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Marian Plotkin Stanislav Volynchik Zahava Barkay David J.Bergman Jacob S.Ishay 《动物学研究》2009,30(1):65-73
东方大黄蜂(胡蜂)Vespa orientalis(膜翅目Vespinae属)的胃部表皮黄色颗粒位于黄色条纹区域。从黄色颗粒产生至在这一区域扩散,这个过程就是胃部黄颜色形成的过程。用几种电子显微镜研究了黄色颗粒的微观形态和发育过程。结果显示黄色颗粒由20—25 µm厚的一层组成,包括总表皮在内厚度约为40—45 µm。从上面看,在上述的区域能看到许多直径大约为0.5 µm周边光感受器细胞(PPC)。在每个黄色颗粒,能观察到一个肌样包膜,它位于一个由9根原纤维组装而成的圆圈内部。黄色颗粒成熟的过程包含通过导管的渗透增加初生黄色粒子数量,这些初生粒子又发育或增生成次生粒子,次生粒子逐渐布满整个区域。在这些黄色粒子层内可产生类似于肝的功能活动。 相似文献
126.
Biological legacies are organic structures and patterns remaining after a disturbance that may contribute to the complexity
of the recovering vegetation. Legacies may, in turn, reduce the impacts of human disturbances such as logging and habitat
transformation on elements of biodiversity. To examine the effects of biological legacies on biotic responses after disturbance,
we surveyed 32 sites for bryophytes in an area subject to large-scale conversion of native eucalypt forest to exotic Pinus radiata D. Don plantations in eastern Australia. We sampled bryophyte and substrate diversity (log, bare ground, upturned tree/log,
and trees) in eight sites in each of four landscape context classes: pine plantation stands, elliptical-shaped remnants, strip-shaped
remnants, and controls in a large area of contiguous, unmanaged eucalypt forest. We found a muted response by individual species
of bryophyte to landscape context. We attribute this, in part, to the presence of logs in the intensively managed pine plantation
sites. The boost in bryophyte diversity from species on logs meant that some pine sites supported similar species composition
to the continuous eucalypt forest controls. Our findings also underline the importance of local controls and structural variation,
including leaving logs and native trees in plantations, for enhancing bryophyte species richness in managed landscapes. 相似文献
127.
根据对福建福安的3种不同茶园(天香有机茶园、北门高山茶园和溪柄平地茶园)的节肢动物群落消长动态调查。并经多样性分析,结果获知:福安3种茶园节肢动物群落的物种丰富度(s)和多样性指数(H)的大小顺序依次为:天香(S=19.64,H=2.537)〉北门(S=18.01,H=2.502)〉溪柄(S=17.59,H=2.297);而均匀度指数的大小顺序是:北门(J=0.621)〉天香(J=0.595)〉溪柄(J=0.559)。表明植被比较丰富、人为干扰较少的茶园,节肢动物群落的物种丰富度、多样性指数和均匀度指数较高,害、益虫群落易于保持较好的平衡状态,有利于减少(或不使用)化学农药、发展绿色无公害茶叶生产。 相似文献
128.
KENTARO TAKAGI KARIBU FUKUZAWA† NAISHEN LIANG‡ MASAZUMI KAYAMA MUTSUMI NOMURA HAJIME HOJYO SADAO SUGATA HIDEAKI SHIBATA TATSUYA FUKAZAWA§ YOSHIYUKI TAKAHASHI‡ TATSURO NAKAJI‡ HIROYUKI OGUMA‡ MASAYOSHI MANO¶ YUKIO AKIBAYASHI TAKESHI MURAYAMA TAKAYOSHI KOIKE KAICHIRO SASA YASUMI FUJINUMA‡ 《Global Change Biology》2009,15(5):1275-1288
To evaluate the effects on CO2 exchange of clearcutting a mixed forest and replacing it with a plantation, 4.5 years of continuous eddy covariance measurements of CO2 fluxes and soil respiration measurements were conducted in a conifer-broadleaf mixed forest in Hokkaido, Japan. The mixed forest was a weak carbon sink (net ecosystem exchange, −44 g C m−2 yr−1 ), and it became a large carbon source (569 g C m−2 yr−1 ) after clearcutting. However, the large emission in the harvest year rapidly decreased in the following 2 years (495 and 153 g C m−2 yr−1 , respectively) as the gross primary production (GPP) increased, while the total ecosystem respiration (RE) remained relatively stable. The rapid increase in GPP was attributed to an increase in biomass and photosynthetic activity of Sasa dwarf bamboo, an understory species. Soil respiration increased in the 3 years following clearcutting, in the first year mainly owing to the change in the gap ratio of the forest, and in the following years because of increased root respiration by the bamboo. The ratio of soil respiration to RE increased from 44% in the forest to nearly 100% after clearcutting, and aboveground parts of the vegetation contributed little to the RE although the respiration chamber measurements showed heterogeneous soil condition after clearcutting. 相似文献
129.
