Microhabitat variations and seed bank-vegetation relationships in a desert wadi ecosystem

Due to extreme variability in patterns of rainfall, plant seed banks are an important component of desert habitats. Here I report on effects of standing vegetation and three different microhabitats (channel, bank and terrace) on the soil seed bank of a desert wadi ecosystem in the Eastern Desert of Egypt. A total of 450 soil samples at 45 stands were collected to represent the different wadi microhabitats. The germinable seed bank was estimated by controlled counts of seedling emergence. The floristic composition, functional properties and diversity of the soil seed bank, as well as its similarity with the standing vegetation varied among wadi microhabitats. Such variation could be attributed to differences in disturbance intensity among microhabitats (terrace < bank < channel) and variation of soil factors along the microtopographic gradient. Channel showed the highest species richness and size of soil seed bank, followed by bank and then terrace. Moreover the Shannon index of diversity of the seed bank and its similarity with standing vegetation were significantly greater in both channel and bank microhabitats than in terrace. At the level of plant functional groups, number of seeds of annuals was higher in both channel and bank than in terrace. Shrubs were more abundant in seed banks of channel compared to terrace. The size and species richness of seed bank were increased with the total plant cover, annual/perennial ratio and species richness of the standing vegetation.     

Experimental evidence for a delayed response of the above-ground vegetation and the seed bank to the invasion of an annual exotic plant in deciduous forests

Invasions by alien plants significantly affect native biodiversity and ecosystem functioning. We conducted a 5-year field experiment to investigate potential effects of the annual invasive plant Impatiens glandulifera on both the native above-ground vegetation and the soil seed bank in a deciduous forest in Switzerland. Eight years after the establishment of I. glandulifera, we set up plots in patches invaded by the alien plant, in plots from which the invasive plant had been manually removed and in plots which were not yet colonized by the invasive plant. We examined plant species richness, diversity and plant species composition in the above-ground vegetation and soil seed bank in all plots one year and five years after the initiation of the experiment. The 36 plots (3 plot types × 6 replicates × 2 sites) were equally distributed over two forest sites. Neither the native above-ground vegetation nor the soil seed bank was influenced by the presence of I. glandulifera one year after the start of the field experiment. After five years, however, plant species richness of both the above-ground vegetation and the soil seed bank was reduced by 25% and 30%, respectively, in plots invaded by the alien plant compared to plots from which I. glandulifera had been removed or uninvaded plots. Furthermore, plots invaded by the alien plant had a lower total seedling density (reduction by 60%) and an altered plant species composition in the soil seed bank compared to control plots. Our field experiment indicates that negative effects of the annual invasive plant on the native above-ground vegetation and soil seed bank of deciduous forests become visible with a delay of several years.     

Comparison of soil seed banks of habitats distributed along an altitudinal gradient in northern Iran

In this study we investigated the variations in soil seed banks along an altitudinal gradient in the Alborz mountains, Iran, covering three habitats from lower to upper altitudes: forest, forest-subalpine grassland ecotone and subalpine meadow. In each habitat from 1850 to 2400 m, 20 quadrats were established along four transects, and the above-ground vegetation and the germinable seed banks were determined. Results show that the similarity between seed bank and vegetation was lowest in the ecotone located at intermediate altitudes. Together with the contrasting highest density and species diversity of seeds at these altitudes, the ecotonal role of this habitat was confirmed.We found evidence that lower altitudes could act as storage for seeds of some species growing at higher altitudes; the role of the ecotone was more prominent as a reserve for the meadow plant seeds than the role of the forest as a reserve for seeds of the meadow and ecotone habitats. Soil seed banks, particularly from the ecotone, can be used for restoring vegetation in some degraded sites.     

Soil seed bank formation during early revegetation after hydroseeding in reclaimed coal wastes

The soil seed bank is an important component of ecosystem resilience and represents a stock of regeneration potential in many plant assemblages; however, little is known about the initial development of seed bank during restoration. We characterized the size and composition of the soil seed bank in a reclaimed coal mine in Spain. For that, the initial seed bank of soil-forming material and cattle manure that was spread over it analyzed before hydroseeding. Later, the seed bank that developed in the two seasons (2.3 years) after hydroseeding was resampled, taking in consideration the distance to natural communities and topography. The seed bank increased from virtually nothing to 1813 seeds m^?2 over the study period, and was composed of mainly native species, which were more abundant near seed sources in the adjacent landscape. Topography only influenced the size of the hydroseeded species seed bank, with four species comprising approximately 45% of the seed bank. There were also variations in seed bank species number and composition in the different areas of the same mine. These results emphasize the necessity of taking care when including foreign species in a hydroseeding mixture, and of considering seed bank development within each area of a site in management planning. Otherwise differences may condition the future vegetation recovery from the desired target, creating very different communities in very close proximity.     

