A provenance experiment involving five native provenances and an Australian landrace of Pinus radiata (D. Don) was established over three sites in the dry river valley area of Sichuan, southwest China in 2004 in order to select the most suitable provenance for environmental planting on the dry, steep and degraded slopes to reduce soil erosion. Although with much lower soil moisture supply and mean minimum temperatures in winter compared to P. radiata provenance trials established elsewhere in the world, these sites are within the working limits of the species defined by previous climate modelling and matching. Because of the difficult site conditions and severe natural disturbances after the experiment was established, mortality was high across the three sites in comparison to provenance trials in other countries. The average mortality rate among the provenance by replicate planting units over the three sites varied from 16% to 76% four years after planting, and from 40% to 88% five years after planting. The repeated measurements of tree size over time were analysed using multilevel linear mixed models to derive growth curves for the mean, median, the 75th and the 90th percentiles of the size distribution of each provenance at each site. There were significant site effects on tree growth, but no significant interactions between site and provenance was detected. Among the six provenances, Cambria was the best performer in diameter, height and stem volume growth across all sites. The better than average and the best trees of this provenance, as represented by the 75th and 90th percentiles of the nominal stem volume distribution, were significantly larger than the Australian landrace, Año Nuevo, and the two island provenances, Guadalupe and Cedros. Monterey was overall the second best performer behind Cambria. The Australian landrace, Guadalupe and Año Nuevo had similar performances in general. Cedros was significantly and consistently inferior to all other native provenances and the Australian land race. Because the genetic base of the present Australian plantations was derived largely from Año Nuevo and Monterey, the superior early growth performance of Cambria at such difficult sites brings a new promise to the search of P. radiata provenances for the vast dryland areas in New South Wales and other parts of Australia.

The presence of a thick snowpack could interfere with forest stability, especially on steep slopes with potential damages for young and old stands. The study of snow gliding in forests is rather complex because this phenomenon could be influenced not only by forest features, but also by snow/soil interface characteristics, site morphology, meteorological conditions and snow physical properties. Our starting hypothesis is that different forest stands have an influence on the snowpack evolution and on the temperature and moisture at the snow/soil interface, which subsequently could affect snow gliding processes and snow forces. The aim of this work is therefore to analyse the snowpack evolution and snow gliding movements under different forest covers, in order to determine the snow forces acting on single trees. The study site is located in a subalpine forest in Aosta Valley (NW-Italy) and includes two plots at the same altitude, inclination and aspect but with different tree composition: Larch (Larix decidua) and Spruce (Picea abies). The plots were equipped with moisture and temperature sensors placed at the snow/soil interface and glide shoes for continuous monitoring of snow gliding. The recorded data were related to periodically monitored snowpack and snow/soil interface properties. Data were collected during two winter seasons (2009–10 and 2010–11). The snow forces on trees were analytically calculated either from snowpack data and site morphology or also from measured snow gliding rates. Different snow accumulations were observed under the two different forest stands, with a significant effect on temperature and moisture at the snow/soil interface. The highest snow gliding rates were observed under Larch and were related to rapid increases in moisture at the snow/soil interface. The calculated snow forces were generally lower than the threshold values reported for tree uprooting due to snow gliding, as confirmed by the absence of tree damages in the study areas.

Deciduous trees with high-density wood that occur in dry seasonal tropical regions respond to rainfall seasonality with synchrony in phenophases. However, they may exhibit interannual differences in synchrony and intensity of phenophases, as strategy for large variations in duration and intensity of rainfall pulses. Nevertheless, it remains unknown how phenophases of deciduous trees of the Brazilian semi-arid region respond to rainfall variations. The phenology of Cordia oncocalyx was monitored in deciduous thorny woodland (Caatinga), from April 2009 to March 2011, and was correlated with rainfall, soil humidity, temperature, and photoperiod. The rainy years 2009 and 2011 exhibited higher duration of rainfall pulses and lower frequency of interpulses, but in 2010 pulse duration and total rainfall were lower. Circular statistics showed leaf flush followed by flowering and fruiting in the rainy season, and leaf fall and seed dispersal in the dry season. Both the vegetative and reproductive phenophases respond similarly to variations in rain pulses, with adjustments in time, duration, and intensity, which were correlated with variations in rainfall and soil humidity, excluding photoperiod as a trigger. Total defoliation occurred in the driest months of each year, November to December 2009 and August to October 2010. A sporadic leaf flush in November 2010 was triggered by occasional rains. Vegetative and reproductive synchronies were high in rainy years, but in 2010 synchrony was low, flowering was delayed and reduced, and, despite the low fruiting, we recorded high density in the seed bank. Lower synchrony, temporal separation of phenophases, and storage of fruits on the ground were risk-spreading strategies used by the population in the dry year, which suggest intrapopulation variability in responses to hydric stress. We believe that this plasticity contributes to high species density in the Caatinga.

