张家口地区“乡土种树”与美丽乡村构建融合

近年来,乡土种树的优势逐渐显露出来,为新农村的发展提供了一个新的方向。国家在"乡土种树"建设中进行了改革与创新,目的是让更多人看到绿化带来的好处。但是现阶段,在改革与创新的过程中,"乡土种树"中仍存在许多问题值得关注。主要分析了张家口地区"乡土种树"与美丽乡村构建融合的问题与对策。

乡土树种在生态园林绿化中的应用探讨

我国一直在打造生态园林城市,但园林植物的配置上应该根据当地的气候环境进行选择。针对此种情况,需要分析生态园林绿化中乡土树种的优势和存在的弊端,探讨出生态园林绿化采用乡土树种的策略,保证园林生态绿化的植物配备合理性以及自然美观性,促进城市绿化取得更佳的效果。

Growth and Influencing Factors of Three Native Tree Species in Coastal Casuarina equisetifolia Plantation

[Objective] The aim was to study the growth and environment factors of three native tree species（Thespesia lampas,Calophyllum inophyllum and Hernandia sonora）in Hainan in coastal Casuarina equisetifolia plantation.[Method] The coastal sandy soil was treated by adding wood chips,bagasse and the control without adding anything in the plant pits.The growth of three native tree species planted for one year was analyzed.[Result] ① One year later,the survival rate showed an order of T.lampasH.sonoraC.inophyllum;the net increase of basal diameter showed an order of H.sonoraT.lampasC.inophyllum;while the net increase of plant height showed an order of T.lampasC.inophyllumH.sonora.The difference of survival rate between T.lampas and C.inophyllum was extremely significant,the difference of survival rate between H.sonora and C.inophyllum was significant,but the survival rate between T.lampas and H.sonora showed no significant difference.The difference on net growth of plant height among T.lampas,C.inophyllum and H.sonora was extremely significant,and the different on the net growth of basal diameter between T.lampas and C.inophyllum was significant.② Among different soil treatments,the survival rate of three native tree species in the treatment by adding wood chips,bagasse were higher than the treatment without adding anything,and the difference of survival rate of T.lampas between the treatment by adding wood chips,bagasse and the treatment without adding anything was extremely significant,but the treatment by adding wood chips and bagasse had not significant difference.③ The growth of three native tree species showed some correlation with environment factors（∣r∣0.3）.The survival rate of T.lampas showed higher correlation with soil pH value and soil moisture,and the basal diameter and height of T.lampas showed some correlation with soil pH value and soil temperature.The survival rate of C.inophyllum showed higher correlation with soil pH value,soil temperature and light intensity,while the basal diameter and height of C.inophyllum showed some correlation with soil temperature.The survival rate of H.sonora showed higher correlation with soil salinity and soil temperature,while the basal diameter and height of H.sonora showed some correlation with soil temperature.The basal diameter and height of three native tree species had higher correlation（r0.5）,which had reached a significant level.[Conclusion] In the one-year growth period in C.equisetifolia forest,the native tree species of T.lampas grew best and it was the most potential forest species mixed with C.equisetifolia.

Native Trees Forage Alternative Protein Feed for Cattle in Tropical ＂Mexico＂

The objective of this study was to find highly nutritious native plants to feed cattle in northern Veracruz （Mexico） as an alternative to avoid deforestation for pasture establishment. Six fodder tree species （Leucaena, Leucaenaleucocephala, Morera, Morus alba, Chacloco, rubiHamelia patents, Guficima, Guasumaulmifolia, Pichoco-bunting, Erythrinaamericana, Cocuite, Gliricidiasepium） were selected for their leave production, rapid growth and high nutritional quality. The plants were evaluated in the bud stage of senescence and flowering, restricting the fraction of mature foliage in the samples located under 2 meters height. Samples were collected from five plants per specie that were randomly selected. The nutritious parameters were evaluated through proximate analysis with the Van Soest technique. This study used a completely randomized design with five replicates. The nutritious composition showed PC （protein content） differences （P 〈 0.05） among species indicating that Leucaenaleucocephala （20%） had the lowest, Gliricidiasepium was （21%） intermediate and Morus alba （23%） had the highest. The FDN （neutral detergent fiber） and FDA （acid detergent） were lowest for Guasumaulmifolia （23.4%） and the other five species exceeded 40%. In conclusion, native foliage of fodder trees in northern, Veracruz are highly nutritious for cattle feeding and could alternative to avoid deforestation for pasture establishment to continue.

Propagation of Grevillea banksfi Affects the Dynamic of Mycorrhizal Fungi Communities Associated with Native Tree Species of Madagascar

Propagation of exotic plant species is found in many regions of Madagascar Island. This work aims to describe the impacts of the propagation of Grevillea banksii on soil microbial activities and on the regeneration of two native tree species （Intsia bij＇uga and Dalbergia trichocarpa） in the eastern part of Madagascar. The study was conducted within Ianjomara forest where some types of the vegetation are observed such as an area characterized by grassland （P 1）, by homogeneous population of G. banksii （P2） and by a natural forest composed mainly of L bijuga or D. trichocarpa （P3 and P4）. Structure of mycorrhizal fungi communities and associated microorganisms were described on soils from each study plot. The development of I. b^juga and 1）. trichocarpa, was evaluated 4 months after planting on P1, P2, P3, P4 soils formerly colonized by G. banksii. According to the nutrients availability on each soil type, the development of G. banksii was accompanied or not by a high formation of cluster roots. The authors＇ results also show that soil occupied by G. banksii decreased the global microbial and phosphatase activities of soil especially on soil within a high density of cluster roots. Moderately mycotrophic, G. banksii disturbs the structure and the dynamics of symbiotic microflora such as endomycorrhizal fungi （MA） and rhizobia associated with the two native tree species. The findings illustrate the negative impact of G. banksii propagation on the regeneration and the conservation of native tree species in Madagascarian forest.