The effect of stand age and microhabitat on soil seed banks in Mediterranean Aleppo pine forests after fire

Soil samples from three microhabitats (gaps, beneath shrubs and beneath trees) in five stands of various post-fire ages (6–55 years) were collected in an east Mediterranean Aleppo pine Pinus halepensis forest. Total germinable seed bank densities varied between 300 and 1300 seeds per m². Herbaceous taxa were the major constituents of the germinable seed bank in gaps, regardless of stand age. Perennials were the major components beneath shrubs in all stands except the youngest stand where herbaceous species were the major components in all microhabitats. Important tree and shrub species (e.g., Pinus halepensis, Quercus calliprinos, Pistacia lentiscus, Phillyrea latifolia) of the mature pine forest were not an important component of the soil seed bank and therefore, little resemblance was observed between the above-ground plant species composition and soil seed bank composition. This is consistent with the fact that these species regenerate by resprouting rather than by germination from the seed bank. Both microhabitats and forest-stands, which were of different ages, contributed to the variation in taxa richness, germinable seed density and diversity among samples. The effect of small-scale spatial heterogeneity (among microhabitats) was much more pronounced. In contrast to other studies, species richness, species diversity, and density of seed banks did not decrease with post-fire age. Moreover, stand age was a poor predictor for these attributes of the soil seed bank in an Aleppo pine forest. The heterogeneity plays an important role in conservation and management of this ecosystem.     

Variations of the germinable soil seed bank along the altitudinal gradient in the northwestern Red Sea region

The variations in the size, composition and diversity of the germinable soil seed bank were studied along an altitudinal gradient in the northwestern Red Sea region. The standing vegetation and the germinable seed bank were studied in 58 stands distributed along the altitudinal range from sea level to coastal mountain peaks. The classification of the germinable seed bank by the two-way indicator species analysis (TWINSPAN) led to the recognition of five groups representing different altitudinal ranges. Detrended correspondence analysis (DCA) shows that these groups are clearly distinguished by the first two DCA axes. The results demonstrate significant associations between the floristic composition of the seed bank and the edaphic factors such as CaCO₃, electrical conductivity, organic carbon and soil texture. Species richness, Shannon index of diversity and the size of the germinable seed bank show a hump-shaped curve along the altitudinal gradient, whereas evenness shows a weak increase with elevation increasing. Beta diversity of the seed bank declines with altitude increasing. The similarity between the standing vegetation and the seed bank approaches a U-shaped pattern along the elevation gradient. About 34.8% of the species that constitute the standing vegetation are vulnerable to elimination from the standing vegetation because they are not represented in the seed bank. Soil seed bank can be used for restoration of the vegetation at some of the degraded sites.     

Invasion by Solidago species has limited impacts on soil seed bank communities

Increasing attention in invasion biology is being paid to measuring and understanding the impacts of invasive species. For plant invasions, however, the impact of invasion on soil seed bank communities has been under-studied. At six sites in southern Germany, we investigated whether areas invaded by Solidago gigantea and Solidago canadensis experienced a reduction in seed bank species richness, size and diversity, and a change in species composition compared to adjacent uninvaded areas. We found no overall effect of invasion on seed bank size, or on species richness and diversity. Seed bank size significantly decreased from 0–5 cm to 5–10 cm depth in both invaded and uninvaded areas. A significant amount of variation in species composition was explained by invasion, but it was only one-tenth of that explained solely by site effects. Our study suggests that invasion by Solidago species may not have the same impacts on the soil seed banks of native species as other invasive perennial forbs that have so far been studied.     

