Invasion Pattern of Herb Garlic Mustard (Alliaria petiolata) in High Quality Forests

The invasion of non-indigenous plant species poses a severe threat to native plant communities. Garlic mustard (Alliaria petiolata) is a naturalized European biennial herb that has spread rapidly through the eastern US and adjacent Canada. To determine garlic mustard rate of spread, eleven permanent plots (50×25 m) were located in seven high quality (relatively undisturbed) forests in the early stages of invasion. Garlic mustard presence was recorded within six 50×2 m permanent belt transects, and density and percent cover by age class were recorded in 36 permanent 1 m² quadrats, between 1989 and 1992, and again in 1997. Garlic mustard spread at an average rate of 5.4 m per year between 1989 and 1992, in all plots combined. Within individual plots rate of spread varied substantially, with location of the front increasing up to 36 m and decreasing as much as 18 m between years. While the front alternately advanced and retreated, over time garlic mustard consistently advanced through all forests. Rate of spread was influenced by establishment of satellite populations, and disturbance (wind-throw and flooding). The pattern of spread within plots was one of a ragged advancing front, supplemented by establishment of satellite populations 6–40 m distant from the front, which then coalesced with the main population. Garlic mustard presence between 1989 and 1997 increased significantly within all plots, and in each age class within each plot. The greatest increases occurred in plots where this plant was initially rarest. Garlic mustard cover and density varied nonsignificantly during the same time period. These results indicate that after garlic mustard invades a forest it becomes a permanent part of the community, annually increasing in presence but fluctuating in cover and density. Garlic mustard maintains a low profile under low disturbance conditions, but increases rapidly with periodic disturbance. This study monitored garlic mustard invasion in high quality relatively undisturbed forests, and may underestimate the rate of spread in low quality highly disturbed forests.     

Patterns of seed mass variation and their effects on seedling traits inAlliaria petiolata (Brassicaceae)

Seed mass is considered to be the least plastic component of reproductive yield. Yet, in invasive populations of garlic mustard, Alliaria petiolata, seed mass was highly variable (eightfold among populations, 2.5-7.5 fold within populations, two-threefold within individuals, and 1.4-1.8 fold within fruits). Variation in seed mass among populations explained nearly half of the total variance. Variation among seeds within fruits accounted for a further 25% of variance. Individual seed mass within a plant decreased with increased distance from the main stem, suggesting that access to parental resources limits seed size in a predictable manner. MANOVAs and Roy-Bargmann stepdown analyses revealed significant effects of seed mass, but not seed position (within a fruit or within an infructescence), on an array of subsequent seedling traits. Smaller seeds germinated significantly earlier, and seedlings from small seeds produced their first primary leaves significantly later and grew significantly taller. After accounting for seed mass as a covariate, only one seedling trait, date of first leaf emergence, was affected by seed position in a fruit. Differences in seed mass may therefore affect seedling recruitment via effects on early seedling growth in this weedy species.     

Spatial and temporal diversity in hyperparasitoid communities of Cotesia glomerata on garlic mustard,Alliaria petiolata

1. Interactions between two trophic levels can be very intimate, often making species dependent on each other, something that increases with specialisation. Some specialised multivoltine herbivores may depend on multiple plant species for their survival over the course of a growing season, especially if their food plants are short‐lived and grow at different times. Later generations may exploit different plant species from those exploited by previous generations. 2. Multivoltine parasitoids as well as their natural enemies must also find their hosts on different food plants in different habitats across the season. Secondary hyperparasitoid communities have been studied on cocoons of the primary parasitoid, Cotesia glomerata (Hymenoptera: Braconidae), on black mustard (Brassica nigra) – a major food plant of its host, the large cabbage white (Pieris brassicae) – which grows in mid‐summer. 3. Here, hyperparasitoid communities on C. glomerata pupal clusters were studied on an early‐season host, garlic mustard, Alliaria petiolata, over ‘time’ (one season, April–July) in six closely located ‘populations’ (c. 2 km apart), and within two different ‘areas’ at greater separation (c. 100 km apart). At the plant level, spatial effects of pupal ‘location’ (canopy or bottom) on the plant were tested. 4. Although large‐scale separation (area) did not influence hyperparasitism, sampling time and small‐scale separation (population) affected hyperparasitism levels and composition of hyperparasitoid communities. Location on the plant strongly increased proportions of winged species in the canopy and proportions of wingless species in bottom‐located pupae. 5. These results show that hyperparasitism varies considerably at the local level, but that differences in hyperparasitoid communities do not increase with spatial distance.     

