共查询到20条相似文献,搜索用时 31 毫秒
1.
通过整理归纳落叶松(Larix)天然林和人工林的生物量文献数据,研究探讨了有关生物量碳计量参数,结果表明:1) 落叶松生物量转化与扩展因子(Biomass conversion and expansion factor, BCEF)的平均值为0.683 4 Mg·m-3 (n=113, SD=0.355 1),其中天然林为0.555 1 Mg·m-3 (n=56, SD=0.058 2),明显小于人工林的0.809 5 Mg·m-3 (n=57, SD=0.465 0)(p<0.05);生物量扩展因子(Biomass expansion factor,BEF)的平均值为1.349 3 (n=134, SD=0.384 4),其中天然林为1.176 3 (n=63, SD=0.039 9),也明显小于人工林的1.502 9 (n=71, SD=0.478 0)(p<0.05)。天然林与人工林的BCEF和BEF随林龄(Stand age, A)、平均胸径(Diameter at breast height, DBH)和林分密度(Stand density, D)的增加呈现相反的变化趋势。天然林的BCEF和BEF随A和DBH的增加而增加,随D的增加而呈降低趋势。人工林随A和DBH的增加呈指数降低并趋于稳定值,随D的增加而呈增加趋势。2) 根茎比(Root∶shoot ratio,R)的平均值为0.245 6 (n=156, SD=0.092 6),其中天然林为0.237 6 (n=64, SD=0.061 8)),人工林为0.251 1 (n=92, SD=0.109 0),二者无明显差异(p<0.05)。天然林的R随A和DBH的增加分别呈明显的指数和幂函数增加,而随D的增加呈幂函数下降,而人工林的R与A、DBH和D没有显著相关性(p<0.05)。3) 群落生物量扩展因子(Community biomass expansion factor,CBEF)的平均值为1.079 2 (n=49, SD=0.100 5),其中天然林为1.103 9 (n=29, SD=0.114 9),明显大于人工林的1.043 4 (n=20, SD=0.061 4) (p<0.05)。由于天然林和人工林的某些碳计量参数(如BCEF、BEF、CBEF)间存在明显差异,在进行落叶松林生物量碳计量时需分别天然林和人工林计算,在使用有关参数时还需考虑A、DBH和D等因素,有利于降低计量中的不确定性。但是人工林的有些参数(如人工林BCEF和BEF与D的关系、天然林和人工林的CBEF等)尚需进一步研究。 相似文献
2.
通过开展思茅松中幼人工林样地调查,基于实测数据计算了相关碳计量参数并研究了碳计量参数与相关林分因子的关系.结果表明:1)思茅松中幼人工林生物量转化与扩展因子(BCEF)的平均值为0.5483 Mg·m~(-3)(n=30,95%置信区间:0.5357~0.5609),低于政府间气候变化专门委员会(IPCC)的缺省值.BCEF和平均树高(H)、林分形高(FH)、蓄积量(V)和林龄(A)存在显著负相关(P<0.05).BCEF和平均胸径(D)负相关,但相关不显著(P>0.05).BCEF和N(林分密度)正相关,但相关不显著(P>0.05).BCEF值与林分因子的关系函数拟合效果不佳.2)思茅松中幼人工林生物量扩展因子(BEF)的均值为1.78378(n=30,95%置信区间:1.71714~1.85043),高于IPCC缺省值.BEF和D、H、FH、V和A存在极显著的负相关(P<0.01),与N存在显著的正相关(P<0.05).BEF与A和V的关系以二次曲线函数形式拟合效果较好,与N的关系则以双曲线形式较好,与FH、H和D的关系以幂函数较好.3)思茅松中幼人工林的根茎比(R)均值为0.2400(n=30,95%置信区间:0.2194~0.2606),与IPCC缺省值基本一致.R与D、H、FH、V和A有极显著的负相关关系,与N有显著的正相关关系.R与D、H、FH、V和A的关系以二次曲线的形式拟合效果较好,与N的关系则以双曲线形式拟合较好. 相似文献
3.
