Quantifying the net ecosystem exchange at a semi-deciduous forest in northeast India from intra-seasonal to the seasonal time scale

Quantification of butterfly diversity and species richness is of prime importance for evaluating the status of protected areas. Permanent line transect counts were used to record species richness and abundance of butterfly communities of different habitat types in Trishna wildlife sanctuary. A total of 1005 individuals representing 59 species in 48 genera belonging to five families were recorded in the present study. Of these, 23 species belonged to the family Nymphalidae and accounted for 38.98% of the total species and 45.20% of the total number of individuals. Mature secondary mixed moist deciduous forest showed the maximum diversity and species richness, while exotic grassland showed minimum diversity and species richness. Out of 59 species, 31 are new records for Tripura state, while 21 are unique species and nine are listed in the threatened category. This study revealed that mature secondary forests are more important for butterfly communities, while exotic grasslands have a negative impact on species composition.

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Prediction of Seasonal Meteorological Drought Onset and Termination over the Southern Great Plains in the North American Multimodel Ensemble

Journal of Hydrometeorology ◽

10.1175/jhm-d-20-0023.1 ◽

2020 ◽

Vol 21 (10) ◽

pp. 2237-2255

Author(s):

Richard Seager ◽

Jennifer Nakamura ◽

Mingfang Ting

Keyword(s):

Great Plains ◽

North American ◽

Time Scale ◽

Meteorological Drought ◽

Atmospheric Variability ◽

Multimodel Ensemble ◽

Southern Great Plains ◽

The North ◽

Seasonal Time Scale ◽

North American Multimodel Ensemble

AbstractThe predictability on the seasonal time scale of meteorological drought onsets and terminations over the southern Great Plains is examined within the North American Multimodel Ensemble. The drought onsets and terminations were those identified based on soil moisture transitions in land data assimilation systems and shown to be driven by precipitation anomalies. Sea surface temperature (SST) forcing explains about a quarter of variance of seasonal mean precipitation in the region. However, at lead times of a season, forecast SSTs only explain about 10% of seasonal mean precipitation variance. For the three identified drought onsets, fall 2010 is confidently predicted and spring 2012 is predicted with some skill, and fall 2005 was not predicted at all. None of the drought terminations were predicted on the seasonal time scale. Predictability of drought onset arises from La Niña–like conditions, but there is no indication that El Niño conditions lead to drought terminations in the southern Great Plains. Spring 2012 and fall 2000 are further examined. The limited predictability of onset in spring 2012 arises from cool tropical Pacific SSTs, but internal atmospheric variability played a very important role. Drought termination in fall 2000 was predicted at the 1-month time scale but not at the seasonal time scale, likely because of failure to predict warm SST anomalies directly east of subtropical Asia. The work suggests that improved SST prediction offers some potential for improved prediction of both drought onsets and terminations in the southern Great Plains, but that many onsets and terminations will not be predictable even a season in advance.

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Decennal geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments.

10.36227/techrxiv.14828256.v2 ◽

2021 ◽

Author(s):

Antoine Lucas ◽

Eric Gayer

Keyword(s):

Time Series ◽

Time Scale ◽

Aerial Images ◽

Sensor Calibration ◽

Dense Matching ◽

Time Period ◽

Digital Elevation ◽

Seasonal Time Scale ◽

Areas Of Interest ◽

Alpine Environments

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>

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Parameters affecting mud floc size on a seasonal time scale: The impact of a phytoplankton bloom in the Dollard estuary, The Netherlands

Coastal and Estuarine Fine Sediment Processes - Proceedings in Marine Science ◽

10.1016/s1568-2692(00)80134-5 ◽

2000 ◽

pp. 403-421 ◽

Cited By ~ 6

Author(s):

W.T.B. van der Lee

Keyword(s):

The Netherlands ◽

Time Scale ◽

Phytoplankton Bloom ◽

Floc Size ◽

Seasonal Time Scale ◽

The Impact

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Asynchronism in leaf and wood production in tropical forests: a study combining satellite and ground-based measurements