Observations of herbivore attack on garlic mustard (Alliaria petiolata) in Southwestern Ontario, Canada

We have observed what appears to be the first significant report of herbivory of a population of Alliaria petiolata (M. Bieb.) Cavara & Grande (Garlic Mustard) in Canada. Ceutorhynchus erysimi Fabr., Plutella xylostella L. (Diamondback Moth), and Philaenus spumarius (Meadow Spittlebug) were identified attacking, and successfully proceeding through different stages of development on A. petiolata. From the field observations, we hypothesize that these species have recognized A. petiolata as a host and therefore may be candidates for the management of the invasive species.     

中国天山野果林种子植物组成及资源状况分析

中国天山野果林种子植物共计60科237属435种,种类组成趋向于集中在少数科内,区系优势现象相当明显,反映出野果林自然环境的特殊性与区系的过渡性。在这些植物种类中有国家重点保护植物9种、中国珍稀濒危保护植物3种、自治区重点保护植物9种;林区野生植物资源非常丰富,统计结果表明：野生果树40种、食用植物30种、饲用植物以种、蜜源植物111种、观赏植物132种、香料植物如种、药用植物131种。文中对各类资源植物的特征进行了分析和讨论,并就野果林的保护及可持续利用提出建议。     

Influence of physical distance between cultivars on yield,outcrossing rate and selective fruit drop in avocado (Persea americana,Lauraceae)

Avocado shows protogynous dichogamy with two complementary cultivar types (A and B) that differ in their floral behaviour. Because of this peculiar flowering system, mixed plantings of cultivars of complementary flower type have been traditionally recommended to increase yield. However, the effect of planting complementary avocado cultivars on outcrossing rate and yield is a subject of controversy. In this work, we have studied the outcrossing rate with microsatellite markers under the growing conditions of Southern Spain. Outcrossing rate was determined at harvest on several ‘Hass’ trees situated in rows at different distances from a ‘Fuerte’ orchard for two consecutive years (2005 and 2006). Outcrossing rate ranged from 0.31 to 0.74 with an average of 0.47 showing a significant decrease from the first row (in proximity to the pollen source) to the rest of the rows. However, using data of 13 years no significant differences in yield have been recorded with increasing distance to the pollen donor trees. The paternity of abscised fruits was recorded weekly from June to the period of commercial harvest in March the following year. The results obtained indicate that the fruits that dropped during June were mostly derived from self‐fertilisation. However, a high proportion of those fruits were derived from flowers fertilised during the last weeks of the ‘Hass’ blooming season when the cultivar Fuerte presents either few or no flowers. Consequently, most of the late fertilised ‘Hass’ fruits were derived from self‐pollination and those small fruits compete for limited maternal resources with the earlier fertilised fruits derived from cross‐pollination. These results suggest that, under our growing conditions, fruit drop in avocado is rather determined by the fertilisation date and not by the embryo genetic composition.     

福建桃、梨果蛀虫及梨小食心虫初步研究

本文报道福建省桃、梨果蛀虫概况及梨小食心虫的初步研究和防治意见。     

果乐对苹果梨生长发育和果形畸变的调控

在苹果梨盛花期分别喷洒一定浓度的果乐1号和6号,改变授粉时的营养条件,促进受精作用,使种子和果实生长发育良好。实验结果表明,喷洒果乐提高了座果率和单果重,降低果形畸变50%左右,增加产量20%左右。同时也改善了果实品质,使含糖量有一定的提高。     

福建省果树寒(冻)害短期精细预报预警技术

根据福建省68个气象站1963-2008年冬季气候资料,利用数理统计和GIS方法,对福建省果树寒(冻)害短期精细预报预警技术进行了研究.结果表明:福建省果树寒(冻)害预警期为12月上旬-翌年2月中旬,预警关键期为12月中旬-翌年1月中旬;利用逐步回归建立的福州、厦门和邵武3个探空站日最低气温短期预报模型,经差值法移植后,可以用于全省各气象台站日最低气温短期预报;建立各气象台站日最低气温与经度、纬度、海拔高度的地理关系推算模型,利用GIS制作日最低气温预报分布图,可以开展日最低气温空间精细预报;结合荔枝、龙眼、香蕉等南亚热带果树寒(冻)害指标,对果树寒(冻)害的发生、发展和范围进行短期预报预警;2009年利用差值移植法开展各气象站最低气温(t_d)的短期预报:≤1℃的预报准确率为58.3%,≤1.5℃的预报准确率为83.3%,≤2℃的预报准确率为91.7%;短期预报模型具有一定的预报能力,能作为冬季低温定量预报方法.

