Factors influencing biomass and carbon storage potential of different land use systems along an elevational gradient in temperate northwestern Himalaya

We observed the influence of five different altitudes and prevailing agro ecosystems on biomass and carbon sequestration potential in Kullu district of Himachal Pradesh, India. The study area had five prevailing land uses viz., agriculture, agro-horticulture, horticulture, silvi-pasture, and forest at four elevations representing about 1 °C temperature change. The results showed that maximum total biomass of 404.35 Mg C ha^?1 was accumulated by forest landuse and followed a decreasing trend in the order as forest > silvi-pasture > agro-horticulture > horticulture > agriculture. Similar trends were also seen with respect to biomass carbon (C) density and C-sequestration potential of different land uses. Biomass and carbon density potential enhanced with the increase in the altitudinal ranges from 1100–1400 to 2000–2300 m a.s.l. But, the rate of C-sequestration potential enhanced from 1100 to 2000 m and declined at 2000–2300 m a.s.l. Maximum carbon density (393.29 Mg C ha^?1) of both plant as well as soil was displayed by the forest-based land use systems situated at an altitudinal gradient of 2000–2300 m a.s.l. The rate of C-sequestration was maximum (2.17 Mg ha^?1) in the agro-horticulture at 2000–2300 m a.s.l. This study brings out the potential of different land use systems influenced by varying factors on their C-sequestration potential in western Himalayan elevation gradient, thereby providing useful information for effective management in a climate change mitigation and carbon budget.     

Possibilities of diverse rubber based agroforestry systems for smallholdings in India

Rubber growers in South East Asian countries are facing acute crisis due to the price volatility, sharp increase in cost of cultivation, increasing drought and declining soil fertility. With an objective to generate additional income and improve small-holder welfare by integrating diverse crops in rubber ecosystem, three experiments were conducted in Rubber Research Institute of India during 2001–2014 period. In one experiment, coffee, vanilla on Glyricidia standards, Garcinia and nutmeg were cultivated along with rubber without altering the planting design and density of rubber trees. Growth of rubber was significantly higher under mixed planting and yield was not influenced. Soil moisture status during summer and microbial population were higher in mixed planting system and soil nutrient status was maintained. Yield of all the intercrops was good during initial years. As the shade from rubber canopy intensified, Garcinia perished but vanilla and coffee continued to yield reasonably well. In another experiment, nine shade tolerant medicinal plants were evaluated in mature rubber plantation. All the medicinal plants established well and produced reasonable biomass, but the performance of Strobilanthes cuspida and Alpinia calcarata were comparatively better. In another study, it was observed that short duration vegetables like amaranthus and salad cucumber can be cultivated during the annual leaf shedding period in mature rubber plantations to meet part of the household requirement. The results showed that diverse crops can be integrated with rubber without any adverse effect on growth and yield of rubber. Crop diversification generated additional income, mitigated drought and sustained soil fertility.     

Relationship between fallow period,forest vegetation and weeds in swidden agriculture in northern Laos

Weed suppression is an important reason for fallowing in swidden systems. Recently, in Laos, an increase in weeds and resulting increase in labor input has become a problem; however, causal factors influencing weed growth and weeding labor other than fallow period have yet to be fully examined. Therefore, an experimental research on swidden weeds, combining a forest survey and interviews with local farmers, was conducted in a mountain village in northern Laos where swidden agriculture is practiced as a major means of livelihood. Weed amount, weed composition and time required for weeding were found to be more influenced by fallow vegetation than fallow period. Bushy vegetation in a short fallow field was shown to lead to abundance of herbaceous weeds, resulting in higher labor input. There was a possibility that increases in some bamboo species were a cause of recent weed increases. Based on the results, we suggest that maintaining a minimum fallow period of forest fallowing, with fallow management to suppress bamboo and promote tree growth may be effective in reducing labor input in swidden agriculture.     

