Multiscale spatial variation of the bark beetle Ips sexdentatus damage in a pine plantation forest (Landes de Gascogne,Southwestern France)

Bark beetles are notorious pests of natural and planted forests causing extensive damage. These insects depend on dead or weakened trees but can switch to healthy trees during an outbreak as mass-attacks allow the beetle to overwhelm tree defences. Climatic events like windstorms are known to favour bark beetle outbreaks because they create a large number of breeding sites, i.e., weakened trees and for this reason, windthrown timber is generally preventively harvested and removed. In December 1999, the southwest of France was struck by a devastating windstorm that felled more that 27 million m³of timber. This event offered the opportunity to study large-scale spatial pattern of trees attacked by the bark beetle Ips sexdentatus and its relationship with the spatial location of pine logs that were temporally stored in piles along stand edges during the post-storm process of fallen tree removal. The study was undertaken in a pure maritime pine forest of 1300 ha in 2001 and 2002. We developed a landscape approach based on a GIS and a complete inventory of attacked trees. During this study more than 70% of the investigated stands had at least one tree attacked by I. sexdentatus  . Spatial aggregation prevailed in stands with n≥15$n\ge 15$ attacked trees. Patches of attacked trees were identified using a kernel estimation procedure coupled with randomization tests. Attacked trees formed patches of 500–700 m² on average which displayed a clumped spatial distribution. Log piles stemming from the sanitation removals were mainly distributed along the large access roads and showed an aggregated spatial pattern as well. The spatial relationship between patches of attacked trees and log pile storage areas was analyzed by means of the Ripley’s statistic that revealed a strong association at the scale of the studied forest. Our results indicated that bark beetle attacks were facilitated in the vicinity of areas where pine logs were stored. The spatial extent of this relationship was >1000 m. Similar results were obtained in 2001 and 2002 despite differences in the number and spatial distribution of attacked trees. The presence of a strong “facilitation effect” suggests that log piles should be removed quickly in order to prevent outbreaks of bark beetles.     

Temporal dynamics of forage succession for elk at two scales: Implications of forest management

Rapid conversion of lodgepole pine (Pinus contorta) dominated landscapes in western Alberta to a mosaic of successional stand ages has long-term implications for elk populations in the region that have not been fully assessed. We developed stand-level models of forage succession using data from 159 cutblocks to simulate forage and cover availability within the home range of an elk under “even-flow” and “pulsed” timber cutting scenarios that are common in this area. We found forage biomass peaked approximately 9 years following felling for both herbaceous (graminoids and forbs) and palatable browse forage. Forage production was determined primarily by the age of the cutblock (time since felling) and to a lesser extent elevation, compound topographic index (a measure of site wetness), and the distance to the nearest deciduous forest patch. Forbs became increasingly abundant as stands matured. Browse composition shifted from palatable species to unpalatable species after approximately 30 years. Within an elk home range (100 km²), we found that simulating an “even-flow” cutting regime resulted in forage availability that was always higher than under the current conditions of 90% forests when more than 10 ha were harvested per year. Further, forest cover (>30$>30$-year-old stands) was never less than the guideline of 60% of the area needed to provide adequate thermal and hiding cover. In contrast, when a “pulsed” harvest scenario was simulated, similar to what occurs for mountain pine beetle control, forage availability changed dramatically over time as a large cohort of harvested timber aged. Without further harvesting the stand conditions in the home range eventually returned to a state of pre-harvest risk for mountain pine beetle outbreak. We demonstrated several additional harvesting scenarios that avoided the potential risk and produced a much higher level of forage than currently exists.     

