Fish assemblages associated with three types of artificial reefs: density of assemblages and possible impacts on adjacent fish abundance

We evaluated the effectiveness of wooden artificial reefs (ARs) as fish habitat. Three types of ARs, made of cedar logs, broadleaf tree logs, and PVC pipes, respectively, were deployed in triplicate at 8-m depth off Maizuru, Kyoto Prefecture, Sea of Japan, in May 2004. Fish assemblages associated with each of the nine ARs were observed by using SCUBA twice a month for four years. Fish assemblages in the adjacent habitat were also monitored for two years before and four years after reef deployment. In the surveyed areas (ca. 10 m2) associated with each of the cedar, broadleaf, and PVC ARs, the average number of fish species was 4.14, 3.49, and 3.00, and the average number of individuals was 40.7, 27.9, and 20.3, respectively. The estimated biomass was also more greater when associated with the cedar ARs than with other ARs. Visual censuses of the habitat adjacent to the ARs revealed that the number of fish species and the density of individuals were not affected by the deployment of the ARs. Our results support the superiority of cedar as an AR material and indicate that deployment of wooden ARs causes no reduction of fish abundance in adjacent natural reefs.

Habitat degradation of Rhinopithecus bieti in Yunnan, China

Black-and-white snub-nosed monkeys (Rhinopithecus bieti) are endemic to the Trans-Himalayas in Northwest Yunnan and Southeast Tibet between the upper Yangtze and Mekong Rivers. Based on field surveys and previous reports, we identified the dark-coniferous forest, the mixed coniferous and broadleaf forest, and oak patches as suitable habitats (SH) for the monkeys. Summer grazing lands (SGL), which were made by local people cutting and burning the dark-coniferous forest at the high altitude belt, replaced SH. To have a general view of the status of the SH in Yunnan, we estimated the areas of SH and SGL from satellite images in 1997, and compared with areas estimated from aerial photo-based maps (ca. 1958). The work resulted in: 1) the area of SH was 4,169 km(2) in 1997; 2) SGL was 1,923 km(2); 3) during the past 40 years, the area of SH decreased by 31% (1,887 km(2)), and SGL increased by 204% (1,291 km(2)); and 4) the mean size of forest patches decreased from 15.6 to 5.4 km(2). In addition, the area of SGL is positively correlated to local human population (R-2 greater than or equal to0.53), implying that the reduction and fragmentation of habitat for Rhinopithecus bieti is a result of population growth of humans, who mostly employ traditional modes of production. Only 11 monkey groups remained in the changing habitat. Considering that forests at lower elevation were also encroached upon by farmlands in a similar way, the forest ecosystem is highly threatened. The destruction will continue unless there is a change in the mode of production in the region.

