Journal of Northeast Forestry University

Semen characteristics of naturally fertile pairs and their correlation with fertility of eggs in Florida sandhill crane (Grus canadensis pratensis) were examined. Six pairs were used in this experiment, and all of them that had bred before were housed in open individual pens. These pairs were isolated physically each other but not visually and audibly. Semen was collected twice (Tuesday morning and Friday afternoon) from February 26 to June 4, 1993. The standard methods at Patuxent Wildlife Research Center were used collecting and evaluating the semen and spermatozoa, and incubating the eggs. There were statistically individual variations (p<0.05) about successful collecting attempts, semen volume, semen concentration, spermatozoon’s motility, spermatozoon’s number per collection, live spermatozoon’s number, male’s response to semen collection, and morphology of spermatozoa except the giant cell. There was a significantly (p<0.05, correlation coefficient was (0.73 or (1.00) negative correlation between fertility of eggs and, the multiple value of semen (sperm) characteristics of naturally fertile pairs in Florida sandhill crane.

Ectomycorrhizal (EM) networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer, seedling survival, internal cycling of nutrients, plant competition, and so on. To deeply their structure and function in ecosystems, we investigated the spatial patterns and nitrogen (N) transfer of EM networks using 15N labelling technique in a Mongolian scotch pine (Pinus sylvestris var. mongolica Litv.) plantation in Northeastern China. In August 2011, four plots (20 × 20 m) were set up in the plantation. 125 ml 5 at.% 0.15 mol/L 15NH 4 15 NO3 solution was injected into soil at the center of each plot. Before and 2, 6, 30 and 215 days after the 15N application, needles (current year) of each pine were sampled along four 12 m sampling lines. Needle total N and 15N concentrations were analyzed. We observed needle N and 15N concentrations increased significantly over time after 15N application, up to 31 and 0.42%, respectively. There was no correlation between needle N concentration and 15N/14N ratio (R2 = 0.40, n = 5, P = 0.156), while excess needle N concentration and excess needle 15N/14N ratio were positively correlated across different time intervals (R2 = 0.89, n = 4, P < 0.05), but deceased with time interval lengthening. Needle 15N/14N ratio increased with time, but it was not correlated with distance. Needle 15N/14N ratio was negative with distance before and 6th day and 30th day, positive with distance at 2nd day, but the trend was considerably weaker, their slop were close to zero. These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network. We found N transfer efficiency was very high, absorbed N by EM network was transferred as wide as possible, we observed N uptake of plant had strong bias for 14N and 15N, namely N fractionation. Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution, and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.

Forest resource management and ecological assessment have been recently supported by emerging technologies. Terrestrial laser scanning (TLS) is one that can be quickly and accurately used to obtain three-dimensional forest information, and create good representations of forest vertical structure. TLS data can be exploited for highly significant tasks, particularly the segmentation and information extraction for individual trees. However, the existing single-tree segmentation methods suffer from low segmentation accuracy and poor robustness, and hence do not lead to satisfactory results for natural forests in complex environments. In this paper, we propose a trunk-growth (TG) method for single-tree point-cloud segmentation, and apply this method to the natural forest scenes of Shangri-La City in Northwest Yunnan, China. First, the point normal vector and its Z-axis component are used as trunk-growth constraints. Then, the points surrounding the trunk are searched to account for regrowth. Finally, the nearest distributed branch and leaf points are used to complete the individual tree segmentation. The results show that the TG method can effectively segment individual trees with an average F-score of 0.96. The proposed method applies to many types of trees with various growth shapes, and can effectively identify shrubs and herbs in complex scenes of natural forests. The promising outcomes of the TG method demonstrate the key advantages of combining plant morphology theory and LiDAR technology for advancing and optimizing forestry systems.

In this study height growth models for hybrid aspen were developed using three growth equations. The mean age of the hybrid aspen was 21 years (range 15–51 years) with a mean stand density of 946 stems ha−1 (87–2374) and a mean diameter at breast height (over bark) of 19.6 cm (8.5–40.8 cm). Site index was also examined in relation to soil type. Multiple samples were collected for three types of soil: light clay, medium clay and till. Site index curves were constructed using the collected data and compared with published reports. A number of dynamic equations were assessed for modeling top-height growth from total age. A Generalized Algebraic Difference Approach model derived by Cieszewski (2001) performed the best. This model explained 99% of the observed variation in tree height growth and exhibited no apparent bias across the range of predicted site indices. There were no significant differences between the soil types and site indices.