We compared morphological and genetic attributes of progeny obtained from three seed production areas (SPAs) and three corresponding unimproved stands (UIS) of teak (Tectona grandis L.f) at three broad teak growing regions in the state of Karnataka, India. In general, seed morphological parameters such as seed weight, seed size and seed emptiness were significantly superior in SPAs compared to UISs. Seed germination percentage was also higher in seeds from SPAs. Seedling performance measured at two monthly intervals for six months was observed to be superior in SPAs at two of the three regions compared. Although the genetic diversity of progeny of SPAs was lower than UIS at all regions, the values were moderately high. Germination percent was positively correlated with fruit weight and kernel weight per seed, while diversity indices were negatively correlated with fruit weight, fruit diameter and kernel weight per seed. SPAs proved important as a source of moderately improved planting material with no severe threat to the genetic diversity of future plantations.

Rhizobia were isolated from Albizia lebbek (L) Benth. seedlings collected from six different places, tested against the nodulation test and inoculated into 45 day old Albizia lebbek seedlings in sterile soil mixture under glass house conditions. After a period of two and three months, the plant samples were taken to study the influence of inoculation treatments on nitrogen fixation, assimilation, biomass production and nitrogen content in different plant parts. The seedlings inoculated with isolates III(1) and III(2) of Lalpani had the maximum nodular biomass, specific (13.73 and 13.59 μ mole C₂H₂ reduced h⁻¹, respectively) and total nitrogenase (11.80 and 11.16 μ mole C₂H₂ reduced h⁻¹, respectively) activities in their nodules statistically at par with each other. These also exhibited high nitrate reductase activity in different plant parts. The seedlings inoculated with slow growing isolates viz. I(2) and IV(1) and the control were amongst poor performers for biomass production, nitrogenase activity and nitrate reductase activity in different plant parts. The minimum nitrogenase (specific and total) activities and low nitrogen content (%) in leaves, stems and roots were estimated in seedlings inoculated with isolate II(4) of Barkot. Nodular biomass was recorded as an indicator of nitrogen fixation activity rather than the number of nodules per plant. The isolates III(1) and III(2) can be utilized to enhance productivity in afforestation and reforestation programmes.

We used a litterbag method to investigate litter decomposition and related soil degradative enzyme activities across four seasons in a broad-leaved forest and a coniferous forest on Zijin Mountain in sub-tropical China. Across four seasons, we quantified litter mass losses, soil pH values, and related soil degradative enzyme activities. Litter decomposition rates differed significantly by season. Litter decomposition rates of broadleaf forest leaves were higher than for coniferous forests needles across four seasons, and maximal differences in litter decomposition rates between the two litter types were found in spring. Obvious differences in litter decomposition rates of the two litter types were found in winter, which were similar to rates in spring. Litter decomposition rates of the two litter types in autumn were significantly higher than in spring. Soil degradative enzyme activities were lowest in winter and highest in summer in most cases across four seasons.

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.

