若尔盖高原土地利用变化对生态系统服务价值的影响

运用GIS和遥感技术分析了若尔盖高原1990年、2000年和2005年的土地利用/覆盖特征, 在此基础上, 使用生态价值系数(C)计算出该区生态系统服务价值, 并使用敏感性指数(CS)对所选的C值进行验证. 结果表明, 该区域1990-2005年间生态系统服务价值从603.10?108元减少到586.07?108元, 共损失17.03?108元, 且损失量和损失幅度呈加速增加趋势; 该区域生态系统服务价值中, 废物处理价值最高, 水源涵养价值次之, 食物生产价值最低, 且各服务类型的价值均呈持续减小趋势; 若尔盖高原1990和2005年人均生态系统服务价值分别为38.93万元和27.03万元, 表明若尔盖高原由于人口增长和土地退化, 环境压力呈明显增大趋势. 湿地和草地退化是导致该区域生态系统服务价值减少的主要原因, 尤其是湿地退化. CS检验说明本文所选C值较为合理.     

Influence of land-use types and climatic variables on seasonal patterns of NDVI in Mediterranean Iberian ecosystems

Question: What is the influence of management on the functioning of vegetation over time in Mediterranean ecosystems under different climate conditions? Location: Mediterranean shrublands and forests in SE Iberia (Andalusia). Methods: We evaluated the Normalized Difference Vegetation Index (NDVI) for the 1997-2002 time series to determine phenological vegetation patterns under different historical management regimes. Three altitudinal ranges were considered within each area to explore climate × management interactions. Each phenological pattern was analysed using time series statistics, together with precipitation (monthly and cumulative) and temperature. Results: NDVI time series were significantly different under different management regimes, particularly in highly transformed areas, which showed the lowest NDVI, weakest annual seasonality and a more immediate phenological response to precipitation. The NDVI relationship with precipitation was strongest in the summer-autumn period, when precipitation is the main plant growth-limiting factor. Conclusions: NDVI time series analyses elucidated complex influences of land use and climate on ecosystem functioning in these Mediterranean ecosystems. We demonstrated that NDVI time series analyses are a useful tool for monitoring programmes because of their sensitivity to changes, ease of use and applicability to large-scale studies.     

Effectiveness of protected areas in maintaining plant production

Given the central importance of protected area systems in local, regional and global conservation strategies, it is vital that there is a good understanding of their effectiveness in maintaining ecological functioning. Here, we provide, to our knowledge, the first such global analysis, focusing on plant production, a "supporting" ecosystem function necessary for multiple other ecosystem services. We use data on the normalized difference vegetation index (NDVI) as a measure of variation in plant production in the core, boundary and surroundings of more than 1000 large protected areas over a 25 year period. Forested protected areas were higher (or similar), and those non-forested were lower (or similar), in NDVI than their surrounding areas, and these differences have been sustained. The differences from surrounding areas have increased for evergreen broadleaf forests and barren grounds, decreased for grasslands, and remained similar for deciduous forests, woodlands, and shrublands, reflecting different pressures on those surroundings. These results are consistent with protected areas being effective both in the representation and maintenance of plant production. However, widespread overall increases in NDVI during the study period suggest that plant production within the core of non-forested protected areas has become higher than it was in the surroundings of those areas in 1982, highlighting that whilst the distinctiveness of protected areas from their surroundings has persisted the nature of that difference has changed.     

长三角地区土地利用时空变化对生态系统服务价值的影响

基于1980—2010年的土地利用数据,估算了各种土地利用类型的生态系统服务价值,分析了长三角30年来生态系统服务价值的时空动态及其对土地利用变化的响应。结果表明,1980—2010年,长三角建设用地面积变化最大,为446.1%,未利用地、耕地、草原、林地、水域的变化分别为285.9%、-31.5%、-76.2%、-5.4%、42.9%;1980—2010年,长三角地区的总生态系统服务价值减少了4.40%,水源涵养、休闲娱乐、废物处理生态系统服务功能价值上升;生态系统服务价值极低区域的面积增加且分布于城市扩张区域,生态系统服务价值中等区域逐年下降且被生态系统服务价值低区域所替代,高生态系统服务价值区域处于增加的趋势而极高区域基本维持不变;常州、湖州、嘉兴、南京、泰州的生态系统服务价值逐年增加,而其他城市的则处于下降趋势。     