LI Jiang MENG Meng ZHU HongTao QIU Qiong ZHAI MingPu CHEN HongWei GUO YongQing 《Plant Diversity》2010,32(1):60-66
Based on data collected from field surveys, biomass carbon accounting parameters including biomass conversion and expansion factor (BCEF), biomass expansion factor (BEF) and root shoot ratio (R) for Pinus kesiya var. langbianensis plantation were calculated, and relationships between the parameters and relative stand factors were studied. Main findings were as follows. (1) Mean BCEF for Pinus kesiya var. langbianensis plantation was 05483 Mg m 3(n=30, 95% confidence interval=05357-05609), lower than the IPCC default value. BCEF for Pinus kesiya var langbianensis plantation was negatively related to stand form height (FH), mean stand height (H), stand growing stock (V) and stand age(A) (P<005). BCEF was negatively related to mean diameter at breast height (D), but not statistically significant(P >005), positively related to stand density (N), not statistically significant(P>005). Regression equations developed for calculating BCEF with stand factors did not give satisfied estimates. (2) Mean BEF for Pinus kesiya var langbianensis plantation was 178378 (n=30, 95% confidence interval=171714-185043), higher than the IPCC default value. BEF was negatively related to D、H、FH、V and A (P <001), positively related to N (P <005). Regression equations of y=a+bx+cx2 performed well to calculating BEF with A and V as variables. Regression equation of y=a+b/x performed well to calculate BEF with N. Regression equations of y=a xb performed well to calculate BEF with FH、H and D as variables. (3) Mean R for Pinus kesiya varlangbianensis plantation was 02400 (n=30, 95% confidence interval=02194-02606), close to the IPCC default value. R was negatively related to D、H、FH、V and A (P <001), positively related to N (P <005). Regression equations of y= a+bx +cx2 performed well to calculate R with D、H、FH、V and Aas variables. Regression equation of y=a+b/x performed well to calculate R with N. 相似文献
4.
Lughaidh Ó Néill Tijmen Veldhuizen Addy de Jongh John Rochford 《European Journal of Wildlife Research》2009,55(4):363-370
We examined the spatial structure and socio-biology of a native wild population of Eurasian otters (Lutra lutra) on mesotrophic rivers in a mild temperate climate. Radio-tracking of 20 individuals revealed exclusive intra-sexual adult
home-ranges. Adult female home-ranges (7.5 km, SD = 1.5 km, n = 7) were inversely related to river width (, F
6 = 13.5, P = 0.014) and so appeared to be based on food resources. The aquatic area within adult male home-ranges (30.2 ha, SD = 9.5 ha,
n = 5) was greater than that within adult female’s (16.8 ha, SD = 7.0 ha) (t
10 = 2.437, P = 0.035), though this result is inconclusive because some males were tracked on oligotrophic rivers. One adult male expanded
its range from 10.2 km to 19.3 km within 5 days of the death of the neighbouring male, suggesting that male home-ranges were
heavily influenced by conspecifics. 相似文献
5.
Henry Bernard Ikki Matsuda Goro Hanya Abdul Hamid Ahmad 《International journal of primatology》2011,32(1):259-267
Primates spend about half of their lives at sleeping sites, and their choice of sleeping sites may affect individual survival.
We identified a total of 88 trees used by proboscis monkeys (Nasalis larvatus) as night sleeping sites on 16 nights from June to September 2008 in riverine, mangrove, and mixed mangrove–riverine forests
along the Garama River, a tributary of the Klias River, in the west of Sabah, Malaysia. We recorded 11 variables for each
tree, including the species, physical structure, distance from the riverbank, and connectivity with surrounding trees. We
compared sleeping trees with 114 trees with ≥30 cm girth at breast height (GBH) located ≤50 m of the riverbank in 8 botanical
plots (total 1 ha). Trees in the plots represented the general vegetation patterns of the study area. Choice of sleeping trees
did not depend on the tree species. Although sleeping trees included trees ≤46 m from the river, those closer to riverbanks
(5–35 m, n = 76) were more likely to be used as sleeping sites. Compared to the available trees, sleeping trees had larger trunks (mean±SD = 143.6 ± 56.9 cm
GBH), and were taller (mean±SD = 34.3 ± 8.1 m), with greater number (median = 6; range = 12) and larger (mean±SD = 24.1 ± 15.2 cm
circumference) main branches. They were also located near to other trees, with overlapping branches, creating good arboreal
connectivity. Choice of sleeping trees by proboscis monkeys is likely to be related to risks of predation and injury from
falling, as well as ease of social interaction and efficiency of locomotion. 相似文献
6.
