Forest seed banks along an intensity gradient of ancient agriculture

2009 ◽  
Vol 19 (2) ◽  
pp. 103-114 ◽  
Author(s):  
J. Plue ◽  
J.-L. Dupouey ◽  
K. Verheyen ◽  
M. Hermy

AbstractRecently, forest seed banks were proven to not only reflect former (decades-old) but also ancient (centuries-old) land use. Yet, as land-use intensity determines the magnitude of seed-bank changes in recent forests, this study aims to identify whether an ancient land-use gradient would also be reflected in the seed bank. On a forested 1600-year-old archaeological site, five different land-use intensities were mapped and sampled. Apart from seed density, species richness and composition, functional seed-bank types, defined by nine seed-bank-related plant traits, were related to the land-use intensity gradient. The land-use gradient from gardens to undisturbed sites was still clearly reflected in the soil seed bank. Six emergent functional seed-bank types, characterized by specific plant traits, changed significantly in abundance, parallel to the land-use gradient. In particular, dispersal agent (and related traits) proved an important explanatory trait of present (functional) seed-bank patterns. Poor dispersers (large and heavy seeds) were not found in the intensively used areas, contrary to animal-dispersed species. Wind-dispersers may have been inhibited in the extension of their distribution by recruitment bottlenecks (low seed production) and/or competitive exclusion. Additionally, the agricultural land-use probably introduced ruderal species into the seed bank of the most intensively used areas, yielding a simultaneous increase in vegetation–seed-bank dissimilarity with land-use intensity, eliminating present vegetation as a driver behind the differences over the seed-bank gradient. We conclude by arguing how coppice-with-standards management possibly maintained the seed-bank gradient.

2008 ◽  
Vol 100 (1-2) ◽  
pp. 83-88 ◽  
Author(s):  
R SMITH ◽  
C MCSWINEY ◽  
A GRANDY ◽  
P SUWANWAREE ◽  
R SNIDER ◽  
...  

2018 ◽  
Vol 434 (1-2) ◽  
pp. 289-304 ◽  
Author(s):  
Safaa Wasof ◽  
An De Schrijver ◽  
Stephanie Schelfhout ◽  
Michael P. Perring ◽  
Elyn Remy ◽  
...  

2011 ◽  
Vol 79 (2) ◽  
pp. 157-166 ◽  
Author(s):  
Maciej Wódkiewicz ◽  
Anna Justyna Kwiatkowska-Falińska

Forest seed banks mostly studied in managed forests proved to be small, species poor and not reflecting aboveground species composition. Yet studies conducted in undisturbed communities indicate a different seed bank characteristic. Therefore we aimed at describing soil seed bank in an undisturbed forest in a remnant of European lowland temperate forests, the Białowieża Forest. We compared similarity between the herb layer and seed bank, similarity of seed bank between different patches, and dominance structure of species in the herb layer and in the seed bank of two related oak-hornbeam communities. We report relatively high values of Sorensen species similarity index between herb layer and seed bank of both patches. This suggests higher species similarity of the herb layer and soil seed bank in natural, unmanaged forests represented by both plots than in fragmented communities influenced by man. Although there was a set of core seed bank species present at both plots, yielding high Sorensen species similarity index values, considerable differences between plots in seed bank size and dominance structure of species were found, indicating spatial variability of studied seed bank generated by edaphic conditions. Dominance structure of species in the herb layer was not reflected in the underlying seed bank. This stresses, that natural forest regeneration cannot rely only on the seed bank, although some forest species are capable of forming soil seed banks. While forest seed banks may not reflect vegetation composition of past successional stages, they may inform on history and land use of a specific plot.


Author(s):  
Ya-Fei Shi ◽  
Zengru Wang ◽  
Bing-Xin Xu ◽  
Jian-Qiang Huo ◽  
Rui Hu ◽  
...  