Two new benzofuran derivatives with anti-inflammatory activity from Liriope spicata var. prolifera

Two new benzofuran derivatives, 2-(4′-hydroxybenzyl)-5,6-methylenedioxy-benzofuran () and 2-(4′-hydroxybenzoyl)-5,6-methylenedioxy-benzofuran (), along with 8 known compounds were isolated from 60% EtOH extract of the fibrous roots of Liriope spicata var. prolifera. Their structures were elucidated on the basis of extensive spectroscopic analysis. In an in vitro bioactive assay, the two new benzofuran derivatives showed anti-inflammatory activity. Compounds 1 and 2 exhibited significant inhibitory activity against neutrophil respiratory burst stimulated by phorbol 12-myristate 13-acetate (PMA) with IC₅₀ value of 4.15 ± 0.07 and 5.96 ± 0.37 μM, respectively.     

Novel indole C-glycosides from Isatis indigotica and their potential cytotoxic activity

Two novel indole C-glycosides, which were the first reported alkaloids C-glycosides from Isatis indigotica, together with five known alkaloids were isolated. The novel alkaloids were elucidated to be indole-3-acetonitrile-4-methoxy-2-C-β-D-glucopyranoside (1) and N-methoxy-indole-3-acetonitrile-2-C-β-D-glucopyranoside (2) on the basis of spectroscopic analysis. 1 exhibited significant cytotoxic activities against human myeloid leukemia HL-60 and human liver cancer HepG2 cells with the IC₅₀ of 1.3 ± 0.1 and 2.1 ± 0.3 μM, respectively. 2 showed potential cytotoxic activities against HL-60 and human myeloid leukemia Mata cells with the IC₅₀ of 5.1 ± 0.4 and 12.1 ± 0.8 μM, respectively.     

The impact of Sirococcus shoot blight on radial and height growth of Norway spruce (Picea abies) in young plantations

The impact of Sirococcus shoot blight on the radial and height growth of Norway spruce in a young plantation (approximately 20 years old) was investigated by examining the increment losses for four infection intensities (classes). The average diameter at breast height of trees in the lightly damaged class was 72% when compared with the average diameter of the healthy trees, whereas moderately and severely damaged tree classes were 67 and 57%, respectively. Using tree ring analysis, the development of radial growth over time due to intensity of infection was studied. Height growth of affected trees was also significantly reduced (up to 43%) compared with the healthy trees, thus indicating a dramatic impact of Sirococcus conigenus on the growth of young Norway spruce.     

A secoiridoid with quinone reductase inducing activity from Cortex fraxini

A new secoiridoid named chinensisol (1) along with twenty known compounds were isolated from the 95% ethanol extract of Cortex fraxini. Their structures were elucidated on the basis of NMR, MS, IR and UV spectral evidences. The quinone reductase (QR) inducing activities of the compounds were evaluated and the results showed that compounds 1, 9 and 14 had moderate QR inducing activities with CD values (concentration required to double the specific activity of QR) of 72.4 ± 7.7, 34.3 ± 3.3 and 42.0 ± 0.4 μM respectively.     

The effects of logging and disease on American chestnut

Disturbance histories drive spatiotemporal patterns of species distributions, and multiple disturbances can have complex effects on these patterns of distribution. The introduction of the chestnut blight (Cryphonectria parasitica (Murril.) Barr.) to the eastern United States in the early 1900s coincided with an increase in logging, thus presenting an ideal situation for studying the effect of two disturbance events, logging and disease. The purpose of this study was to compare chestnut (Castanea dentata) abundance and the prevalence of chestnut blight among (1) sites that were and were not logged for chestnuts during the blight pandemic and (2) sites that varied in time since the last logging event. Current chestnut abundance and chestnut blight prevalence were assessed in areas where chestnut was known to occur before the blight. Elevation, soil pH, slope, aspect, age of canopy trees, and presence or absence of chestnut stumps indicating selective logging of chestnuts were recorded at each site. Chestnuts were more abundant on sites that had not been selectively logged for pre-blight chestnuts. Chestnut presence was more likely at high elevations (857 m ± 33 m). Chestnut abundance was greater at high elevations (>1000 m) and acidic soils (pH 4-5). Chestnut blight prevalence was not correlated with any measured environmental variable. Rather, 15.1% of all chestnut stems were infected with blight regardless of chestnut density. Thus, higher chestnut abundance is not due to lower mortality from the chestnut blight, although the temporal dynamics of blight infection and stem recovery were not within the scope of this study. This research shows that local rates of chestnut population decline differ between locations with different chestnut logging histories. Chestnut site preferences are better understood within the context of history, and thus teasing apart the effects of disease, logging, and environment will result in more successful chestnut restoration efforts.     