Impact of bark and foliage harvesting on fruit production of the multipurpose tree <Emphasis Type="Italic">Afzelia africana</Emphasis> in Burkina Faso (West Africa)

In sub-Saharan Africa, extraction for daily livelihood needs often results in uncontrolled exploitation of bark and leaves of valuable medicinal and fodder trees. However, overharvesting of bark and foliage can reduce fruit production and threaten reproduction. This study evaluates the impact of combined bark and foliage harvesting on the performance of fruit production of Afzelia africana in Burkina Faso. We compared fruit and seed production at different harvesting intensities. Data on fruit yields were collected by stratified random sampling of 91 trees with no, low, severe, and very severe harvesting intensities. The fruit production varied with harvesting intensity, tree size and number of branches. Fruit and seed quantity and quality decreased with increasing harvesting intensity. However, no significant difference was detected between trees without and trees under low harvesting. Trees of all size classes under very severe harvesting intensity had no fruits. Under low harvesting impact, large trees had twice as many fruits as the control, whereas fruits were reduced by half to 95 % for the small trees. High harvesting intensity is an unsustainable practice that should be completely prohibited in order to ensure longterm persistence of Afzelia africana. Low harvesting intensity should be allowed, but only on large reproductive individuals.     

Provenance and pretreatment effect on seed germination of six provenances of <Emphasis Type="Italic">Faidherbia albida</Emphasis> (Delile) A. Chev

A nursery experiment was conducted to determine the effects of seed pretreatment methods on the germination of Faidherbia albida at ICRAF, Nairobi from six provenances consisting of Awassa, Taveta, Lake Koka, Maseno, Chinzombo and Wagingombe. Seeds were subjected to five pretreatment methods namely nicking, soaking in acid, hot water, cold water and control. Germination percentages (GP), mean germination time (MGT) and germination index (GI) were calculated and the data was subjected to ANOVA. The study revealed significant (p ≤ 0.05) differences in seed treatments among provenances in all studied parameters. Highest germination among pretreatments in Awassa (99 %) and Wagingombe (80 %) was observed in nicked seeds, Chinzombo (81 %) in nicked and acid treated seeds, Lake Koka (90 %) in acid treated seeds and Taveta (28 %) and Maseno (64 %) in cold water treated seeds. Nicking gave the highest cumulative GP (69.67) while lowest GP was observed in hot water treated seeds (23.17). Acid treatment exhibited lowest MGT (8.85 days) and highest GI (2.29) while highest MGT (24.35 days) and lowest GI (0.31) were observed in control and hot water treatment respectively. Although acid treatment gave a high GP and lowest MGT and GI, nicking and soaking in cold water for 24 h is being recommended as cheaper and less hazardous pretreatment methods to improve germination in F. albida since sulphuric acid is expensive and requires proper handling techniques. Significant correlation between geo-climatic data and germination parameters of seeds subjected to different pretreatments indicates that provenances are as important as pretreatments in germination of the species.     

Tree establishment and management on farms in the drylands: evaluation of different systems adopted by small-scale farmers in Mutomo District,Kenya

Agroforestry systems in Sub-Saharan African drylands are complex and heterogeneous in nature even under similar biophysical conditions. This can be attributed to household needs and socioeconomic status which influence the species and utility of the adopted trees. This has an impact on the trees establishment and management system through planting or Farmer Managed Natural Regeneration (FMNR). This study evaluates how trees for different utilities are managed and which socioeconomic factors influence these decisions. The study used primary data collected in Mutomo District, Kenya through a household survey based on a structured questionnaire. A paired sample t-test was done to assess the preferred mode of adopting trees for different utilities while factor analysis was used to characterize the households as either planting trees or practicing FMNR. Multiple linear regression using household regression factor scores as independent variables and socioeconomic indicators as dependent variables was done to ascertain which socioeconomic factors affect tree adoption. The results show that trees planted were mostly exotic species valued for their nutrition and commercial value, while FMNR was used for subsistence products and environmental services. Household size, livestock levels and mobility had a positive correlation with tree planting, while income, access to markets and roads had an inverse correlation. Access to natural woodland, distance to the nearest motorable road and land size had a positive correlation with tree protection. It is hoped that this knowledge will act as a reference point when designing agroforestry projects in similar areas to ensure they are more aligned to specific site and household conditions.     