Biomass conversion and expansion factors (BCEF) which convert tree stem volume to whole tree biomass and biomass allocation
patterns in young trees were studied in order to estimate tree and stand biomass in naturally regenerated forests. European
beech (Fagus sylvatica L.), Sessile oak (Quercus petraea (Mattuschka) Liebl.) and Scots pine (Pinus sylvestris L.) stands were compared. Seven forest stands of each species were chosen to cover their natural distribution in Slovakia.
Species-specific BCEF are presented, generally showing a steep decrease in all species in the smallest trees, with the only
exception in the case of branch BCEF in beech which grows with increasing tree size. The values of BCEF for all tree compartments
stabilise in all species once trees reach about 60–70-mm diameter at base. As they grow larger, all species increase their
allocation to stem and branches, while decreasing the relative growth of roots and foliage. There are, however, clear differences
between species and also between broadleaves and conifers in biomass allocation. This research shows that species-specific
coefficients must be used if we are to reduce uncertainties in estimates of carbon stock changes by afforestation and reforestation
activities. 相似文献
7.
William E. Magnusson M. Carmozina de Araújo Renato Cintra Albertina P. Lima Luiz A. Martinelli Tânia M. Sanaiotti Heraldo L. Vasconcelos Reynaldo L. Victoria 《Oecologia》1999,119(1):91-96
We studied the energy flow from C3 and C4 plants to higher trophic levels in a central Amazonian savanna by comparing the carbon stable-isotope ratios of potential
food plants to the isotope ratios of species of different consumer groups. All C4 plants encountered in our study area were grasses and all C3 plants were bushes, shrubs or vines. Differences in δ13C ratios among bushes (xˉ = −30.8, SD = 1.2), vines (xˉ = −30.7, SD = 0.46) and trees (xˉ = −29.7, SD = 1.5) were small. However the mean δ13C ratio of dicotyledonous plants (xˉ = −30.4, SD = 1.3) was much more negative than that of the most common grasses (xˉ = −13.4, SD = 0.27). The insect primary consumers had δ13C ratios which ranged from a mean of −29.5 (SD = 0.47) for the grasshopper Tropidacris collaris to a mean of −14.7 (SD = 0.56) for a termite (Nasutitermes sp.), a range similar to that of the vegetation. However, the common insectivorous and omnivorous vertebrates had intermediate
values for δ13C, indicating that carbon from different autotrophic sources mixes rapidly as it moves up the food chain. Despite this mixing,
the frogs and lizards generally had higher values of δ13C (xˉ = −21.7, SD = 1.6; xˉ = −21.9, SD = 1.8, respectively) than the birds (xˉ = −24.8, SD = 1.8) and the only species of mammal resident in the savanna (xˉ = −25.4), indicating that they are generally more dependent on, or more able to utilise, food chains based on C4 grasses.
Received: 7 May 1998 / Accepted: 30 November 1998 相似文献
8.
Washington J. Gapare Miloš Ivković Brian S. Baltunis Colin A. Matheson Harry X. Wu 《Tree Genetics & Genomes》2010,6(1):113-125
Genetic variation for wood quality traits and diameter growth for radiata pine (Pinus radiata D. Don) at age 20/21 years was estimated from eight trials in Australia. The traits studied were wood density, acoustic time-of-flight
(an indirect measure of stiffness) and diameter at breast height (DBH). Wood density and DBH exhibited significant additive
genetic variation whereas non-additive effects were not significantly different from zero. Time of flight was also not significantly
different from zero for both additive and non-additive effects, respectively. Average single-site heritability estimates (±SE)
for wood density and DBH were 0.38 ± 0.10 and 0.16 ± 0.08, respectively. Pooled-site heritability estimates for wood density
and DBH were 0.38 ± 0.10 and 0.08 ± 0.10, respectively. For density, there was little evidence of genotype-by-environment
interaction (GEI) across the eight trials at the additive level (type B additive genetic correlation; r
BADD = 0.73 ± 0.08) and type B genetic correlation for full-sib families (r
BFS = 0.64 ± 0.08). In contrast, the type B additive genetic correlation for DBH was lower, (r
BADD = 0.51 ± 0.14), suggesting evidence of GEI. However, type B genetic correlation for full-sib families was moderate (0.63 ± 0.11)
for DBH, suggesting that there may be some stable full-sib families. On the basis of the results of this study, GEI should
be considered in order to optimise deployment of improved germplasm in Australia. 相似文献
9.
