The impact of community-based forest management on timber treeregeneration in north-eastern Honduras,with specific reference tobig-leaf mahogany (Swietenia macrophylla)

Reduced-impact logging is used to minimise the negative effects of selective logging. However, it has been suggested that low-impact logging may create too little disturbance for the regeneration of the light-demanding timber tree species, hence compromising forest productivity. This study evaluates the impact of low-intensity, non-mechanised, certified community forest management on timber tree regeneration. Particular attention was paid to big-leaf mahogany (Swietenia macrophylla), which has a regeneration pattern linked with large-scale disturbances. Logging gaps were compared to natural treefall gaps of an unlogged forest. There were more species of the light-demanding timber trees, but fewer individuals of the shade-tolerant timber species in the certified forest logging gaps, compared to unlogged forest treefall gaps. Furthermore, significant differences were found in the environmental characteristics of the logging and natural treefall gaps, although these only partially explained the differences in timber regeneration. Mahogany was found in over half of the logged forest gaps, whilst being nearly absent in the natural treefall gaps. However, all mahoganies in the established logging gaps were seedling-sized, indicating that regeneration may be hampered due to competing vegetation. The results of the study suggest that low-impact forest management may, at least in the short term, favour light-demanding species over the shade-tolerant ones, similarly to conventional forest management.     

Temperature sensitivity and recruitment dynamics of Siberian larch (Larix sibirica) and Siberian spruce (Picea obovata) in northern Mongolia’s boreal forest

This study sought to clarify the recruitment dynamics and growth of Siberian larch (Larix sibirica) and Siberian spruce (Picea obovata) in relation to changing temperatures in northern Mongolia. These tree species are the primary forest species found in the closed-canopy boreal forest of north-central Mongolia. Mongolia’s boreal forests exist along the southern terminus of the Siberian boreal system in both pure and mixed species stands. I collected tree cores and cross-sections as well as site and tree stature parameters from 118 forest plots in the Darhad valley of north-central Mongolia. Principle components analysis of 130 L. sibirica tree ring series informed the construction of two composite chronologies for this species. A chronology for P. obovata was developed using 24 tree ring series. Correlation analysis between tree ring indices and temperature data showed two distinct growth signals: a positive response to growing season temperatures was exhibited by one L. sibirica chronology and a negative response to spring temperatures was exhibited by a second L. sibirica chronology. The P. obovata chronology exhibited strong negative correlations with mean monthly and mean maximum monthly growing season temperatures. Multiple analyses of variance (MANOVA) indicated that tree stature (dbh, height) and site parameters (latitude, longitude, slope, aspect, elevation) did not significantly predict growth response or species. Forest recruitment events appear episodic for both species. Synchronous establishment of saplings, based on approximate root collar age, suggests an initial floristic model for mixed composition stands likely due to supra-annual variations of fire, land-use and climate. Forest management activities in the region should consider the diverging growth response to temperature shown here by prioritizing protection forests and the various ecosystem services provided by forests in arid ecosystems. In addition, promoting selection harvests over clear-felling would maximize future alternatives under conditions of rapidly changing climate. Care should be taken in new forest management planning activities until adequate information exists on the likely trajectory of this system due to climate-induced forest change.     

Genetic (AFLP) diversity of nine Cedrela odorata populations in Madre de Dios,southern Peruvian Amazon

Cedrela odorata L., one of the most important neotropical timber species, is threatened by deforestation and unsustainable logging in many parts of its natural range. Information on patterns of genetic variation is useful in informing both reforestation and genetic conservation activities. However, to date, no such information is available in Peru or elsewhere in South America. In the present study, genetic diversity between and within nine Peruvian populations of the species, based on amplified fragment length polymorphism (AFLP) markers, is reported. Overall diversity level was high (Ht = 0.22), as expected for a widespread, long-lived tropical species, and consistent with previous studies carried out in Central America. Levels of intrapopulation diversity were higher than those previously reported for the species (Hs = 0.13–0.21). Analysis of molecular variation revealed genetic differences between two population groups located on different rivers and between populations located on the same rivers. Differences between groups were greater than those within groups. Genetic and geographical distances were significantly correlated. The relatively strong genetic differences between populations may be related to the riparian, essentially one-dimensional spatial distribution pattern of the populations studied. No difference was found in percentage of polymorphic loci between relatively undisturbed and logged populations. The existence of appreciable genetic differentiation over a relatively small part of the species range in the Peruvian Amazon suggests the need for caution in use of seed outside its zone of origin. For genetic conservation purposes, it would probably be prudent to sample (ex situ) or conserve (in situ) populations in each of the major watersheds of the Peruvian Amazon.     