Flooding, soil seed bank dynamics and vegetation resilience of a hydrologically variable desert floodplain

1. This paper explores soil seed bank composition and its contribution to the vegetation dynamics of a hydrologically variable desert floodplain in central Australia: the Cooper Creek floodplain. We investigated patterns in soil seed bank composition both temporally, in response to flooding (and drying), and spatially, with relation to flood frequency. Correlations between extant vegetation and soil seed bank composition are explored with respect to flooding. 2. A large and diverse germinable soil seed bank was detected comprising predominantly annual monocot and annual forb species. Soil seed bank composition did not change significantly in response to a major flood event but some spatial patterns were detected along a broad flood frequency gradient. Soil seed bank samples from frequently flooded sites had higher total germinable seed abundance and a greater abundance of annual monocots than less frequently flooded sites. In contrast, germinable seeds of perennial species belonging to the Poaceae family were most abundant in soil seed bank samples from rarely flooded sites. 3. Similarity between the composition of the soil seed bank and extant vegetation increased following flooding and was greatest in more frequently flooded areas of the floodplain, reflecting the establishment of annual species. The results indicate that persistent soil seed banks enable vegetation in this arid floodplain to respond to unpredictable patterns of flooding and drying.     

Temperature thresholds for germination and survival of Pittosporum undulatum: implications for management by fire

One consequence of human-induced changes in fire regimes has been the invasion of fire-prone Mediterranean ecosystems by weeds from more mesic habitats. In southern Australia, the tree Pittosporum undulatum Vent. has established in new areas, causing a serious reduction in floristic and structural diversity. Pittosporum undulatum has a high competitive ability and creates an environment that favours its own progeny at the expense of other species, making control difficult. We tested the hypothesis that fire effectively disrupts this invasion cycle by (1) eliminating the soil and canopy seed bank, (2) reducing the competitive ability of adults, and (3) minimising the number of sites favourable to invasion. To test this, the ability of P. undulatum to re-establish after a prescribed burn was estimated in a field study. The field data were then compared with the experimentally determined sensitivity of seeds and seedlings to elevated temperatures. The experimentally determined combination of temperatures and exposure time required for seed mortality (90–120 °C, depending on duration) was such that most seed stored in the canopy would be killed by prescribed burning. In addition, 90% of seedlings (ca. 0.4 m tall) were killed when heated to 180 °C for 5–10 min in the laboratory, consistent with the observed 100% seedling mortality in the burnt plots. Of the adult trees, 20% resprouted within 6 months of the fire. We conclude that the temperatures associated with wildfires are sufficient to act as a circuit breaker on the invasion cycle allowing other control measures, such as poisoning and weeding to be employed to greater effect.     

Seed-bank convergence under different tree species during forest development

Seed banks are of vital importance for local plant persistence and recruitment, for maintaining both plant and genetic diversity and for habitat restoration. Yet, seed-bank dynamics, particularly on the long term and in deciduous forests, remain poorly understood. Additionally, information on compositional seed-bank differences under contrasting tree canopies remains scarce.This study aims at quantifying long-term seed-bank dynamics by sampling vegetation and seed banks along a four-stage successional chronosequence (40, 80, 120 and 250 years) using 12 10 m×10 m plots per forest stand age–class under fully developed oak–hornbeam and beech canopies.Seed banks were remarkably abundant and diverse. Species richness and seed density declined steeply with forest stand age, regardless of canopy species. Seed-bank composition differed significantly with stand age, yet also with tree species. Most likely, tree species-dependent ecosystem engineer effects on light availability and possibly also litter quality affect the seed bank through the vegetation. Compositional differences between seed banks from stands with a different canopy diminished with increasing stand age, possibly due to a gradual loss of species with a less persistent seed bank.Long-term seed-bank dynamics in deciduous forests seem to consist predominantly of a unidirectional and predictable depletion of the seed bank as long as large disturbances, which would allow seed-bank replenishment of early-successional species, are lacking. Furthermore, forest seed-banks appear to converge upon a characteristic seed bank in the later stages of forest development, irrespective of canopy composition, driven by seed-bank depletion and limited input from the herb layer.     

Carbon allocation in a Costa Rican dry forest derived from tree ring analysis

The rising discussion on carbon balance of tropical forests often does not consider the sequestration potential of secondary dry forests, which are becoming an increasing importance due to land use change and reforestation. We have developed an easy applicable tool for the estimation of biomass increment of tropical secondary forest stands on the base of tree ring analysis. The existence of annual rings was shown by a combination of anatomical examination and radiocarbon estimations. With tree ring analysis, forest inventories and destructive sampling the above-ground biomass increment of secondary forest stands of age between 9 and 48 years in the dry forest region of Guanacaste, Costa Rica were estimated. The above-ground biomass increment of the tree layer varies between 2.4 and 3.2 Mg/ha yr in different stands. Lianas contribute with up to 23% additional production. Differences in productivity among the stands along a chronosequence were not significant. The measured carbon allocation potential of 1.7–2.1 Mg C/ha yr lies in the range of reported values from other tropical dry forests and old growth humid forests as well.     