Wang Xi-Ling Zhou Jin-Xing Yu Mao-De Li Zhen-Gang Jin Xiao-Yun Li Qi-You 《In vitro cellular & developmental biology. Plant》2011,47(3):434-440
Efficient plant regeneration is essential for successful transformation and in vitro polyploidy induction in mulberry. A high frequency (80%) of plant regeneration from hypocotyls occurred under in vitro conditions in mulberry (Morus multicaulis Poir.). We identified three key factors for enhancing successful regeneration based on earlier work: (1) hypocotyl position,
(2) the combination and concentration of growth regulators, and (3) the addition of AgNO3. The highest frequency of shoot regeneration was achieved using hypocotyl segments, which are proximal to apical meristems,
and the optimal culture conditions were Murashige and Skoog’s (MS) (Murashige and Skoog, 1962) basal medium supplemented with 3.0 mg l−1 6-benzylamino purine, 0.3 mg l−1 indole-3-acetic acid, 0.1% polyvinypyrrolidone, and 1.0 mg/l silver nitrate (AgNO3) under subdued light at 25 ± 2°C. Treating the shoots with 0.2% colchicine (dipping for 72 h) resulted in a 14% tetraploid
frequency, whereas a 20% tetraploid frequency resulted from using a 0.25% colchicine (dripping for 5 d) treatment, as determined
by chromosome number counts. The diploid plant chromosome number was 28 (2n = 2x = 28) and that of tetraploid plants was 56 (2n = 4x = 56). Regenerated shoots rooted easily in 8–10 d using half-strength basal MS medium with 0.5 mg l−1 indole-3-butyric acid and were successfully established in the soil. 相似文献
10.
Under intracellular recording, we studied the effect of ATP on nerve cells of the rat intact nodose ganglion. The resting
membrane potential of the examined neurons was, on average, –60.3 ± 1.4 mV (n = 84); among such units, 88% were classified as C cells. Local application of 2 mM ATP to the surface of the ganglion using
a modified laminar flow system led to depolarization of neurons by 7.1 ± 0.9 mV, on average (n = 19). A blocker of P2X receptors, PPADS (100 μM), suppressed these depolarization responses, decreasing their amplitude,
on average, to 16 ± 3% (n = 3) of the initial value. The obtained data indicate that an overwhelming majority of neurons of the intact nodose ganglion
possess functional P2X receptors on their membranes. The absence of the corresponding responses in a considerable part of
neurons of intact spinal ganglia [13-15] was, apparently, determined by the fact that P2X receptors in the course of the described experiments had enough time to
desensitize before ATP reached the effective concentration. 相似文献
11.
Akio Shimizu Kagayaki Morishima Masahiro Kobayashi Masahiko Kunimoto Ichiro Nakayama 《Journal of applied phycology》2008,20(1):83-88
Conchospore germlings of Porphyra yezoensis were stained with a fluorescent dye for DNA and observed with confocal laser scanning microscopy (CLSM). Relative DNA values
of the germling nuclei were obtained by measuring fluorescence intensities of nuclear regions of the optically sliced specimens,
using the mean value of the smallest blade cells as a reference of the genomic n value. Such quantification revealed that the nuclear DNA amounts of the one-cell, two-cell, and four-cell-stage germlings
are approximately 4 × n, 2 × n, and n ∼2 × n values respectively; these values agreed well with the expected ones from the hypothesis that meiosis corresponds to the
first successive cell divisions after the conchospore germination. These results are consistent with a previous study on cytogenetic
analysis of the chimaera blade formation (Ohme and Miura 1988, Plant Sci 57:135–140) and not consistent with a recent microscopic study (Wang et al. 2006, Phycol Res 54:201–207) which proposed that the first meiotic division occurs at the conchospore formation and the second
division at the germination. 相似文献
12.
Toshihiro Yokoo Kouki Kanou Masato Moteki Hiroshi Kohno Prasert Tongnunui Hisashi Kurokura 《Ichthyological Research》2006,53(4):330-336
Juveniles of three eleotrid Butis species (B. butis, B. humeralis, and B. koilomatodon) are described; their occurrence patterns were examined in Sikao Creek, a mangrove estuary located in southern Thailand.
