Carbon Stocks in Chir Pine (Pinus roxburghii) Forests on Two Different Aspects in the Mahabharat Region of Makawanpur, Nepal

Despite the significant contribution of forests in climate change mitigation, studies to establish the potential of sub-tropical forest ecosystems at different aspects in enhancing soil health indicators are only partly known. The study was carried out to quantify vegetation and soil carbon stocks of a natural Chir Pine (Pinus roxburghii) forest at two different aspects (northern and southern) of a typical sub-tropical environment in Nepal. Stratified random sampling was used for forest inventory and soil sample collection. Aboveground forest biomass was calculated using standard allometric models. Soil was sampled up to 60 cm depth and at 20 cm intervals. Walkey and Black method was used to determine soil organic carbon. Total aboveground plant biomass carbon in southern aspect (140.20 t ha-1) was higher compared to that on the northern aspect (115.34 t ha-1). Similarly, soil carbon stock on southern aspect (46.65 t ha-1) was higher than that of northern aspect (42.14 t ha-1). This resulted to total carbon stock on southern and northern aspect of P. roxburghii forest of 186.85 t ha-1 and 157.48 t ha-1 respectively. The total carbon stock of P. roxburghii forest is significantly higher on southern aspect than on northern aspect with p value 0.001 (p<0.05). Hence, we conclude that the southern aspect of the Mahabharat range favour the growth of P. roxburghii forest compared to the northern aspect. However, the contribution of the entire Chir pine forest ecosystem to carbon sequestration and global climate warming mitigation can’t be neglected.

Spatial distribution of spotted-wing drosophila (Diptera: Drosophilidae) and other insects in fruit of a sweet cherry (Rosaceae) orchard

Spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is an invasive pest of many small and soft fruits. We present the first results concerning its oviposition in the canopy of a sweet cherry (Prunus avium Linnaeus; Rosaceae) orchard. We examined the distribution of arthropods emerging from fruits of five cultivars ripening successively over seven weeks, in interior and border rows, within four regions of the tree canopy (top/bottom height × north/south aspect), and measured the associated fruit ripeness (ºBrix). Single fruits were reared for more than two weeks: 1328 arthropods emerged from 887 cherries in June, and 10 426 emerged from 1071 cherries in July. When populations were low, significantly more D. suzukii were present in the northernmost row and northern canopy aspect. Later, its distribution with respect to cherry row, height, and aspect was homogenous. Drosophila suzukii density per sweet cherry was highest in the latest ripening cultivar, when its distribution was not homogeneous; significantly more D. suzukii were in the centre than the southernmost row, in the lower canopy, and the southern aspect, than elsewhere. In the early season, single egg clutches were found without aggregation. As population density increased, so did intraspecific aggregation, but D. suzukii did not co-exist with other Drosophila Fallén species, nor with Rhagoletis indifferens Curran (Diptera: Tephritidae) when present.

Green Sequestration Potential of Chir Pine Forests Located in Kumaun Himalaya

Himalayan forests act as reservoirs of carbon due to their high percentage of forest cover. The biomass values of these forests cluster around two different levels, which dwell between higher values (approximately 400 t/ha for Shorea robusta and Quercus leucotrichophora forests) and lower values (approximately 200 t/ha) for Pinus roxburghii forests. The present study is focused on assessment of variation in tree biomass and carbon sequestration at four sites dominated by chir pine (P. roxburghii Sarg.) forests located on two different slope aspects. We calculated the tree biomass following allometric equations based upon circumference at breast height by Chaturvedi and Singh (1982). The tree biomass values ranged between 97.87 ± 9.84 t/ha and 158.97 ± 9.39 t/ha; however, tree carbon values ranged between 46.48 ± 4.67 t/ha and 74.66 ± 7.17 t/ha across the study sites. Rates of carbon sequestration ranged between 0.2 ± 0.01 t/ha/yr and 3.96 ± 1.36 t/ha/yr. The rates were higher on slopes of northern aspect in comparison with southern aspect. The results emphasize that the biomass accumulation was higher in the trees located on northern aspects and can be better managed for developing a payment for ecosystem services strategy for following up of REDD+ in the country.

Assessment of Soil Organic Carbon Stock of Churia Broad Leaved Forest of Nawalpur District, Nepal

The present article is based on the study carried out to quantify aspect wise variation in Soil Organic Carbon (SOC) stock of Churia broad leaved forest in Bhedawari Community Forest of Nawalpur district, Nepal. The total amount of SOC stock in upto 30 cm soil depth in Bhedawari Community Forest was found to be 33.91 t/ha. Aspect had made significant difference upon SOC stock with p value of 0.002 (p<0.05). The total SOC was higher in the northern aspect (36.83 ± 1.34 t/ha) than in the southern aspect (30.98 ± 1.22 t/ha). Hence, soil carbon sequestration through community managed forest is a good strategy to mitigate the increasing concentration of atmospheric CO2.

