Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth (diameter at breast height, total height), natural pruning (height to first dead and first live branch and branchiness) and stem and crown form of 24-year-old pedunculate oak (Quercus robur [L.]) and European ash (Fraxinus excelsior [L.]) were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha⁻¹. Mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots and inadequate self-pruning can be controlled with trainer species, the initial stocking may be reduced significantly in oak.

Forest restorations conducted in semiarid, seasonally dry climates must deal with the intense drought stress that affects tree seedlings during the dry season. Although this water deficit is the most commonly invoked source of mortality for seedlings, several other environmental factors may also preclude survival of transplants. For instance, it has been widely reported that excessive light reduces the efficiency of the photosynthetic apparatus, hence decreasing plant survival, but most seedling transplants in deforested areas are conducted under these light conditions. This study is focused in determining whether excessive light affects the photosynthetic performance and survival of Quercus coccolobifolia, a Mexican oak species, when their seedlings are transplanted in semiarid deforested areas. Further, this study tests the possibility of using artificial shade shelters to improve the ecophysiological performance and survival of seedlings. Oak seedlings were transplanted under full sunlight conditions and beneath artificial shade shelters of two different colors: white and black. To reduce water stress, and hence isolate the effects of light treatments, a drip irrigation system was implemented at each experimental plot. Seedling survival was monitored weekly for 128 days and photosynthetic performance was assessed by measuring chlorophyll fluorescence at three opportunities during the experiment. Sun-exposed seedlings showed lower photosynthetic performance and survival rates than those beneath shelters of both colors. These results suggest that sunlight damage can reduce seedling survival when they are transplanted in exposed sites, and that shade shelters can improve the success of forest restoration programs in semiarid climates.

The potential role of exotic tree plantations in facilitating successional processes on degraded areas was evaluated in southern Ethiopia by comparing seedling characteristics, transpiration and photosynthetic performance of Podocarpus falcatus seedlings in Eucalyptus plantation, Pinus plantation, adjacent natural forest and clear-felled plantation site. P. falcatus seedlings exhibited differences in architecture between Eucalyptus and Pinus plantations. They had higher leaf area, shorter internode length and greater number of lateral branches in Eucalyptus plantation. At similar vapor pressure deficit (VPD), P. falcatus transpired much less than E. saligna, especially at higher VPDs. Analysis of fluorescence parameters in the leaves showed no significant differences in the level of dark-adapted and light-adapted fluorescence yield (F_v/F_m and ΔF/F_m′, respectively), electron transport rate (ETR) and nonphotochemical quenching (NPQ) among seedlings grown inside plantations and adjacent natural forest, indicating similar photosynthetic performance. Nevertheless, there was evidence of photoinhibition in P. falcatus in the clear-felled site which had low fluorescence yield but high values of NPQ as protection from photoamage. The light response curves of ETR, NPQ and ΔF/F_m′ showed similar light saturation behavior among the seedlings grown inside plantations and natural forest and suggested a sequence of light-adapted to shade-adapted behavior in Natural forest > Eucalyptus plantation > Pinus plantation. The results show the structural flexibility, better water-use and adaptability of P. falcatus in its use of the understory environment of plantation species.

We analyze the structure and composition of old-growth wet evergreen forest of Nelliampathy hills, the chain of hills lying immediately south of Palghat Gap, in the southern Western Ghats of India. We sampled 30 plots of 0.1 ha each (50 m × 20 m) at six locations enumerating all plants ⩾ 10 cm girth at breast height. We pooled the data and computed various structural parameters. There were 152 species of 120 genera and 51 families of the study area. Of these, 118 (77%) were trees, 24 were climbers (16%) and 10 were shrubs (7%). Species richness varied from 58–99 per 0.5 ha sample and Shannon indices of diversity ranged from 4.4 to 5.2. Fifty-nine per cent (89 species) of the species were Indian Sub-continent elements and 34% (51 species) are endemic to the Western Ghats. Fifteen species are listed in various threat categories. Aglaia and Litsea were the most species-rich genera. Numbers of families ranged from 27–43 per 0.5 ha sample. Euphorbiaceae and Lauraceae were the most species-rich families. Stand density varied from 1714 to 2244 stems·ha⁻¹ and basal area from 53.6 to 102.1 m²·ha⁻¹. The vegetation was dominated by 3–6 species and six dominance patterns characterized the species composition within the hill complex. The old-growth evergreen forests of Nelliampathy exist as small fragments rich in biodiversity and can be used as benchmarks for comparison with disturbed forests.

