A first look at the impediments to forest recovery in bracken-dominated clearings in the African Highlands

The forest-forming giant kelp Macrocystis pyrifera and the communities it supports have been decreasing across their native ranges in many parts of the world. The sudden removal of giant kelp canopies by storms increases space and light for the colonization by understory macroalgae, such as Desmarestia herbacea, which can inhibit M. pyrifera recovery and alter local community composition. Understanding the mechanisms by which algae such as D. herbacea interact with M. pyrifera can provide insight into patterns of kelp forest recovery following these disturbances and can aid in predicting future community structure. This study experimentally tested the independent and combined effects of two likely competitive mechanisms by which D. herbacea might inhibit recovery of M. pyrifera in the Point Loma kelp forest in San Diego, California (USA). Specifically, we conducted field experiments to study the individual and combined effects of shade and scour by D. herbacea on the survival of M. pyrifera microscopic life stages, and the recruitment, survival, and growth of its young sporophytes. Our results show that scour had the strongest negative effect on the survival of M. pyrifera microscopic life stages and recruitment, but shade and scour both adversely affected survival and growth of these sporophytes as they grew larger. Canopy-removing storms are increasing in frequency and intensity, and this change could facilitate the rise of understory species, like D. herbacea, which might alter community succession and recovery of kelp forests.

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Transient dynamics during kelp forest recovery from fishing across multiple trophic levels

Ecological Applications ◽

10.1002/eap.2367 ◽

2021 ◽

Author(s):

Robert P. Dunn ◽

Jameal F. Samhouri ◽

Marissa L. Baskett

Keyword(s):

Kelp Forest ◽

Trophic Levels ◽

Forest Recovery ◽

Transient Dynamics

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Short term fallow and partitioning effects of green manures on wheat systems in East African highlands

Field Crops Research ◽

10.1016/j.fcr.2021.108175 ◽

2021 ◽

Vol 269 ◽

pp. 108175

Author(s):

Tilahun Amede ◽

Gizachew Legesse ◽

Getachew Agegnehu ◽

Tadesse Gashaw ◽

Tulu Degefu ◽

...

Keyword(s):

Green Manures ◽

East African ◽

Short Term ◽

African Highlands ◽

East African Highlands

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Effect of Seasonal Drought on the Agronomic Performance of Four Banana Genotypes (Musa spp.) in the East African Highlands

Agronomy ◽

10.3390/agronomy11010004 ◽

2020 ◽

Vol 11 (1) ◽

pp. 4

Author(s):

Brigitte Uwimana ◽

Yasmín Zorrilla-Fontanesi ◽

Jelle van Wesemael ◽

Hassan Mduma ◽

Allan Brown ◽

...

Keyword(s):

Yield Traits ◽

East African ◽

Ploidy Levels ◽

Early Effect ◽

Seasonal Drought ◽

Musa Spp ◽

Drought Tolerant ◽

Genome Group ◽

African Highlands ◽

East African Highlands

Banana (Musa spp.), a perennial (sub-)tropical crop, suffers from seasonal droughts, which are typical of rain-fed agriculture. This study aimed at understanding the effect of seasonal drought on early growth, flowering and yield traits in bananas grown in the East African highlands. A field experiment was set up in North Tanzania using four genotypes from different geographical origins and two different ploidy levels. The treatments considered were exclusively rain-fed versus rain supplemented with irrigation. Growth in plant girth and leaf area were promising traits to detect the early effect of water deficit. Seasonal drought slowed down vegetative growth, thus significantly decreasing plant girth, plant height and the number of suckers produced when compared to irrigated plants. It also delayed flowering time and bunch maturity and had a negative effect on yield traits. However, the results depended on the genotype and crop cycle and their interaction with the treatments. “Nakitengwa”, an East African highland banana (EAHB; AAA genome group), which is adapted to the region, showed sensitivity to drought in terms of reduced bunch weight and expected yield, while “Cachaco” (ABB genome group) showed less sensitivity to drought but had a poorer yield than “Nakitengwa”. Our study confirms that seasonal drought has a negative impact on banana production in East Africa, where EAHBs are the most predominant type of bananas grown in the region. We also show that a drought-tolerant cultivar not adapted to the East African highlands had a low performance in terms of yield. We recommend a large-scale screening of diploid bananas to identify drought-tolerant genotypes to be used in the improvement of locally adapted and accepted varieties.