岷江冷杉林群落几种树苗对光强的响应与适应

在青藏高原东部的亚高山针叶林区，如何尽快恢复这一生态脆弱地区的植被，改变生态环境恶化的趋势，是一个十分重要的课题。光一直被认为是植物种间相互替代，尤其是森林演替过程中植物相互替代或植被恢复中的关键环境要素之一。植物能否适应林冠下或林窗中异质的、或多变的光照条件，对其在林中的生存、分布、更新以及森林动态都是非常重要的。 本文以青藏高原东部亚高山针叶林的主要森林类型——岷江冷杉林群落的几种树苗为研究对象，采用实验生态学、生理及生物化学等方法，通过模拟针叶林不同大小林窗内光照强度的变化，在中国科学院茂县生态站内采用遮荫处理设置6个光照梯度（100、55、40、25、15与7%全光照），来研究具有不同喜光特性的植物对光强的响应与适应机制，其研究结果可为揭示亚高山针叶林的演替规律、以及人工林下幼苗的存活与定居提供科学依据，也能为苗木的生产与管理提供科学指导，尤其是对针阔树种在不同光强下的响应与适应的比较研究，能为如何将阔叶树种整合到人工针叶林中提供新的思路。 光强对植物生长的影响 光强对植物的生长具有重要作用，不同植物在各自适宜的光强梯度下才能生长良好。通过一个野外盆栽实验，来研究不同光强对植物生长的影响（第三章）。主要研究结果如下，低光强下植物株高/茎生物量增加，说明植物会将生物量更多用于高生长，以便有效地拦截光资源；在强光下，植物将生物量更多地向根部分配，使得植物在强光下能够吸收更多的水分，而避免干旱胁迫。 在第一个生长季节，以相对生长速率（RGR）表示，红桦和青榨槭在100%全光照下RGR最大，粗枝云杉在55%最大，岷江冷杉在25-40%下较好；然而，在第二个生长季节，2种阔叶树的相对生长速率（RGR）的适宜光强则变为25-55%，云杉为55-100%，而冷杉为25-100%。可见，从第一年到第二年，2种阔叶树苗更适宜在部分荫蔽的条件下生长；而2种针叶树苗对光的需求则逐渐增加，这可能是增加对根生物量相对投资的结果，因为以这种方式，强光下生长的针叶树幼苗更能保持其内部水分平衡，其生长不会因干旱胁迫而受到严重影响。另外，严重遮荫会引起冷杉幼苗死亡。 植物对光强的生理适应 植物可以通过自身形态和生理特征的调整，来发展不同的光能利用策略从而能够在林中共存。通过一个野外盆栽实验，研究了不同光强下生长的几种树苗的生理特征（第四章）对不同光强的响应与适应。结果显示：强光下，粗枝云杉和红桦的光合能力增加，而岷江冷杉和青榨槭在中度遮荫（25-55%）的条件下光合能力最大。植物叶氮和叶绿素含量增高，而光补偿点和暗呼吸速率降低，这些都是植物对低光环境的适应性反应；而强光下植物叶片和栅栏组织变厚，是对强光的一种保护性反应。 植物对光的可塑性反应 不同植物会表现出对光适应有利的生理和形态可塑性反应。本文对第三章、第四章的实验数据进行可塑性指数分析，来研究植物对光强的表型可塑性反应（第五章）。结果显示，生理特征调整是植物对不同光环境的主要适应途径。红桦和青榨槭的可塑性指数平均值要大于粗枝云杉和岷江冷杉，充分表明这2种阔叶树在生理和形态上较强的可塑性更有利于对光环境的适应，而具有比耐荫树种更强的适应能力。另外，2种针叶树相比，云杉的适应性更强。本研究结果支持树种的生理生态特性决定了其演替状况和生境选择的假说。 植物的光抑制与防御 当植物叶片吸收了过多光能，会发生光抑制现象。植物对光抑制的敏感性及防御能力对其生长具有重要意义。本文通过两个野外盆栽实验，研究了生长在强光下（第六章）和变化光强下（第八章）植物的光抑制现象及其防御策略。结果表明，在强光下或从遮荫状态转入强光下，植物都会发生光抑制，其对光抑制的敏感性与植物的耐荫性（或喜光）和演替状态有密切联系。长期生长在强光下的植物受到光抑制是可恢复的，而当处于荫蔽环境的植物突然暴露于强光下时，受到的光抑制不能完全恢复，可能是（部分）光合机构受到破坏的缘故。粗枝云杉和青榨槭防御光抑制伤害的能力较强，热耗散是其防御光抑制的主要途径。长期的强光作用能使岷江冷杉和红桦发生严重光抑制，甚至光伤害，而红桦能够通过“凋落老叶，萌发新叶”的途径来适应新的强光环境。 How to restore the vegetation of subalpine coniferous forest in eastern Qinghai-Tibet Plateau, and change the trend of ecological deterioration is a very important issue. Acclimation of tree seedlings to different and varing light environment affects to a great extent the successful regeneration and establishment of subalpine coniferous forests in southwestern China’s montane forest areas, because the ability to respond to such changing resource are commonly assumed to be critical to plant success, and have a growth advantage than others. In this paper, several species seedlings in Abies faxoniana community were chosed to study the response and adaptation to light intensity and the interspecific differences of adaptability in six shaded sheds (100, 55, 40, 25, 15 and 7% of full sunlight) in the Maoxian Ecological Station of Chinese Academy of Sciences. Our results could provide a strong theoretical evidence for understanding the forest succession laws of subalpine coniferous forests, and the survival and settlement of seedlings under plantations, and provide scientific direction for the production and management of seedlings, especially the comparative studies of the acclimation to light between the conifer and broadleaf trees could provide new ideas for how to integrate the broad-leaved trees into the artificial coniferous forest. Growth under different light intensity Light intensity plays an important role on plant growth. One field experiments was conducted to study the growth of tree seedlings of Picea asperata, Abies faxoniana, Betula albo-sinensis and Acer davidii under different light intensities. The results showed that plants under low light environment could increase the specific stem length (stem length/ stem dry mass), in order to effectively intercept light resources, while biomass greater allocation to the roots, could make plants under high light environment absorb more water, and