Patterns of change in body condition in wintering Neotropical-Nearctic migratory birds in shaded plantations in the Andes

Despite the widely accepted idea that shaded plantations are valuable habitats for Neotropical migrants in disturbed landscapes, little empirical evidence is available in relation to the quality of this habitat for Neotropical-Nearctic migratory birds in the Andes. We evaluated the suitability of shaded plantations for overwintering Neotropical-Nearctic migratory birds by examining diurnal and seasonal variation in body condition of migrants in these agroforests in the Andes. During October to April 2008–2009 and 2009–2010, we mist-netted eight species of Neotropical-Nearctic migrants in shaded plantations in the Colombian Andes. Body condition improved throughout the day for Cerulean Warbler (Setophaga cerulea), Blackburnian Warbler (Setophaga fusca), Tennessee Warbler (Leiothlypis peregrina), and especially Canada Warbler (Cardellina canadensis). Similarly, body condition improved across the season for Tennessee Warbler, Rose-breasted Grosbeak (Pheucticus ludovicianus), and Summer Tanager (Piranga rubra). Our results provided additional evidence that several common Neotropical migrants, including species of conservation concern such as Cerulean Warbler and Canada Warbler, may improve their body condition in shaded plantations. However, about half of the species assessed in this study did not show any significant improvement in their body condition (e.g. Red-eyed Vireo). Furthermore, on average, species were in poor condition (i.e. body condition scores were negative) in these coffee farms. Thus, the extent to which this agricultural system represents high quality habitat should be looked with caution. Overall, our data contribute novel information on daily patterns of body condition improvement for several common migratory birds in Andean shaded plantations.     

Soil aggregate characteristics and stability of soil carbon stocks in a <Emphasis Type="Italic">Pinus tabulaeformis</Emphasis> plantation

Pinus tabulaeformis has been widely planted in order to conserve soil and water and improve the ecological environment in China. This study aimed to unravel how soil aggregates and soil carbon (C) stock stability of a P. tabulaeformis plantation change after 60 years of natural development and was performed in Vitex negundo var. heterophylla and Ziziphus jujuba var. spinosa shrub (shrub), a P. tabulaeformis forest (pine), and a coniferous broadleaf P. tabulaeformis mixed forest (pine-oak). Afforestation increased the stability of soil aggregates in the 0–10 cm soil layer but resulted in a decrease in the 10–20 cm soil layer. However, the presence of deciduous broadleaf species in the pine plantation improved the stability of soil aggregates. The total soil C stock was increased by afforestation, especially in the pine-oak forest, where it reached a significant level. The mineral soil C stock in the shrub stand was higher than that in pine and lower than that in pine-oak forests, but the C fractions had a different change. Afforestation increased the C fraction of macroaggregates in the 0–10 cm soil layer but decreased it in the 10–20 cm soil layer. This result suggested that afforestation could improve soil C stabilization in deeper soil. However, the pine-oak forest had a higher C fraction of macroaggregates than the pine forest in the 10–20 cm soil layer, indicating that soil C stabilization of the P. tabulaeformis plantation decreased when deciduous broadleaf species were present and thus formed the coniferous broadleaf mixed forest.     

Ecosystem services assessment using a valuation framework for the Bangladesh Sundarbans: livelihood contribution and degradation analysis

The ecosystem services provided by the Bangladesh Sundarbans contribute in various sectors especially to the livelihood of the surrounding peoples, but they are often overlooked in the valuation process. This study investigates the significance of ecosystem services on peoples’ lives and how these services are affected by climate change and other factors. Here an economic valuation framework was used to list the ecosystem services provided by this mangrove forest. Direct uses included timber, golpata (Nypa fruticans), honey, beeswax, fish, shrimp larvae and tourism. Indirect uses included carbon storage, protection from cyclones and tidal surges, breeding and nursery grounds for the aquatic species, and biodiversity conservation. This work also found that the ecosystem services were diminished by fresh water flow reduction, overharvesting, sea level rise, salinity increase, poaching, and climate change. In the present context and future scenario, sea level rise will be an important contributor to changes in ecosystem services. But because many factors impact sea level rise, the impact of climate change takes on less importance than many other causes of ecosystem service degradation in the Bangladesh Sundarbans.