割后各淹水处理互花米草根茎上迅速萌发克隆苗,种子的萌发比克隆苗晚约3个月。不同淹水深度对克隆苗的萌发和生长均有抑制作用,克隆苗株数、株高和地上生物量均随淹水深度增加而减少。第二次刈割后各淹水处理均没有再萌发克隆苗,但有少量种子实生苗,其中20 cm水深处理的实生苗数量最少。刈割加淹水可以很好地抑制互花米草的萌发和幼苗生长,据此建议互花米草防治方案为:在春季萌芽前,修筑堤坝,保持淹水20 cm,在营养生长期后期贴地刈割互花米草,继续淹水,第二年重复同样的刈割和淹水。为防止二次入侵,需要在邻近的互花米草分布区同时进行治理。     

Allometric growth, disturbance regime, and dilemmas of controlling invasive plants: a model analysis

Disturbed communities are observed to be more susceptible to invasion by exotic species, suggesting that some attributes of the invaders may interact with disturbance regime to facilitate invasion success. Alternanthera philoxeroides, endemic to South America, is an amphibious clonal weed invading worldwide. It tends to colonize disturbed habitats such as riparian zones, floodplain wetlands and agricultural areas. We developed an analytical model to explore the interactive effects of two types of physical disturbances, shoot mowing and root fragmentation, on biomass production dynamics of A. philoxeroides. The model is based on two major biological assumptions: (1) allometric growth of root (belowground) vs. shoot (aboveground) biomass and (2) exponential regrowth of shoot biomass after mowing. The model analysis revealed that the interaction among allometric growth pattern, shoot mowing frequency and root fragmentation intensity might lead to diverse plant ‘fates’. For A. philoxeroides whose root allocation decreases with growing plant size, control by shoot mowing was faced with two dilemmas. (1) Shoot regrowth can be effectively suppressed by frequent mowing. However, frequent shoot mowing led to higher biomass allocation to thick storage roots, which enhanced the potential for faster future plant growth. (2) In the context of periodic shoot mowing, individual shoot biomass converged to a stable equilibrium value which was independent of the root fragmentation intensity. However, root fragmentation resulted in higher equilibrium population shoot biomass and higher frequency of shoot mowing required for effective control. In conclusion, the interaction between allometric growth and physical disturbances may partially account for the successful invasion of A. philoxeroides; improper mechanical control practices could function as disturbances and result in exacerbated invasion.     

Soil feedback does not explain mowing effects on vegetation structure in a semi-natural grassland

Due to its ability to create aboveground conditions that favour plant diversity, mowing is often used to preserve the high conservation value of semi-natural species-rich grasslands. However, mowing can also affect belowground conditions. By decreasing plant carbon supply to soil, mowing can suppress the activity of soil decomposers, diminish plant nutrient availability and thus create a feedback on plant growth. In this study, we first documented the effects of three-year mowing on plant community structure in a species-rich grassland. We found that mowing decreased the total areal cover of woody plants and increased the total cover of leguminous forbs. At the species level, mowing further increased the cover of two non-leguminous forbs, Prunella vulgaris and Sagina procumbens. Mowing did not affect the species number, diversity or evenness of the plant community. To study whether any of these effects could be explained by mowing-induced changes in the soil, and particularly by reduced nutrient availability, we then collected soil from different treatment plots and monitored the growth of nine plant species in these soils in a greenhouse. Plant growth did not differ between soils collected from mowed and unmowed plots, suggesting that our mowing regimes did not impose such changes in soil decomposer activity and nutrient supply that would feedback on plant growth. Moreover, each of the nine species responded equally to the different nutrient availability in different parts of the grassland, which indicates that even if mowing had reduced plant nutrient supply, this would not have led to changes in plant community structure. It appears that those changes in aboveground vegetation that we recorded after three years of mowing were purely due to the aboveground effects, such as frequent cutting of woody plants and enhanced light availability for low-growing forbs.     