Response of litter decomposition and soil C and N transformations in a Norway spruce thinning stand to removal of logging residue

Increasing demand for production of bioenergy has led to an interest in forest management which uses logging residue from both clear-cuttings and thinning stands. The aim of this study was to investigate the effects of removal of logging residue in a thinning Norway spruce stand on (1) litter decomposition and (2) soil microbial processes in C and N cycling and the quality of soil organic matter. The study site was a 40-year-old Norway spruce stand growing on a relatively fertile site. During thinning, logging residue was either removed (whole-tree harvest) or left on the site (stem-only harvest). Different types of material in the logging residue, from main branches to needles, were weighed separately into mesh bags. The bags were placed above the moss layer in the whole-tree harvest treatment and in the logging residue layer in the stem-only harvest treatment, and decomposition was monitored for 5 years after treatment. From the humus layer, samples were taken 10 years after treatment. Harvest method affected the mass loss of the litter material very little but the C-to-N ratio of the remaining material was slightly higher in whole-tree harvest than in stem-only harvest, particularly in the needle material. In the humus layer samples, taken 10 years after treatment, the rate of C mineralization was lower in whole-tree harvest than in stem-only harvest; also the rate of net N mineralization and the amounts of C and N in the microbial biomass tended to be lower, although not statistically significantly. Removal of logging residue had no effect on pH (pHH₂O$\text{p}{\text{H}}_{{\text{H}}_2\text{O}}$ 3.9 in both treatments) or C-to-N ratio (28 in both treatments) in the humus layer. The concentrations of total water-soluble phenols and an important group of phenols, condensed tannins, were both lower in the humus layer of whole-tree harvest than in that of stem-only harvest. Concentrations of sesqui-, di- or triterpenes in the humus layer were similar in both treatments. In conclusion, 10 years after harvest, soil microbial activities and organic matter characteristics in whole-tree harvest differed from those in stem-only harvest.     

Sesquiterpenoids and norterpenoids from Vitex negundo

Chemical investigation on the seeds of Vitex negundo has afforded a new furan-containing sesquiterpenoid, negunfurol (1), a new norlabdane-type diterpenoid, negundoal (2), and two new norursane-type triterpenoids, negundonorins A (3) and B (4), together with two know compounds, 3-formyl-4,5-dimethyl-8-oxo-5H-6,7-dihydronaphtho[2,3-b]furan (5) and 3-epi-corosolic acid (6). Their structures and configurations were elucidated by detailed spectroscopic analyses on the basis of NMR, IR, and MS data. Compound 3 was strongly cytotoxic against ZR-75-30 cell line with IC₅₀ value of 0.56 ± 0.19 μg/mL, whereas compound 1 was most active against HL-60 cell line with IC₅₀ value of 0.94 ± 0.26 μg/mL.     

Antioxidant flavanes from Livistona chinensis

Three new flavanes and eight known flavonoids were isolated from the fruits of Livistona chinensis. The structure of the new flavanes were established as 2S,3S-3,5,7,3′,5′-pentahydroxyflavane (1), 2R,3R-3,5,6,7,8,4′-hexahydroxyflavane (2) and 2R,3R-3,5,6,7,8,3′,5′-heptahydroxyflavane (3), respectively, on the basis of chemical and spectroscopic data. The antiproliferative activity against four human tumor cell lines (HL-60, Mata, HepG2 and CNE-1) was evaluated. 1 had significantly antiproliferative effects against HL-60 and CNE-1 with the IC₅₀ of 0.2 ± 0.01 and 1.0 ± 0.1 μM, respectively, overpowering the reference compound in the assay (cisplatin). Most compounds also exhibited potent antioxidant activity.     