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Regeneration dynamics in fragmented landscapes at the leading edge of distribution: Quercus suber woodlands as a study case

Plant and Soil ◽

10.1007/s11104-021-05077-7 ◽

2021 ◽

Author(s):

Jorge Luis Montero-Muñoz ◽

Carmen Ureña ◽

Diego Navarro ◽

Valentín Herrera ◽

Pilar Alonso-Rojo ◽

...

Keyword(s):

Tree Growth ◽

Quercus Suber ◽

Forest Recovery ◽

Tree Cover ◽

Distribution Area ◽

Soil Parameters ◽

Old Fields ◽

Summer Drought ◽

Regeneration Dynamics ◽

Positive Effect

Abstract Aims We studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits of rainfall and temperature. Two hypotheses were established: (1) regeneration of Quercus species is strongly favored by the presence of tree cover; and (2) growth of Q. suber is driven by the climatic variables that represent the lower ecological limit of its leading distribution edge. Methods We selected woodlands and old fields with and without tree remnants (n = 3 per type), and analyzed stand structure, soil parameters and tree growth. Results Succession was arrested in old fields without tree remnants. By contrast, remnant trees were accelerators of forest recovery in old fields. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation that mitigate the effects of summer drought on seedlings. Also, tree cover improved soil parameters (e.g., organic matter) that are important factors for understanding differences in regeneration. Winter/spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September. Conclusions Regeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover.

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Forest recovery in set-aside windthrow is facilitated by fast growth of advance regeneration

Annals of Forest Science ◽

10.1007/s13595-018-0765-z ◽

2018 ◽

Vol 75 (3) ◽

Cited By ~ 4

Author(s):

Jerzy Szwagrzyk ◽

Zbigniew Maciejewski ◽

Ewa Maciejewska ◽

Andrzej Tomski ◽

Anna Gazda

Keyword(s):

Fast Growth ◽

Forest Recovery ◽

Advance Regeneration

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Feasibility of Sustainable Management of Secondary Atlantic Forest: Recovery and Mortality Rates of Damaged Trees Two Years After Harvesting

Environmental Sciences Proceedings ◽

10.3390/iecf2020-08484 ◽

2020 ◽

Vol 3 (1) ◽

pp. 39

Author(s):

Pedro C. Britto ◽

Dirk Jaeger ◽

Stephan Hoffmann ◽

Renato C. G. Robert ◽

Alexander C. Vibrans ◽

...

Keyword(s):

Atlantic Forest ◽

Sustainable Management ◽

Sustainable Forest Management ◽

Strong Relationship ◽

Mortality Rates ◽

Timber Harvesting ◽

Forest Recovery ◽

Native Forest ◽

Harvesting Method ◽

Conservation And Management

Subject to overexploitation in past centuries, the Atlantic Forest is now strictly protected, including a ban on timber harvesting. However, this strict protection is a very controversial issue. It resulted in a lack of willingness of landholders to conserve and possibly even expand native forest areas. The lack of knowledge on impacts of potential timber-harvesting causes conflicts between conservation and management of the remnant Atlantic Forest. We believe that sustainable forest management, with reduced harvesting impact, has the potential to generate income for the landowners while sustaining important ecological services of the forest. Therefore, we assessed the harvesting impact of a conventional harvesting method (CM) and compared it to an alternative harvesting method (AM) in three different stands. We measured damage intensities of all remnant trees directly after harvesting and two years after harvesting. Tree damages were recorded in three different tree zones (crown, bole and leaning) and rated in three different intensity classes (minor, moderate and severe). Furthermore, we assessed the recovery and mortality rates of each damaged tree two years after harvesting. Improved AM harvesting reduced the impacts on trees with multiple damages, in particular to crown and bole damages combined. There is a strong relationship between steep terrains and crown damage. High mortality rates were related to stands with a high density of smaller trees and also to trees with leaning damage. Moreover, completely recovered trees were related to trees with light bole damage.