Juveniles of each species were distinguished by the following characters: B. butis with no bands on body and pale pelvic fins; B. humeralis with no bands on body and densely pigmented pelvic fins; and B. koilomatodon with 5–6 regular bands on body and a fleshy process (preorbital knob) on the snout. Although B. butis shared the aforementioned characters with B. amboinensis found in the same estuary, the former was distinguished from the latter by having a greater number of pectoral fin rays (18–21
vs. 17) and a deeper caudal peduncle. Distribution patterns of the three Butis species in Sikao Creek were distinguishable from each other. Smaller B. butis [mean ± SD = 22.7 ± 16.9 mm in standard length (SL), n = 32] occurred in the upper reach of the estuary, while larger specimens (52.4 ± 26.2 mm SL, n = 18 and 51.5 ± 29.7 mm SL, n = 10, respectively) were found in the middle and lower reaches and none in the marine area. In B. humeralis and B. koilomatodon, only juveniles were caught except for one adult specimen each. Juveniles (8.9–16.5 mm SL, n = 79) of B. humeralis occurred in the upper and middle reaches and the marine area. B. koilomatodon juveniles (9.9–13.7 mm SL, n = 30) were distributed in all areas from the lower to upper reaches. 相似文献
13.
Olivier Monteuuis Doreen K. S. Goh Charles Garcia David Alloysius Jikos Gidiman Roberto Bacilieri Gilles Chaix 《Tree Genetics & Genomes》2011,7(6):1263-1275
Forty-two different genetic origins of teak (Tectona grandis) comprising 26 open-pollinated families from a clonal seed orchard (CSO) were planted in a replicated trial under 2,500 mm
of annual rainfall and no distinct dry season, in 1997, in Sabah, East Malaysia. The trees were measured or scored for various
traits at 13, 35, 49, 61, 72, 85, 96, and 106 months after planting. Mortality rate, height (H), diameter at breast height
(DBH), volume (V), and fork height (FH) varied strongly among populations and origins. The best population means after 106 months for growth
H (21.1 m), DBH (21.1 cm), and V (278 dm3) were for the CSO families. Narrow sense heritabilities for the CSO families increased gradually with age but remained lower
after 106 months for DBH (h
2 = 0.24) and V (h
2 = 0.34) than for H (h
2 = 0.51) and FH (h
2 = 0.56). Overall, the CSO families were also straighter, less forked, and grew more vertically than the native provenance
and seed-derived sources. Such differences did not exist for flowering ability, and at 106 months, the great majority of the
trees of the various origins had not yet entered the flowering stage. Overall, at 106 months, the phenotypic correlations
between the various quantitative and qualitative traits were weak, except between straightness and bending with values higher
than 0.50. These findings confirm the usefulness of CSO for teak improvement and demonstrate the beneficial influence of wet
tropical conditions on traits of major economical importance for this species. 相似文献
14.
Eric Mortreau Sonia Siljak-Yakovlev Malika Cerbah Spencer C. Brown Hélène Bertrand Claudie Lambert 《Tree Genetics & Genomes》2010,6(1):137-148
The subsection Asperae of genus Hydrangea L. (Hydrangeaceae) has been investigated for three reasons: several ambiguous classifications concerning Hydrangea aspera have been published, unexpected differences in genome size among seven accessions have been reported Cerbah et al. (Theor
Appl Genet 103:45–51, 2001), and two atypical chromosome numbers (2n = 30 for Hydrangea involucrata and 2n = 34 for H. aspera) have been found when all other species of the genus present 2n = 36. Therefore, these two species and four subspecies of Hydrangea in all 29 accessions were analyzed for their genome size, chromosome number, and karyotype features. This investigation includes
flow cytometric measurements of nuclear DNA content and bases composition (GC%), fluorochrome banding for detection of GC-
and AT-rich DNA regions, and fluorescent in situ hybridisation (FISH) for chromosome mapping of 5 S and 18 S-5.8 S-26 S rDNA
genes. In the H. aspera complex, the genome size ranged from 2.98 (subsp. sargentiana) to 4.67 pg/2C (subsp. aspera), an exceptional intraspecific variation of 1.57-fold. The mean base composition was 40.5% GC. Our report establishes the
first karyotype for the species H. involucrata, and for the subspecies of H. aspera which indeed present different formulae, offering an element of discrimination. FISH and fluorochrome banding revealed the
important differentiation between these two species (H. involucrata and H. aspera) and among four subspecies of the H. aspera complex. Our results are in agreement with the Chinese classification that places the groups Kawakami and Villosa as two
different species: Hydrangea villosa Rehder and Hydrangea kawakami Hayata. This knowledge can contribute to effective germplasm management and horticultural use. 相似文献
15.
