Vegetation and ecosystem carbon recovery following shifting cultivation in Mizoram-Manipur-Kachin rainforest eco-region, Southern Asia

Abstract

Background Shifting cultivation (locally known as “jhum”) is a major driver of deforestation and loss of ecosystem services in rainforests. For developing any effective conservation of biodiversity and carbon service program, an in-depth understanding to the recovery of vegetation and carbon after abandonment of jhum is essential. We estimated species richness, abundance and composition of trees, shrubs and herbs, carbon distribution in aboveground and belowground components along a chronosequence of jhum fallow in northeast India, and elucidated the factors affecting the recovery processes of jhum fallows. Methods Species composition and other plant community attributes, carbon storage in different pools were studied in 5 jhum fallows (< 5, 5–10, 11–15, 16–20, 21–25 years old) and an old-growth forest. The data were subjected to linear mixed effect modeling using R-package “nlme” for identifying the important factors contributing to the recovery of vegetation and carbon. Results Species composition varied significantly (P < 0.05) between jhum fallows and old-growth forest. Tree density varied from 28 stems ha−1 in 5 years old jhum fallow to 163 stems ha−1 in old-growth forest. Both biomass carbon in all components and soil organic carbon were significantly (P = 0.01) lower in jhum fallows than in the old-growth forest except living non-woody biomass component. The recovery of aboveground biomass carbon was faster during early successive years than the mid-successive jhum fallows. Total ecosystem carbon and soil organic carbon stock in the oldest jhum fallow was 33% and 62% of those in the old-growth forest, respectively. The fallow age was found to be the most important explanatory factor in the recovery process of vegetation and carbon stock in re-growing fallows. Conclusion The shifting cultivation fallows gradually recovered both vegetation and carbon and are potential repository sites for biodiversity conservation, which may take much longer time to reach up to old-growth forest in northeast India.

Floristic Composition and Structure in Relation to Elevation in the Togo Plateau Forest Reserve in Ghana

“…Saplings and seedlings diversity and evenness index also followed a similar pattern. However, these results from the communities fall within the ranges of (2.00 to 4.86) and (0.21 to 1.00) reported in tropical forests in Ghana [20], [21], [22] and elsewhere [15], [17], [23]. These results showed that each community is very diverse, stable and well adapted [17], [23].…”

“…However, these results from the communities fall within the ranges of (2.00 to 4.86) and (0.21 to 1.00) reported in tropical forests in Ghana [20], [21], [22] and elsewhere [15], [17], [23]. These results showed that each community is very diverse, stable and well adapted [17], [23]. Probable causes for the local variations in species composition and structure among the communities include the geographical locations of these communities which somehow correspond with different elevations to the plateau (i.e., BO, NK occur in lower and gentle elevations, AK, SA in mid elevation and HH, AL in higher elevations with rocky and varied inclined slope areas).…”

“…Basal area of trees (BA) provides a parameter that compare vegetation structure and quality [17]. The average basal area of 44.72 m 2 ha− 1 recorded in this study across the six communities was greater than that recorded in the Kade forest (30.85m 2 [17]).…”

“…All the plant growth forms were identified in the 180 plots distributed throughout the TPFR in Ghana. The discovery of Leguminosae, Euphorbiaceae, Apocynaceae and Malvaceae as the most dominant plant families is not surprising as this is typical of tropical forests in Ghana [22], [26] and elsewhere [1], [17], [22]-[35]. These families are also the most important and well distributed across the six communities studied, an indication of their wide ecological amplitude and tolerance of diverse environmental conditions [17].…”

“…The discovery of Leguminosae, Euphorbiaceae, Apocynaceae and Malvaceae as the most dominant plant families is not surprising as this is typical of tropical forests in Ghana [22], [26] and elsewhere [1], [17], [22]-[35]. These families are also the most important and well distributed across the six communities studied, an indication of their wide ecological amplitude and tolerance of diverse environmental conditions [17]. This result also suggests that tropical forests throughout the world showed much similarity at the family level [17], [23], and a prove of maturity as these families are generally represented by woody species [17], [23].…”