Non destructive methods for quantification of carbon sequestration in tropical trees are inadequately developed. We described a standardized method for estimating carbon stock in teak (Tectona grandis Linn. F.). We developed linear allometric equations using girth at breast height (GBH), height and age to quantify above ground biomass (AGB). We used AGB to estimate carbon stock for teak trees of different age groups (1.5, 3.5, 7.5, 13.5, 18.5 and 23.5 years). The regression equation with GBH, y = 3.174x − 21.27, r ²=0.898 (p <0.01), was found precise and convenient due to the difficulty in determination of height and age in dense natural forests of teak. The equation was evaluated in teak agroforestry systems that included Triticum aestivum (wheat), Cicer arietinum (gram), Withania somnifera (ashwagandha), Avena fatua (wild oat) and Hordeum vulgare (barley) as agricultural crops established at Tropical Forest Research Institute, Jabalpur, M.P. (India). The annual carbon stock gain in teak in different agroforestry systems was in the order: teak-barley (60.47%) > teak-wheat (56.92%) > teak-wild oat (54.94%) > teak-gram (37.15%) > teak-ashwagandha (11.86%). The results from GBH-based regression equations provided satisfactory estimates of carbon stock in tropical trees.

Soil salinity is becoming an increasingly serious constraint to plant growth in many parts of the world; this is particularly common in semi-arid and arid zones. This study was conducted to evaluate the effect of different concentrations of salt on seed germination and seedling growth of Acacia albida and A. salicina. Collected seeds were treated with H₂SO₄ 98% for 35 min then left to germinate in a controlled growth chamber. Seeds were grown at salinity levels of 0.1, 0.2 and 0.3 mol·L⁻¹ of NaH₂PO₄.H₂O. Germination parameters and seedling growth indices were measured after 35 days. The mean of total length of A. salicina in all salinity concentrations was more than that of A. albida. The fresh weight of stem and root of A. albida was more than that of A. salicina. Growth of control seedlings was higher than for other treatments and the fresh weight of stems of two species at salt concentrations of 0.2 and 0.3 mol·L⁻¹ decreased with increasing concentration of salt. Most control seeds germinated at salinity of 0.1 mol·L⁻¹ and germination index, final germination and seeds stamina was greater at low levels of salinity.

Seeds of Albizia chinensis(Osb.) Merr. in addition to water were also treated with different treatments by incubating in ethyl alcohol, acetone, and petroleum ether at room temperature for different durations. Seed heat treatment was done at temperatures of 30, 40 and 60°C for different durations up to 24 h. To overcome dormancy caused by the impermeable seed coat, seeds were nicked and also treated with concentrated sulphuric acid for different durations. Seeds responded to treatments with sulphuric acid and nicking only. Treatment with sulphuric acid for 20 and 30 min showed maximum germination at all incubation temperatures as compared to untreated controls and seeds treated with sulphuric acid for 10 min and nicking. Seedling length was greatest from seeds treated with sulphuric acid for 20 and 30 min and incubated at 30 °C. Seedling dry weight was highest from nicked seeds incubated at 20°C. The most favourable incubation temperature was 30 °C as evidenced from G _RI (germination rate index) and G _V (germination value). After ascertaining the seed response and performance we recommend that seeds of Albizia chinensis be treated with sulphuric acid for 20 or 30 min and incubation temperature of 25 to 30°C.

We investigated the plant population structure and the phytosociological and regeneration status in two disturbed tropical forests in Assam Province, the Hojai Reserve Forest and Kumorakata Reserve Forest. A total of 166 species (80 trees, 20 shrubs and 66 herbs) of 136 genera and 63 families were recorded in both study sites. The disturbance index at the two sites, Kumorakata Reserve Forest and Hojai Reserve Forest, were recorded at 11.4% and 3.70% respectively. Reverse J-shaped population curve and exploitation of tree species in higher girth classes were recorded at both study sites. In the girth classes (10–30 cm, 30–60 cm, 60–90 cm and 90–120 cm in size) the percentage of cut stump density was higher than the percentage of individual living trees. The 18% (Kumorakata Reserve Forest) and 7% (Hojai Reserve Forest) species were recorded as “not regenerating.” Illegal felling and over-exploitation of forest resources may lead to species-specific changes in the population structure and can alter the future structure and composition of the forests.

