Extensive clonal propagation and resprouting drive the regeneration of a Brazilian dry forest

Woody plant resprouting has received considerable attention in the last two decades as human disturbances continue to encroach on terrestrial ecosystems globally. We examined the regeneration mechanisms of a Caatinga dry forest in the context of slash-and-burn agriculture and resprouting ability of the local flora. We excavated two old fields (from 32) experiencing early forest regeneration dominated by the tree Pityrocarpa moniliformis (Fabaceae) to map clonal propagation and, in parallel, submitted 260 seedlings from 13 woody plant species to experimental clipping. What seemed to be ‘seedlings’ popping up around P. moniliformis stumps and remaining adults actually were condensed sets of root suckers connected via complex networks of long, ramified shallow horizontal roots without taproots. We mapped respectively 39 and 783 connected root suckers, which summed 96 m and 910 m in root length. Regarding the seedlings, 33% resprouted across nine species with resprouting rates varying between 5–100%. Seedling height before clipping positively influenced resprouting vigour. Our preliminary results suggest that the Caatinga dry forest supports a relatively high proportion of resprouting species, some of them able to clonally propagate and playing an ecosystem-level role by responding to early forest regeneration and high abundance/biomass across both regenerating and old-growth forests.

Terra Ronca State Park: A potential natural Cratylia argentea (Desv.) Kuntze conservation area in Goiás, Brazil

Cratylia argentea (cratília) is a neo-tropical leguminous plant with high resprouting ability, showing great potential as both an animal feed and to fertilize the soil through its N-fixing ability. During scientific expeditions carried out in 2016 to identify and collect germplasm in different states of Brazil, the Terra Ronca State Park (PETeR) stood out as a potential conservation area for this species. There, cratília is well adapted to the dry season, retaining green leaves even during extended dry periods and was found to develop a shrub or climbing habit, depending on light conditions. In the traditional cattle production systems of the region livestock readily consume cratília, making it an important asset for local inhabitants. Based on several populations identified and collected in PETeR, the value of traditional knowledge and use of cratília is discussed as is the potential role of the Park as an in situ conservation unit.

Post-Fire Resprouting in New Zealand Woody Vegetation: Implications for Restoration

Resprouting is an important trait that allows plants to persist after fire and is considered a key functional trait in woody plants. While resprouting is well documented in fire-prone biomes, information is scarce in non-fire-prone ecosystems, such as New Zealand (NZ) forests. Our objective was to investigate patterns of post-fire resprouting in NZ by identifying the ability of species to resprout and quantifying the resprouting rates within the local plant community. Fire occurrence is likely to increase in NZ as a consequence of climate change, and this investigation addresses an important knowledge gap needed for planning restoration actions in fire-susceptible regions. The study was conducted in two phases: (1) A detailed review of the resprouting ability of the NZ woody flora, and (2) a field study where the post-fire responses of plants were quantified. The field study was undertaken in the eastern South Island, where woody plants (>5 cm diameter at 30 cm height) were sampled in 10 plots (10x10 m), five- and 10-months post-fire. The research synthesized the resprouting ability of 73 woody species and is the first to provide extensive quantitative data on resprouting in NZ. Most of the canopy dominant species were non-resprouters, but many smaller trees and shrubs were capable of resprouting, despite their evolution in an environment with low fire frequency. Species composition and abundance were important predictors of resprouting patterns among plots, with similar communities resulting in similar resprouting responses. Resprouting capacity provides species with a competitive advantage in the post-fire recovery. We suggest that it is possible to engineer more fire resilient restoration plantings by planting higher proportions of the resprouters identified in this study. The incorporation of resprouting as a trait in restoration plans is likely to be relevant not just in NZ, but also in other non-fire-prone regions facing increases in fire frequency.

Laurel (Litsea glaucescens Kunth) Regeneration in the Presence of Disturbance Events: A Case Study

A study was carried out in an Abies religiosa Kunth Schltdl. et Cham forest of the community of San Antonio Tecocomulco Tres Cabezas, Municipality of Singuilucan, Hidalgo, to evaluate the resprouting ability of laurel (Litsea glaucescens Kunth) in response to controlled burning treatments and removal of entire stems. The number of laurel bushes, shoots, and mean plant height were evaluated, and three treatments were applied: controlled surface burn; all sprouts cut from the base; and control treatment. Nine weeks after the treatments were applied, the plants in the stem removal treatment remained alive (100 percent), and the appearance of shoots with a mean height of 4.8 cm increased by 18 percent, whereas in the controlled burning treatment, the number of live plants and shoots decreased by 38.2 and 71.5 percent, respectively, with a mean height of 1.1 cm. In the control, the number of bushes remained at 100 percent, and shoots increased by 9.9 percent with a mean bush height of 7.6 cm. This indicates that although surface forest fires tend to affect laurel, surviving plants tend to emit more vigorous shoots, whereas stem removal in laurel bushes generates more shoots

