Tropical Deciduous Forest Ecosystem Research Articles

Understanding the relationship between soil properties and litter chemistry in three forest communities in tropical forest ecosystem.

In this study, we investigated the relationship between soil properties and litter chemistry in three forest communities, i.e., Sal mixed forest (SMF), dry mixed forest (DMF), and teak plantation forest (TPF), in tropical deciduous forest ecosystem in North India. Fresh leaf litter and soil samples were collected at two soil depths (0-15 and 15-30 cm) from all these three forest communities. Litter bag experiment was also conducted to know differences in litter nutrients after its decomposition. The concentrations (mg kg-1) of different nutrients such as sodium (Na) 2.6, potassium (K) 38.5, calcium (Ca) 425, and carbon (C) 45.54% were highest in fresh litter collected from DMF. Total organic carbon (g kg-1) was significantly higher in SMF (19.23) in comparison to DMF (18.41) and TPF (13.61) at 0-15-cm soil depth. Na, K, Ca, available P, total P, available N, and total N were highest in DMF soil. We observed significantly positive correlation between all nutrients of litter and soil. Although soil bulk density (BD) and particle density (PD) showed their significant negative correlation with litter C, total porosity was positively correlated. Similarly, litter Na has its significant negative correlation with BD and positive correlation with PD. The litter chemistry played a significant role in changing soil pH and TOC. All litter nutrients, except total P, have their significant positive correlation with soil pH. Total P, C, and N of litter have their significant positive correlation with total soil organic carbon. This indicates that litter chemistry and soil properties have specific relation among them despite unique species composition in each forest community.

Effect of soil macroaggregates crushing on C mineralization in a tropical deciduous forest ecosystem

Soil aggregates strongly influence C dynamics by affecting microbial activity. Our study tested the effect of soil crushing on C mineralization by laboratory incubation experiments of soil samples from a tropical deciduous forest ecosystem in Western Mexico. Soil samples were taken in January (dry season) and in October (rainy season). For each sampling date, the incubation experiment had a two factorial design with litter and macroaggregates (>250 μm) crushing as the main factors, both with two levels (with and without). At both sampling dates, the soil samples with intact macroaggregates had significantly higher C mineralization than the soil samples in which macroaggregates were crushed. The pH of leached solution was higher in the crushed soil samples than in uncrushed soil samples. The reduction of C mineralization caused by the disruption of soil aggregates is explained by the disturbance of environmental conditions within macroaggregates. The effect of macroaggregates crushing also reduced the differences of C mineralization between both seasons. We concluded that macroaggregates promote microbial activity by reducing the impact of variations in soil chemical and physical environmental conditions.

Tropical deciduous forests and the adivasi. Indigenous traditions as response to leaf fall in Bastar, India

Abstract This article draws attention to the crucial link between the tropical deciduous forest ecosystem and the lifestyle of the adivasi (indigenous) people. Taking the case of Bastar District in Chhattisgarh, Central India, an analysis is made of the various commonly used wild plants, their deciduous habit, and the adivasi calendar that regulates the peoples’ use of these plants. By examining the specific seasonal patterns of leaf fall of plants and the dates set for the commencement of their use, the article shows that there is an implicit relation between adivasi festivals and the deciduous character of Bastar's forests.

Seasonal effects on soil organic carbon dynamics in a tropical deciduous forest ecosystem in western Mexico

Our study examines the effect of seasonal rains on soil organic C dynamics in a tropical deciduous forest ecosystem in Western Mexico. At the end of the wet season, an accumulation of labile nutrient forms developed and was maintained during the dry season. This accumulation enhances microbial activity in the first rains of the wet season. For example, the litter samples of the dry season had a higher C and N mineralization than those of the wet season. Similarly, the January soil samples had higher C mineralization than October soil samples (55 and 34 μg C g-1 d-1, respectively). These results suggest that the quality of C is strongly affected by the seasonality of rains, which in turn influences microbial activity. This seasonality also influences nutrient redistribution between soil aggregate fractions. Chemical changes across seasons suggest that soil organic matter associated with macro-aggregates represents the main source of energy for microbial activity at the beginning of the wet season, while micro-aggregates protect the labile nutrient forms during the growing season.

Distribution and annual net accumulation of above-ground dead phytomass and its influence on throughfall quality in a Mexican tropical deciduous forest ecosystem

The amount and annual net accumulation of above-ground dead woody material were quantified in a tropical deciduous forest in western Mexico. Three plots were located within a small watershed (16 ha) and distributed along a 150-m-elevation gradient (Upper, Middle and Lower plot). Total amount of above-ground dead phytomass (fine + coarse) was 27.2 Mg ha-1. Coarse dead category (branches + logs) made up 70.6% (19.2 Mg ha-1) of the total. The rest comprised the fine fraction, which was lying on the forest floor as surface litter. Of the total coarse dead woody mass, 70.8% was standing, hanging or still attached to live trees (13.6 Mg ha-1). Dead wood net accumulation was 6.6 Mg ha-1 y-1; 58% of this was coarse woody material and the rest comprised the fine litterfall fraction. The amount of standing, hanging/attached dead branches (2-20 cm circumference) varied significantly among plots, with the highest value in the Upper plot. Dead wood net accumulation was similar between the Upper and Middle plots, and significantly higher than the Lower plot. Compared to the intact canopy, the removal of dead mass (hanging/attached dead branches and standing dead logs) caused a significant decrease in throughfall nutrient concentration and nutrient flux by this pathway.