槐树三刺角蝉生物学特性及防治

槐树三刺角蝉 Tricentrussophorae Yuan et Yan是国槐上发现的新害虫 ,在山东商河 1年发生 2代 ,以卵在国槐枝条内越冬。本文报道了该虫的生活史、生活习性、活动规律及发生与环境的关系。用 10 %高效氯氰菊酯 2 0 0 0 ,30 0 0倍稀释液和甲基 16 0 5的 10 0 0倍稀释液喷雾防治 ,若虫死亡率达 10 0 %。     

根系在凋落物层生长对凋落叶分解及酶活性的影响

根系向凋落物层生长是森林生态系统存在的普遍现象,研究根系存在对凋落物分解的影响对理解森林生态系统的养分物质循环具有重要意义。在福建三明市楠木和格氏栲林进行1年的凋落叶分解试验,设置有根处理和无根处理(对照),研究根系生长对凋落叶分解速率、养分释放和酶活性的影响。结果表明: 在分解360 d后,有根处理楠木和格氏栲凋落叶干重残留率比对照分别降低8.4%和19.7%;根系在分解前期(90~180 d)对凋落叶分解影响最为显著。在分解360 d后,与对照相比,有根处理凋落叶碳、氮、磷残留率在楠木人工林分别降低6.0%、19.1%和20.6%,在格氏栲人工林分别降低21.3%、23.2%和20.5%。在整个分解过程中,根系生长对凋落叶水解酶活性无显著影响;在分解180 d时,楠木和格氏栲有根处理凋落叶过氧化物酶活性比对照显著升高111.4%和92.4%。碳、氮、磷残留率与纤维素水解酶、β-葡萄糖苷酶、酸性磷酸酶和过氧化物酶活性呈显著负相关。根系在凋落物层生长会通过养分吸收和刺激氧化酶活性来加速凋落叶分解和养分释放过程。     

刈割制度对呼伦贝尔草原群落特征及牧草质量的影响

为确定呼伦贝尔草原高效生产和可持续利用的最佳刈割制度,于2019—2021年在呼伦贝尔草原开展刈割时间(7月31日、8月10日、8月20日、8月30日、9月9日)、留茬高度(3、9、15 cm)及两者交互作用对草原群落特征、牧草产量和品质影响的研究。结果表明: 较晚时间刈割和低留茬刈割会降低翌年群落高度和盖度;低留茬刈割降低翌年地上部分生物量,但刈割时间对其影响不显著。禾草、莎草相对生物量随刈割时间的延迟表现出先增加后减少的趋势,杂类草则与之相反,而豆科植物无明显变化。低留茬刈割在当年能够获得高的干草产量,但翌年的干草产量显著下降;8月30日,留茬3 cm刈割时干草产量达到最高值(469 g·m^-2),高于最低值361.5%。牧草品质中粗蛋白含量在8月30日刈割时亦达到峰值,高于最低值约6.5%,且在高留茬刈割下含量更高;酸、中性洗涤纤维含量随刈割时间延迟逐渐升高,9月9日刈割高于7月31日8.0%、5.9%,并且随留茬高度增加而降低。呼伦贝尔草原刈割制度设置为留茬高度9 cm左右、8月20—30日刈割为最佳,但需更长期的刈割试验观测才能得到更可靠、更客观的结论。     

Early effects of forest regeneration with selective and small scale clear-cutting on ground beetles (Coleoptera,Carabidae) in a Norway spruce stand in Southern Bavaria (Höglwald)

