Riparian Vegetation Dynamics Across Two Different Landscapes Along the River Cauvery in the Kodagu Region of Western Ghats

Decades of commercial planting and other anthropogenic processes are posing a threat to the riparian landscapes of the Cauvery river basin, which supports a high floral diversity. Despite this, the habitats in the upstream sections of the River Cauvery are still intact, as they are located in sacred groves. To understand the dynamism of riparian forests exposed to anthropogenic pressures, the upstream stretch of Cauvery extending from Kushalanagara to Talacauvery （~102 km） was categorized into two landscapes： agro ecosystem and sacred （i.e. preserved）. The tree species were sampled using belt transects at 5 km intervals and the regeneration status of endemic species assessed using quadrats. A total of 128 species belonging to 47 families, and representing 1,590 individuals, was observed. Amongst them, 65% of unique species were exclusive to sacred landscapes. A rarefaction plot confirmed higher species richness for the sacred compared to the agro ecosystem landscapes, and diversity indices with more evenness in distribution were evident in sacred landscapes. A significant loss of endemic tree species in the agro ecosystem landscapes was found. Overall, this study demonstrates that an intense biotic pressure in terms of plantations and other anthropogenic activities have altered the species composition of the riparian zone in non-sacred areas. A permanent policy implication is required for the conservation of riparian buffers to avoid further ecosystem degradation and loss of biodiversity.

Assessment of Soil Quality Using Microarthropod Communities Under Different Land System： A Case Study in the Mid-Hills of Central Nepal

The study aimed to evaluate soil quality using microarthopods density, diversity and soil biological quality index （QBS-ar） under different land use systems and elevation gradients. A secondary aim was to determine the relationship among soil biological and physiochemical indicators. Three groups of soil microarthropods were recognized viz. （1） Collembola （38%） （2） Acarina （33%） and （3） other microarthropods （29%）. ANOVA indicated that total microarthropods densities differed significantly with land use and elevation. Population density of Acarina and other mieroarthropods were weakly significant different according to land use, while Collembola and Acarina densities showed highly significant difference with elevation. Total microarthropods, Acarina and Collembola densities were positively significantly correlated with soil organic carbon （SOC） and moisture but negatively correlated with bulk density, pH and temperature of the soil. SOC and soil moisture appeared to be good indicators of soil quality as reflected by the higher density and diversity of soil total microarthropods, Collembola, Acarina and other microarthropods group. The use of microarthropods for soil quality assessment could be effective and relatively inexpensive tool; however, further research is required to evaluate the impact of agricultural practices and elevation gradient on soil microarthropods density, diversity and species composition for the sustainable management of agro ecosystems.

Conservation and Adaptive Management of Globally Important Agricultural Heritage Systems (GIAHS)

Worldwide specific agricultural systems and landscapes have been created, shaped and maintained by generations of farmers and herders based on diverse natural resources using locally adapted management practices. Building on local knowledge and experience these ingenious agricultural systems reflect the evolution of humankind, the diversity of its knowledge and its profound relationship with nature. These systems have resulted not only in outstanding landscapes maintenance and adaptation of globally significant agricultural biodiversity indigenous knowledge systems and resilient ecosystems, but above all, in the sustained provision of multiple goods and services, food and livelihood security and quality of life. However, many of these systems are facing severe threats from various sources including globalization. In 2002 FAO initiated an international partnership initiative： ＂conservation and adaptive management of Globally Important Agricultural Heritage Systems （GIAHS）＂. The global GIAHS initiative aims to establish the basis for the international recognition, dynamic conservation and sustainable management of such systems, agricultural biodiversity and their associated biodiversity knowledge systems, food and livelihood security, landscapes and cultures.

Eco-environmental Impact of Bioenergy Production

生物质能源生产是能源发展领域的重大挑战,在解决新的替代能源中扮演着重要角色。本文着重论述了美国生物能源生产的生态环境问题。从经济、环境和战略方面考虑,生物能源有望提高国家安全,因而受政策驱动的美国生物能源生产技术备受注目。尽管生物能源具有诸多潜在效益,但是在北美,生物原料供应、高强度经营的土地上农药使用及其对陆地野生动物的潜在影响等令人担忧,我们分析了其中的原因。通常认为,未来生物能源的环境、经济效应是正面的;然而,谨慎地审视和发展生物能源经济以保护生态系统的可持续性显得至关重要。

Cascade effects of crop species richness on the diversity of pest insects and their natural enemies

Understanding how plant species richness influences the diversity of herbivorous and predatory/parasitic arthropods is central to community ecology.We explore the effects of crop species richness on the diversity of pest insects and their natural enemies.Using data from a four-year experiment with five levels of crop species richness,we found that crop species richness significantly affected the pest species richness,but there were no significant effects on richness of the pests’natural enemies.In contrast,the species richness of pest insects significantly affected their natural enemies.These findings suggest a cascade effect where trophic interactions are strong between adjacent trophic levels,while the interactions between connected but nonadjacent trophic levels are weakened by the intermediate trophic level.High crop species richness resulted in a more stable arthropod community compared with communities in monoculture crops.Our results highlight the complicated cross-trophic interactions and the crucial role of crop diversity in the food webs of agro-ecosystems.

Microbial Biomass Dynamics in a Tropical Agroecosystem： Influence of Herbicide and Soil Amendments

The influences of herbicide alone and in combination with the soil amendments with contrasting resource qualities on dynamics of soil microbial biomass C （MBC）, N （MBN）, and P （MBP） were studied through two annual cycles in rice-wheat-summer fallow crop sequence in a tropical dryland agroecosystem. The experiment included application of herbicide （butachlor） alone or in combination with various soil amendments having equivalent amount of N in the forms of chemical fertilizer, wheat straw, Sesbania aculeata, and farm yard manure （FYM）. Soil microbial biomass showed distinct temporal variations in both crop cycles, decreased from vegetative to grain-forming stage, and then increased to maximum at crop maturity stage. Soil MBC was the highest in herbicide ＋ Sesbania aculeata treatment followed by herbicide ＋ FYM, herbicide ＋ wheat straw, herbicide ＋ chemical fertilizer, and herbicide alone treatments in decreasing order during the rice-growing period. During wheat-growing period and summer fallow, soil MBC attained maximum for herbicide ＋ wheat straw treatment whereas herbicide ＋ FYM, herbicide ＋ Sesbania, and herbicide ＋ chemical fertilizer treatments showed similar levels. The overall trend of soil MBN was similar to those of soil MBC and MBP except that soil MBN was higher in herbicide ＋ chemical fertilizer treatment over the herbicide ＋ wheat straw treatment during rice-growing period. In spite of the addition of equivalent amount of N through exogenous soil amendments in combination with the herbicide, soil microbial biomass responded differentially to the treatments. The resource quality of the amendments had more pronounced impact on the dynamics of soil microbial biomass, which may have implications for long-term sustainability of rainfed agroecosystems in dry tropics.