Christof Janko Stefan Linke Thomas Romig Dorothea Thoma Wolfgang Schröder Andreas König 《European Journal of Wildlife Research》2011,57(5):1033-1042
This study investigated the epidemiological and ecological factors to assess the infection pressure of alveolar echinococcosis
to human which are living in villages and small towns. Foxes and fox faeces were examined for Echinococcus multilocularis and foxes were observed by radio telemetry in Upper Bavaria, Germany. Forty-three percent of the village foxes (n = 65) had been infected with E. multilocularis. This prevalence rate did not differ significantly from the prevalence among rural foxes, which was 39% (n = 33; χ
2 = 0.12, df = 1, p = 0.727) determined by the intestinal scraping technique. PCR analyses of fox faeces showed a higher infection rate of 35%
(n = 26) among rural foxes than among foxes in villages and small towns (26%, n = 69; χ
2 = 0.68, df = 1, p = 0.411). One quarter of the fox faecal samples come from private gardens of residents. The radio-tracking study on 17 foxes
showed that foxes preferred the built-up area and grassland outside the villages. Village foxes concentrated their activity
within a range of 500 m around the settlement. Sixty-four percent of all bearings for radio-tracked foxes showed positions
in areas outside the town, and 36% of bearings were within the settlement. Village foxes, which are infected with E. multilocularis, are able to carry the parasite continuously into settlements and fox faeces present an immediate source of infection to
humans, especially within their gardens. Therefore, foxes are responsible for environmental E. multilocularis egg contamination in the vicinity of humans, leading to an infection risk to inhabitants of villages and small towns. 相似文献
16.
Nina Giotto Alain Laurent Nabil Mohamed Nicolas Prevot Jean-François Gerard 《European Journal of Wildlife Research》2008,54(4):539-547
Observations on the behaviour and ecology of the beira (Dorcatragus megalotis) were made during spring 2004 in a wild population discovered in 1993 in a low mountain range in the South of the Republic
of Djibouti. Spring was found to be both a birthing and a mating season. Beiras fed in the first and last daylight hours,
mainly on dicotyledons and in patches supporting trees and/or bushes. They spent the warmest hours of the day in the shade
of trees, or in rock shelters when the temperature became too hot. Observed groups (n = 56) ranged in size from one to five individuals (mean ± SD = 2.70 ± 1.49). Most of these groups included a single adult
male (62.5%) or no adult male at all (33.9%). The only encounter observed between two adult males resulted in the chasing
of one by the other. Furthermore, the mixed-sex groups including a single adult male seemed rather stable, and their members
used collective urination–defecation sites. From a behavioural point of view, the beira thus appears not very far from the
dik-diks (Madoqua spp.), but differs from them by a greater sociability between adult females and its type of habitat. 相似文献
17.
Shortleaf pine (n = 93) and loblolly pine (n = 112) trees representing 22 seed sources or 16 physiographic populations were sampled from Southwide Southern Pine Seed
Source Study plantings located in Oklahoma, Arkansas, and Mississippi. The sampled trees were grown from shortleaf pine and
loblolly pine seeds formed in 1951 and 1952, prior to the start of intensive forest management across their native ranges.
Amplification fragment length polymorphism (AFLP) markers were developed and used to study genetic diversity and its structure
in these pine species. After screening 48 primer pairs, 17 and 21 pairs were selected that produced 794 and 647 AFLPs in shortleaf
pine and loblolly pine, respectively. High-AFLP-based genetic diversity exists within shortleaf pine and loblolly pine, and
most (84.73% in shortleaf pine; 87.69% in loblolly pine) of this diversity is maintained within physiographic populations.