Abstract：

Based on the 1963-2008 meteorological data from 68 weather stations in Fujian Province,and by using mathematic statistics and GIS technique,the short-term subtle forecast and early warming methods for cold (freezing) damage of fruit trees in the province were approached.The forecast period for cold (freezing) damage of fruit trees was from early December to next early February,and the key period for warning low temperature was from mid December to next mid January.The short-term forecast equations for the minimum daytime temperature in Fuzhou,Xiamen,and Shaowu were established by stepwise regression analysis,which could be used for the forecast of short-term minimum temperature by all of the meteorological observation stations in Fujian Province by means of differential algorithms.Based on the data of longitude,latitude,and altitude,the geographical relational prediction model of the minimum daytime temperature was established,and the distribution map of forecasted low temperature was drawn with GIS technology,which could subtly forecast the minimum daytime temperature of whole Fujian Province.In combining with the cold (freezing) damage indices of fruit trees such as litchi,longan,and banana in southern subtropical monsoon climate zone,the forecast information of warning cold (freezing) damage of fruit trees were popularized,and the occurrence,development,and range of cold (freezing) damage for fruit trees were forecasted in short-term.By means of differential algorithms,the short-term minimum temperature was forecasted by all weather stations in the Province in 2009,and the forecast accuracy of ≤1 ℃,≤1.5 ℃,and ≤2 ℃was 58.3%,83.3%,and 91.7%,respectively.It could be seen that our short-term forecast model possessed a certain forecast capability,and could be used for the quantificational forecasting of low temperature in winter.     

Combined effects of water, nutrient, and UV-B stress on female fitness in Brassica (Brassicaceae)

Our knowledge of the effects of increased levels of ultraviolet-B radiation (UV-B) on plant fitness is limited mainly to yield studies in a few crop species. Previous greenhouse and garden studies of Brassica have found greater detrimental effects of UV-B on fitness in gardens than in the greenhouse, suggesting the possibility that additional stresses in the field decrease the ability of Brassica to cope with UV-B. Possible interactions between UV-B and water/nutrient stress in determining plant fitness have rarely, if ever, been studied experimentally. Here we report measurements of female fitness in two species of Brassica in an experiment in which both UV-B and levels of water and nutrients were varied in a 2 x 2 factorial design. Water and nutrient stress reduced female fitness in both species, while UV-B caused fitness reductions in only one of the species. There was evidence for interactions between UV-B and water/nutrient stress for only a few of the traits measured; most traits, including those closely related to fitness, showed no evidence of an interaction.     

Effects of pollen load size and composition on pollen donor performance in wild radish, Raphanus sativus (Brassicaceae)

A critical concern in the debate over the importance of sexual selection in plants is whether the nonrandom mating demonstrable in greenhouse crosses can occur in the field. Field populations likely experience smaller and more variable pollen load sizes than those that have been used in many greenhouse experiments. Therefore, we performed a greenhouse experiment in which we varied both pollen load size and composition in wild radish, Raphanus sativus, and examined the paternity of seeds. We used five maternal plants and four pairs of pollen donors. We were able to produce pollen loads of 40, 118, and 258 grains per stigma. The smallest of the pollen loads was scant enough to result in a slight, but significant reduction in seed number per fruit. While variation in pollen load composition significantly affected the proportions of seeds fathered by different donors, variation in pollen load size did not. The relative performance of different donors was constant across pollen load sizes, suggesting that, for this species, differential performance of pollen donors can occur at pollen load sizes that are likely to occur in field populations.     

Effect of pollen load size and source (self, outcross) on seed and fruit production in highbush blueberry cv. 'Bluecrop' (VACCINIUM CORYMBOSUM; Ericaceae)

Reproductive fitness of a plant is ultimately determined by both number and quality of seed offspring. This is determined by sexual selection of pollen microspores and ovules during pollination and fertilization. These processes may include pollen competition and seed abortion, which reduce the number of microspores and ovules available for final seed production. Thus, even an excess of pollen microspores to ovules does not result in fertile seeds equal to ovule number. We investigated pollen requirements of highbush blueberry (Vaccinium corymbosum cultivar 'Bluecrop') for maximal seed production and how fertile seed number translates into fruit quality, since fruit quality would ultimately determine the dispersal of its offspring. We demonstrate that individual blueberry flowers with a mean of 106 ovules reach their maximum fruit set and mass and minimum time to ripen when 125 outcross pollen tetrads pollinate a flower, compared to 10 or 25. Three hundred tetrads resulted in the increase of fertile seeds, but did not result in a further increase of fruit mass or fruit set, or decrease in time to ripen. We also examined the effect of pure and mixed loads of self and outcross pollen (25 and 125 tetrads), and found no differences in fertile seed number, fruit mass, or percentage fruit set when pollen loads were either 25 self or outcross pollen tetrads, although number of days to ripen was significantly shorter by 8 d with 25 outcross tetrads. When the pollen load of 125 tetrads consisted of self or a 50:50 mixture of self and outcross pollen, fruit mass, days to ripen, and percentage fruit set were not different from loads of 125 outcross pollen. In addition, a pollen load of 25 outcross tetrads resulted in fertile seed number and fruit quality in between that of 25 self, and 125 self, 125 mixed, or 125 outcross tetrads. Large, small, and flat seed types were identified, and only large seeds (length = 1.7 mm) were fertile. These results improve our understanding of pollen load size and source requirements of a crop plant and the limits to pollen transfer when translated to fruit growth.     