Effect of experimental fire on seedlings of Australian and Gondwanan trees species from a Tasmanian montane vegetation mosaic

The montane area of the Tasmanian Wilderness World Heritage Area was recently burnt by large fires ignited by lightning, and such fires are predicted to become more frequent with climate change. The region has a mix of fire-sensitive and fire-tolerant vegetation, but there is little information available on resprouting ability of seedlings of the dominant species of these mosaics. We predicted that seedlings of species found in fire-prone locations would exhibit more post-fire resprouting than seedlings of Gondwanan relictual species, which typically occur in fire-protected locations. To test this hypothesis we compared topkill and resprouting ability of seedlings from five tree species characteristic of the montane vegetation mosaics by exposing them to a propane burner flame for 0, 15, 30, 45 and 60s, simulating a fire intensity of 33 kW m–1. Overall, 93 of 100 flame-exposed plants were topkilled. Topkill was related to duration of flame exposure and seedling size rather than species. By contrast, resprouting of topkilled seedlings was strongly correlated with species rather than seedling size, and was not affected by duration of flame exposure. Contrary to expectations, the rainforest plant Nothofagus cunninghamii was the strongest resprouter, whereas few of the topkilled eucalypt seedlings resprouted. Our study shows the commonly held association between palaeoendemic Gondwanan species and low fire tolerance versus Australian species and high fire tolerance is overly simplistic. We need to better understand fire recovery mechanisms in the Tasmanian flora using a combination of field observation and experimental approaches.

PENGARUH UKURAN BIJI TERHADAP KEMAMPUAN TANAMAN TUMBUH KEMBALI SETELAH RUSAK AKIBAT HERBIVORI

The objective of the study is to investigate the effect of seed size in the resprouting ability of seedling after being damaged and whether it correlates with the reserve effect. We grew the seedlings of two species of oak, namely Quercus robur and Quercus petraea from different seed size, in a greenhouse. The seedlings were harvested at different stages; after emergence, at the first shoot fully developed, and after the seedling had re- grown after the initial shoot was clipped. The result showed that: firstly, at the time of full seedling development, large seeds translocated less percentage of reserve from the seed to seedling. After clipping, the seedlings from large seeds translocated additional resources to the seedling. Secondly, although the larger seed has the larger biomass to re-sprout, the total mass invested in re-sprouting proportional with seedling size. We concluded that the seedlings of larger seeds re-sprout better than those of the smaller seeds. However, we did not find the improved performances correlating with the Reserve Effect Theory

REGENERATION THROUGH RESPROUTING AFTER CLEAR-CUTTING AND TOPSOIL STRIPPING IN A TROPICAL DRY FOREST IN CENTRAL BRAZIL1

ABSTRACT Tropical dry forest trees have high resprouting ability, which may be useful for ecological restoration purposes. However, resprouting ability is affected by the type and severity of the disturbance. This study described the regeneration of trees through resprouting in a seasonally deciduous forest in Central Brazil, six months after being subjected to a gradient of disturbance. In order to expand a limestone quarry, 10 ha of deciduous forest were deforested in May 2013, creating areas with three increasing levels of disturbance: Clear-Cutting, Stump Removal and 5-20 cm of Topsoil Stripping. Twenty 3.14 m² circular plots were randomly selected in each type of disturbance. All resprouts were counted and identified to species level. The plant organ where each resprout grew from and the distance of the resprout insertion to the soil were recorded. There were 27 species in the Clear-Cutting and Stump Removal areas, and 24 in the Topsoil Stripping site. Resprout density was 3.0 ± 0.3a/m² in the Clear-Cutting, 1.7 ± 0.4b in the Stump Removal and 1.4 ± 0.4b in the Topsoil Stripping area (mean ± SD; Tukey HSD). Stems contributed to 61% of the resprouts in the Clear-Cutting area, while 60% of the resprouts in Stump Removal grew from root collars and 70% of the resprouts in Topsoil Stripping grew from roots. Underground resprouts emerged from a depth of up to 24 cm. An increase in disturbance severity negatively affected resprouting ability, but natural regeneration was high regardless of disturbance severity. The high resprouting ability of the deciduous forest trees provides resilience even after topsoil stripping.