Improving seed germination and seedling growth of Omphalea oleifera (Euphorbiaceae) for restoration projects in tropical rain forests

To improve the restoration of tropical rain forests, we tested the germination of seeds of Omphalea oleifera collected from soil (S) and from trees (T) in the 2001 dry season (Spring), at the beginning of a dry season (2005a, winter) and in the rainy season (2005b, winter). All seeds had high water content (WC, 31–33%), and the lipid content varied from 14 to 46%. Seedlings from seeds collected in 2001 were subjected to moderate water stress as a preconditioning treatment for severe stress. T-seeds collected in the dry season had high WC, rapid and high germination percentage; S and T-seeds collected in winter (2005) had also high WC but were dormant. GA₃ (250 ppm) broke this dormancy. S-seeds collected in the dry season or at the beginning of it had relatively low WC and low and delayed germination. Some 2001 S-seeds produced albino seedlings. The critical water content for maintaining ecological longevity in these seeds was ∼15%. Seeds collected in 2005b that were dehydrated for 20 days in a moist and fresh atmosphere lost their viability, showing recalcitrant behavior. T-seeds with the lowest lipid content (2005a) after dehydration maintained low germination (15 ± 18%). In all samples the seed size varied widely and was not predictive of seed WC. Embryos taken from dehydrated seeds had two to four times higher WC than the seeds, but germination did not take place. Laboratory and field germination of dormant seeds showed that viability may be maintained for at least 2–3 months on a moist substrate (soil or agar). Moderate water stress at the seedling stage reduced the efficiency of biomass production. Response to this water stress was expressed more in physiological traits than in morphological characters, consequently biomass allocation was maintained and plants retained most of their morphological characteristics (root:shoot ratio, leaf area ratio, specific leaf area, leaf weight ratio). Moderate water stress did not increase the tolerance of seedlings to severe stress, causing leaf shedding and plant death. For restoration purposes we recommend that T-seeds be germinated immediately avoiding dehydration. The use of S-seeds could result in unhealthy seedlings. Seed recalcitrance and the response to moderate water stress restrict germination and establishment to small gaps, where this species naturally grows. We suggest that before introducing O. oleifera in restoration programs, a plant cover should be built to reduce soil water deficit. It is necessary to improve methods to increase potential seed longevity in storage.     

Antitrypanosomal activity of polycarpol from Piptostigma preussi (Annonaceae)

Polycarpol, sitosterol and sitosterol-3-O-β-D-glucoside isolated for the first time from Piptostigma preussi (Annonaceae) occur regularly in some Annonaceae such as Piptostigma genus. Polycarpol exhibits interesting antitrypanosomal activity with an ED₅₀ value of 5.11 µM on Trypanosoma brucei cells. Moreover, it inhibits T. brucei glycolytic enzymes GAPDH and PFK with IC₅₀ values of 650 and 180 µM respectively.     

Possibility of grouping of Cyclobalanopsis species (Fagaceae) grown in Japan based on an analysis of several regions of chloroplast DNA

Four regions of chloroplast DNA were sequenced as a prospective genetic marker to identify Japanese representatives of Cyclobalanopsis: Quercus acuta, Q. sessilifolia, Q. salicina, Q. myrsinaefolia, Q. glauca, and Q. gilva. We found that Q. gilva was distinguished from other species based on both the trnL-trnF and trnT-trnL intergenic spacers. The evidence shows good coincidence with the fact that Q. gilva has several peculiar morphological features distinguishable from those of other species. There was no difference in trnL intron and matK. Both trnT-trnL and trnL-trnF intergenic spacers are capable of being used as genetic markers to identify Q. gilva among Cyclobalanopsis species.Part of this paper was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 3–5, 1998     

特有种野生血皮槭的生长状况

血皮槭(Acer griseum(Franch)Pax)是无患子科(Sapindaceae)槭树属(Acer)落叶乔木,为我国特有种。其树干赭褐色,树皮卷曲状剥落,秋季叶色红艳或黄色,是世界著名的观赏树种。1901年,西方植物学家威尔逊在湖北发现血皮槭,将其和珙桐一起作为园林树种引入欧洲[1],继而血皮槭又被引入美国等其他西方国家。1993年,血皮槭获得英国皇家园艺学会园艺奖,目前在国外用于庭院观赏。血皮槭不仅具有观赏价值,而且具有用材和药用价值[2-3]。血皮槭在2004年出版的《中国物种红色目     

Historical fire and vegetation dynamics in dry forests of the interior Pacific Northwest,USA, and relationships to Northern Spotted Owl (Strix occidentalis caurina) habitat conservation