We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Karnataka covering different age groups (11–36 years), density (516–2061 trees/ha) and sites. From these plantations, a total of 130 trees were felled for estimating the yield and bark content in relation to diameter at breast height (DBH), age and density. Bark content ranged from 22.2%–54.3%. Heartwood and sapwood content were analyzed by sampling five trees each from two different plantations, one 30 years old at 553 trees·ha⁻¹ and the other 32 years old at 911 trees·ha⁻¹. The highest heartwood proportion of stem wood volume (over-bark) was 56.3% and the lowest was 37.1%. The sapwood proportion ranged from 12.9%–23.0%, while the bark content ranged from 27.8%–43.5%. The heartwood proportion increased with DBH, while the proportion of bark decreased. The sapwood proportion did not vary with DBH. The bark content decreased with increasing age, but increased with stand density. There was no significant difference in heartwood content with respect to age or stand density because the ages of the two stands were similar. A larger dataset from young to mature stands is needed to describe the relationships between age and stand density and heartwood, sapwood and bark content of trees.

Moose (Alces alces cameloides) is typically representative of the fauna of the frigid temperate zone and has been put on the Chinese second priority list of protected animals. The moose of northeast China is on the southern most edge of its distribution in Asia. To study resource selection characteristics of moose and their response to human disturbances and forest resource variables, the field work was conducted in Heilongjiang Provincial Shengshan Forestry Farm, which is located in the northwestern slope of Lesser Khingan Mountains, northeastern China, from January to March in both 2006 and 2007. A total of 428 plots were examined within the study area. Signs of moose use were found in 19 plots. Based on the analysis of resource selection function, we found that moose selected areas with higher densities of mixed deciduous broadleaf patch and mixed coniferous and broad leaf patch, and a higher NDVI value. Moose avoided settlement 6 km away and remained low probability of occurrence within 3 km from roads, whereas higher within 4 km from trails. Our results suggested that the behavior of avoidance for human disturbance (i.e. settlement and roads) may indirectly pose habitat loss. Therefore, resource selection function models and corresponding graphs of important habitat disturbances can be used to guide and evaluate future development plans.

Internal bond (IB) strength is one of the most important mechanical properties that indicate particleboard quality. The aim of this study was to find a simple regression model that considers the most important parameters that can influence on IB strength. In this study, IB strength was predicted by three kinds of equations (linear, quadratic, and exponential) that were based on the percentage of adhesive (8%, 9.5%, and 11%), particle size (+5, −5 +8, −8 12, and −12 mesh), and density (0.65, 0.7, and 0.75 g/cm³). Our analysis of the results (using SHAZAM 9 software) showed that the exponential function best fitted the experimental data and predicted the IB strength with 18% error. In order decrease the error percentage, the Buckingham Pi theorem was used to build regression models for predicting IB strength based on particle size, density, percentage of adhesive, face-screw withdrawal resistance (SWR_f), and edge-screw withdrawal resistance (SWR_e). From there, three dimensionless groups were created by Buckingham’s Pi theorem and IB strength was predicted based on multiple regression models. The results showed these models can predict IB strength with 10.68% and 18.17% error, based on face-screw withdrawal resistance and edge-screw withdrawal resistance, respectively.

We improved the overall performance of fast-growing poplar by utilizing a low-cost, effective and simple method. The fast-growing poplar was modified by a vacuum-pressure impregnation method with three types of modification solutions composed of phenol-melamine-formaldehyde (PMF) co-condensed resin, diatomite, and 3-aminopropyl (diethoxy) methylsilane. We measured the weight percent gain (WPG), bulking, leaching, anti-swelling efficiency (ASE), water-repellent effectiveness (WRE), and oxygen index of the modified specimens. All of the wood physical properties, which are beneficial for human uses, were significantly improved by the treatment. We improved various characteristics of wood and the oxygen index of poplar above 48.6% after the modification using diatomite and PMF co-condensed resin.

We investigated forest road networks and forestry operations before and after mechanization on aggregated forestry operation sites. We developed equations to estimate densities of road networks with average slope angles, operational efficiency of bunching operations with road network density, and average forwarding distances with operation site areas. Subsequently, we analyzed the effects of aggregating forests, establishing forest road networks, and mechanization on operational efficiency and costs. Six ha proved to be an appropriate operation site area with minimum operation expenses. The operation site areas of the forest owners’ cooperative in this region aggregated approximately 6 ha and the cooperative conducted forestry operations on aggregated sites. Therefore, 6 ha would be an appropriate operation site area in this region. Regarding road network density, higher-density road networks increased operational expenses due to the higher direct operational expenses of strip road establishment. Therefore, road network density should be reduced to approximately 200 m·ha⁻¹ within average pre-yarding distances on which a grapple loader could conduct bunching without winching. With larger stem volumes a larger reduction in operational expenses occurred for the mechanized operation system compared to the conventional operation system. However, with smaller stem volumes, the operational expenses for the mechanized operation system were higher than for the conventional operation system. Therefore, the appropriate operation system and machine sizes should be determined based on stem volumes.