Plantations have been widely established to improve ecosystem services and functioning. Black locust, Robinia pseudoacacia L. is a common, widely planted species to control soil erosion on the Loess Plateau. Previous studies have focused on economic values but the interactions between soil and plant carbon (C), nitrogen (N) and phosphorus (P) remain unknown. Investigating variations of soil, green and senesced leaf C, N and P levels in R. pseudoacacia along a latitudinal gradient is useful to understanding its ecological functions. The results show that soil C, N and senesced leaf N and P significantly decreased with an increase in latitude, but there were no significant changes in the senesced leaf C and soil P. The resorption efficiency of N was related with latitude and soil N levels, and the relation between green leaf N and soil N was significant. These relations suggest that soil N was the key in affecting green leaf N levels. At higher latitudes, senesced leaves had lower N levels associated with higher N resorption efficiency to maintain a stable N content in green leaves. With a decrease of soil N, R. pseudoacacia can enhance N resorption efficiency to meet the demand of growth. Thus, it is an important species for reforestation, especially in nutrient-poor environments.

The effect of heat treatment on the surface colour and hygroscopic properties of pine wood were investigated in this study. Boards of Scots pine wood (Pinus sylvestris L.) were subjected to thermal treatment at 200°C, for 4, 6, and 8 h. The change of equilibrium moisture content and density values of the specimens in order to facilitate the understanding of the treated material behavior. The colour parameters L*, a* and b*, used to depict the total colour change (Δ E) of wood surface, were shown to change proportionally to the treatment intensity. Moreover, swelling in the tangential and radial directions and absorption of the specimens appeared to be enhanced in great extent by the thermal treatment process. The mean value of swelling percentage in the tangential direction decreased 10.26%, 17.22%, and 19.60% for specimens treated for 4, 6, and 8 h, respectively, referring to the final measurement after 72 h of immersion. In radial direction, mean value of swelling percentage decreased 19.56%, 32.75%, and 34.65% for treated for 4, 6 and 8 h, respectively, after 72 h immersion, which attests the decrease in swelling and improvement in the hygroscopic behavior of Scots pine wood.

The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz. Acacia mangium Willd. and Acacia auriculiformis A. Cunn. Ex Benth. and their hybrid. Acid insoluble lignin content (Klason), mean stem density and fibre length differed considerably among the species and hybrids. A. mangium possessed a high percent of lignin content compared to A. auriculiformis and the Acacia hybrid. However, mean stem density of A. auriculiformis was higher than A. mangium and the hybrid. Fibre length of heartwood tissues was generally shorter than that of sapwood tissues. The hybrid had longer fibres than the parent species. Lignin was negatively correlated with mean stem density. Generally, the wood properties of the hybrid were superior to its parent species. The significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two species. Considering the difficulty involved in accurately measuring the lignin content compared to mean stem density, selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.

We investigated the floristic composition of the Hyrcanian forests and the related forest-steppe ecotone in Northern Iran by using two long ecological transects, from lowland to upper mountain areas. The study was conducted during 2008 and 2009 and yielded the identification of 395 plant taxa belonging to 233 genera and 78 families. Dicots with 300 taxa were the richest groups of the flora, followed by monocots with 75 taxa, pteridophytes with 18 species, and gymnosperms with two species. The largest families were Asteraceae (33 taxa); Rosaceae (32 taxa); and Poaceae (30 taxa), and the most diverse genera included Carex (15 taxa); Alchemilla (7 taxa); and Poa, Geranium and Acer (6 taxa each). Hemicryptophytes were the most dominant life forms in the area (40 %); followed by geophytes (31.4 %); phanerophytes (15.4 %); therophytes (11.4 %); and chamaephytes (1.8 %). Phytogeographically, Euro-Siberian/Irano-Turanian elements (86 taxa, 21.8 %) and Euro-Siberian elements (85 taxa, 21.5 %) were the most common chorotypes in the area. Out of 395 taxa, 66 taxa (16.7 %) were endemics and subendemics in Iran, of which 26 taxa were exclusively endemics of Iran. According to the IUCN Red List Categories, 48 threatened plant taxa were found in the study area. Plant diversity, life form, and chorotypes in the current study were compared with similar transect studies in other areas of the Hyrcanian forests and in different altitudinal belts, using Sørenson similarity indices. Floristic composition of the surveyed transects demonstrated almost 50 % similarity between them.