Stem radial growth is driven by the interaction between environmental conditions and tree physiological processes. As a result, tree rings serve as valuable natural archives, recording environmental information over time. In tropical forests, data on past climate variability and historical canopy greenness—an important indicator of forest health—are often limited in duration. Studying tree rings can thus provide essential insights into historical climate dynamics and canopy condition, helping us better predict the responses of tropical forests to global environmental changes. Here we present the first ring-width index chronologies (RWI) and normalized difference vegetation index (NDVI) (as a proxy of canopy greenness) time series of Zanthoxylum rhetsa (Roxb.) DC. from three moist forest sites in Bangladesh aligned along a gradient of increasing human disturbance. We compared historical annual radial growth rates with monthly, seasonal and annual climate data and seasonal NDVI values derived from high resolution satellite images. Our analyses showed that the growth of Z. rhetsa is primarily influenced by pre-monsoon temperatures and monsoon precipitation, with pre-monsoon climate signals becoming stronger in recent decades. The signal strength of the RWI chronologies, however, varied across study sites along the disturbance gradient, with stronger signals in the sites with low disturbance intensity. At the ecosystem level, canopy greenness (NDVI) was highly correlated with tree growth rates over the past two decades. NDVI showed high sensitivity to drought, particularly at drier sites. Global warming and drought are detrimental to forest health and thus limiting the carbon sequestration potential of moist tropical forests. By taking Zanthoxylum rhetsa as a model tree species in three Bangladeshi moist tropical forests we demonstrate how tree-ring analysis can be combined with remote sensing to reconstruct canopy dynamics for periods preceding the availability of satellite imagery for NDVI calculations that could be replicable to other tropical forests.
Tag: canopy
Site selection for Alternatives to Slash-and-Burn in Indonesia: report on a site-selection exercise in Kalimantan and Sumatra. 18-17 August 1992
A global research effort is underway to develop sustainable alternatives to slash-and-burn agriculture.it is a collaborative effort among eight tropical countries and six international research centers. The program which is founded by the consortium of donors is divided in to four parts; a global project and three regional projects in humid tropics of Africa, Latin America and Southeast Asia.The Southeast Asia component is being connected in Indonesia the Philippines and Thailand.Indonesia, which has the largest forest area in Asia, represents the equItorial tropics. The Philippines represents the mid-latitude, wet-dry tropics, while Thailand represents the hilly region of mainland Southeast Asia.
Species characteristics modulate tropical mammal responses to forest quality in Southeast Asia
Anthropogenic activities such as forest loss and degradation threaten many species-rich tropical forests. However, how species respond to forest quality and the role of species characteristics (i.e., body mass, carnivory, and habitat breadth) in mediating such responses remain poorly understood. We assessed how the occupancy of 61 mammal species in tropical forests of Southeast Asia responded to forest cover, canopy height, and disturbance history. We used data from 627 camera trap sites across 11 landscapes in Southeast Asia and applied a customized Bayesian multi-species occupancy modelling framework. Higher forest quality was positively related to the occupancy of 77 % mammal species while 5 % showed a negative relationship. Species with limited habitat breadths (habitat specialists) showed the strongest positive relationships, such as the dusky monkey (Trachypithecus obscurus). Similarly, large-bodied species like the Asian elephant (Elephas maximus) also exhibited strong positive relationships. Our study highlights the critical need to maintain and restore forests with dense canopies and with old and tall trees, especially for large-bodied and habitat-dependent species. Despite recent suggestions that Asian wildlife may not always be negatively influenced by forest degradation, our study underscores the dependency of most mammal species on relatively undisturbed interior forests for long-term conservation.