Germination response and viability of an endangered tropical conifer Widdringtonia whytei seeds to temperature and light

The tropical conifer Widdringtonia whytei Rendle is an endangered species endemic to Mulanje Mountain in Malawi. A study was conducted for the first time under controlled conditions in order to assess the effects of temperature and light on germination and viability of W. whytei seeds. Seeds incubated at a constant temperature of 20 °C attained the highest cumulative germination percentage (100%) followed by 87% germination under fluctuating temperatures of 15 °C night/25 °C day. No seed germination occurred at temperatures below 15 °C. Seeds that failed to germinate at temperatures below 15 °C showed the highest (> 90%) viability compared to the seeds incubated at 25 °C (60%). Across temperature regimes, germination was significantly higher under light (44.7%) than dark (35.6%) conditions. It is concluded that temperature is one of the critical factors for germination of W. whytei seed. The ability of W. whytei seeds to germinate both in light and darkness implies that the species would unlikely form a persistent soil seed bank, an attribute which is common in species that survive in habitats frequently disturbed by fires.     

Can the soil seed bank contribute to revegetation of the drawdown zone in the Three Gorges Reservoir Region?

The drawdown zone of the Three Gorges Reservoir Region was assumed to be completely formed in 2009 and the water level would range from ~145 m in flood season (summer) to ~175 m during non-flood season (winter). The soil seed bank is an important propagule source for vegetation restoration. In order to evaluate the potential of the soil seed bank to revegetate the drawdown zone of this region, we examined the quantitative relationships between the germinable soil seed bank and the established vertical and horizontal vegetation patterns. A total of 45 soil samples at four sites was collected to examine seed bank density, species richness, and composition using the seedling-emergence method. Forty-five species (from 20 families) germinated from the soil seed bank, and the average seed density was 4578 m⁻². The seed bank was dominated by annual plants, suggesting reestablishment of some above-ground species was plausible. However, most established woody plants and perennials were absent from the seed bank indicating a low probability of reestablishment for non-annuals through the seed bank. Thus, due to low species compositional similarity to extant vegetation and the dominance of annual plants, the soil seed bank had a low potential to restore pre-dam vegetation in the drawdown zone of the Three Gorges Reservoir Region, but its potential as a propagule source should be considered regarding the management of the drawdown zone for vegetation cover.     

The seed ecology of an ornamental wattle in South Africa — Why has Acacia elata not invaded a greater area?

Australian Acacia species introduced to South Africa as ornamentals have notably smaller invasive ranges than those introduced for forestry or dune stabilization. We asked whether the relatively small invasive extent of Acacia elata, a species used widely for ornamental purposes, is due to low rates of reproduction. Age at reproductive maturity, seed dispersal, annual seed production, seed bank dynamics and seed germination and viability were assessed at five sites in the Western Cape. Results indicate that A. elata has similar traits to other invasive Australia Acacia species: annual seed input into the leaf litter was high (up to 5000 seeds m^− 2); large seed banks develop (> 20,000 seeds m^− 2) in established stands; seed germinability is high (> 90%); seeds accumulate mostly in the top soil layers but can infiltrate to depths of 40 cm; and seed germination appears to be stimulated by fire. However the age at the onset of reproduction (~ 4 years) is longer than most widespread invaders (~ 3 years) and dispersal is fairly limited (seeds fell up to distances of 6 m from the parent canopy; the highest density of seed rain was found directly under the canopy with over 20% of seeds falling directly under the terminal branches). We suggest that the current limited distribution of invasive A. elata populations is the result of the relatively small size of initial populations (cf. large plantations and widespread plantings for forestry and dune stabilization species), the species' apparent lack of secondary dispersal vectors, and the planting of trees in gardens and urban settings offer limited opportunities for recruitment, proliferation and spread. The species is, however, increasing in abundance and range. We propose methods to improve management of invasions of the species. Management to reduce seed production of this species through classical biological control, as has been achieved for other Australian Acacia species in South Africa, should be prioritised.     