I analyzed the spatial distribution and structure of trees in a cross timber forest in the Tallgrass Prairie Preserve (Pawhuska, Oklahoma, USA). I mapped and measured diameter of all stems, saplings (>1.5 m tall) and dead trees in a 4-ha plot. The stand was dominated by Quercus stellata and Q. marilandica. In total, I mapped 7,636 trees, consisting of 6,785 Q. stellata, 846 Q. marilandica, 2 Celtis occidentalis, 1 Fraxinus pensilvanica and 2 Prunus americana. For saplings, I mapped 54 Q. stellata and 21 Q. marilandica. The size class distribution of the two dominant species did not differ. The dominant mortality class was “standing dead”, while I only found saplings less than 2 m tall. The spatial distribution of the species indicated segregation in the use of the environment, generating a clumped univariate distribution of stems of the same species within radii of 30 m, but repulsion outside 30 m. This segregation can be explained by the different ecological requirements of each species.

To confirm a hybrid swarm population of Pinus densiflora × P. sylvestris in Jilin, China, we used needles and seeds from P. densiflora, P. sylvestris, and P. densiflora × P. sylvestris collected from natural stands or experimental stations to study whether shoot apex morphology of 4-year old seedlings can be correlated with the sequence of a chloroplast DNA simple sequence repeat marker (cpDNA SSRs). Total genomic DNA was extracted and subjected to sequence analysis of the pine cpDNA SSR marker Pt15169. Results show that morphological characters from 4-year old seedlings did not correlate with sequence variants of this marker. Marker haplotypes from all P. sylvestris trees had a CTAT element that was absent from all sampled P. densiflora trees. However, both haplotype classes involving this insertion/deletion element were found in a P. densiflora × P. sylvestris population and its seedling progeny. It was concluded that the P. densiflora × P. sylvestris accessions sampled from Jilin, China resulted from bi-directional crosses, as evidenced by both species’ cpDNA haplotypes within the hybrid swarm population.

Arasbaran forests are located in East Azerbaijan (northwest Iran). Increasing of socio-economic problems in this area causes destruction of biodiversity and structure of these forests. Using multipurpose trees such as cornelian cherry (Cornus mas L) to encourage villagers to produce forest by-products is a basic approach for preserving these forests. This species grows naturally in Arasbaran forests and the fruit is annually exploited using traditional harvest methods. This study aims to assess the ecological requirements of cornelian cherry and the important factors affecting its distribution. For this purpose, 40 circular sampling plots (300 m²) on various slope aspects were demarcated for sampling the occurrence of cornelian cherry in forest stands. DBH and crown cover percentage on north aspects were significantly greater than on other aspects and 4.5% of all trees were cornelian cherry in mature forest stands. North aspects had more seed-origin trees (standards) of cornelian cherry than coppiced trees, while west facing aspects had more coppiced than standard trees. This species had the highest regeneration rate in the sapling stage of 0–2.5 cm DBH. Thus, I recommend cultivation and development of cornelian cherry as a multi-purpose tree in the Arasbaran region on degraded forest lands on north and west aspects.

We investigated characteristics (scales and composition) of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring. We also surveyed the vegetation communities at the eight study sites to explore the role of soil seed banks in vegetation restoration. The storage capacity of soil seed banks at the eight sites ranked from 766.26 to 2461.92 seeds·m⁻². A total of 23 plant species were found in soil seed banks, of which 63–80% of seeds were herbs in various soil layers and 60% of seeds were located in the soil layer at 0–5 cm depth. Biodiversity indices indicated clear differences in species diversity of soil seed banks among different plant communities. The species composition of aboveground vegetation showed low similarity with that based on soil seed banks. In the aboveground plant community, the afforestation tree species showed high importance values. The plant species originating from soil seed banks represented natural regeneration, which also showed relatively high importance values. This study suggests that in the rocky mountain region of Beijing the soil seed banks played a key role in the transformation from pure plantation forest to near-natural forest, promoting natural ecological processes, and the role of the seed banks in vegetation restoration was important to the improvement of ecological restoration methods.