The high value of unbiased measures of genetic identity and low value of genetic distance for all pairwise comparisons indicates
that the populations have similar genetic structures. For shortleaf pine, there was no significant correlation between geographic
distance and genetic distance (r = 0.28), while for loblolly pine there was a weak but significant correlation (r = 0.51). 相似文献
18.
The effect of pulse repetition rate, pulse intensity, and bicuculline on the minimum threshold and latency of bat inferior collicular neurons 总被引:2,自引:0,他引:2
P. H.-S. Jen Q.-C. Chen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(4):455-465
This study examines the effect of pulse repetition rate (PRR), pulse intensity, and bicuculline on the minimum threshold (MT)
and latency of inferior collicular neurons of the big brown bat, Eptesicusfuscus, under free-field stimulation conditions. It tests the hypothesis that changes in MT and latency of collicular neurons are
co-dependent on PRR. The number of impulses in inferior collicular neurons (n = 245) increased either monotonically (25%) or non-monotonically (75%) with pulse intensity. Latencies either decreased to
a plateau (72%), fluctuated unpredictably within 3 ms (21%) or changed very little (7%) with increasing pulse intensity. Latencies
and MTs of most collicular neurons increased by 1.5–24 ms (mean ± SD = 4.8 ± 3.3 ms) and 4–75 dB (mean ± SD = 22.1 ± 16.2 dB)
with increasing PRR. In most neurons (94%), the latency increase was completely (42%) or partially (52%) eliminated when pulse
intensity was compensated for the MT increase with PRR. Complete elimination of latency was achieved by bicuculline application.
In a few neurons (6%), the latency increase with PRR was not affected by compensated pulse intensity or bicuculline application.
Accepted: 8 October 1997 相似文献
19.
Data on the concentration of the elements in the human body are important, for example, to estimate the amounts required to
maintain a good healthy state or find their connections with morbidity and mortality. In this paper, the concentration of
copper (by flame atomic absorption spectrometry) in material obtained from autopsy cases of nonpoisoned people (n = 130), aged from 14 to 80 years, between 1990–2006, is presented. The following values were found (mean ± SD in micrograms
of copper per gram or per milliliter): brain 3.32 ± 1.50 (n = 43), liver 3.47 ± 1.51 (n = 79), kidney 2.15 ± 0.90 (n = 76), stomach 1.10 ± 0.76 (n = 65), intestines 1.54 ± 1.19 (n = 25), lung 1.91 ± 1.30 (n = 27), spleen 1.23 ± 0.28 (n = 3), heart 3.26 ± 0.59 (n = 5), bile 3.60 ± 1.67 (n = 13), and blood 0.85 ± 0.19 (n = 73). 相似文献
20.
Doo-Ahn Kwak Woo-Kyun Lee Hyun-Kook Cho Seung-Ho Lee Yowhan Son Menas Kafatos So-Ra Kim 《Journal of plant research》2010,123(4):421-432
The objective of this study was to estimate the stem volume and biomass of individual trees using the crown geometric volume
(CGV), which was extracted from small-footprint light detection and ranging (LiDAR) data. Attempts were made to analyze the
stem volume and biomass of Korean Pine stands (Pinus koraiensis Sieb. et Zucc.) for three classes of tree density: low (240 N/ha), medium (370 N/ha), and high (1,340 N/ha). To delineate
individual trees, extended maxima transformation and watershed segmentation of image processing methods were applied, as in
one of our previous studies. As the next step, the crown base height (CBH) of individual trees has to be determined; information
for this was found in the LiDAR point cloud data using k-means clustering. The LiDAR-derived CGV and stem volume can be estimated on the basis of the proportional relationship between
the CGV and stem volume. As a result, low tree-density plots had the best performance for LiDAR-derived CBH, CGV, and stem
volume (R
2 = 0.67, 0.57, and 0.68, respectively) and accuracy was lowest for high tree-density plots (R
2 = 0.48, 0.36, and 0.44, respectively). In the case of medium tree-density plots accuracy was R
2 = 0.51, 0.52, and 0.62, respectively. The LiDAR-derived stem biomass can be predicted from the stem volume using the wood
basic density of coniferous trees (0.48 g/cm3), and the LiDAR-derived above-ground biomass can then be estimated from the stem volume using the biomass conversion and
expansion factors (BCEF, 1.29) proposed by the Korea Forest Research Institute (KFRI). 相似文献