Soil seed banks may offer great potential for restoring and maintaining desert ecosystems that have been degraded by climate change and anthropogenic disturbance. However, few studies have explored the annual dynamics in the composition and relative abundance of these soil seed banks. We conducted a long-term observational study to assess the effects of environmental factors (meteorology and microtopography) and aboveground vegetation on the soil seed bank of the Tengger Desert, China. The desert seed bank was dominated by annual herbs. We found that more rainfall in the growing season increased the number of seeds in the soil seed bank, and that quadrats at relatively higher elevations had fewer seeds. The species composition had more similarity in the seed bank than in the aboveground vegetation, though the seed bank and aboveground vegetation did change synchronously due to the rapid propagation of annuals. Together, our findings suggest that the combined effects of environmental factors and plant life forms determine the species composition and size of soil seed banks in deserts. Thus, if degraded desert ecosystems are left to regenerate naturally, the lack of shrub and perennial herb seeds could crucially limit their restoration. Human intervention and management may have to be applied to enhance the seed abundance of longer-lived lifeforms in degraded deserts.


Bothalia ◽  
2007 ◽  
Vol 37 (2) ◽  
pp. 249-258 ◽  
Author(s):  
M. J. S. Kellerman ◽  
M. W. Van Rooyen

Seasonal variation in seed bank size and species composition of five selected habitat types within the Tembe Elephant Park. South Africa, was investigated. At three-month intervals, soil samples were randomly collected from five different habitat types: a, Licuati forest; b, Licuati thicket; c, a bare or sparsely vegetated zone surrounding the forest edge, referred to as the forest/grassland ecotone; d, grassland; and e, open woodland. Most species in the seed bank flora were either grasses, sedges, or forbs, with hardly any evidence of woody species. The Licuati forest and thicket soils produced the lowest seed densities in all seasons.  Licuati forest and grassland seed banks showed a two-fold seasonal variation in size, those of the Licuati thicket and woodland a three-fold variation in size, whereas the forest/grassland ecotone maintained a relatively large seed bank all year round. The woodland seed bank had the highest species richness, whereas the Licuati forest and thicket soils were poor in species. Generally, it was found that the greatest correspondence in species composition was between the Licuati forest and thicket, as well as the forest/grassland ecotone and grassland seed bank floras.


2020 ◽  
Vol 13 (3) ◽  
pp. 256-265 ◽  
Author(s):  
José Djalma de Souza ◽  
Bruno Ayron de Souza Aguiar ◽  
Danielle Melo dos Santos ◽  
Vanessa Kelly Rodrigues de Araujo ◽  
Júlia Arruda Simões ◽  
...  

Abstract Aims In dry tropical forests, herbaceous species may have dormancy mechanisms and form persistent and transient seed banks in the soil. Evolutionarily acquired, these mechanisms are efficient for the establishment and survival of these herbs, especially in forests with unpredictable climates, such as the Caatinga. Thus, our objective was to verify whether the studied herbaceous species adopt the physical dormancy mechanism and how these natural barriers are overcome, to understand the temporal dynamics existing in the soil seed bank from a Brazilian dry tropical forest. Methods Seeds of five native herbaceous species from the Caatinga forests were selected and submitted to pre-germinative treatments for verifying the presence of physical dormancy. We collected soil samples in the rainy and dry seasons for four consecutive years and monitored the emergence of the selected herbaceous in the greenhouse. We verified the differences in germination and seed bank emergence in the soil by generalized linear models. Important Findings The presence and absence of physical dormancy were observed in seeds from Caatinga herbaceous species. We found intraspecific and interspecific differences in the herbaceous emergence from soil seed banks between years and climatic seasons. In perennial herbs, consecutive lack of emergence between seasons and years was frequent, which suggests a direct relationship with the mechanism of physical dormancy and the environmental conditions necessary to overcome integument barriers. In these species, seed dimorphism and dormancy may confer additional advantages to their survival. Moreover, presenting intermediate levels of physical dormancy in an annual species may be an evolutionary adjustment to rainfall unpredictability. In contrast, we found that the annual herb without dormancy is more sensitive to seasonal and interannual climate changes, as evidenced by the increase and significant reduction of its emergence in the soil seed bank. These differences acquired evolutionarily are advantageous for the establishment of herbaceous populations, mainly in semiarid regions with an unpredictable climate.