avoid drought stress. During the first growing season, the relative growth rates (RGRs) of Betula albo-sinensis and Acer davidii had the greatest values under the 100% of full light, for 55% of Picea asperata, and for 25-40% of Abies faxoniana. However, in the second growing season the the relative growth rates of the two broad-leaved trees changed and were appropriate for 25-55% of full light, for 55-100% of spruce, and for 25-100% of fir. Thus, from the first year to the second year, two broad-leaved seedlings maybe more suitable to partly shading environment, and two coniferous seedlings would have an increase in light demand, which may be an increased root biomass investment. Because in this way, seedlings grown under high light could better maintain their internal water balance, and thus its growth would not be seriously affected by drought stress. In addition, serious shading would cause fir seedlings to die. Acclimation of physiology to light Plants could coexist in forest ecosystem by forming different strategies of light use. One field experiments was conducted to study the acclimation of tree seedlings to different light intensity of Picea asperata, Abies faxoniana, Betula albo-sinensis and Acer davidii. The results showed that the photosynthetic capacity of Picea asperata and Betula albo-sinensis exhibited a general tendency of increase with more light availability; but for Abies faxoniana and Acer davidii seedlings, their highest values of the same parameters were found under intermediate light regime (i.e. 25-55% of PFD relative to full sunlight). Plants under low light environment could increase the specific stem length (stem length/ stem dry mass), in order to effectively intercept light resources. Leaf nitrogen and chlorophyll content increased, while dark respiration rate and light compensation points decreased, all of which were adaptive response to the low light environment. On the contrary, plants under high light environment had the thicken leaves and palisade tissue, which was a protective response to high light. Phenotypic plasticity to light Phenotypic plasticity can be exhibited in morphological and physiological processes. Physiological characteristical adjustment is the main for plant adaptation to different light environment.The means of plasticity indexes for Betula albo-sinensis and Acer davidii seelings were greater than Picea asperata and Abies faxoniana, amplied that the two broad-leaved trees were much more adaptable to the environment. In addition, spruce had the higher adaptablity than fir. The findings supported the hypothesis that the ecological characteristics of the species determined the biological status and its biological habitat selection. Photoinhibition and photoprotection to light Compared with conifer, broad-leaved trees could better change leaf morphology and adjust biomass allocation to adapt to changing light environment. However, excess light can photoinhibit photosynthesis and may lead to photooxidative destruction of the photosynthetic appatus. Two field experiments were conducted to study the photoinhibition of photosynthesis. The results showed that when plants grown under high light environment or plants transferred from low to high irradiance, the four tree seedlings would undergo a period of photoinhibition. In four species, photoinhibited leaves could recover to initial photosynthetic rates when they were long-term planted under high light environment. However, when plants were suddenly exposed to high irradiance, this photoinhibition could not be reversible, may be the photosynthesis apparatus were (or partly) photooxidatively destructed.