Tree-line dynamics in relation to climate variability in the Shennongjia Mountains, central China

Subalpine tree lines are particularly sensitive to climate variability. In this study, tree-ring chronologies and age structure of the subalpine fir Abies fargesii Franch. are developed to examine subalpine tree-line dynamics in relation to climate variability on the northern and southern aspects of the Shennongjia Mountains in central China. Response function analysis shows that radial growth is significantly positively correlated with temperatures during the previous November and in February and March of the current year on the northern aspect and with temperatures during the previous October and in March, April, and June of the current year on the southern aspect. Recruitment of A. fargesii is positively influenced by temperature in March and April on the northern aspect and in February, March, and May on the southern aspect. Precipitation shows no significant correlation with radial growth or recruitment of A. fargesii on either aspect. Thus, spring temperatures are the major factor limiting both radial growth and seedling establishment of this subalpine fir species. Radial growth and recruitment of A. fargesii show similar responses to climate variability and provide critical information for assessing the impacts of climate warming on tree-line dynamics, such as an increase in tree density and an upward shift of the altitudinal tree line in this mountainous region of central China.

Habitat-Distribution Modeling of a Recolonizing Black Bear, Ursus americanus, Population in the Trans-Pecos Region of Texas

Black Bears (Ursus americanus) were once widespread across Texas, but their numbers were reduced in the early 1900s. Recolonization of the Trans-Pecos region of Texas has occurred via bears migrating northward from Mexico. Recent bear sightings have increased in this area. This could be an indication that the population in Texas is beginning to recover, but the population will continue to expand only if there is suitable habitat to occupy. To help identify suitable habitat and restoration areas, we developed a predictive habitat-distribution model by using records of Black Bear sightings from 1996 to 2003 to map the species' distribution. Using Bayesian statistics, we modeled the probability of occurrence of Black Bears in the Trans-Pecos region based on sighting locations. We used GIS layers for land use/landcover, elevation, water sources, and road networks to obtain covariates in our modeling. We used a 10-fold cross-validation to test the effectiveness of using sighting data. Our results indicated a negative association with bare areas, agriculture, and grassland landcovers. In addition, southern aspect, elevation, distance to water, slope, and western aspect also influenced suitable habitat. Both the original and validation datasets correctly classified bear sightings 93.9% and 93.7% of the time, respectively. Our model can be used to target restoration efforts to enhance the ability of the Black Bear to expand in the Trans-Pecos region. It can also identify private landowners most likely to be affected by the expansion of Black Bears for education and cooperative efforts.

Transpiration by Trees From Contrasting Forest Types

Temperate rainforests and eucalypt forests of coastal south-eastern Australia are distributed differentially with aspect. Rainforests, in which Ceratopetalum apetalum D.Don and Doryphora sassafras Endl. are the dominant tree species, occur on slopes of southerly aspect and along gully bottoms, whereas eucalypt forests, dominated by Eucalyptus maculata Hook., occur on upper slopes of northerly aspect and on ridge tops. Whether transpiration rates of trees differed across the rainforest-eucalypt forest boundary on north and south facing aspects was tested by measuring stem sap flow in trees in a single catchment during winter, summer and autumn. Differences in transpiration rate by trees in these stands were due to various combinations of biological and physical factors. Firstly, mean maximum transpiration rate per tree (crown area basis) was greater in rainforest on the gully bottom where deep soil water from down-slope drainage was greater than in eucalypt forest located upslope on the northern aspect. By contrast, there was no difference between maximum transpiration rates in rainforest and eucalypt forest on the southern aspect. Variation in transpiration rate between seasons was not related to variation in surface soil moisture content (< 0.35 m depth). Secondly, transpiration rates per unit crown area in rainforest at the gully bottom were associated with higher leaf area indices than upslope on the northern aspect. However, in rainforest upslope on the southern aspect, higher transpiration rates were not associated with higher leaf area indices. Thirdly, trees in eucalypt forest maintained similar sapwood moisture contents in summer as in winter and autumn, whereas sapwood moisture contents declined in rainforest trees in summer, suggesting that eucalypts had access to water from deep within the soil profile which was unavailable to more shallow rooting rainforest trees. Fourthly, higher modal and maximal sap velocities in eucalypt trees were partly due to wider xylem vessels and resulted in faster maximum sap flow and greater daily total water use in all seasons on both aspects than in rainforest species. Finally, as atmospheric demand for water increased from winter to summer, transpiration rates were mediated by stomata1 closure as indicated by lower average midday shoot conductance to water vapour during summer than other seasons. The interaction between microenvironment, which deteimines water availability, and physiological attsibutes, which determine tree water acquisition and use, may contribute to the differential distribution of rainforest and eucalypt forest with aspect in south-eastern Australia.

Patterns of foliar injury to red spruce on Whiteface Mountain, New York, during a high-injury winter

Winter injury to red spruce (Picearubens Sarg.) after the winter of 1992–1993 was measured at an elevation of 1050 m at a site on Whiteface Mountain in the Adirondack Mountains of New York. Approximately 21% of the 1992 foliage was injured. Damage increased with height in the canopy (P < 0.0001), and was highest on the southern aspect (P < 0.0001), followed by the western aspect, which sustained more damage than the northern and eastern aspects (P < 0.0001). Damage was highest on trees whose canopy was fertilized with nitrogen, intermediate on ground-fertilized trees, and lowest on untreated trees, but differences were not significant (P = 0.45) and were confounded with stand structure differences. The strong aspect and height patterns of damage confirm earlier work showing that solar radiation plays an important role in causing the freezing injury that leads to winter damage in red spruce.