Environmental control of reproductive phenology and the effect of pollen supplementation on resource allocation in the cleistogamous weed, Ruellia nudiflora (Acanthaceae)

• Background and Aims Mixed reproductive strategies may have evolved as a response of plants to cope with environmental variation. One example of a mixed reproductive strategy is dimorphic cleistogamy, where a single plant produces closed, obligately self-pollinated (CL) flowers and open, potentially outcrossed (CH) flowers. Frequently, optimal environmental conditions favour production of more costly CH structures whilst economical and reliable CL structures are produced under less favourable conditions. In this study we explore (1) the effect of light and water on the reproductive phenology and (2) the effect of pollen supplementation on resource allocation to seeds in the cleistogamous weed Ruellia nudiflora.• Methods Split-plot field experiments were carried out to assess the effect of shade (two levels: ambient light vs. a reduction of 50 %) and watering (two levels: non-watered vs. watered) on the onset, end and duration of the production of three reproductive structures: CH flowers, CH fruit and CL fruit. We also looked at the effect of these environmental factors on biomass allocation to seeds (seed weight) from obligately self-pollinated flowers (CL), open-pollinated CH flowers and pollen-supplemented CH flowers.• Key Results CH structures were produced for a briefer period and ended earlier under shaded conditions. These conditions also resulted in an earlier production of CL fruit. Shaded conditions also produced greater biomass allocation to CH seeds receiving extra pollen.• Conclusions Sub-optimal (shaded) conditions resulted in a briefer production period of CH structures whilst these same conditions resulted in an earlier production of CL structures. However, under sub-optimal conditions, plants also allocated more resources to seeds sired from CH flowers receiving large pollen loads. Earlier production of reproductive structures and relatively larger seed might improve subsequent success of CL and pollen-supplemented CH seeds, respectively.     

Living near the limits: Effects of interannual variation in food availability on diet and reproduction in a temperate primate,the Taihangshan macaque (Macaca mulatta tcheliensis)

Nutrient intake of animals is influenced by an interplay of external and internal factors, such as food availability and reproductive state, respectively. We used the nutritional geometry framework to analyze individual-based data on energy and nutrient intake in relation to reproductive state in a population of rhesus macaques (Macaca mulatta tcheliensis), which live in a harsh high-latitude habitat, the Taihangshan mountains of China, and exhibit strong reproductive seasonality. We combined data over a 3-year period on food availability, diets, reproductive output, and components of maternal investment to understand how Taihangshan macaques respond to variation in food availability and nutrition in reproduction. Our results show there was high interannual variation in availability of an important staple source of fat and carbohydrates (nonprotein energy), seeds of oak (Quercus spp). Despite this variability in seed availability skewing the dietary macronutrient ratios considerably (from 12.96% to 30.12% dietary energy from protein), total metabolizable energy intake was maintained across years during pregnancy. Lactating females had higher mean daily energy intakes than pregnant females. As in pregnant females, energy intake was maintained constant across years, but only when seed availability enabled the contribution of available protein to energy intake to be maintained between 15.32% (2013) and 17.97% (2015). In 2014, when seeds were scarce, lactating females had a shortfall in energy intake compared with 2013 and 2015. This corresponded with a reduction in the number of females giving birth (11 out of 23), but there was no interannual difference in survival rates. Compared to 2013 and 2015, in 2014 females had greater weight loss (drew on body reserves), moved less, and spent more time nursing their offspring. We discuss implications of these results for range limitation in Taihangshan macaques.     

The effects of seed size, cotyledon reserves, and herbivory on seedling survival and growth in Quercus rugosa and Q. laurina (Fagaceae)

In a greenhouse experiment, seedling survival of two oak species (Quercus rugosa and Q. laurina) was greatly affected by the excision of cotyledons 1 mo after germination, with a greater impact on Q. laurina. The effect of seed size was also significant for both species, with a positive correlation between seed mass and survival and growth. The effect of cotyledon excision on seedling growth persisted throughout the first growing season in Q. rugosa and was not analyzed for Q. laurina due to the low number of seedlings that survived cotyledon excision. Seed size significantly affected seedling height, diameter, leaf area, and biomass at 6 mo. Seed size and cotyledon retention affected the ability of Q. rugosa to recover from herbivory, as both factors had a significant effect on relative growth rates after aerial biomass removal. The results show that seedlings originating from large seeds can better endure loss of cotyledons and aerial biomass and thus are better equipped to confront stress early in their lives.