This study investigates the early effects of forest regeneration with selective, and small scale clear-cutting, on ground beetle (Coleoptera, Carabidae) community composition in a homogenous, mature spruce forest in Southern Bavaria (Höglwald), Germany. Carabid beetles were sampled with pitfall-, emergence-, and window-traps, from 1999 to 2001 during a pre-treatment year, the year of cutting, and the year after cutting. In the spruce stand we found a relatively low species richness with few dominating species. Selective cutting preserved this carabid assemblage. At the clear-cuts carabid species richness increased in the year of cutting, because of the invasion of small open field species, and the persistence of most forest species. Also, number of individuals increased due to higher numbers caught in the window-traps. The first open habitat species appeared just a few months after felling. However, in the next year the numbers of individuals, especially of forest species,were drastically reduced. Also, the number of species decreased, and was just slightly higher than on the control plot (mature stand). According to the DCA (detrended correspondence analysis) forest interior species had the same habitat preferences as net building spiders (Amaurobiidae, Linyphiidae) and other families of beetles (Staphylinidae, Curculionidae). Several groups of open habitat species responded positively on different patches found in the clear-cut: (1) diversity ofground vegetation, respectively coverage of shrubs, (2) favour for moist patterns, and water filled ruts (together with Gastropoda), or (3) low coverage of ground vegetation (together with free hunting spiders, Lycosidae). Different structures side by side (mature forest, selective cutting, open areas) may improve diversity on a forest scale. Small openings can serve as an important retreat for open habitat species. However, if clear-cuts become the dominant element, forest species maybe threatened. With selective cutting species richness of carabids is not improved; however, the remaining forest carabid species may be preserved during the early phase of the regeneration process.     

Aboveground Tree Growth Varies with Belowground Carbon Allocation in a Tropical Rainforest Environment

Young secondary forests and plantations in the moist tropics often have rapid rates of biomass accumulation and thus sequester large amounts of carbon. Here, we compare results from mature forest and nearby 15–20 year old tree plantations in lowland Costa Rica to evaluate differences in allocation of carbon to aboveground production and root systems. We found that the tree plantations, which had fully developed, closed canopies, allocated more carbon belowground - to their root systems - than did mature forest. This increase in belowground carbon allocation correlated significantly with aboveground tree growth but not with canopy production (i.e., leaf fall or fine litter production). In contrast, there were no correlations between canopy production and either tree growth or belowground carbon allocation. Enhanced allocation of carbon to root systems can enhance plant nutrient uptake, providing nutrients beyond those required for the production of short-lived tissues such as leaves and fine roots, and thus enabling biomass accumulation. Our analyses support this deduction at our site, showing that enhanced allocation of carbon to root systems can be an important mechanism promoting biomass accumulation during forest growth in the moist tropics. Identifying factors that control when, where and for how long this occurs would help us to improve models of forest growth and nutrient cycling, and to ascertain the role that young forests play in mitigating increased atmospheric carbon dioxide.     

刈割与水位调节集成技术控制互花米草(Spartina alterniflora)

治理和控制外来物种互花米草（Spartina alterniflora）对维护崇明东滩自然保护区生物多样性具有重要的意义和必要性。研究在上海崇明东滩鸟类国家级自然保护区建立的受损滩涂湿地生态修复示范样地中开展“刈割与水位调节集成技术”治理互花米草的物理控制实验,以期寻求有效治理互花米草的控制技术。示范研究结果表明,单一的水位调节方法虽然可以降低互花米草群落的密度和叶面积指数（LAI）,但至水淹处理100d后,处理样区内互花米草的生长和生物量已与对照区无显著差异。单一的水位调节方法不能达到有效快速控制互花米草的效果。通过在互花米草生长关键期（7月的扬花期）刈割＋水位调节集成技术处理后,互花米草地上部分无再新生现象,至当年10月份（生长季末期）,样区内互花米草的地上部分和地下部分已完全死亡并开始腐烂,达到了有效控制互花米草的效果。因此,应用刈割＋水位调节集成技术治理互花米草,必须选择关键季节刈割互花米草地上部分,同时配合一定水位的持续淹水（约3个月）,才能有效发挥其迅速有效治理互花米草的效果。扬花期刈割＋水位调节集成技术可为沿海地区大范围防治互花米草扩散提供有效途径。