土壤水分状况对长白山阔叶红松林主要树种叶片生理生态特性的影响

Potted seadlings of Pinus koraiensis , Fraxinus mandshurica,Juglans mandshurica,Tilia amurensis, and Quercus mongolica ,which are five dominant species in the Korean pine broadleaf forest at Changbai mountain,were grown in different soil moistures.We designed three soil moisture scenarios:85%～100%(high water,CK),65%～85% (medium water,MW) and 45%～65% (low water,LW) of field water holding capacity.The results show that characteristics of typical drought resistance on the leaves are significantly developed.The net photosynthetic rate and water use efficiency of F. mandshurica were higher compared with CK at MW.The net photosynthetic rate and water use efficiency of other 4 tree species at CK were lower than those at MW and LW.The transpiration rate of 5 tree species responses differently to various soil water status.

中国黄土高原洛川剖面 630 kyr 以来的孢粉记录

It is known that global climate changed from the early Tertiary “Green House” to the Quaternary “Ice House” of cyclic glacial-interglacial climatic changes. Since the middle Pleistocene, the climate cycles changed from 40 kyr to 100 kyr, and the amplitudes of climatic fluctuations increased significantly. Therefore, it is important to study the climate changes since the middle Pleistocene. The loess-paleosol sequence in China is considered as one of the most continuous continental records of the last 2.58 Ma. Paleoclimatic and environmental changes have been widely extracted through various climatic parameters. However, the history of paleovegetation on the Loess Plateau still remains unclear. Did an extensive broadleaf forest ever exist on the Loess Plateau? Pollen preserved in the loess and paleosol provides a direct record for vegetation and paleoenvironmental change on the Plateau. However, because it is difficult to extract sufficient pollen grains from loess, the pollen record since the middle Pleistocene especially in the central part of the Chinese Loess Plateau has not been well studied. So we preliminarily focus on the palynological records of the loess-paleosol sequence spanning the last 630 kyr at Luochuan and aim to understand the evolution of vegetation and climate change on the Chinese Loess Plateau. The main results and conclusions are as follows: 1. The palynological results show that the grassland has been a dominant vegetation in the Luochuan area since 630 kyr, even during the intervals of relatively warm and wet climatic conditions. 2. The pollen concentration of Luochuan section sharply decreases from the bottom of S1 to downward depth. This decrease can be attributed to depositional environment rather than climate change. In loess, not only oxidation, but also the PH of deposits and bacteria or fungi have been able to degrade sporopollenin. 3. The paleoclimatic condition during S4 stage, characterized with warmer condition during the early stage, was warmer and wetter than that during S5 in Luochuan area. Paleoclimate was warmer and wetter during the early stage of S5 and became colder and drier later. The special pedogenic features of S5-I can be attributed to a prolonged pedogenic duration rather than a warm-wet climate. 4. Evidence from pollen assemblage suggests that the Holocene vegetation has been affected by human impacts, especially after the Yangshao Culture. 5. The present steppe environment on the loess plateau is mainly due to natural conditions. Temperature, seasonal precipitation and soil structure are three important factors which control the vegetation type. 6. The vegetation on the loess plateau is characterized with zonal or azonal distribution. So local conditions should be taken into account when recover natural vegetation. Finally, the restoration and reconstruction of ecosystem on the loess plateau area should be focused on planting grassland rather than forests.

Habitat re-creation and restoration at the landscape scale: woodlands in Wales

The aim of this three year project funded by the Countryside Council for Wales (CCW) is to develop techniques firstly, to refine and update existing targets for habitat restoration and re-creation at the landscape scale and secondly, to develop a GIS-based model for the implementation of those targets at the local scale. Landscape Character Assessment (LCA) is being used to map Landscape Types across the whole of Wales as the first stage towards setting strategic habitat targets. The GIS habitat model uses data from the digital Phase I Habitat Survey for Wales to determine the suitability of individual sites for restoration to specific habitat types, including broadleaf woodland. The long-term aim is to develop a system that strengthens the character of Welsh landscapes and provides real biodiversity benefits based upon realistic targets given limited resources for habitat restoration and re-creation.