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Tree Species Diversity and Composition of Miombo Woodlands in South-Central Angola: A Chronosequence of Forest Recovery after Shifting Cultivation

International Journal of Forestry Research ◽

10.1155/2017/6202093 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 16

Author(s):

Francisco M. P. Gonçalves ◽

Rasmus Revermann ◽

Amândio L. Gomes ◽

Marcos P. M. Aidar ◽

Manfred Finckh ◽

...

Keyword(s):

Shifting Cultivation ◽

Stand Structure ◽

Woody Species ◽

Distinct Group ◽

Forest Recovery ◽

Miombo Woodlands ◽

Principal Coordinates Analysis ◽

South Central ◽

Principal Coordinates ◽

Management Plans

The study was carried out in the Cusseque area of the Municipality of Chitembo in south-central Angola. Our objectives were to assess the floristic diversity, the species composition, and stand structure of Miombo woodlands during regeneration after shifting cultivation. A total of 40 plots of 1000 m2were surveyed and analyzed, corresponding to mature forests/woodlands and three fallow types of different age. The analyses were based on plot inventories of all trees with DBH ≥ 5 cm. A total of 51 woody species, 38 genera, and 19 families were recorded. The dominant family was Fabaceae, with subfamily Caesalpinioideae being very abundant. Shannon Diversity and Evenness were highest in mature forests and young fallows, while the mature forest stands showed the highest species richness. A Principal Coordinates Analysis (PCoA) showed many species shared between the intermediate fallow types, but only few species were shared with young fallows. Mature forests formed a clearly distinct group. This study shows potential pathways of forest recovery in terms of faster regeneration after agricultural abandonment and, thus, the results presented here can be used in future conservation and management plans in order to reduce the pressure on mature forests.

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Model-Based Estimation of Amazonian Forests Recovery Time after Drought and Fire Events

Forests ◽

10.3390/f12010008 ◽

2020 ◽

Vol 12 (1) ◽

pp. 8

Author(s):

Bruno L. De Faria ◽

Gina Marano ◽

Camille Piponiot ◽

Carlos A. Silva ◽

Vinícius de L. Dantas ◽

...

Keyword(s):

Recovery Time ◽

Regional Scale ◽

Forest Growth ◽

Forest Recovery ◽

Fire Intensity ◽

Natural Ecosystems ◽

Spatial And Temporal Patterns ◽

Southeastern Part ◽

Forest Growth Model ◽

Carbon Losses

In recent decades, droughts, deforestation and wildfires have become recurring phenomena that have heavily affected both human activities and natural ecosystems in Amazonia. The time needed for an ecosystem to recover from carbon losses is a crucial metric to evaluate disturbance impacts on forests. However, little is known about the impacts of these disturbances, alone and synergistically, on forest recovery time and the resulting spatiotemporal patterns at the regional scale. In this study, we combined the 3-PG forest growth model, remote sensing and field derived equations, to map the Amazonia-wide (3 km of spatial resolution) impact and recovery time of aboveground biomass (AGB) after drought, fire and a combination of logging and fire. Our results indicate that AGB decreases by 4%, 19% and 46% in forests affected by drought, fire and logging + fire, respectively, with an average AGB recovery time of 27 years for drought, 44 years for burned and 63 years for logged + burned areas and with maximum values reaching 184 years in areas of high fire intensity. Our findings provide two major insights in the spatial and temporal patterns of drought and wildfire in the Amazon: (1) the recovery time of the forests takes longer in the southeastern part of the basin, and, (2) as droughts and wildfires become more frequent—since the intervals between the disturbances are getting shorter than the rate of forest regeneration—the long lasting damage they cause potentially results in a permanent and increasing carbon losses from these fragile ecosystems.

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