bioRxiv Science⌕ Search

Biology subjects

Teegalapalli, K.

Publications and source records attributed to Teegalapalli, K..

2 recordsLinked to original sources
bioRxiv2019

Factors affecting the survival of tree seedlings following shifting cultivation in the Eastern Himalaya

O_LIThe seedling stage is considered an important bottleneck determining forest community composition during succession. Seedling growth and survival are known to be affected by factors such as light availability, herbivory and competition with existing vegetation. A shifting cultivation landscape with a cycle of clearing and regeneration provides an experimental setup to understand secondary succession.\nC_LIO_LIWe introduced tree seedlings of three species with differing life history strategies in an uncut forest and in sites formed 2, 6, 12, 25, 50 and 100 years following shifting cultivation in a subtropical landscape in the Eastern Himalaya. Seedlings of a pioneer species Saurauia nepalensis, a mid-successional species Terminalia myriocarpa and a mature forest species Castanopsis indica were introduced in plots with a control and three treatments: shading (light manipulated), clearing of vegetation (reduced competition), and exclosures (mammal herbivory excluded) and monitored for 18, 22 and 23 months, respectively.\nC_LIO_LISaurauia survived relatively well in all sites, Terminalia seedlings survived relatively well in the 12 and 25 year sites, and Castanopsis seedlings survived well in the 100 year site and the uncut forest. In the early successional site, survival of Saurauia was higher within exclosures indicating negative effects of herbivory. In the same site, clearing vegetation improved the survival of Terminalia, implying competition with existing vegetation. Castanopsis had the highest survival in uncut forest and survival was almost nil in the early successional site.\nC_LIO_LISynthesis: Seedling survival in a successional landscape depended on species-as well as site-specific factors. The existing vegetation in an early successional site had a negative effect on the survival of the mid-successional species, while herbivory had a negative effect on the pioneer species. Survival of the mature forest species in the early successional site was negligible but was high in old successional and uncut forest sites, indicating that mature forest species can colonize sites and survive only after certain physical and biotic aspects of the environment have been met. Our experiments were useful to examine factors that affect survival of tree species with differing life history strategies in a shifting cultivation landscape.\nC_LI

ecology↗
bioRxiv2019

Understanding the variation in wood densities of trees and its implications for carbon assessments

Wood density is a key functional trait used to estimate aboveground biomass (AGB) and carbon stocks. A common practice in forest AGB and carbon estimation is to substitute genus averages (across species with known wood densities) in cases where wood densities of particular species are unknown. However, the extent to which genus-level averages are reflective of species wood densities across tree genera is uncertain, and understanding this is critical for estimating the accuracy of carbon stock estimates. Using primary field data from India and secondary data from a published global dataset, we quantified the extent to which wood density varied among individuals within species (intraspecific variation) at the regional scale and among species within genera (interspecific variation) at regional to global scales. We used a published global database with wood density data for 7743 species belonging to 1741 genera. Linear models were used to compare the species values with the genera averages and the individual values with the species averages, respectively. To estimate the error associated with using genus-level averages for carbon stocks estimation, we compared genus values averaged at the global, old world and continental scales with species values from actually measured data. We also ran a simulation using vegetation data from a published database to calculate the estimation errors in a 1 hectare plot level when genera-averaged wood densities are used. Intraspecific variation was significantly lower than interspecific variation. Continental level genera averages led to estimates closer to the species values for the 10 genera for which most data on species was available. This was also evident from a comparison of genera averages at these three spatial scales with species values from our data. Species within certain hypervarying genera showed relatively high levels of variation, irrespective of the spatial scale of the dataset used. The error in estimation of AGB when genera-averaged values were used for species wood densities was 0.35, 0.71 and 2.43% when 0, 10 and 25% of the girth of the trees in the simulated plot were from hypervariable genera. Our findings indicate that species values provide the most accurate estimates for individuals. Genus average wood density values at the continental scale provided more reliable estimates than those at larger spatial scales. The aboveground biomass estimation error when species wood densities were approximated to the genera-average values was 1.4 to 3.7 tonnes per ha when 10% and 25%, respectively, of the girth of trees was from species from hypervariable genera. Our findings indicate that regional or continental scale genera averages provide more reliable estimates than global data and we propose a method to identify hypervariable genera, for which species values rather than genera averages can provide better estimates of carbon stocks.

ecology↗