We inventoried plant regeneration and soil compaction along mule trails to evaluate damage to forest stands and regeneration following mule hauling before and after operations in Kheyrud Forest in the Hyrcanian Forest in northern Iran. About 22% of regenerating plants on mule trails were damaged following mule logging, and damage to trees was observed. In harvested units after timber extraction, 4.3% of the total area (12 ha) was covered with mule trails. Mule passes and slope gradient, and twofold interactions between mule passes × slope gradient had no significant effect on soil bulk density (p < 0.05). Mule logging had a statistically significant effect on soil bulk density along the mule trails before and after mule passes. Soil bulk density increased significantly as mule passes increased in number. The degree and level of compaction did not differ with trail slope. With respect to damage to residual stands and seedlings, soil compaction and disturbance to soil, traditional mule logging is the preferred skidding method in the steep terrain conditions in the Hyrcanian Forest in northern Iran.

Data Envelopment Analysis (DEA) is a mathematical technique to assess relative efficiencies of decision making units (DMUs). The efficiency of 14 Iranian forest companies and forest management units was investigated in 2010. Efficiency of the companies was estimated by using a traditional DEA model and a two-stage DEA model. Traditional DEA models consider all DMU activities as a black box and ignore the intermediate products, while two-stage models address intermediate processes. LINGO software was used for analysis. Overall production was divided into to processes for analyses by the two-stage model, timber harvest and marketing. Wilcoxon’s signed-rank test was used to identify the differences of average efficiency in the harvesting and marketing sub-process. Weak performance in the harvesting sub-process was the cause of low efficiency in 2010. Companies such as Neka Chob and Kelardasht proved efficient at timber harvest, and Neka Chob forest company scored highest in overall efficiency. Finally, the reference units identified according to the results of two-stage DEA analysis.

Hedgerows with intercropping systems were established at the ICIMOD test and demonstration site at Godawari to assess the effectiveness of Sloping Agricultural Land Technology (SALT) in reducing runoff water volume, controlling soil loss, increasing crop production, and improving soil fertility in the mid-hills of Nepal. Runoff water volume (1996–2002), soil loss (1996–2002) and maize yield (1995–2001), and soil fertility-related parameters were assessed on SALT models with three factors: the type of nitrogen-fixing plant, the farmers’ practice, and fertilizer use. Results showed a significant effect of Alnus nepalensis and/or Indigofera dosua on runoff water volume, soil loss, crop production, soil water retention, and soil nutrients (NPK). Farmers’ practice and fertilization did not play a significant role in reducing runoff water and soil loss. However, farmers’ practice significantly increased crop production. Therefore, integrating soil conservation approaches on SALT systems enhances stable economic output to hills and mountain farmers.