In the Sudano-Sahelian zone of Burkina Faso, Piliostigma reticulatum (DC) Hochst and Piliostigma thonningii (Schumach) are precursor species of fallow land colonization and they are used by rural villagers. The present study aimed to assess the contribution of Piliostigma species to soil quality improvement. We quantified organic carbon, total nitrogen, soil microbial biomass, soil basal respiration and metabolic quotient from soil samples taken under and outside Piliostigma canopies. We used one-way ANOVA to test for differences in the above parameters between locations (beneath and outside Piliostigma canopies). We recorded increased total organic carbon under Piliostigma from 31%–105% and in total nitrogen from 23%–66%. Microbial biomass was 13%–266% higher beneath canopies as compared to outside canopies. Basal respiration was also higher beneath canopies. The chemical elements varied by class of soil texture. Metabolic quotient (qCO₂) was significantly correlated to clay (r = 0.80) and silt (r = 0.79) content. Piliostigma stands produced abundant litter due to their leaf biomass. Thus, they contribute to improved total organic carbon and total nitrogen content in the different phytogeographic zones and improve soil fertility.

The continuing increase in human activities is causing global changes such as increased deposition of atmospheric nitrogen. There is considerable interest in understanding the effects of increasing atmospheric nitrogen deposition on soil enzyme activities, specifically in terms of global nitrogen cycling and its potential future contribution to global climate change. This paper summarizes the ecological effects of atmospheric nitrogen deposition on soil enzyme activities, including size-effects, stage-effects, site-effects, and the effects of different levels and forms of atmospheric nitrogen deposition. We discuss needs for further research on the relationship between atmospheric nitrogen deposition and soil enzymes.

Santalum album (Indian Sandalwood) is found in the mountainous regions of the intermediate zone of Sri Lanka. Few studies have been conducted on sandalwood ecology in this region, and ours is the first recorded study of essential oil content and chemical composition of heartwood. We harvested two trees with State permission and took cross-sections for analysis. We demonstrated a difference in the heartwood formation and oil yield of the trees. The composition of the oil was found to be consistent between trees and along the trunk of the tree. Main aromatic compounds were santalols and other compounds are recorded in lesser quantities. Results of this study comply with the other published work on sandalwood elsewhere. This initial study on S. album in Sri Lanka provided promising results for the future of sandalwood agroforestry.

I developed a weeding-duration model for Sakhalin fir (Abies sachalinensis (Fr. Schmidt) Masters) plantations that employs a generalized linear model. The number of years following planting that weeding is necessary is the response variable, and elevation, slope steepness, maximum snow depth, annual precipitation, geology, soil, site index, slope aspect, and vegetation type are explanatory variables. Among the explanatory variables, geology, soil, slope aspect, and vegetation type are categorical data. A Poisson distribution is assumed for the response variable, with a log-link function. Elevation, slope steepness, maximum snow depth, annual precipitation, site index, and vegetation type had a significant effect on weeding duration. Among the eight models with the smallest Akaike information criterion (AIC), I chose the model with no multicollinearity among the explanatory variables. The weeding-duration model includes site index, maximum snow depth, slope steepness (angle) and vegetation type as explanatory variables; elevation and annual precipitation were not included in the selected model because of multicollinearity with maximum snow depth. This model is useful for cost-benefit analyses of afforestation or reforestation with Abies sachalinensis.