A new natural spiro heterocyclic compound and the cytotoxic activity of the secondary metabolites from Juniperus brevifolia leaves

A new natural spiro compound 3,4-dehydrotheaspirone and the known arctiol [1β,6α-dihydroxy-4(14)-eudesmene] were isolated from Juniperus brevifolia. Arctiol is reported for the first time in the Juniperus genus. Their structures were established by 1D, and 2D NMR and MS spectra. Antimicrobial and cytotoxic activities of 1 and several secondary metabolites ,,,,,,,,, previously isolated by our group from J. brevifolia were evaluated and some SAR has been established. The 18-hydroxydehydroabietane (4) displayed great antiproliferative activity against cancer cell lines tested, namely HeLa, A-549 and MCF-7. Compound 4 also presented a significant bactericidal effect against Bacillus cereus at different concentrations tested.     

Early results from genetic trials on the growth of Spanish cedar and its susceptibility to the shoot borer moth in the Yucatan Peninsula,Mexico

Cedrela odorata (Spanish cedar) is a neotropical broadleaf tree species that is in high demand for furniture and interior fittings. In 1998, seed collections were made from Spanish cedar in the Yucatan Peninsula, Mexico, for genetic conservation and tree improvement projects. Progeny from these collections were established in genetic trials at Bacalar, Noh Bec, and Zoh Laguna in the Yucatan. Survival at 2 years was 73.5% at Bacalar, 72% at Noh Bec, but only 20% after 6 months for several replicates at Zoh Laguna. Mean 2-year height, number of years of Hypsipyla attack on apical shoots (over 2 or 3 years) and total branching over 2 years, were 1.3 m, 0.04 years, and 2.5 branches at Bacalar, and 1.9 m, 0.35 years, and 1.6 branches at Noh Bec. Selection of the three best provenances (Escárcega, Bacalar, and Calakmul) would result in an estimated cross-site gain of 8.6% in 2-year height. Within-provenance, cross-site heritabilities for 2-year height, shoot borer attack, and branching were 0.1 ± 0.02, 0.0 ± 0.02, and 0.0 ± 0.02, respectively. Single-site heritabilities for height at 2 years, shoot borer attack, and branching were 0.09 ± 0.05, 0.02 ± 0.04, and 0.09 ± 0.05 at Bacalar and 0.16 ± 0.07, 0.0 ± 0.06, and 0.0 ± 0.07 at Noh Bec. Given the known advantage of rapid growth to avoid Hypsipyla damage over the long term and the stable performance of provenances across sites for growth traits, we recommend provenance selection over multiple trials to reduce the risk of serious damage by the insect. Good provenances and other suitable seed sources, as well as proper site selection and silvicultural practices, are important tools for increasing yields from plantations of C. odorata.     

New diterpenoids and cytotoxic and anti-inflammatory diterpenoids from Amentotaxus formosana

Two new abietane diterpenoids, ramentoxide (1) and ramentoxidone (2) and a new icetexane diterpenoid, amentonone (3) were isolated from the barks of Amentotaxus formosana. The structures of 1-3 were determined by spectroscopic methods. Known compounds brevitaxin (4), and (+)-ferruginol (5) and ent-kaur-16-en-15-one (6) isolated from this plant revealed potent cytotoxic activity against human breast adenocarcinoma cells, MCF-7 cells with an IC₅₀ value of 0.08 ± 0.05 μg/mL, and significant anti-inflammatory activities, respectively.     