Regional conservation planning frequently relies on general assumptions about historical disturbance regimes to inform decisions about landscape restoration, reserve allocations, and landscape management. Spatially explicit simulations of landscape dynamics provide quantitative estimates of landscape structure and allow for the testing of alternative scenarios. We used a landscape fire succession model to estimate the historical range of variability of vegetation and fire in a dry forest landscape (size ca. 7900 km²) where the present-day risk of high severity fire threatens the persistence of older closed canopy forest which may serve as Northern Spotted Owl (Strix occidentalis caurina) habitat. Our results indicated that historically, older forest may have comprised the largest percentage of the landscape (∼35%), followed by early successional forest (∼25%), with about 9% of the landscape in a closed canopy older forest condition. The amount and condition of older forest varied by potential vegetation type and land use allocation type. Vegetation successional stages had fine-grained spatial heterogeneity in patch characteristics, with older forest tending to have the largest patch sizes among the successional stages. Increasing fire severities posed a greater risk to Northern Spotted Owl habitat than increasing fire sizes or frequencies under historical fire regimes. Improved understanding of historical landscape-specific fire and vegetation conditions and their variability can assist forest managers to promote landscape resilience and increases of older forest, in dry forests with restricted amounts of habitat for sensitive species.     

Effects of fragmentation on juvenile morphology of Acer saccharum Marsh. (sugar maple) in temperate forests of northeastern Ohio,USA

The influence of forest fragmentation on population and community dynamics of woody plants has been well established worldwide, but rarely at the level of an individual plant. We evaluated the influence of fragmentation on juvenile stem morphology of Acer saccharum Marsh. (sugar maple), while also examining light levels and considering possible confounding effects attributed to elevation gradients in temperate forests of northeastern Ohio, USA. At two sites, plant stem dimensions, canopy openness, and relative ground level elevation were measured using randomly positioned plots in forest edge and interior habitats that were within 25 and 60–100 m from a forest edge, respectively. Ratios of stem length to stem basal diameter were greater in forest interiors than near forest edges. These differences in stem morphology between habitats were likely a result of stem elongation in relation to a shade avoidance response in forest interiors that were consistently darker than forest edge areas across study sites. By contrast, such morphological differences were likely not related to variation in relative ground level elevation since a subtle elevation gradient was detected at only one site. We encourage experimentation to identify mechanisms that affect plant stem morphology of young individuals and its influence, in turn, on plant population dynamics in fragmented forests.     

Quinone reductase (QR) inducers from Andrographis paniculata and identification of molecular target of andrographolide

In the present study, it was demonstrated that the petroleum extract of Andrographis paniculata (AP) had quinone reductase (QR) inducing activity, which might be attributed to the modification of key cysteine residues in Keap1 by Michael addition acceptors (MAAs) in it. To screen MAAs in AP, glutathione (GSH) was employed, and a LC/MS/MS method was implied. Three compounds, andrographoside, andrographolide, 14-deoxy-14,15-dehydroandrographolide were revealed could well conjugated with GSH. Then, andrographolide along with 4 new and 14 known compounds were isolated to conduct QR induction evaluation, and the CD (the concentration required to double the activity of QR) value of andrographolide is 1.43 μM. The QR induce activity of andrographolide might be attributed to its targeting multiple cysteine residues in Keap1, therefore, the alkylation of Keap1 by andrographolide was further studied and the result showed that four cysteine residues: Cys77, Cys151, Cys273 and Cys368 were alkylated, which indicated that Keap1 is a potential target for the QR induce activity of andrographolide.     

Numerical response of birds to an irruption of elm spanworm (Ennomos subsignarius [Hbn.]; Geometridae: Lepidoptera) in old-growth forest of the Appalachian Plateau, USA

Populations of forest birds were studied during two years of an outbreak of the elm spanworm Ennomus subsignarius (Hbn.) in a silviculturally unmanaged, old-growth conifer–northern hardwood forest on the Appalachian Plateau, PA. Canopy defoliation of hardwoods (mostly American beech Fagus grandifolia and red maple Acer rubrum) increased by at least 50% during the local peak of the outbreak (1993); territorial densities of birds were the highest (15% greater) during the regional peak of the outbreak (1994). Compared to a nearby but uninfested forest of similar age and composition, total bird abundance was as much as 22–33% higher at sites with extensive spanworm defoliation. In addition to canopy gleaners, several other foraging guilds exhibited one or more significant numerical responses to outbreak location or intensity, including bark foraging, understory gleaning, ground foraging, and pursuing species. Like other irruptions of forest Lepidoptera, populations of arboreal canopy-gleaning Parulinae (the warblers D. magnolia, D. fusca) were especially prone to fluctuate during this geometrid irruption.     