Epidemiological risk assessment using linked network and grid based modelling: Phytophthora ramorum and Phytophthora kernoviae in the UK

We developed a stochastic simulation model incorporating most processes likely to be important in the spread of Phytophthora ramorum and similar diseases across the British landscape (covering Rhododendron ponticum in woodland and nurseries, and Vaccinium myrtillus in heathland). The simulation allows for movements of diseased plants within a realistically modelled trade network and long-distance natural dispersal. A series of simulation experiments were run with the model, representing an experiment varying the epidemic pressure and linkage between natural vegetation and horticultural trade, with or without disease spread in commercial trade, and with or without inspections-with-eradication, to give a 2 x 2 x 2 x 2 factorial started at 10 arbitrary locations spread across England. Fifty replicate simulations were made at each set of parameter values. Individual epidemics varied dramatically in size due to stochastic effects throughout the model. Across a range of epidemic pressures, the size of the epidemic was 5-13 times larger when commercial movement of plants was included. A key unknown factor in the system is the area of susceptible habitat outside the nursery system. Inspections, with a probability of detection and efficiency of infected-plant removal of 80% and made at 90-day intervals, reduced the size of epidemics by about 60% across the three sectors with a density of 1% susceptible plants in broadleaf woodland and heathland. Reducing this density to 0.1% largely isolated the trade network, so that inspections reduced the final epidemic size by over 90%, and most epidemics ended without escape into nature. Even in this case, however, major wild epidemics developed in a few percent of cases. Provided the number of new introductions remains low, the current inspection policy will control most epidemics. However, as the rate of introduction increases, it can overwhelm any reasonable inspection regime, largely due to spread prior to detection. (C) 2009 Elsevier B.V. All rights reserved.

Palaeovegetation in China during the late Quaternary: Biome reconstructions based on a global scheme of plant functional types

Two previous reconstructions of palaeovegetation across the whole of China were performed using a simple classification of plant functional types (PFTs). Now a more explicit, global PFT classification scheme has been developed, and a substantial number of additional pollen records have become available. Here we apply the global scheme of PFTs to a comprehensive set of pollen records available from China to test the applicability of the global scheme of PFTs in China, and to obtain a well-founded reconstruction of changing palaeovegetation patterns. A total of 806 pollen surface samples, 188 mid-Holocene (MH, 6000 14C yr BP) and 50 last glacial maximum (LGM, 18,000 14C yr BP) pollen records were used to reconstruct vegetation patterns in China, based on a new global classification system of PFTs and a standard numerical technique for biome assignment (biomization). The biome reconstruction based on pollen surface samples showed convincing agreement with present potential natural vegetation. Coherent patterns of change in biome distribution between MH, LGM and present are observed. In the MH, cold and cool-temperate evergreen needleleaf forests and mixed forests, temperate deciduous broadleaf forest, and warm-temperate evergreen broadleaf and mixed forest in eastern China were shifted northward by 200–500 km. Cold-deciduous forest in northeastern China was replaced by cold evergreen needleleaf forest while in central northern China, cold-deciduous forest was present at some sites now occupied by temperate grassland and desert. The forest–grassland boundary was 200–300 km west of its present position. Temperate xerophytic shrubland, temperate grassland and desert covered a large area on the Tibetan Plateau, but the area of tundra was reduced. Treeline was 300–500 m higher than present in Tibet. These changes imply generally warmer winters, longer growing seasons and more precipitation during the MH. Westward shifts of the forest–shrubland–grassland and grassland–desert boundaries imply greater moisture availability in the MH, consistent with a stronger summer monsoon. During the LGM, in contrast, cold-deciduous forest, cool-temperate evergreen needleleaf forest, cool mixed forests, warm-temperate evergreen broadleaf and mixed forest in eastern China were displaced to the south by 300–1000 km, while temperate deciduous broadleaf forest, pure warm-temperate evergreen forest, tropical semi-evergreen and evergreen broadleaf forests were restricted or absent from the mainland of southern China, implying colder winters than present. Strong shifts of temperate xerophytic shrubland, temperate grassland and desert to the south and east in northern and western China and on the Tibetan Plateau imply drier conditions than present.