Nutritious Food Portfolios for targeting year-round food harvest and nutrient gaps – Rumuruti
Allometric equations for predicting above-ground biomass of selected woody species to estimate carbon in East African rangelands
Agroforestry technical manual: Option: Longan – Maize – Forage Grass
A set of technical manual of 7 Agroforestry options implemented in Northwest Viet Nam under Agroforestry for livelihoods of smallholder farmers in Northwest Viet Nam (Phase I) and Developing and promoting market-based agroforestry and forest rehabilitation options for Northwest Viet Nam (Phase II) project. Each guideline includes (1) Introduction, (2) Design, (3) Planting techniques and fertilizing, (4) pruning and canopy formation, (5) pests and diseases prevention, (6) harvesting, (7) economic efficiency and (8) reference
Agroforestry technical manual. Option: Teak – Plum – Coffee – Soybeans – Forage Grass
A set of technical manual of 7 Agroforestry options implemented in Northwest Viet Nam under Agroforestry for livelihoods of smallholder farmers in Northwest Viet Nam (Phase I) and Developing and promoting market-based agroforestry and forest rehabilitation options for Northwest Viet Nam (Phase II) project. Each guideline includes (1) Introduction, (2) Design, (3) Planting techniques and fertilizing, (4) pruning and canopy formation, (5) pests and diseases prevention, (6) harvesting, (7) economic efficiency and (8) reference
Woody species diversity and carbon stock under different land use types at Gergera watershed in eastern Tigray, Ethiopia
Woody diversity and carbon stock estimation of land use types have critical role for the successful implementation of climate change mitigation and adaptation strategies. This study investigated relationships between woody species diversity and carbon stock in different land use types. Three land use types (area exclosure, homestead agroforestry and woodlot) were selected in the Gergera watershed, Tigray, Ethiopia. A total of 45 sample plots were established using stratified random sampling, 15 plots in each land use types. Vegetation parameters such as diameter at breast height, diameter at stump height, tree height and species type were recorded. Woody species diversity and carbon stocks significantly varied among the land use types. Woody species diversity, species richness and species density were significantly higher in exclosure compared to the other land use types. Mean above-ground woody species carbon stock in woodlot (8.79 ± 7.72) was significantly higher than both in exclosure (2.29 ± 2.73) (p = 0.002) and homestead agroforestry (4.17 ± 4.18) (p = 0.022) and similarly had higher below ground woody species carbon stock than the other two systems. However, there were no significant difference among exclosure and homestead agroforestry in total carbon stock. There were a significant relationship between woody species diversity and carbon stock (R2 = − 0.349, p = 0.019) in each land use types. Land-use change can lead to changes in species diversity and significantly contribute to carbon sequestration. Although, more carbon stock was found in woodlot dominated by Eucalyptus, this would result in water competition and other fast growing trees may be preferable.
Selection for reproductive stage drought avoidance in rice using infrared thermometry
Water deficits cause major yield reductions on the world’s rainfed riceland. The most severe water deficits occur during the reproductive phase. Differences in canopy temperature among crop cultivars are known to be related to drought avoidance characters. In developing a practical field screening system for reproductive phase drought resistance in rice (Oryza sativa L.), we assessed the canopy temperature response of a range of germplasm, and related the results to other plant characters related to drought resistance. Field experiments were conducted on a silty clay loam Typic Hapludoll at the International Rice Research Institute. Planting of the test cultivars was staggered, to synchronize flowering during the water-deficit period. Canopy temperature measurements were made on 12 dates in Trial 1 and 8 dates in Trial 2. Mean canopy temperatures (Tc) increased from 28 to 37 degrees C during the stress period. Grain yield (r2 = -0.63**) and spikelet fertility (r2 = 051**) were related to midday Tc on the day of flowering. Highly significant differences were observed in canopy temperature among entries, with low coefficients of variation (2.0-2.7%). Entries with a history of outstanding vegetative stage drought screening scores consistently remained coolest under stress. Visual drought tolerance scores (r = 0.72**) and leaf rolling scores (r = 0.68**) were correlated with mean canopy temperatures under moderate water stress, but not under severe stress (r =
Predictors of tree growth in a Dipterocarp-based agroforest: a critical assessment
Growth records from three 1 ha plots of old-growth agroforest that have been monitored for 3–7 years in Sumatra are analysed. These plots of damar agroforest show typical multi-species composition. Tree species were grouped into five sets according to species ecology and average growth rate. Variables used in the multiple linear regression to predict average annual increment were crown form index, crown position (CP) index and initial girth. Crown form (CF) index is indicative both of photosynthetic capacity and of general vigour of the tree. Crown position index is indicative of the amount of light available to a tree. Results show that crown form is the most effective predictor of growth and that initial girth, and crown position only marginally increase the percentage of variance accounted for in most cases. About 40–50% of the variance is explained by using the above mentioned variables depending on the sites. The significance of these results is discussed and some methodological improvements to the monitoring techniques currently in use are suggested.