We studied formaldehyde emission from uncoated particleboard with 16-mm thickness using the large chamber and the desiccator method. A chamber of 28.4 m3 was installed to simulate a mobile home. The formaldehyde off-gassing properties of particleboard were evaluated using the chamber. The relationship between the concentration obtained by the chamber and the values by the desiccator test was discussed in this study under different conditions of conditioning day, air exchange, and loading ratio. These two methods were compared and discussed regarding the formaldehyde emission level. Three loading ratios, 0.429 m²/m³, 0.264 m²/m³, and 0.132 m²/m³, were chosen to represent different applications of particleboard products. There was strong correlation between emissions and air exchange rates at equal product-loading ratios in the large chamber, the related coefficient R ² exceeded 0.90. There was also an indication of a generic correlation between the large chamber and the two-hour desiccator test with a single product designated loading ratio, air exchange rate, and climatic conditions.

Wood plastic composite (WPC) of wood flour (WF), high density polyethylene (HDPE), maleic anhydride-grafted polyethylene (MAPE) and lubricant was prepared by extrusion, and then exposed to different temperatures to evaluate the effects of freezing and thermal treatment on its dimensional and mechanical properties. At elevated temperatures, WPC expanded rapidly initially, and then contracted slowly until reaching an equilibrium state. Treatment at 52°C and relative humidity of 50% for 16 days improved the mechanical properties of WPC: flexure, tensile strength, and izod unnotched impact strength increased by 8%, 10% and 15%, respectively. Wide-angle X-ray diffraction (XRD) tests showed that the degree of crystalization of HDPE in WPC declined with increasing treatment temperature.

Kevlar® fiber (KF) is a synthesized product with strong mechanical properties. We used KF as a reinforcement to improve the mechanical properties of wood-flour/polypropylene (WF/PP) composites. KF was pretreated with NaOH to improve its compatibility with the thermoplastic matrix. Maleated polypropylene (MAPP) was used as a coupling agent to improve the interfacial adhesion between KF, WF, and PP. Incorporation of KF improved the mechanical properties of WF/PP composites. Treatment of KF with NaOH resulted in further improvement in mechanical strength. Addition of 3% MAPP and 2% hydrolyzed KF (HKF) led to an increment of 93.8% in unnotched impact strength, 17.7% in notched impact strength, 86.8% in flexure strength, 50.8% in flexure modulus, and 94.1% in tensile strength compared to traditional WF/PP composites. Scanning electron microscopy of the cryo-fractured section of WF/PP showed that the HKF surface was rougher than the virgin KF, and the KF was randomly distributed in the composites, which might cause a mechanical interlocking between KF and polypropylene molecules in the composites.

This study was conducted to analyze the effect of joint type, and numbers and types of dovetail keys on diagonal tension and compression performance of corner joints in a furniture frame. Joint members were cut from white fir lumber. Butted and mitered joints were constructed with one and two dovetail key(s) with butterfly and H shapes. Joints were glued by polyvinyl acetate (PVAc) and cynoacrylate (CA). Compression capacity of joints was higher than diagonal tension. Mitered joints were stronger than butted ones. Butterfly dovetail keys were superior to H shape keys. Double keys performed better than single key. Experimental joints glued with PVAc were stronger than those glued with CA glue and control specimens. In terms of strength, butterfly dovetailed joints were comparable with doweled joints.

Most community forests in hill regions of northeast India have been managed by traditional local institutions for centuries and most of these institutions remain functional even today. Higher forest coverage on private and community lands as compared to government land indicates that traditional institutions effectively manage community forests in the region. The present study was conducted through a survey of literature and field work using participatory research tools viz., PRA exercises, group discussions and questionnaire interviews with key informants in northeast India. We categorized the institutions involved in conservation and management of forests into three major types: traditional, quasi-traditional and modern. Traditional institutions with hierarchal structure were found in all states and are intact and functional in the state of Meghalaya. Quasi-traditional institutions, a blend of traditional and modern institutions were prevalent in Nagaland while modern institutions have almost replaced traditional institutions in Mizoram. We recorded at least eleven types of community forests viz., group of village forest, village forest, restricted forest, sacred forest, clan forest, cemetery forest, regeneration forest, bamboo forest, recreation forest, village reserved forest and medicinal plantation in villages of three states. The tribal people, through long-term trial and error experiments, have developed an elaborate, functional and generally democratic system of conservation and management of forests and associated natural ecosystems. Several forest and natural resource management lessons can be learnt from the institutional structure and decision making system of the evolving and dynamic institutions of tribal communities of the region.