Biogeosciences Discussions ◽

10.5194/bgd-10-8247-2013 ◽

2013 ◽

Vol 10 (5) ◽

pp. 8247-8281 ◽

Cited By ~ 3

Author(s):

F. Wagner ◽

V. Rossi ◽

C. Stahl ◽

D. Bonal ◽

B. Hérault

Keyword(s):

Carbon Cycle ◽

Tropical Forests ◽

Time Scale ◽

Carbon Allocation ◽

Net Primary Production ◽

Time Lag ◽

Production Model ◽

Wood Production ◽

Modis Evi ◽

Seasonal Time Scale

Abstract. The fixation of carbon in tropical forests mainly occurs through the production of wood and leaves, both being the principal components of net primary production. Currently field and satellite observations are independently used to describe the forest carbon cycle, but the link between satellite-derived forest phenology and field-derived forest productivity remains opaque. We used a unique combination of a MODIS EVI dataset, a climate-explicit wood production model and direct litterfall observations at an intra-annual time scale in order to question the synchronism of leaf and wood production in tropical forests. Even though leaf and wood biomass fluxes had the same range (respectively 2.4 ± 1.4 Mg C ha−1yr−1 and 2.2 ± 0.4 Mg C ha−1yr−1), they occured separately in time. EVI increased with the magnitude of leaf renewal at the beginning of the dry season when solar irradiance was at its maximum. At this time, wood production stopped. At the onset of the rainy season when new leaves were fully mature and water available again, wood production quickly increased to reach its maximum in less than a month, reflecting a change in carbon allocation from short lived pools (leaves) to long lived pools (wood). The time lag between peaks of EVI and wood production (109 days) revealed a substantial decoupling between the irradiance-driven leaf renewal and the water-driven wood production. Our work is a first attempt to link EVI data, wood production and leaf phenology at a seasonal time scale in a tropical evergreen rainforest and pave the way to develop more sophisticated global carbon cycle models in tropical forests.

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Testing the influence of snow and meteorological conditions on snow avalanche deposit volumes

10.5194/egusphere-egu21-10762 ◽

2021 ◽

Author(s):

Hippolyte Kern ◽

Vincent Jomelli ◽

Nicolas Eckert ◽

Delphine Grancher

Keyword(s):

Time Scale ◽

Snow Depth ◽

Snow Avalanche ◽

Wet Snow ◽

The Mean ◽

Seasonal Time Scale ◽

Snow Conditions ◽

Complex Relationships ◽

The Relationship ◽

Annual Time

<p>Snow avalanche deposit volume is an important characteristic that determines vulnerability to snow avalanche. However, there is insufficient knowledge about snow and meteorological variables controlling deposit volumes. Our study focuses on the analysis of 1986 deposit volumes from 182 paths located in different regions of the French Alps including Queyras, and Maurienne valleys, between 2003 and 2017. This work uses data from the Permanent Avalanche Survey (EPA) database, an inventory of avalanche events occurring at well-known, delineated and mapped paths in France. We investigated relationships between snow deposit volumes and meteorological quantities, such as precipitation and temperature determined from SAFRAN reanalyses and snow-depth and wet snow-depth estimated from CROCUS reanalyses at a daily time scale at 2100m a.s.l. Analysis was conducted at an annual and seasonal time scale considering winter (November-February) and spring (March-May) between the mean deposit volumes and the mean meteorological and snow conditions.<span>&#160;</span></p><p>Results do not show any significant relationship between deposit volumes and meteorological or snow conditions at an annual time scale or for spring season. However, correlations between deposit volumes and meteorological and snow variables are high in winter (R<sup>2</sup>=0.78). The best model includes two snow variables: mean snow-depth and maximal wet snow-depth. We suggest that these two important snow variables reflect variations in the snow cover characteristics later influencing the nature of the flow and the deposit volumes. Dividing the studied paths sample into several classes according to their morphology (i.e: surface area or mean slope) increases the significance of the relationship for both seasons and highlights more complex relationships with meteorological and snow variables.</p>

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