Floristic patterns and disturbance history in karri (Eucalyptus diversicolor: Myrtaceae) forest,south-western Australia: 2. Origin,growth form and fire response

We examined the influence of disturbance history on the floristic composition of a single community type in karri forest, south-western Australia. Cover-abundance of 224 plant species and six disturbance and site-based environmental variables were recorded in 91, 20 m × 20 m quadrats. Numerical taxonomic and correlation approaches were used to relate these and 10 plant species-group variables based on origin, growth form and fire response. Ordination revealed no discernable pattern of sites based on floristic composition. However, all 10 species-group variables were significantly correlated with the ordination axes. Species richness within these groups varied with category and with respect to many of the disturbance and site variables. We encountered low diversity of vascular plants at the community level and limited diversity of growth forms. Thus most species were herbs (62.1%) or shrubs (30.3%), and there were no epiphytes and few species of trees or climbers. Although many introduced species were recorded (18.3% of all taxa), virtually all (83%) were herbs that demonstrated little persistence in the community, and there was limited evidence of transformer species. Time-since-fire (and other disturbance) influenced species richness more than the number of recent past fires because of a high proportion of ephemerals associated with the immediate post-fire period. Long-lived shrubs with soil stored seed dominate numerically, and in understorey biomass in comparison with neighboring vegetation types because of their greater flexibility of response following irregular, but intense disturbance events. However, interactions between nutrient status, regeneration mechanisms and community composition may be worthy of further investigation.     

Germinable soil seed bank of a gallery forest in Brazilian Cerrado

The soil seed bank is a dynamic biotic component of plant communities that represents the population’s memory in relation to selective events. Few studies have investigated the natural stock of germinable seeds in the gallery forests to evaluate their regeneration potential, although they are target of anthropogenic action. Thus, seasonal, horizontal, and vertical qualitative and quantitative variations of the seed bank of a gallery forest in the Brazilian Cerrado were studied to test the influence of the climatic seasonality, the influence of the physical structure, and depth of the soil in different microhabitats of the forest in this natural seed store. It was also compared the richness and abundance of species in the germinable seed bank with the above-ground vegetation. Three hundred and seventy-five soil samples were collected at the beginning (April 1998 and 1999) and at the end of the dry season (September 1998). These samples were collected in three microhabitats distributed transversally in relation to drainage line of a large stream, at five depths. The density of germinable seeds decreases with depth, and is similar among microhabitats and seasons. In 24,690 cm³ of soil and 4.05 m² of litter, 1390 seedlings emerged, being 743 dicotyledons and 647 monocotyledons. From 761 survivors, 263 were Cyperaceae, 206 Melastomataceae, 153 Poaceae, and 82 Onagraceae, the most abundant families. This study suggests that the diversity of the germinable soil seed bank is lower than that of the above-ground vegetation of the forest, and that the soil seed bank is not the principal regeneration form of this environment.     

The seed bank in a subtropical freshwater marsh: implications for wetland restoration

Seed bank samples were collected from Huli Marsh, a subtropical shallow water mountainous marsh in Hunan Province, South China. Core samples were divided into upper and lower layers (each 5 cm in depth) and allowed to germinate in three water levels (0, 5 and 10 cm) over a 4-month period. A total of 51 species germinated and the mean density was 9211 ± 7188 seedlings m⁻². In the top 5 cm 41 species and 5747 ± 5111 seedlings m⁻² germinated, whereas 40 species and 3464 ± 3363 seedlings m⁻² did so from 5–10 cm. Germinated seedling density was significantly higher in the upper layer, largely due to differences in eight species. With increasing experimental water depth, less seedlings germinated: respectively, 9788 ± 7157 m⁻², 2050 ± 2412 m⁻² and 1978 ± 2616 m⁻², of 44, 21 and 19 species, submerged under 0, 5 or 10 cm. Seven species could emerge only in 0 water level. Vallisneria natans occurred only in 5 cm water, whereas Ottelia alismoides occurred in 10 cm water. In the vegetation survey of the marsh, 25 species were recorded, which was less than half of the species recorded in the seed bank. The top 10 dominants in the standing vegetation, accounting for 89% of vegetation abundance, represented only 10% in the seed bank. Twenty germinated species that also occurred in the standing vegetation accounted for 56% of the total seed bank. Our observed number of species germinating from a Chinese wetland seed bank is within the range observed elsewhere in the northern hemisphere (15–113 species).     