The relationship between solar radiation interception and soil water content in a tropical deciduous forest in Mexico

Spatial and temporal patterns of potential solar radiation interception (SRI) were estimated in a tropical deciduous forest ecosystem in the West of Mexico using a Geographic Information System modeling approach. The study area was a small catchment (16 ha) divided into three altitudinal segments: top, middle and bottom. Both amount and pattern of SRI were strongly influenced by aspect. It increased with slope inclination. Catchment relief affected SRI distribution throughout the year: the highest values were on the gently sloping top segments and south-facing bottom locations, and the lowest values were in the steep north-facing bottom locations. With the onset of the rainy season soil water content (SWC) was affected by soil characteristics, but SRI was still more important than these during the rainy season. Consequently, north-facing bottom locations had less SRI but greater SWCs for longer periods. In contrast, the top and middle locations with high SRI had smaller SWCs. Vegetation structure was also affected by SWC: the north-facing bottom locations had greater tree density and, greater tree diameter at breast height and greater leaf area than the top and middle levels.

Net primary productivity of a tropical deciduous forest ecosystem in western Mexico

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Long-term net soil erosion as determined by 137Cs redistribution in an undisturbed and perturbed tropical deciduous forest ecosystem

Erosion is the main cause of soil degradation in tropical regions, where the lack of methods for long-term studies is the principal constraint to addressing soil erosion problems. Recently, the analysis of 137Cs redistribution within the landscape has been used for assessing long-term soil erosion and net deposition. In the present study, measurements of 137Cs distribution were used to calculate long-term soil erosion in a Mexican tropical deciduous ecosystem under undisturbed forest and pasture conditions. Sheet erosion processes caused 137Cs redistribution within the landscape. The crests had significantly higher 137Cs activity than midslopes and lower concentration than the footslopes. There was no clear relationship between 137Cs redistribution and local topographic variables in our study (that is, slope). Soils in a gentle midslope had lower 137Cs activity than those in a steeper midslope. However, hill morphology explained 137Cs redistribution within landscape, that is, high 137Cs activity was associated with sites at the base of hillslopes. Thus, net erosion was found to be strongly influenced by hill morphology. Calculated erosion and deposition rates for the undisturbed watershed were 13.2 Mg ha −1 yr −1 and 4.9 Mg ha −1 yr −1, respectively. Net erosion within the pasture conversion plots was strongly influenced by rainfall erosivity during the year following perturbation. High net erosion was associated with plots with high annual erosivity immediately after forest burn. This suggests that the first year after slash and burn is critical for susceptibility to soil erosion. Based on erosion rates calculated in the present study, the top 5 cm of soil could be removed in only 25 years. This represents soil productivity loss, as this top layer represents the principal soil nutrient pool for the Chamela region.

Seasonal changes of leaf area index (LAI) in a tropical deciduous forest in west Mexico

Light canopy transmittance and the Beer-Lambert equation were utilized to assess monthly leaf area index (LAI) of a tropical deciduous forest ecosystem on the west coast of Mexico. The light transmittance coefficient ( k) was obtained by analyzing vertical leaf and light distribution in the forest canopy. An independent LAI estimate was obtained using litterfall data. The calculated k value was 0.610 ± 0.035 (standard error). Average maximum LAI obtained with litterfall data was 4.2 ± 0.4 m 2m −2. There was a significant correlation ( P < 0.001, r = 0.98) between litter-LAI estimations and those obtained with the Beer-Lambert equation. The regression explained 95% of the variation; however, light-LAI overestimated litter-LAI by a constant of 0.87 ± 0.12 m 2 m −2 (the slope was 1.03 and Y intercept was 0.87). The discrepancy is partially attributed to leaf retention of the few evergreen species, and perhaps leaf retention of a few deciduous species beyond the end of the litterfall collection. Maximum annual LAI was similar in both study years (4.5 ± 0.3 m 2 m −2 in 1990 and 4.9 ± 0.4 in 1991). Minimum LAI showed considerable variation between years with similar values in the dry seasons of 1990 and 1991 (1.0 ± 0.1 m 2 and 0.9 ± 0.1 m 2 m −2, respectively), but much higher values in 1992 (2.7 ± 0.2 m 2 m −2). The difference is probably attributed to an atypical rainfall event in January 1992 (644 mm), which retarded leaf abscission.

Distribution and population dynamics of soil nematodes in a tropical forest ecosystem from Sambalpur, India

An ecological study on soil nematodes was made in a tropical deciduous forest ecosystem. Seventeen species of nematodes were identified of whichRotylenchus sp. was the dominant plant parasitic form andAcrobeloides sp. was the dominant microbivore species. The mean annual importance value for the miscellaneous feeders, plant parasites, microbivores and predators were 57·5, 22·5, 12·6 and 7·4 respectively. The Shannon index of general diversity was maximum during February (1·73) and minimum during June (1·41). Nematodes were distributed in clusters resulting in so called pocket effect. Of the total nematodes 88·4% occurred in the top 10 cm soil during the peak period of density and the microbivores were more frequent in the top 5 cm soil due to the litter layer. Total nematode density ranged from 15·1 × 104/m2 (May) to 66·1 × 104/m2 (November). Monthly mean nematode biomass was 18·86 ± 8·36 mg dry wt/m2. Temperature, soil organic carbon and soil total nitrogen apparently played an important role in regulating the nematode population.