Seasonal variations in nocturnal aboveground forest level respiration were measured using static, automated foliage and stem chambers in the Yamashiro Experimental Forest (YEF), a broadleaved secondary forest in Kyoto, Japan. The growth component of the respiration during the growing season equaled 12% of the total annual aboveground nocturnal forest level respiration in the YEF. These findings suggest that growth respiration is an important component of total respiration in similar forests.

Some infrared CO₂ sensors, such as GMD20 and GMT222 (VAISALA), are widely used for soil CO₂ efflux measurements despite the fact they have a slow response rate. The output signal is delayed both from diffusion processes in the sample cell and internal averaging calculations necessary for stable data output. For accurate estimations of CO₂ efflux, we therefore need to know the actual increase in CO₂ concentration in a chamber without composite delays. To parameterize these delays, we conducted laboratory experiments to determine the response characteristics of sensors under diffusion and flow-through conditions. Next, we developed a backward calculation method for estimation of the actual CO₂ concentration increase using the delayed sensor output (BCDC: Backward calculation for delay compensation). The results showed that the slow response of sensors caused large estimation errors in CO₂ efflux measurements. In the case of GMT222, a 10% underestimation was suggested when the soil CO₂ efflux was calculated with non-corrected data using a nonlinear regression method with sampling intervals of 300 seconds. Thus, correction of the sensor response with a backward estimation might be effective. We also calculated and evaluated the CO₂ efflux from a forest floor in a deciduous forest employing the BCDC method.

Measurements of net ecosystem CO₂ exchange using continental tower flux networks provide a critical constraint in models of regional and global carbon budgets. Uncertainty exists in these measurements due to the effects of complex terrain and vegetation gradients. Using an array of seven towers distributed across a mountain landscape, we estimated that a significant error exists in the five-year record of measured net ecosystem CO₂ exchange. The error was due to the previously ignored influence of advective CO₂ fluxes. When this error was rectified by explicit consideration of the advective flux components, the forest was predicted to exhibit a 38% higher potential for carbon sequestration than previously thought.

Leaf and branch biomass productivity of plant communities have been little studied in northern Mexico. Global warming concerns are prompting research dealing with biomass production and carbon sequestration by plant communities. Biomass components and productivity are key pieces of information for running several carbon models. In this research, we developed information on leaf and branch biomass productivity of sixteen different plant communities encompassing native pine, oak, shrub, and exotic pine forests. We established sampling plots, measured dasometric features of trees, and collected leaf and branch biomass for periods of 7 to 21 days during 2004 in Nuevo Leon, Mexico. Results indicate that leaf and branch productivity is on the average 3.70 Mg ha^-1 y^-1 (±0.98 Mg ha^-1 y^-1) with only two plant communities (intermittent riverine Tamaulipan matorral and upland planted Cupressus spp communities) surpassing 7 Mg ha^-1 y^-1. The exotic pine species (P. nelsoni, P. pinceana, and P. cembroides) planted in proceeding trials produced less than 3 Mg ha^-1 y^-1. The statistical analysis of this information showed large spatial and temporal variations. The former was explained by microsite and plant density. The last source of variation was partially dependent on climate fluctuations and the natural annual productivity cycle. Further research is required to understand the fate of leaf and branch on soils.

Reforestation is an important mean to protect soils, to restore habitat for plants and animals, to regulate the hydrological cycle, to recharge aquifers, to produce oxygen and to sequester carbon dioxide. Global warming concerns are prompting reforestation practices and studies dealing with biomass production and carbon sequestration by exotic and native species. This research presents information on biomass and carbon sequestration projections in reforested sites of northern Mexico. A total of 124 sampling plots were sampled for dasometric features and biomass components in the Mexican states of Durango, Coahuila, and Nuevo Leon of the Eastern and Western mountain ranges of northern Mexico. Results showed the potential carbon sequestration and biomass projections by component for each of three main regions separated by multivariate statistics and productivity curves. Mean annual carbon sequestration rates approach 3.90, 0.90, and 0.45 Mg ha^-1 y^-1 for reforested sites of the States of Durango, Nuevo Leon, and Coahuila, respectively. Native species of coniferous forests of Durango (P. durangensis, P. cooperii, and P. engelmannii) and Nuevo Leon (P. pseudostrobus) sequester carbon at higher rates than the introduced pine species of Durango (P. arizonica), Nuevo Leon (P. cembroides, P. pinceana, and P. nelsoni), and Coahuila (P. halepensis). Stands reforested are sequestered carbon at a higher rate than stands of native coniferous forests because of the largest plant density of the former sites, therefore they provide additional environmental benefits.

This report presents information on land use changes and carbon stocks and fluxes resulting from land use-change in the subtropical dry forest of the State of Morelos, Mexico. Biomass components of standing vegetation were estimated from 40 quadrats (400 m² each) distributed across this ecosystem. Regional land use changes using forest cover for two different periods (1976 and 1993) and present forest cover, as well as measurements of soil organic matter and soil organic carbon were used to predict carbon stocks and fluxes in this ecosystem. The results showed for the period of 1976-1993 that the annual deforestation rate is 0.87% indicating that approximately 20,000 ha of subtropical dry forest were lost during this period and that 57% of the original ecosystem has been lost since 1950. On the other side, intensive agriculture, including induced grasslands increased (22 000 ha) 15% of the total studied area largely at the expense of the tropical dry forest. Land use changes from the subtropical dry forest to agriculture contributed to carbon emissions of 6.49 Tg, of which standing biomass averaged 2.79 (± 0.28) Tg, root biomass averaged 1.75 (± 0.18) Tg, and soil organic carbon averaged 1.95 ( ± 0.2) Tg. Projected land-use changes will likely contribute to an additional carbon flux of 2.88 (± 0.14) Tg by the year 2050. Practices to conserve, sequester, and transfer carbon stocks in this ecosystem are discussed as a means to reduce carbon flux by deforestation practices.

Eddy covariance measurements of CO₂ were taken for five years above six forests distributed from the northern to southernmost main islands of Japan. These forests included cool- and warm-temperate deciduous and coniferous forests. The climate of Japan is characterized by apparent seasonal changes and adequate precipitation affected by the East Asian monsoon. In this report, we compared net ecosystem production (NEP) among forests using the eddy covariance method and analyzed the climatic factors that affect seasonal and inter-annual changes in NEP in relation to forest type. The observed annual NEP from 2000 to 2002 ranged from 286 to 566 gCm^-2yr^-1, and this basically increased with decreasing latitude. The observed maximum 10 days mean NEP was about 1.5 times larger in the deciduous sites, although the growing period was more than 2 times longer in the coniferous sites.

We report modeling experiments with a new global dynamic land model (LM3V), to reconstruct possible causes of the terrestrial carbon sources and sinks over the past century.  The model is unique, in that it is capable of representing the global history of land use, including the management of secondary forests (those forests that have re-grown at least once following harvest). Several published carbon inventories attribute the majority of the carbon sink caused by land use in the temperate zone to the management of secondary forests.

The present research is an attempt to examine and investigate the impact of land use land cover changes on the environmental sustainability and livelihood security of the local community in the Upper Kullu Valley of the Western Himalaya. Research is based on both the primary as well as secondary data sources. For the primary data were collected through Direct Field Investigation Technique (DFIT) based on Stratified Random Sampling (SRS) Technique. The secondary data were colleted from various Governmental as well nongovernmental offices working in the field of Himalayan environment and sustainability.