Author(s):  
Li Yu ◽  
Zhanqi Wang ◽  
Hongwei Zhang ◽  
Chao Wei

Scientifically characterizing the spatial-temporal distribution characteristics of agricultural land use intensity and analyzing its driving factors are of great significance to the formulation of relevant agricultural land use intensity management policies, the realization of food safety and health, and the achievement of sustainable development goals. Taking Hubei Province as an example, and taking counties as the basic evaluation unit, this paper establishes an agricultural land use intensity evaluation system, explores the spatial autocorrelation of agricultural land use intensity in each county and analyzes the driving factors of agricultural land use intensity. The results show that the agricultural land use intensity in Hubei Province increased as a whole from 2000 to 2016, and the spatial agglomeration about the agricultural land use intensity in Hubei Province experienced a process of continuous growth and a fluctuating decline; the maximum of the Global Moran’s I was 0.430174 (in 2007) and the minimum was 0.148651 (in 2001). In terms of Local Moran’s I, H-H agglomeration units were mainly concentrated in two regions: One comprising the cities of Huanggang, Huangshi and Ezhou, and the other the cities of Xiangyang and Suizhou; the phenomenon is particularly obvious after 2005. On the other hand, factors such as the multiple cropping index (MCI) that reflect farmers’ willingness to engage in agricultural production have a great impact on agricultural land use intensity, the influence of the structure of the industry on agricultural land use intensity varies with the degree of influence of different industries on farmers’ income, and agricultural fiscal expenditure (AFE) has not effectively promoted the intensification of agricultural land use. The present research has important significance for enhancing insights into the sustainable improvement of agricultural land use intensity and for realizing risk control of agricultural land use and development.


2020 ◽  
Vol 42 (2) ◽  
pp. 85
Author(s):  
Annemieke Ruttledge ◽  
Ralph D. B. Whalley ◽  
Gregory Falzon ◽  
David Backhouse ◽  
Brian M. Sindel

A large and persistent soil seed bank characterises many important grass weeds, including Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock), a major weed in Australia and other countries. In the present study we examined the effects of constant and alternating temperatures in regulating primary and secondary dormancy and the creation and maintenance of its soil seed bank in northern NSW, Australia. One-month-old seeds were stored at 4, 25°C, 40/10°C and 40°C, in a laboratory, and germination tests were conducted every two weeks. Few seeds germinated following storage at 4°C, compared with seeds stored at 25°C, 40/10°C and 40°C. Nylon bags containing freshly harvested seeds were buried among N. trichotoma stands in early summer, and germination tests conducted following exhumation after each season over the next 12 months. Seeds buried over summer and summer plus autumn had higher germination than seeds buried over summer plus autumn plus winter, but germination increased again in the subsequent spring. Seeds stored for zero, three, six and 12 months at laboratory temperatures were placed on a thermogradient plate with 81 temperature combinations, followed by incubation at constant 25°C of un-germinated seeds. Constant high or low temperatures prolonged primary dormancy or induced secondary dormancy whereas alternating temperatures tended to break dormancy. Few temperature combinations resulted in more than 80% germination.


2019 ◽  
Vol 41 (5) ◽  
pp. 383 ◽  
Author(s):  
Vinod K. Chejara ◽  
Paul Kristiansen ◽  
R. D. B. (Wal) Whalley ◽  
Brian M. Sindel ◽  
Christopher Nadolny

Hyparrhenia hirta (L.) Stapf (also known as Coolatai grass, South African bluestem or thatching grass) has become a serious invasive weed in Australia. Within its native range, it is generally regarded as a useful grass particularly for thatching, and seed production is low with a low soil seed bank of from 2 to 200seedsm–2. Several hundred accessions of H. hirta were deliberately introduced into Australia up until the 1980s and nearly all were discarded because of poor seed production. However, at least one introduction in the 1890s in northern New South Wales (NSW), Australia, has possibly contributed to the present serious weed problem. Annual seed production from roadside stands in northern NSW ranged from 7000 to 92000seedsm–2 in 2015. The soil seed bank under dense H. hirta infestations in the same region in 2006 and 2007, was found to be ~30000seedsm–2 mostly confined to the top 2cm, with few dormant seeds and a large reduction of these numbers over the next 12 months when further seed input was prevented. Similar studies of other perennial grass weeds have found seed banks of similar sizes, but dormancy mechanisms ensure that their seed banks last for at least 10 years without further seed input. These results suggest that the present weedy populations of H. hirta have dramatically increased fecundity enabling a large seed bank to develop beneath dense stands. The development of seed dormancy and consequently a long-lived seed bank would make this weed even more difficult to control. Until seed dormancy develops, control of H. hirta in northern NSW can be effective provided further input into the seed bank can be prevented.


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