The phenylpropanoids of Aster flaccidus

Aster flaccidus bge has been used as traditional medicine in northwestern China. Two new phenylpropanoids (1–2) including one lignan: (7′R, 8S)-9′-lariciresinol-(α-methyl)-butanoate (1), 5,9-dimethoxyl-7-(α-methyl)-butanoxyl-phenyl-2E-propenol-(α-methyl)-butanoate (2) isolated from the chloroform extract of the root of Aster flaccidus bge were identified by means of extensive spectroscopic studies: 1D and 2D NMR spectra as well as HRMS analysis. They have not obvious anti-HIV-1 therapeutic activity (TI = 1.0–1.1) compared with AZT (TI = 55,556) as the result of the determination of their in vitro anti-HIV-1 activity while compound 2 displays strong antitumor activity against BEL 7402 (human liver carcinoma) with cisplatin as a positive control and the effect increases with the measuring-time going on (24 h, IC₅₀: 106.67 ± 8.47 µM — 72 h, IC₅₀: 50.51 ± 6.11 µM).     

Net primary productivity of Bruguiera parviflora (Wight & Arn.) dominated mangrove forest at Kuala Selangor,Malaysia

The net primary productivity of Bruguiera parviflora dominated mangrove forest at Kuala Selangor, Malaysia was estimated from the average yearly biomass increment and litter production. The average yearly biomass increment in saplings and trees was 0.58 and 16.51 t ha⁻¹, respectively, and the annual amount of total litter production was 10.35 t ha⁻¹. The biomass increment in saplings and trees was not significantly different (t-test, p > 0.05) in 2 successive years and the estimated net primary productivity was 27.44 t ha⁻¹ year⁻¹. The ratio (2.65:1) of net primary productivity and litterfall suggests that this mangrove forest is at a juvenile stage.     

Effect of species and spacing of fast-growing nurse trees on growth of an indigenous tree, Hopea odorata Roxb., in northeast Thailand

We tested the effects of species and spacing of nurse trees on the growth of Hopea odorata, a dipterocarp tree indigenous to Southeast Asia, in a two-storied forest management system in northeast Thailand. Eucalyptus camaldulensis, Acacia auriculiformis, and Senna siamea were planted as nurse trees in 1987 at spacings of 4 m × 8 m, 2 m × 8 m, 4 m × 4 m, and 2 m × 4 m in the Sakaerat Silvicultural Research Station of the Royal Forest Department, Thailand. Seedlings of H. odorata were planted in the nurse tree stands at a uniform spacing of 4 m × 4 m and in control plots (no nurse trees) in 1990. Stem numbers of some nurse trees were thinned by half in 1994. The stem diameter and height of all trees were measured annually until 1995 and again in 2007. The mean annual increment (MAI) in volume was estimated as 8.2–10.1 m³ ha⁻¹ year⁻¹ for E. camaldulensis and 0.9–1.2 m³ ha⁻¹ year⁻¹ for S. siamea, smaller than reported elsewhere. This suggests that the site properties were not suitable for them. The MAI of A. auriculiformis was 7.9–9.8 m³ ha⁻¹ year⁻¹, within the reported range. Survival rates of H. odorata in the S. siamea stands and the control plots decreased rapidly during the first 2 years but then stayed constant from 1992. In contrast, survival rates of H. odorata in the E. camaldulensis and A. auriculiformis stands were initially high (>70%), but then decreased after 1995. Stem diameter, tree height, and stand basal area of H. odorata were large in both the S. siamea stands and the control plots from then. The growth of H. odorata was largest in the 2 m × 8 m S. siamea stands. In contrast, it was restricted in the E. camaldulensis and A. auriculiformis stands owing to strong shading by their canopies. Thinning by 50% tended to facilitate the growth of H. odorata temporarily in the E. camaldulensis and A. auriculiformis stands. The stand basal areas of nurse trees and of H. odorata showed a trade-off. These results suggest that the growth of H. odorata was maximized in the S. siamea stands. We assume, however, that the growth of H. odorata could be improved even in the E. camaldulensis and A. auriculiformis stands by frequent or heavy thinning.