基于MODIS数据的中国三种主要土地类型变化的空间特征分析

人类活动使得土地利用和植被覆盖发生了巨大变化,直接影响着全球气候。本研究通过从2000—2013年对中国三种主要土地利用类型的NDVI变化特征进行了分析,结果表明:(1)14年来,中国三种主要土地利用类型NDVI平均值均有增强的趋势。(2)三种主要土地利用类型中除耕地中的水田,林地中的有林地和草地中的高覆盖草地增长速率不显著外,其他土地类型增长速率均显著。(3)三种土地利用类型均以改善面积大于退化面积,耕地中改善面积占总耕地的64.21%,退化的区域占18.50%;林地改善的区域占总林地的54.21%,退化的区域占20.13%;草地改善的区域占55.53%,退化的区域占18.23%。三种土地类型均有所改善且改善明显的区域主要集中在甘肃以南,陕西以北和东北部分地区。     

The importance of environment vs. disturbance in the vegetation mosaic of Central Arizona

Abstract. The vegetation of central Arizona is a mosaic of four vegetation types: chaparral, chaparral grassland, woodland, and woodland grassland. We analysed ten environmental variables, three disturbance variables, and five disturbance indicators to answer the question: What is the relative importance of environment and disturbance in explaining the vegetation pattern of our study area? We found that chaparral, chaparral grassland, and woodland are differentiated primarily by environmental factors and have high stability in the landscape. In contrast, woodland grassland is differentiated primarily by disturbance and is likely an early‐successional stage of woodlands. Although other researchers have indicated that semi‐arid vegetation is generally unstable, the vegetation of central Arizona is composed of two systems: those with a more stable landscape position determined primarily by environmental factors and those with a less stable landscape position determined primarily by disturbance factors.     

The interplay between facilitation and habitat type drives spatial vegetation patterns in global drylands

The spatial configuration of vascular vegetation has been linked to variations in land degradation and ecosystem functioning in drylands. However, most studies on spatial patterns conducted to date have focused on a single or a few study sites within a particular region, specific vegetation types, or in landscapes characterized by a certain type of spatial patterns. Therefore, little is known on the general typology and distribution of plant spatial patterns in drylands worldwide, and on the relative importance of biotic and abiotic factors as predictors of their variations across geographical regions and habitat types. We analyzed 115 dryland plant communities from all continents except Antarctica to: 1) investigate the general typology of spatial patterns, and 2) assess the relative importance of biotic (plant cover, frequency of facilitation, soil amelioration, height of the dominant species) and abiotic (aridity, rainfall seasonality and sand content) factors as predictors of spatial patterns (median patch size, shape of patch‐size distribution and regularity) across contrasting habitat types (shrublands and grasslands). Precipitation during the warmest period and sand content were particularly strong predictors of plant spatial patterns in grasslands and shrublands, respectively. Facilitation associated with power‐law like and irregular spatial patterns in both shrublands and grasslands, although it was mediated by different mechanisms (respectively soil ammelioration and percentage of facilitated species). The importance of biotic attributes as predictors of the shape of patch‐size distributions declined with aridity in both habitats, leading to the emergence of more regular patterns under the most arid conditions. Our results expand our knowledge about patch formation in drylands and the habitat‐dependency of their drivers. They also highlight different ways in which facilitation affects ecosystem structure through the formation of plant spatial patterns.     