How far a protected area contributes to conserve habitat species composition and population structure of endangered African tree species (Benin,West Africa)

The Pendjari Biosphere Reserve located in the Sudanian zone of Bénin, is a protected area well managed, but mainly aimed at wild animal conservation. This study assessed its effectiveness to conserve habitat species composition and population structure of three endangered African tree species: Afzelia africana Sm., Pterocarpus erinaceus Poir. and Khaya senegalensis (Desv.) A. Juss. We randomly sampled 120 plots in the protected and surrounding unprotected habitats by inventorying plant species. For the three target species, we estimated adult and juvenile densities and recorded size classes. According to floristic composition four habitats groups were recognized in relation to human disturbance, vegetation type, and moisture. These were protected savannas, unprotected savannas, old fallows and gallery forests. The estimated adult densities of A. africana were similar between protected (14 ± 1.2 tree/ha) and unprotected savannas (17 ± 0.9 tree/ha) while for P. erinaceus the adult density was significantly higher in protected (12 ± 3.7 tree/ha) than in unprotected savannas (5 ± 1.9 tree/ha). Estimated adult density of K. senegalensis was also significantly higher in protected gallery forest (40 ± 5.8 tree/ha) than in unprotected one (29 ± 4.8 tree/ha). Juvenile densities of A. africana, K. senegalensis and P. erinaceus were higher in protected habitats than in unprotected ones but the difference was not significant. Skewness coefficient indicated that populations of investigated trees were declining in their protected habitats. However, in the case of A. africana and K. senegalensis populations seemed to be mostly threatened in the protected area. We concluded that although the studied protected area is effective to conserve some habitats species compositions, protection is not sufficient to guarantee future conservation of some threatened tree species.     

Optimizing the bioindication of forest soil acidity,nitrogen and mineral nutrition using plant species

Soil moisture and nutritional characteristics are frequently assessed using plant species and community bioindication, e.g., the Ellenberg system of species indicator values. This method, based on complete inventories of plant species present in plots, is time-consuming, which could prevent its general use for forest or other natural land management. Our aim was to determine the impact of a reduction in the time spent to carry out a floristic inventory on the quality of soil characteristic assessment using plant bioindication. We compared the measurements of soil pH-H₂O (pH), organic carbon to total nitrogen ratio (C:N) and base saturation (BS) in the 0–5 cm soil layer of 470 plots with the same variables estimated from floristic inventories of increasing duration, using plant indicator values (IV) from the EcoPlant database. The performance of predictions was evaluated by the square of the linear correlation coefficient between measured and predicted values (R²) and the root mean square error (RMSE) of predictions.The number rather than the percentage of total plot species used for the estimations was determinant for the prediction of soil pH quality. Performance of bioindication of pH, BS and C:N reached the maximum R² using the first 20–25 species recorded per plot, corresponding to a 14-min-long floristic inventory in comparison to a mean of 28 min spent to carry out a complete floristic inventory. A precision of prediction of 80% of the maximal precision was obtained after 4–5 min (6–12 inventoried species) for the three studied variables. These results are independent of the nutritional capability of the soils and were similar at the national and local scales. In order to estimate soil nutritional resources by plant bioindication, it is feasible to significantly reduce the time spent on floristic inventories and, thus, their cost. This is especially useful when the goal is to map the soil quality for decision-making in forest management.     

The impact of forest encroachment after agricultural land abandonment on passerine bird communities: The case of Greece

Agricultural land abandonment is one of the main drivers of land use change, leading to various responses of farmland ecological communities. In an effort to better understand the effect of agricultural land abandonment on passerine bird communities, we sampled 20 randomly selected sites [1 km × 1 km] in remote Greek mountains, reflecting an abandonment gradient, in terms of forest encroachment. We sampled 169 plots using the point count method of fixed distance (47 passerine species), and we investigated bird diversity and community structure turnover along the gradient. We found that grazing intensity has a beneficial effect hampering forest encroachment that follows progressively land abandonment. Habitat composition changes gradually with forests developing at the expense of open meadows and heterogeneous grasslands. Forest encroachment has a significant negative effect on bird diversity and species richness, affecting in particular typical farmland and Mediterranean shrubland species. Birds form five distinct ecological clusters after land abandonment: species mostly found in pinewoods and cavity-dwelling species; species that prefer open forests forest edges or ecotones; species that prefer shrubland or open habitats with scattered woody vegetation; Mediterranean farmland birds that prefer semi-open habitats with hedges and/or woodlots; and, generalist forest-dwelling or shrubland species. We extracted a set of 22 species to represent the above ecological communities, as a new monitoring tool for agricultural land use change and conservation. We suggest that the maintenance of rural mosaics should be included in the priorities of agricultural policy for farmland bird diversity conservation.