Pollen-based reconstructions of biome distributions for Australia, Southeast Asia and the Pacific (SEAPAC region) at 0,6000 and 18,000 14C yr B.P.

Aim  This paper documents reconstructions of the vegetation patterns in Australia, Southeast Asia and the Pacific (SEAPAC region) in the mid-Holocene and at the last glacial maximum (LGM). Methods  Vegetation patterns were reconstructed from pollen data using an objective biomization scheme based on plant functional types. The biomization scheme was first tested using 535 modern pollen samples from 377 sites, and then applied unchanged to fossil pollen samples dating to 6000 ± 500 or 18,000 ± 1000 14C yr bp. Results  1. Tests using surface pollen sample sites showed that the biomization scheme is capable of reproducing the modern broad-scale patterns of vegetation distribution. The north–south gradient in temperature, reflected in transitions from cool evergreen needleleaf forest in the extreme south through temperate rain forest or wet sclerophyll forest (WSFW) and into tropical forests, is well reconstructed. The transitions from xerophytic through sclerophyll woodlands and open forests to closed-canopy forests, which reflect the gradient in plant available moisture from the continental interior towards the coast, are reconstructed with less geographical precision but nevertheless the broad-scale pattern emerges. 2. Differences between the modern and mid-Holocene vegetation patterns in mainland Australia are comparatively small and reflect changes in moisture availability rather than temperature. In south-eastern Australia some sites show a shift towards more moisture-stressed vegetation in the mid-Holocene with xerophytic woods/scrub and temperate sclerophyll woodland and shrubland at sites characterized today by WSFW or warm-temperate rain forest (WTRF). However, sites in the Snowy Mountains, on the Southern Tablelands and east of the Great Dividing Range have more moisture-demanding vegetation in the mid-Holocene than today. South-western Australia was slightly drier than today. The single site in north-western Australia also shows conditions drier than today in the mid-Holocene. Changes in the tropics are also comparatively small, but the presence of WTRF and tropical deciduous broadleaf forest and woodland in the mid-Holocene, in sites occupied today by cool-temperate rain forest, indicate warmer conditions. 3. Expansion of xerophytic vegetation in the south and tropical deciduous broadleaf forest and woodland in the north indicate drier conditions across mainland Australia at the LGM. None of these changes are informative about the degree of cooling. However the evidence from the tropics, showing lowering of the treeline and forest belts, indicates that conditions were between 1 and 9 °C (depending on elevation) colder. The encroachment of tropical deciduous broadleaf forest and woodland into lowland evergreen broadleaf forest implies greater aridity. Main conclusions  This study provides the first continental-scale reconstruction of mid-Holocene and LGM vegetation patterns from Australia, Southeast Asia and the Pacific (SEAPAC region) using an objective biomization scheme. These data will provide a benchmark for evaluation of palaeoclimate simulations within the framework of the Palaeoclimate Modelling Intercomparison Project.