Spatial variability of above‐ground net primary production in Uruguayan grasslands: a remote sensing approach

Question: How does above‐ground net primary production (ANPP) differ (estimated from remotely sensed data) among vegetation units in sub‐humid temperate grasslands? Location: Centre‐north Uruguay. Methods: A vegetation map of the study area was generated from LANDSAT imagery and the landscape configuration described. The functional heterogeneity of mapping units was analysed in terms of the fraction of photosynthetically active radiation absorbed by green vegetation (fPAR), calculated from the normalized difference vegetation index (NDVI) images provided by the moderate resolution imaging spectroradiometer (MODIS) sensor. Finally, the ANPP of each grassland class was estimated using NDVI and climatic data. Results: Supervised classification presented a good overall accuracy and moderate to good average accuracy for grassland classes. Meso‐xerophytic grasslands occupied 45% of the area, Meso‐hydrophytic grasslands 43% and Lithophytic steppes 6%. The landscape was shaped by a matrix of large, unfragmented patches of Meso‐xerophytic and Meso‐hydrophytic grasslands. The region presented the lowest anthropic fragmentation degree reported for the Rio de la Plata grasslands. All grassland units showed bimodal annual fPAR seasonality, with spring and autumn peaks. Meso‐hydrophytic grasslands showed a radiation interception 10% higher than the other units. On an annual basis, Meso‐hydrophytic grasslands produced 3800 kg dry matter (DM) ha^?1 yr^?1 and Meso‐xerophytic grasslands and Lithophytic steppes around 3400 kg·DM·ha^?1·yr^?1. Meso‐xerophytic grasslands had the largest spatial variation during most of the year. The ANPP temporal variation was higher than the fPAR variability. Conclusions: Our results provide valuable information for grazing management (identifying spatial and temporal variations of ANPP) and grassland conservation (identifying the spatial distribution of vegetation units).     

人类活动对资源型城市生态系统服务价值的影响——以鄂尔多斯为例

资源型城市通过资源开采驱动城市快速发展,同时通过生态恢复维持生态系统稳定。探究典型人类活动对资源型城市生态系统服务的消极和积极影响对于可持续城市建设具有重要意义。以鄂尔多斯市为例,基于1990-2018年土地利用/覆盖、NDVI等数据,修订了生态系统服务价值计算方法,量化了区域生态系统服务价值的时空格局,进而评估了人类活动过程对生态系统服务的影响。研究结果表明,研究时段内鄂尔多斯市城镇建设用地、林地和草地面积总体增加,耕地及未利用土地面积减少。区域生态系统服务总价值总体呈上升趋势,从1990年的2312.24亿元上升至2018年的2421.38亿元,增加了4.72%。2000年以后鄂尔多斯市退耕还林、未利用地植被恢复等措施使得生态系统服务价值增加了113.53亿元,同期城镇建设用地扩展占用生态生产用地导致生态系统服务价值减少了91.36亿元,生态建设的积极影响大于城镇建设用地扩展的消极影响。     

Bird community composition in an actively managed savanna reserve, importance of vegetation structure and vegetation composition

The mosaic of trees, shrubs and open grassland in mesic African savannas is highly dynamic and strongly influenced by mammal herbivory and fire. We investigated the bird fauna in four different savanna habitats to help assess the impacts of vegetation change on this component of faunal diversity. Birds were censused, plant species were identified and vegetation structure was measured in four different vegetation types (Acacia nilotica woodland, Acacia nigrescens woodland, broadleaf thicket and open grassland) in the Hluhluwe-Umfolozi Park in northern KwaZulu Natal, South Africa. Multivariate ordination analyses were used to determine the relative importance of vegetation structure and floristic composition in defining bird assemblages. The bird communities of the grasslands, the acacia woodlands, and the broadleaf woodlands were clearly separated on the first axis of the detrended canonical correspondence analysis (DCCA). Canopy cover and foliage height diversity (FHD) were strongly correlated with the first axis of DCCA, possibly reflecting a secondary successional series from grassland to woodland, known as bush encroachment. Floristic composition (based on presence–absence data only) seemed to be less important for bird community composition than vegetation structure. The results indicate that changes in vegetation structure, caused by bush encroachment, could cause concomitant changes in bird community composition.     

