Natural recovery of corals after severe disturbance

Ecosystem recovery from human-induced disturbances, whether through natural processes or restoration, is occurring worldwide. Yet, recovery dynamics, and their implications for broader ecosystem management, remain unclear. We explored recovery dynamics using coral reefs as a case study. We tracked the fate of 809 individual coral recruits that settled after a severe bleaching event at Lizard Island, Great Barrier Reef. Recruited Acropora corals, first detected in 2020, grew to coral cover levels that were equivalent to global average coral cover within just 2 years. Furthermore, we found that just 11.5 Acropora recruits per square meter were sufficient to reach this cover within 2 years. However, wave exposure, growth form and colony density had a marked effect on recovery rates. Our results underscore the importance of considering natural recovery in management and restoration and highlight how lessons learnt from reef recovery can inform our understanding of recovery dynamics in high-diversity climate-disturbed ecosystems.

Natural Vegetation Recovery on Excavated Archaeological Sites: A Case Study of Ancient Burial Mounds in Bulgaria

As a distinctive component of the cultural landscape in Eurasia, burial mounds are well known for their historical value. Recently their role as biodiversity hotspots, especially in the homogenous agricultural landscape, has become particularly important. Archaeological excavations, although necessary, are destructive to the natural elements on the mounds. Restoration and vegetation recovery after such disturbances are needed for the preservation of biodiversity and for the cultural landscape integrity. In this study, we aimed to find out how effective is the natural vegetation recovery on the mounds after archaeological excavations. Successional stages between 2- and 30-years post-excavations have been studied. Vegetation sampling was performed on 15 mounds within 300 plots (1 × 1 m). Spontaneous succession was found to start immediately, and during the first decade, anthropophytes prevailed. In the subsequent years, their cover significantly decreased at the expense of species typical for the natural communities in the surroundings. Total species richness increased with the successional age and the vegetation composition became more similar to the semi-natural communities commonly established on mounds in Bulgaria. In the advanced successional stages, we registered a high rate of heterogeneity on the mounds, facilitated by the establishment of target plant species with different ecological requirements, including bryophytes. Provided the obtained results, we conclude that the natural vegetation recovery on the excavated and subsequently recovered mounds were very successful, and the current practice must continue in the future.

Seedling recruitment under isolated trees in a tea plantation provides a template for forest restoration in eastern Africa

Natural regeneration is less expensive than tree planting, but determining what species will arrive and establish to serve as templates for tropical forest restoration remains poorly investigated in eastern Africa. This study summarises seedling recruitment under 29 isolated legacy trees (14 trees comprised of three exotic species and 15 trees comprised of seven native species) in tea plantations in the East Usambara Mountains, Tanzania. Among the findings were that pioneer recruits were very abundant whereas non-pioneers were disproportionately fewer. Importantly, 98% of all recruits were animal-dispersed. The size of legacy trees, driven mostly by the exotic Grevillea robusta, and to some extent, the native Milicia excelsa, explained abundance of recruits. The distribution of bird-dispersed recruits suggested that some bird species use all types of legacy trees equally in this fragmented landscape. In contrast, the distribution of bat-dispersed recruits provided strong evidence that seedling composition differed under native versus exotic legacy trees likely due to fruit bats showing more preference for native legacy trees. Native, as compared to exotic legacy trees, had almost two times more non-pioneer recruits, with Ficus and Milicia excelsa driving this trend. Implications of our findings regarding restoration in the tropics are numerous for the movement of native animal-dispersed tree species in fragmented and disturbed tropical forests surrounded by farmland. Isolated native trees that bear fleshy fruits can attract more frugivores, resulting not only in high recruitment under them, but depending on the dispersal mode of the legacy trees, also different suites of recruited species. When selecting tree species for plantings, to maximize visitation by different dispersal agents and to enhance seedling recruit diversity, bat-dispersed Milicia excelsa and Ficus species are recommended.