MODIS-based vegetation index has sufficient sensitivity to indicate stand-level intra-seasonal climatic stress in oak and beech forests

Context: Variation in photosynthetic activity of trees induced by climatic stress can be effectively evaluated using remote sensing data. Although adverse effects of climate on temperate forests have been subjected to increased scrutiny, the suitability of remote sensing imagery for identification of drought stress in such forests has not been explored fully. Aim: To evaluate the sensitivity of MODIS-based vegetation index to heat and drought stress in temperate forests, and explore the differences in stress response of oaks and beech. Methods: We identified 8 oak and 13 beech pure and mature stands, each covering between 4 and 13 MODIS pixels. For each pixel, we extracted a time series of MODIS NDVI from 2000 to 2010. We identified all sequences of continuous unseasonal NDVI decline to be used as the response variable indicative of environmental stress. Neural Networks-based regression modelling was then applied to identify the climatic variables that best explain observed NDVI declines. Results: Tested variables explained 84–97% of the variation in NDVI, whilst air temperature-related climate extremes were found to be the most influential. Beech showed a linear response to the most influential climatic predictors, while oak responded in a unimodal pattern suggesting a better coping mechanism. Conclusions: MODIS NDVI has proved sufficiently sensitive as a stand-level indicator of climatic stress acting upon temperate broadleaf forests, leading to its potential use in predicting drought stress from meteorological observations and improving parameterisation of forest stress indices.

Improved simulation of fire–vegetation interactions in the Land surface Processes and eXchanges dynamic global vegetation model (LPX-Mv1)

The Land surface Processes and eXchanges (LPX) model is a fire-enabled dynamic global vegetation model that performs well globally but has problems representing fire regimes and vegetative mix in savannas. Here we focus on improving the fire module. To improve the representation of ignitions, we introduced a reatment of lightning that allows the fraction of ground strikes to vary spatially and seasonally, realistically partitions strike distribution between wet and dry days, and varies the number of dry days with strikes. Fuel availability and moisture content were improved by implementing decomposition rates specific to individual plant functional types and litter classes, and litter drying rates driven by atmospheric water content. To improve water extraction by grasses, we use realistic plant-specific treatments of deep roots. To improve fire responses, we introduced adaptive bark thickness and post-fire resprouting for tropical and temperate broadleaf trees. All improvements are based on extensive analyses of relevant observational data sets. We test model performance for Australia, first evaluating parameterisations separately and then measuring overall behaviour against standard benchmarks. Changes to the lightning parameterisation produce a more realistic simulation of fires in southeastern and central Australia. Implementation of PFT-specific decomposition rates enhances performance in central Australia. Changes in fuel drying improve fire in northern Australia, while changes in rooting depth produce a more realistic simulation of fuel availability and structure in central and northern Australia. The introduction of adaptive bark thickness and resprouting produces more realistic fire regimes in Australian savannas. We also show that the model simulates biomass recovery rates consistent with observations from several different regions of the world characterised by resprouting vegetation. The new model (LPX-Mv1) produces an improved simulation of observed vegetation composition and mean annual burnt area, by 33 and 18% respectively compared to LPX.

Eficácia de herbicidas no controle de plantas daninhas na cultura da cebola em semeadura direta

As plantas de cebola provenientes da semeadura direta no campo são mais danificadas pelo cultivo mecânico e são mais sensíveis aos herbicidas, principalmente os latifolicidas, do que quando transplantadas. Com o objetivo de avaliar a eficácia dos herbicidas oxyfluorfen, ioxynil-octanoato e fluazifop-p-butil, aplicados em pós-emergência, isoladamente ou em mistura no tanque, com ou sem aplicação de paraquat, antes da emergência das plantas de cebola, conduziu-se este trabalho no município de Monte Alto, SP. Nenhum dos herbicidas aplicados isoladamente foi eficiente no controle de todas as espécies daninhas presentes na área experimental. As misturas no tanque de fluazifop-p-butil com oxyfluorfen ou ioxynil-octanoato, independente da aplicação ou não de paraquat aos cinco dias após a semeadura, controlaram eficientemente Portulaca oleracea, Amaranthus lividus, Echinochloa crusgalli, Eragrostis pilosa, Digitaria horizontalis, Eleusine indica e Brachiaria plantaginea, com produção de bulbos semelhante à da testemunha capinada.

