Characteristics of total soil seed banks and permanent soil seed banks in three microhabitats in a Mediterranean coastal sand dune were investigated by using natural germination method combined with physically scannin...Characteristics of total soil seed banks and permanent soil seed banks in three microhabitats in a Mediterranean coastal sand dune were investigated by using natural germination method combined with physically scanning separation method. The composition and structure of soil seed banks were analyzed between the microhabitats by using functional group method. The distribution patterns of soil seed bank were also analyzed between the microhabitats. We also analyzed the relationship between seed size and seed persistence in soil. The results show greatly spatial heterogeneity existed in soil seed bank of the Mediterranean coastal sand dune, even in the same microhabitats seed distribution was uneven. Sometimes a great difference occurred between them. Microhabitats significantly affected the distribution patterns of total soil seed banks and seed banks of the functional groups. The open area generally had the greater densities of seeds, but the seed densities under shrub and in trail were lower than that in the open area. Legumes seeds accounted for 76.0% total persistent seed banks. Annual and perennial grasses produced transient seed banks as no seeds were retrieved from the sieved soils. Seed persistence of legumes, umbeliferaes, perennial forbs, compositaes, annual forbs, crucifer decreased gradually. They were 50.1%, 45.6%, 40.6%, 6.3%, 5.6% and 0.6% respectively in the soil. There was a positive relationship between seed size and seed persistence. Bigger seeds had higher persistence, and vice versa.展开更多
Aims Climate change in the eastern Mediterranean region will have a strong impact on ecosystem functioning and plant community dynamics due to a reduction in annual rainfall and increased variability.We aim to underst...Aims Climate change in the eastern Mediterranean region will have a strong impact on ecosystem functioning and plant community dynamics due to a reduction in annual rainfall and increased variability.We aim to understand the role of seed banks as potential buffers against climatic uncertainty determined by climate change.Methods We examined germination strategies of 18 common species present along an aridity gradient.Data were obtained from soil seed banks germinated during nine consecutive years from arid,semi-arid,Mediterranean and mesic Mediterranean ecosystems.At the semi-arid and Mediterranean sites,rainfall manipulations simulating 30%drought and 30%rainfall increase were applied.Germination strategies were tested under optimal irrigation conditions during three consecutive germination seasons to determine overall seed germinability in each soil sample.Changes in germination strategy were examined using a novel statistical approach that considers the climatic and biotic factors that may affect seed germinability.Important Findings The results showed that dominant species controlled their germination fractions by producing seeds with a different yearly germination fraction probability.The amount of rainfall under which the seeds were produced led to two major seed types with respect to germinability:high germinability,seeds leading to transient seed banks,and low germinability,seeds leading to persistent seed banks.We conclude that differential seed production among wet and dry years of both seed types creates a stable balance along the aridity gradient,enabling the soil seed bank to serve as a stabilizing mechanism buffering against rainfall unpredictability.Additionally,we present a general model of germination strategies of dominant annual species in Mediterranean and arid ecosystems that strengthens the notion of soil seed banks as buffers against climatic uncertainty induced by climate change in the region.展开更多
文摘Characteristics of total soil seed banks and permanent soil seed banks in three microhabitats in a Mediterranean coastal sand dune were investigated by using natural germination method combined with physically scanning separation method. The composition and structure of soil seed banks were analyzed between the microhabitats by using functional group method. The distribution patterns of soil seed bank were also analyzed between the microhabitats. We also analyzed the relationship between seed size and seed persistence in soil. The results show greatly spatial heterogeneity existed in soil seed bank of the Mediterranean coastal sand dune, even in the same microhabitats seed distribution was uneven. Sometimes a great difference occurred between them. Microhabitats significantly affected the distribution patterns of total soil seed banks and seed banks of the functional groups. The open area generally had the greater densities of seeds, but the seed densities under shrub and in trail were lower than that in the open area. Legumes seeds accounted for 76.0% total persistent seed banks. Annual and perennial grasses produced transient seed banks as no seeds were retrieved from the sieved soils. Seed persistence of legumes, umbeliferaes, perennial forbs, compositaes, annual forbs, crucifer decreased gradually. They were 50.1%, 45.6%, 40.6%, 6.3%, 5.6% and 0.6% respectively in the soil. There was a positive relationship between seed size and seed persistence. Bigger seeds had higher persistence, and vice versa.
基金supported by the GLOWA Jordan River project and funded by the German Federal Ministry of Education and Research(BMBF)in collaboration with the Israeli Ministry of Science and Technology(MOST).
文摘Aims Climate change in the eastern Mediterranean region will have a strong impact on ecosystem functioning and plant community dynamics due to a reduction in annual rainfall and increased variability.We aim to understand the role of seed banks as potential buffers against climatic uncertainty determined by climate change.Methods We examined germination strategies of 18 common species present along an aridity gradient.Data were obtained from soil seed banks germinated during nine consecutive years from arid,semi-arid,Mediterranean and mesic Mediterranean ecosystems.At the semi-arid and Mediterranean sites,rainfall manipulations simulating 30%drought and 30%rainfall increase were applied.Germination strategies were tested under optimal irrigation conditions during three consecutive germination seasons to determine overall seed germinability in each soil sample.Changes in germination strategy were examined using a novel statistical approach that considers the climatic and biotic factors that may affect seed germinability.Important Findings The results showed that dominant species controlled their germination fractions by producing seeds with a different yearly germination fraction probability.The amount of rainfall under which the seeds were produced led to two major seed types with respect to germinability:high germinability,seeds leading to transient seed banks,and low germinability,seeds leading to persistent seed banks.We conclude that differential seed production among wet and dry years of both seed types creates a stable balance along the aridity gradient,enabling the soil seed bank to serve as a stabilizing mechanism buffering against rainfall unpredictability.Additionally,we present a general model of germination strategies of dominant annual species in Mediterranean and arid ecosystems that strengthens the notion of soil seed banks as buffers against climatic uncertainty induced by climate change in the region.