Resilience and restoration of tropical and subtropical grasslands,savannas, and grassy woodlands

Despite growing recognition of the conservation values of grassy biomes, our understanding of how to maintain and restore biodiverse tropical grasslands (including savannas and open‐canopy grassy woodlands) remains limited. To incorporate grasslands into large‐scale restoration efforts, we synthesised existing ecological knowledge of tropical grassland resilience and approaches to plant community restoration. Tropical grassland plant communities are resilient to, and often dependent on, the endogenous disturbances with which they evolved – frequent fires and native megafaunal herbivory. In stark contrast, tropical grasslands are extremely vulnerable to human‐caused exogenous disturbances, particularly those that alter soils and destroy belowground biomass (e.g. tillage agriculture, surface mining); tropical grassland restoration after severe soil disturbances is expensive and rarely achieves management targets. Where grasslands have been degraded by altered disturbance regimes (e.g. fire exclusion), exotic plant invasions, or afforestation, restoration efforts can recreate vegetation structure (i.e. historical tree density and herbaceous ground cover), but species‐diverse plant communities, including endemic species, are slow to recover. Complicating plant‐community restoration efforts, many tropical grassland species, particularly those that invest in underground storage organs, are difficult to propagate and re‐establish. To guide restoration decisions, we draw on the old‐growth grassland concept, the novel ecosystem concept, and theory regarding tree cover along resource gradients in savannas to propose a conceptual framework that classifies tropical grasslands into three broad ecosystem states. These states are: (1) old‐growth grasslands (i.e. ancient, biodiverse grassy ecosystems), where management should focus on the maintenance of disturbance regimes; (2) hybrid grasslands, where restoration should emphasise a return towards the old‐growth state; and (3) novel ecosystems, where the magnitude of environmental change (i.e. a shift to an alternative ecosystem state) or the socioecological context preclude a return to historical conditions.     

Desertification alters patterns of aboveground net primary production in Chihuahuan ecosystems

Abstract The Chihuahuan desert of New Mexico, USA, has changed in historical times from semiarid grassland to desert shrublands dominated by Larrea tridentata and Prosopis glandulosa. Similar displacement of perennial grasslands by shrubs typifies desertification in many regions. Such structural vegetation change could alter average values of net primary productivity, as well as spatial and temporal patterns of production. We investigated patterns of aboveground plant biomass and net primary production in five ecosystem types of the Jornada Basin Long‐Term Ecological Research (LTER) site. Comparisons of shrub‐dominated desertified systems and remnant grass‐dominated systems allowed us to test the prediction that shrublands are more heterogeneous spatially, but less variable over time, than grasslands. We measured aboveground plant biomass and aboveground net primary productivity (ANPP) by species, three times per year for 10 years, in 15 sites of five ecosystem types (three each in Larrea shrubland, Bouteloua eriopoda grassland, Prosopis dune systems, Flourensia cernua alluvial flats, and grass‐dominated dry lakes or playas). Spatial heterogeneity of biomass at the scale of our measurements was significantly greater in shrub‐dominated systems than in grass‐dominated vegetation. ANPP was homogeneous across space in grass‐dominated systems, and in most growing seasons was significantly more patchy in shrub vegetation. Substantial interannual variability in ANPP complicates comparison of mean values across ecosystem types, but grasslands tended to support higher ANPP values than did shrub‐dominated systems. There were significant interactions between ecosystem type and season. Grasslands demonstrated higher interannual variation than did shrub systems. Desertification has apparently altered the seasonality of productivity in these systems; grasslands were dominated by summer growth, while sites dominated by Larrea or Prosopis tended to have higher spring ANPP. Production was frequently uncorrelated across sites of an ecosystem type, suggesting that factors other than season, regional climate, or dominant vegetation may be significant determinants of actual NPP.     