Efeito do trinexapac-ethyl na anatomia foliar de quatro espécies de grama

Os reguladores de crescimento podem retardar o desenvolvimento vegetativo das plantas de gramas e, assim, reduzir a frequência de cortes; contudo, existem poucas informações referentes aos efeitos desses produtos sobre as estruturas da anatomia foliar. Dessa forma, o presente trabalho teve por objetivo avaliar os efeitos da aplicação sequencial de duas doses de trinexapac-ethyl sobre a anatomia foliar das espécies de gramas São Carlos (Axonopus compressus), Batatais (Paspalum notatum), Santo Agostinho (Stenotaphrum secundatum) e Esmeralda (Zoysia japonica). Os tratamentos utilizados foram constituídos de duas aplicações sequenciais de trinexapac-ethyl nas doses de 56,5+56,5 e 113,0+113,0 g ha-1; além de uma testemunha sem aplicação, para cada espécie avaliada. Os gramados foram cortados à altura de 3 cm, com auxílio de um aparador de grama motorizado, e, em seguida, foram realizadas as aplicações dos tratamentos. Após 20 dias da primeira aplicação de trinexapac-ethyl, as parcelas foram novamente aparadas à altura de 3 cm e foi realizada a segunda aplicação dos tratamentos. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições. Aos 70 dias após a segunda aplicação dos tratamentos, foram realizadas as amostragens do material foliar, para as quatro espécies estudadas. Os dados das variáveis quantitativas foram submetidos ao teste estatístico multivariado de análise de componentes principais. Os resultados evidenciaram a formação de três e dois grupos principais, para os caracteres da região da quilha (nervura mediana) e da região da asa (situada entre a nervura mediana e a margem do limbo foliar), respectivamente. de modo geral, em cada formação dos agrupamentos, os tratamentos com trinexapac-ethyl apresentaram maior similaridade entre si, em relação às respectivas testemunhas. Conclui-se que a aplicação sequencial de trinexapac-ethyl alterou algumas estruturas anatômicas da região da quilha e da asa do limbo foliar das espécies de gramas estudadas.

Seletividade de herbicidas aplicados na grama Batatais e na grama São Carlos

Objetivou-se avaliar a seletividade de herbicidas aplicados na grama Batatais (Paspalum notatum) e na grama São Carlos (Axonopus compressus) em campo. O delineamento experimental utilizado foi o de blocos casualizados com quatro repetições. As gramas foram cortadas a 3 cm de altura e, em seguida, realizaram-se as aplicações dos herbicidas. Os tratamentos utilizados foram: testemunha (sem aplicação), fluazifop-p-butil (125 g ha-1), sethoxydim+óleo mineral (276 g ha-1 + 0,5% v v-1 de Assist), bispyribac-sodium (25 g ha-1), chlorimuron-ethyl (15 g ha-1), ethoxysulfuron (150 g ha-1), halosulfuron (112,5 g ha-1), iodosulfuron-methyl (10 g ha-1), metsulfuron-methyl (2,4 g ha-1), nicosulfuron (125 g ha-1), pyrithiobac-sodium (140 g ha-1), trifloxysulfuron-sodium (22,5 g ha-1), 2,4-D (720 g ha-1), quinclorac (375 g ha-1), atrazina (1.250 g ha-1), bentazon (600 g ha-1), linuron (1.350 g ha-1), fomesafen (187,5 g ha-1), lactofen (120 g ha-1), oxadiazon (600 g ha-1) e oxyfluorfen (720 g ha-1). Os herbicidas que apresentaram potencial de seletividade para o gramado de P. notatum foram o chlorimuron-ethyl, ethoxysulfuron, pyrithiobac-sodium, 2,4-D, bentazon e fomesafen; já para o gramado de A. compressus foram o chlorimuron-ethyl, ethoxysulfuron, halosulfuron, iodosulfuron-methyl, metsulfuron-methyl, pyrithiobac-sodium, 2,4-D, quinclorac, atrazina, bentazon, além do fomesafen.