Leaves of multipurpose tree species (those providing more than one function or product of human use) can serve as sources of fertilizer for nutrient supply, especially nitrogen (N). In this study chopped leaves of tropical tree species (5 N-fixing species, 5 non-N-fixing species and combinations of 5 N-fixing with a non-N-fixing species) were incorporated in soil to evaluate its effects on wheat biological productivity (including grain yield, G _YIELD) under dryland conditions. High quality leaves of N-fixing tree species (e.g. Dalbergia sissoo, Cassia fistula and Prosopis cineraria) had lower carbon/nitrogen (C/N), lignin/nitrogen (L _IG/N), polyphenol/nitrogen (P _PL/N) and lignin+polyphenol /nitrogen (L _IG+P _PL/N) ratios than low quality leaves of non-N-fixing species. Combination treatments had intermediate values of different parameters. Application of high quality leaves caused greater increases in wheat productivity and yield than other species. By the application of leaves of N-fixing trees, on average, wheat yield increased 160% relative to the control (no addition of leaves), and when combined with non-N-fixing Terminalia chebula leaves the yield increased 108%. Mean total net productivity (T _NP) with N-fixing species treatments, exceeded mean T _NP with non-N-fixing species and combination treatments by 50% and 28%, respectively. Multivariate regressions indicated that nitrogen (N) concentration in leaves (main nutrient), interacting with lignin (L _IG) and polyphenol (P _PL) concentrations, explained 79%–86% of variability in productivity parameters and yield. Strong correlation between L _IG+PP _L/N ratio of leaves with G _YIELD of wheat crop suggests that the ratio can be used as a reliable index for mass screening of multipurpose tree species for use as soil amendments especially in dryland agriculture. Direct application of high quality N-fixing tree species leaves (especially D. sissoo, C fistula and P. cineraria), an uncommon practice in dry tropics in India, may serve as a short-term option for rapid enhancement of wheat productivity and soil fertility.

The performance of maize, beans and sunflower was evaluated under a canopy of Populus deltoides and Ulmus wallichiana at Faculty of Agriculture, Wadura. The germination, growth and yield of the three test crops were suppressed under both tree species. The reduction, however, decreased when the cultivation of test crops was continued for three years. The inhibition potential generally is in the order of P. deltoides < U. wallichiana for maize and sunflower and P. deltoides > U. wallichiana for beans. Available soil N, P and K increased under the canopy of the selected tree species. The soils under U. wallichiana were more fertile than those under P. deltoides. Chromatographic investigation of extracts showed that the soils under P. deltoides and U. wallichiana differed in their composition of phenolic acids and phenolic glycocides. Except for caffic acid, all other allelochemicals disappeared and were no longer recovered in soil samples obtained after the second or third year of cultivation. Tree-crop compatibility can be explored in greater detail for improved management of traditional agro-ecosystems in Kashmir to increase the overall productivity of the land.

This study reports the effects of shifting cultivation at slashing stage on soil physicochemical properties at Bandarban Sadar Upazila in Chittagong Hill Tracts of Bangladesh. At this initial stage of shifting cultivation no general trend was found for moisture content, maximum water holding capacity, field capacity, dry and moist bulk density, particle density for some chemical properties between shifting cultivated land and forest having similar soil texture. Organic matter was significantly (p≤ 0.05) lower in 1-year and 3-year shifting cultivated lands and higher in 2-year shifting cultivation than in adjacent natural forest. Significant differences were also found for total N, exchangeable Ca, Mg and K and in CEC as well as for available P. Slashed area showed higher soil pH. Deterioration in land quality starts from burning of slashing materials and continues through subsequent stages of shifting cultivation.

After Kyrgyzstan gained independence in 1991, the importance of the primary sector for food- and energy-supply increased significantly. This has led to a discussion about the sustainability of current firewood use. We investigated firewood collection and use practices in three selected villages and analysed differences between the annual increment of woody biomass and firewood consumption for heating during winter months. The calculated individual firewood consumption is on average 3.90 kg/capita/heating day and the calculation of differences between increment and consumption shows that in minimum one village the surrounding forests are overused for firewood collection. Pressure on the forest and the overuse of preferred tree species for firewood can lead to an overuse of the resource and to a decrease in the genetic diversity of these species in the walnut-fruit forests which are considered as a biodiversity hotspot of international significance due to the diversity of woody.

The northeastern region of India constitutes one of the biodiversity hotspots of the world. The ethnic groups inhabiting this region practice their distinctive traditional knowledge systems using biodiversity for food, shelter and healthcare. Among the less-studied plants, Paederia foetida has been used by various ethnic tribes as food and medicine. Many of its therapeutic properties relate to the gastrointestinal system and suggest its potential utility for gastrointestinal ailments. This is a review of the ethnobotanical uses, phytochemistry and therapeutic properties of P. foetida compiled from various reports. P. foetida is promising as a remedy for life-style related conditions, especially treatment of ulcers. Its utility highlights the need for proper evaluation of tribal plants as medicines and the species could be considered for development of new drugs.