2000—2015年西南地区土地利用与植被覆盖的时空变化

西南地区是我国重要的生态资源区和生态脆弱区,在国家“绿水青山”战略发展中具有重要地位。本研究基于1 km空间分辨率的土地利用数据集,结合土地利用转移矩阵,定量分析2000—2015年间西南地区土地利用变化特征及其驱动力。并基于MODIS遥感植被指数,利用像元二分模型计算西南地区植被覆盖度,分析归一化植被指数(NDVI)和植被覆盖度的变化规律。结果表明: 研究期间,西南地区的主要地类是林地、农田和草地。建设用地面积增加5874 km²,增长率为55.8%;农田面积减少最多,下降6211 km²,其次是草地,减少2099 km²。2000—2015年间,西南地区建设用地的转入面积最多,主要由农田(贡献率68.2%)、林地(贡献率19.2%)和草地(贡献率13.1%)转化而来,转化的区域多靠近城区。农田的转出面积和转出率分别为7079 km²和2.2%,占所有转出类型面积的46.0%。林地多由草地(贡献率61.8%)转化而来,转化区域多分布在贵州中南部和云南西部等地。全区NDVI和植被覆盖度均呈显著增加趋势,说明研究区整体呈变绿趋势。其中,自然植被和农田的NDVI均显著增长,建设用地扩张地区的NDVI下降,说明自然植被和农田主导了该地区植被变化。通过残差分析发现,气候变化和人类活动对研究区变绿趋势的贡献显著。     

Vegetation and songbird response to land abandonment: from landscape to census plot

While intensification of human activities and its ecological effects in many natural areas have recently received much attention, land abandonment in marginal areas is still the largely ignored side of a process rooted in the same socioeconomic context. Decreasing human impact in marginal rural areas often triggers a recovery of seminatural vegetation. Over a period of 25 years, we studied the changes in landscape and vegetation structure that followed land abandonment in a traditional Mediterranean mosaic of crops, grasslands, shrublands and woodlands, and assessed their effects on songbird occurrence and distribution. We combined an analysis of vegetation changes based on aerial photo interpretation with an analysis of bird censuses from 1978, 1992 and 2003 at two spatial scales: landscape and census plot (respectively 2800 and 3 ha). The perceived temporal changes in the vegetation were scale dependent. At the landscape scale, open habitats tended to disappear and woodlands matured. The contrasts in vegetation structure that defined habitat patches at the onset of the study tended to disappear. There was an overall shift of the bird community in favour of woodland species. At the scale of the census plot, however, the colonization by woody vegetation of patches formerly characterized by a homogeneous grass cover increased the local diversity of the vegetation, at least temporarily. Of seven species dependent on open habitats, the occurrence rate of five species significantly decreased, whereas it increased for two species: woodlark (Lulula arborea) and melodious warbler (Hippolais polyglotta). This increase was linked to the transitional increase in local vegetation diversity. In patches originally dominated by woodlands, local vegetation diversity decreased as woody vegetation expanded into clearings. The occurrence rate significantly increased for seven species relying on closed woodlands, while it decreased for two woodland species. As most species of high conservation profile in the Mediterranean are tied to open or to heterogeneous transitional habitats, these trends raise questions concerning their persistence in the future.     

Identification of current ecosystem functional types in the Iberian Peninsula

Aim To examine the geographical patterns of the interception of photosynthetically active radiation by vegetation and to describe its spatial heterogeneity through the definition of ecosystem functional types (EFTs) based on the annual dynamics of the Normalized Difference Vegetation Index (NDVI), a spectral index related to carbon gains. Location The Iberian Peninsula. Methods EFTs were derived from three attributes of the NDVI obtained from NOAA/AVHRR sensors: the annual integral (NDVI‐I), as a surrogate of primary production, an integrative indicator of ecosystem functioning; and the intra‐annual relative range (RREL) and month of maximum NDVI (MMAX), which represent key features of seasonality. Results NDVI‐I decreased south‐eastwards. The highest values were observed in the Eurosiberian Region and in the highest Mediterranean ranges. Low values occurred in inner plains, river basins and in the southeast. The Eurosiberian Region and Mediterranean mountains presented the lowest RREL, while Eurosiberian peaks, river basins, inner‐agricultural plains, wetlands and the southeastern part of Iberia presented the highest. Eurosiberian ecosystems showed a summer maximum of NDVI, as did high mountains, wetlands and irrigated areas in the Mediterranean Region. Mediterranean mountains had autumn–early‐winter maxima, while semi‐arid zones, river basins and continental plains had spring maxima. Based on the behaviour in the functional traits, 49 EFTs were defined. Main conclusions The classification, based on only the NDVI dynamics, represents the spatial heterogeneity in ecosystem functioning by means of the interception of radiation by vegetation in the Iberian Peninsula. The patterns of the NDVI attributes may be used as a reference in evaluating the impacts of environmental changes. Iberia had a high spatial variability: except for biophysically impossible combinations (high NDVI‐I and high seasonality), almost any pattern of seasonal dynamics of radiation interception was represented in the Peninsula. The approach used to define EFTs opens the possibility of monitoring and comparing ecosystem functioning through time.     

