Diversity, composition and richness of soil seed banks in different forest communities at Dotalugala Man and Biosphere Reserve, Sri Lanka

Abstract

The soil seed bank provides an indication of the regenerative potential of forest ecosystems following disturbances. The present study was conducted to examine the spatial and temporal distribution of soil seed bank in three different forest communities identified in an upper montane forest ecosystem (Dotalugala Forest Reserve) in the Knuckles Range, Sri Lanka. The three forest communities were upper-montane forest (UMF), midelevational wet face forest (MWF) and midelevational dry face forest (MDF), hereafter referred to as UMF, MWF and MDF, respectively. Ten surface soil samples were collected from five, 10 m × 15 m permanent plots (2 composite samples from each plot) established in each of the three forest communities. The soil samples were spread on seed beds in a glasshouse and emerging seedlings were counted and identified into different morphospecies. Two soil samplings were conducted during dry and wet seasons. Seed beds were maintained for nearly 3-4 months until no seedlings emerged. The results revealed higher number of germinable seeds in the wet season (1,157, 1,381 and 1,231 seeds) than in the dry season (507, 641 and 597 seeds) in UMF, MWF and MDF forest communities, respectively. The richness had similar trend between seasons (31, 35 and 34 morphotypes in the wet season and 24, 27 and 27 in the dry season in UMF, MWF and MDF, respectively). However, the density and richness showed no significant differences between forest communities during both seasons. Species composition differed between seasons and forest communities. Woody species dominated the soil seed bank during the dry season, while non-woody species dominated in the soil seed bank during the wet season. These temporal fluctuations in seed banks may possibly be due to site-specific (predation, senescence and germination of seeds) and plant-specific (phenology, dormancy of seeds) factors prevailing in these forest communities. Seeds of invasive species were represented comparatively less in all three communities, indicating no significant threat from invasive species to these forest communities. A number of pioneer species including Maesa indica, Acronychia pedunculata and Macaranga spp. were recorded in all three sites signifying their resilience and regenerative potential following a disturbance.

Prosopis juliflora invasion and environmental factors on density of soil seed bank in Afar Region, Northeast Ethiopia

“…These findings were incomparable with a report made by Bekele (2000) in the dry Afromontane forest in South Wollo of Ethiopia. On the other hand, our findings were similar to SBs of dry seasons, but in contrast to SSB in the wet season of the report by Madawala et al (2016). Furthermore, the number of growth forms in the form of forbs, climbers, and woody species had similar rends both in the forest relic and closed areas with that of research works by Reubens et al (2007) in dry tropical forests of Northern Ethiopia.…”

“…The changeover from seed to plant is a fundamental scheme shaping plant community structure and dynamics (Espinosa et al 2013). However, in the long run, human-impacted landscapes (Zobel et al 2007) form a variety of different patterns both in the soil and standing vegetation after disturbances and colonization by aggressive invasive species (Madawala et al 2016). Soil seed bank (SB) refers to a viable seed which is present in the soil or associated with litter/hummus (Zhang et al, 2017).…”

Composition and density of soil seed bank in Afar Region, Northeast Ethiopia

“…While the number of soil seeds recovered in both districts were also low in comparison to other sites in the region and elsewhere in Ethiopia. The reasons might be due to temporal and spatial variations of the status of seeds in the soil [33], the effects in the variations of nutrient conditions [18], and potential of the seeds rains in the districts [62].…”

“…The changeover from seed to plant is a fundamental scheme shaping plant community structure and dynamics [13]. However, in the long run of human-impacted landscapes [56] and different physiographic factors, vegetation forms a variety of different patterns both in the soil and standing vegetation after disturbances and colonized by aggressive invasive species [33]. Soil seed banks (SB) refers to a viable seed which is present in the soil or associated with hummus [34].…”

Ecology of soil seed banks: Implications for conservation and restoration of natural vegetation: A review

“…According to Madawala et al (2016), SBs are dominated by seeds of herbaceous species, although they can be highly variable in features such as species number and composition, seed longevity and viability, germination strategies and depth distribution of seeds in the soil. SBs have the capacity to survive for a longer period of time in the soil, and overcome the poor establishment and low survival rates of seedlings during drier years, which are typical of the afromontane vegetation types (Santos et al, 2018) and contribute to the re-establishment of plant species lost from the original plant community.…”