Nonrandom processes maintain diversity in tropical forests

An ecological community\u27s species diversity tends to erode through time as a result of stochastic extinction, competitive exclusion, and unstable host-enemy dynamics. This erosion of diversity can be prevented over the short term if recruits are highly diverse as a result of preferential recruitment of rare species or, alternatively, if rare species survive preferentially, which increases diversity as the ages of the individuals increase. Here, we present census data from seven New and Old World tropical forest dynamics plots that all show the latter pattern. Within local areas, the trees that survived were as a group more diverse than those that were recruited or those that died. The larger (and therefore on average older) survivors were more diverse within local areas than the smaller survivors. When species were rare in a local area, they had a higher survival rate than when they were common, resulting in enrichment for rare species and increasing diversity with age and size class in these complex ecosystems

The global abundance of tree palms

Aim Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location Tropical and subtropical moist forests. Time period Current. Major taxa studied Palms (Arecaceae). Methods We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work. Conclusions Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests

Diversity, Structure and Dynamics of a Mangrove Forest: a Case Study

<p><span lang="EN-GB" style="font-size: 10.0pt; font-family: 'Times New Roman',serif">The intertidal vegetation along tropical and subtropical coast is defined as mangrove vegetation. India has a long coast line measuring 7516 km. The ecology of mangrove forest is relatively less studied. Mangrove systems are known to be one of the most productive systems in the world. The study aimed to estimate the carbon sequestration potential of a relatively protected sacred grove along the western coast of India, in Kagekanu, Kumta, Karnataka. One hectare permanent plot was established, with all woody stems &gt; 1 cm dbh (diameter at breast height), which were marked and identified. Repeated measurements were made to register the growth and other parameters. Allometric equation was used to estimate the biomass, out of which 50% was considered as carbon content. A total of 1100 stems &gt; 1 cm dbh, belonging to 4 species, were enumerated. There was an overall decline of 13.9% stems during the study period. Mean mortality rate was found to be 5.83 ± 1.85% and there was no recruitment. The biomass increased from 155.53 tons/ha to 164.28 tons/ha. There was a net gain of 4.38 tons. <i>Avicinnia officinalis</i> was found to contribute significantly to carbon sequestration.</span></p

Diversity, Structure and Dynamics of a Mangrove Forest: a Case Study

The intertidal vegetation along tropical and subtropical coast is defined as mangrove vegetation. India has a long coast line measuring 7516 km. The ecology of mangrove forest is relatively less studied. Mangrove systems are known to be one of the most productive systems in the world. The study aimed to estimate the carbon sequestration potential of a relatively protected sacred grove along the western coast of India, in Kagekanu, Kumta, Karnataka. One hectare permanent plot was established, with all woody stems &gt; 1 cm dbh (diameter at breast height), which were marked and identified. Repeated measurements were made to register the growth and other parameters. Allometric equation was used to estimate the biomass, out of which 50% was considered as carbon content. A total of 1100 stems &gt; 1 cm dbh, belonging to 4 species, were enumerated. There was an overall decline of 13.9% stems during the study period. Mean mortality rate was found to be 5.83 ± 1.85% and there was no recruitment. The biomass increased from 155.53 tons/ha to 164.28 tons/ha. There was a net gain of 4.38 tons. Avicinnia officinalis was found to contribute significantly to carbon sequestration