Importance of sediment deposition and denitrification for nutrient retention in floodplain wetlands

Questions: Various floodplain communities may differ in their relative abilities to influence water quality through nutrient retention and denitrification. Our main questions were: (1) what is the importance of sediment deposition and denitrification for plant productivity and nutrient retention in floodplains; (2) will rehabilitation of natural floodplain communities (semi‐natural grassland, reedbed, woodland, pond) from agricultural grassland affect nutrient retention? Location: Floodplains of two Rhine distributaries (rivers Ussel and Waal), The Netherlands. Methods: Net sedimentation was measured using mats, denitrification in soil cores by acetylene inhibition and bio‐mass production by clipping above‐ground vegetation in winter and summer. Results: Sediment deposition was a major source of N and P in all floodplain communities. Highest deposition rates were found where water velocity was reduced by vegetation structure (reedbeds) or by a drop in surface elevation (pond). Sediment deposition was not higher in woodlands than in grassland types. Denitrification rates were low in winter but significantly higher in summer. Highest denitrification rates were found in an agricultural grassland (winter and summer) and in the ponds (summer). Plant productivity and nutrient uptake were high in reedbeds, intermediate in agricultural grasslands, ponds and semi‐natural grasslands and very low in woodlands (only understorey). All wetlands were N‐limited, which could be explained by low N:P ratios in sediment. Conclusions: Considering Rhine water quality: only substantial P‐retention is expected because, relative to the annual nutrient loads in the river, the floodplains are important sinks for P, but much less for N. Rehabilitation of agricultural grasslands into ponds or reedbeds will probably be more beneficial for downstream water quality (lower P‐concentrations) than into woodlands or semi‐natural grasslands.     

Invasive plants have different effects on trophic structure of green and brown food webs in terrestrial ecosystems: a meta‐analysis

Although invasive plants are a major source of terrestrial ecosystem degradation worldwide, it remains unclear which trophic levels above the base of the food web are most vulnerable to plant invasions. We performed a meta‐analysis of 38 independent studies from 32 papers to examine how invasive plants alter major groupings of primary and secondary consumers in three globally distributed ecosystems: wetlands, woodlands and grasslands. Within each ecosystem we examined if green (grazing) food webs are more sensitive to plant invasions compared to brown (detrital) food webs. Invasive plants have strong negative effects on primary consumers (detritivores, bacterivores, fungivores, and/or herbivores) in woodlands and wetlands, which become less abundant in both green and brown food webs in woodlands and green webs in wetlands. Plant invasions increased abundances of secondary consumers (predators and/or parasitoids) only in woodland brown food webs and green webs in wetlands. Effects of invasive plants on grazing and detrital food webs clearly differed between ecosystems. Overall, invasive plants had the most pronounced effects on the trophic structure of wetlands and woodlands, but caused no detectable changes to grassland trophic structure.     

The spatial distribution of vegetation types in the Serengeti ecosystem: the influence of rainfall and topographic relief on vegetation patch characteristics