New amide alkaloid from the aerial part of Piper capense L.f. (Piperaceae)

Together with apigenine dimethylether and piperchabamide A, a new amide alkaloid, Kaousine and the Z form of antiepilepsirine were isolated from the aerial part of Piper capense L.f (Piperaceae). Their structures were elucidated by spectrometric methods and their in vitro antiparasitic activities were evaluated on Plasmodium falciparum.     

不同地区柚木人工林生长及土壤理化性质的研究

[目的]通过对不同地区13年生柚木人工林的标准地调查,研究柚木人工林的生长状况与土壤理化性质,以期为柚木人工林的立地选择和经营管理提供科学依据。[方法]在云南勐腊、广东揭阳、海南中南部设置48个20 m×20 m临时标准地,调查标准地内柚木生长,分层采集土壤样品测定土壤理化性质,研究不同地区柚木生长和土壤理化性质的差异及相关关系。[结果]表明:13年生勐腊柚木人工林标准地的平均树高、胸径、单株材积和蓄积量分别为14.4 m、16.82 cm、0.226 m~3、192.0 m3·hm-2,显著优于海南、揭阳的;勐腊土壤粉砂粒含量高,p H值高,盐基饱和度高,柚木生长好;揭阳的土壤黏粒含量高,p H值低,全N和全K含量低,交换性Ca~(2+)、Mg~(2+)含量极低,因而,柚木生长比其它两地差。柚木生长与土壤粉砂粒含量、p H值、全K、有效Zn~(2+)、有效Fe~(2+)、Fe3+、交换性Al3+、交换性Ca~(2+)、交换性Mg~(2+)和盐基饱和度等紧密相关。[结论]柚木在通气透水性较好的粉砂质壤土的生长比砂壤土、重壤土好;土壤的酸度对柚木生长影响显著,在强酸性、交换性Al3+和有效Fe含量高的立地,柚木生长极差;在全N、全K、有效Zn~(2+)、交换性Ca~(2+)、交换性Mg~(2+)和盐基饱和度含量均较高的立地上,柚木生长最好。     

Age structure and regeneration of subalpine fir (Abies fargesii) forests across an altitudinal range in the Qinling Mountains,China

Age structure and regeneration dynamics of subalpine fir (Abies fargesii) forest were studied across the altitudinal range in both the north and south aspects of the Qinling Mountains, China. Ages of individual fir trees were determined based on the number of rings counted from cores and the number of years to reach coring height estimated using age–height regression. Fir age structure and regeneration dynamics were similar in both the north and south aspects. A unimodal population age structure was found at the low- and mid-elevations in both aspects, indicating that environmental factors might play an important role in shaping A. fargesii age structure and regeneration at those sites. There was a recruitment pulse during the time period 1830–1890 at each altitudinal site, but no stem recruitment occurred at the low- and mid-elevations in the last century, which might be attributed to the intensive cover of understory bamboo. Fir trees were, however, persistently recruited at the upper limits during the last 150 years, and the fir tree density at the upper limits was significantly higher than that at the lower limits in both aspects. The fir population at the upper limits showed a significant increase in recruitment and stem density relative to the fir population at the low- and mid-elevations in the last century. We propose that the differences in recruitment might promote variations in stand structure and regeneration dynamics of the subalpine fir forests along the altitudinal gradient in the Qinling Mountains, China.     

Modulation of some estrogen-responsive genes in the vena cava of ovariectomised Wistar rats by griffonianone C, an isoflavone derived from Millettia griffoniana Baill. (Fabaceae)

In the present study, we investigated whether griffonianone C (Griff C), extracted from root bark of Millettia griffoniana, changes the expression of several estrogen-responsive genes in the vena cava of ovariectomised rats. For this purpose, we subcutaneously administered Griff C (2, 10, or 20 mg/kg/d BW), 17β-estradiol (E2: 10 μg/kg/d BW) as positive control, and a vehicle control respectively for three days. Relative expression levels of estrogen receptor α (ERα), progesterone receptor (PR), cyclooxygenase2 (Cox-2), vascular endothelial growth factor (VEGF), VEGF-receptor 2, angiotensin converting enzyme (ACE), endothelial NO synthase (eNOS), proliferating cell nuclear antigen (PCNA) and Ki67 mRNA extracted from the vena cava of these rats were quantified by real-time PCR. Results showed that Griff C up-regulated the expression of PR, ACE, ERα, VEGF, VEGFR2 and Ki67. However, the results of Cox-2, PCNA, and eNOS expression did not reach significance in the E2 and Griff C treated samples. These results show that griffonianone C regulated a few of the analysed genes in a similar fashion than estradiol; however, others showed a different pattern. This suggests that some of the biological effects attributed to M. griffoniana are mediated via ER pathway others may be mediated via other pathways.