Free air CO2 enrichment (FACE) experiments in aggrading temperate forests and plantations have been initiated to test whether temperate
forest ecosystems act as sinks for anthropogenic emissions of CO2. These FACE experiments have demonstrated increases in net primary production and carbon (C) storage in forest vegetation
due to increased atmospheric CO2 concentrations. However, the fate of this extra biomass in the forest floor or mineral soil is less clear. After 6 years
of FACE treatment in a short-rotation poplar plantation, we observed an additional sink of 32 g C m−2 y−1 in the forest floor. Mineral soil C content increased equally under ambient and increased CO2 treatment during the 6-year experiment. However, during the first half of the experiment the increase in soil C was suppressed
under FACE due to a priming effect, that is, the additional labile C increased the mineralization of older SOM, whereas during
the second half of the experiment the increase in soil C was larger under FACE. An additional sink of 54 g C m−2 y−1 in the top 10 cm of the mineral soil was created under FACE during the second half of the experiment. Although, this FACE
effect was not significant due to a combination of soil spatial variability and the low number of replicates that are inherent
to the present generation of forest stand FACE experiments. Physical fractionation by wet sieving revealed an increase in
the C and nitrogen (N) content of macro-aggregates due to FACE. Further fractionation by density showed that FACE increased
C and N contents of the light iPOM and mineral associated intra-macro-aggregate fractions. Isolation of micro-aggregates from
macro-aggregates and subsequent fractionation by density revealed that FACE increased C and N contents of the light iPOM,
C content of the fine iPOM and C and N contents of the mineral associated intra-micro-aggregate fractions. From this we infer
that the amount of stabilized C and N increased under FACE treatment. We compared our data with published results of other
forest FACE experiments and infer that the type of vegetation and soil base saturation, as a proxy for bioturbation, are important
factors related to the size of the additional C sinks of the forest floor–soil system under FACE.
Author Contribution: MRH conceived of and designed the study, performed research, analyzed data, and wrote the paper; GES
conceived of and designed the study and performed research. 相似文献
130.
Hannes Schroeder Tamsin C. O'Connell Jane A. Evans Kristrina A. Shuler Robert E.M. Hedges 《American journal of physical anthropology》2009,139(4):547-557
The question of the ultimate origin of African slaves is one of the most perplexing in the history of trans‐Atlantic slavery. Here we present the results of a small, preliminary isotopic study that was conducted in order to determine the geographical origin of 25 enslaved Africans who were buried at the Newton plantation, Barbados, sometime between the late 17th and early 19th century. In order to gain a more nuanced understanding of the slaves' origin, we used a combination of carbon, nitrogen, oxygen, and strontium isotope analyses. Carbon and nitrogen isotope ratios were determined in bone and dentinal collagen; oxygen and strontium isotopes were measured in tooth enamel. Results suggest that the majority of individuals were born on the island, if not the estate itself. Seven individuals, however, yielded enamel oxygen and strontium ratios that are inconsistent with a Barbadian origin, which strongly suggests that we are dealing with first‐generation captives who were brought to the island with the slave trade. This idea is also supported by the fact that their carbon and nitrogen stable isotope values differ markedly between their teeth and bones. These intra‐skeletal shifts reflect major dietary changes that probably coincided with their enslavement and forced migration to Barbados. While it is impossible to determine their exact origins, the results clearly demonstrate that the slaves did not all grow up in the same part of Africa. Instead, the data seem to suggest that they originated from at least three different areas, possibly including the Gold Coast and the Senegambia. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc. 相似文献