Aim The aim of this study is to introduce a structural vegetation map of the Serengeti ecosystem and, based on the map, to test the relative influences of landscape factors on the spatial heterogeneity of vegetation in the ecosystem. Location This study was conducted in the Serengeti–Maasai Mara ecosystem in northern Tanzania and southern Kenya, between 34° and 36° E longitude, and 1° and 2° S latitude. Methods The vegetation map was produced from satellite imagery using data from over 800 ground‐truthing points. Spatial characteristics of the vegetation were analysed in the resulting map using the fragstats software package. Average patch area and nearest neighbour distance (NND) were determined for grassland, shrubland and woodland vegetation types. The heterogeneity of vegetation types was estimated with Simpson’s diversity index (D). Structural equation modelling (SEM) was used to explore the relationships between the spatial characteristics of vegetation and three predictor variables: annual rainfall, coefficient of variation (CV) in annual rainfall, and topographic moisture index (TMI). Results A vegetation map is presented along with a detailed summary of the distribution of land‐cover classes and spatial heterogeneity in the ecosystem. Significant relationships were found between vegetation diversity (D) and TMI, and also between D and average rainfall. The average area of grassland patches showed significant relationships with average rainfall, with rainfall CV and with TMI. Grassland NND was positively associated with average rainfall. Woodland patch area showed a unimodal response to average rainfall and a negative linear association with TMI. Woodland NND showed a U‐shaped association with annual rainfall and a weaker positive linear association with TMI. An acceptable model that explained variation in shrubland patch characteristics could not be identified. Main conclusions The vegetation map and analysis thereof resulted in three significant causal explanatory models that demonstrate that both rainfall and topography are important contributors to the distribution of woodlands and grasslands in the Serengeti. These findings further indicate that changes in patch characteristics have a complex interaction with rainfall and with topography. Our results are concordant with recent studies suggesting that percent woody cover in African savannas receiving less than c. 650 mm year^?1 is bounded by average annual rainfall.     

Consistent variation in seed germination across an environmental gradient in a Neotropical savanna

Environmental conditions experienced by mother plants determine germination patterns. Here, we investigated the germination ecology of Miconia albicans (Melastomataceae), a widespread apomictic shrub, along a soil fertility gradient in the Brazilian Cerrado (a Neotropical savanna). The mosaic of vegetations in the Cerrado ranges from grasslands to woodlands, which present different conditions for seedling establishment. Cerrado grasslands are a more unpredictable environment because they are more prone to disturbances such as fires and prolonged droughts than closed woodlands. We expect lower reproductive investment but increasing germinability, germination speed and synchrony in areas with more dense vegetation, due to prolonged droughts in grasslands and higher soil properties in woodlands. Seeds of M. albicans were collected in grasslands, shrublands and woodlands for three years in a Cerrado area in southeastern Brazil. Seeds collected in all vegetations were set to germinate under identical experimental conditions. According to our prediction, we found a consistent pattern of increasing germinability, mean germination time and synchrony in areas with more closed vegetation. Both slower and asynchronous germination in seeds from grassland plants are likely to increase seedling survival under a more unpredictable environment. On the other hand, seeds from plants in the woodlands germinated at higher rates and germination was more synchronous, thus increases the chances of survival under a more competitive light-limited environment. This pattern was found in all three years of study. Our study suggests that stressful environmental conditions experienced by mother plants in the Cerrado may act as cues signalizing unfavourable conditions for seed germination and help explain functional divergence in germination traits within species. In conclusion, we showed for the first time a temporally consistent pattern of intraspecific variation in the germination traits of M. albicans, with different germination strategies at the extremes of the ecological gradient.     

Woodland restoration on agricultural land: long‐term impacts on soil quality

Woodland restoration is underway globally to counter the negative soil quality and ecological impacts of agricultural expansion and woodland fragmentation, and restore or enhance biodiversity, ecosystem functions and services. However, we lack information about the long‐term effects of woodland restoration on agricultural soils, particularly at temporal scales meaningful to woodland and soil development. This study utilized soil and earthworm sampling across a chronosequence of sites transitioning from “agricultural land” to “secondary woodland” (50–110 years) and “ancient woodland” (>400 years), with the goal of quantifying the effects of woodland restoration on agricultural land, on key soil quality parameters (soil bulk density, pH, carbon and nitrogen stocks, and earthworm abundance, biomass, species richness and diversity). Broad‐leaved woodland restoration led to significantly greater soil organic carbon (SOC) stocks compared to arable land, and young (50–60 years) secondary woodland increased earthworm species and functional diversity compared to both arable and pasture agricultural land. SOC stocks in secondary broad‐leaved woodlands (50–110 years) were comparable to those found in long‐term ancient woodlands (>400 years). Our findings show that broad‐leaved woodland restoration of agricultural land can lead to meaningful soil ecological improvement and gains in SOC within 50–110 years, and provide intel on how restoration activities may be best targeted to maximize soil quality and functions.