Winners and losers among tree species in Xishuangbanna: which traits are most important?

Massive human interference in natural ecosystems is resulting in a few ＂winners＂ and many ＂losers＂. However, the drivers of this winner-loser replacement pattern remain poorly understood. The aim of the study reported here was to identify winners among the tree flora of Xishuangbanna and compare their functional traits, specific leaf area （SLA）, wood density （WD）, seed mass （SM） and maximum height （MH） with previously identified losers （i.e., endangered species）. Fifteen native tree species were identified as winners from expert opinion, plot-based surveys of secondary forests and plotless surveys along roads. Twelve endangered tree species for which trait information could be obtained were used for comparison. Traits were compared with a Wilcoxon rank-sum test. Winners had significantly higher SLA, but lower WD. SM and MH did not differ significantly between groups. When the effects of phylogeny were removed by using phylogenetic generalized least squares, the difference in SLA became marginally insignificant. Principal component analysis resulted in two overlapping groups, showing that the selected traits were insufficient to distinguish winners and losers. Our results suggest that the ＂few winners, many losers＂ paradigm applies to trees in Xishuangbanna, with15 species accounting for most trees in the disturbed habitats sampled.

Soil fungi of three native tree species inhibit biomass production and shift biomass allocation of invasive Mikania micrantha Kunth

Soil microbes contribute to native plant species successful resistance against invasive plant.Three native tree species,Heteropanax fragrans (HF),Cinnamomum burmanii (CB),and Macaranga tanarius (MT) were effective in controlling the notorious invasive vine Mikania micrantha (MM).Biomass production and allocation patterns (shoot/root biomass ratio (shoot/root)) are important indicators of MM climbing coverage and competitive light-capturing capacity.An investigation was conducted to test the role of soil microbes associated with the three native tree species to inhibit MM biomass production and shift MM shoot/root.Rhizosphere soils originating from preculture HF,CB,MT,and MM plots were collected separately for use as inocula.The inocula were mixed with sterilized river sand at a 1:9 (w/w) ratio to grow MM.The fungicide carbendazim (methyl benzimidazol-2-ylcarbamate) was applied to half the treatments to kill pathogenic soil fungi.Two nutrient levels were established based on the natural soil nutrient concentration from a field stand invaded by MM.MM were grown from seeds in a glasshouse,harvested 15 weeks after sowing,and separated into shoot and root portions.Results showed that under interaction of soil origin and nutrient levels,MM biomass production was unchanged,but biomass allocation patterns were significantly different.MM biomass production grown in the three native tree soils under two nutrient levels was similar or higher than MM biomass production in MM conspecific soil,indicating the absence of species-specific pathogens that inhibited MM biomass production in native tree soils.However,in both conspecific and tree soils,MM biomass production was significantly reduced in the presence of pathogenic soil fungi,i.e.MM experienced significant fungal inhibition,demonstrating the pathogenic soil fungi promoted native tree resistence to MM.MM exhibited decreased shoot biomass allocation when cultivated in native tree soil relative to MM conspecific soil under field stand nutrient level conditions.Reduced resource allocation to shoot biomass could result in diminished capacity to climb,cover,and subsequent smother to native trees,and reduced surface area exposed to available light.Following fungicide application,significant biomass allocation differences disappeared,suggesting the native tree soil fungi were responsible for decreasing MM shoot biomass.The overall results indicated tree soil fungi serve an integral role in controlling invasive MM through fungal inhibition on MM biomass production,and shifts in MM biomass allocation patterns.

Invasion and predation in aquatic ecosystems

This article reviews biological invasions in which predation （or its absence） plays a major role in the success of the invader. Examples are described in which the invader out-competes native species for the same food, and cases in which the in-vader consumes valued native species. In many instances, better predator avoidance by the invasive species or the absence of predators in the new habitat contributes to the success of the invaders; in other cases native or introduced predators appear to be able to keep the invasive species in check. A relatively new management approach in the US is the idea of adding another trophic level - to have humans act as the predators and consume the invasive species. This approach is being utilized in Florida and throughout the Caribbean against the lionfish, but could be extended to other fishes, as well as to various invasive crustaceans and mollusks. This idea is controversial, and current regulations prohibiting the possession of individuals of the invasive species （e.g., mitten crabs or snakefish） would preclude the development of a fishery for them [Current Zoology 57 （5）： 613~524, 2011].

Can native species crucian carp Carassius auratus recognizes the introduced red swamp crayfish Procambarus clarkii？

Procambarus clarkii is native to the south-central United States （Louisiana） and northeastern Mexico, and is a highly efficient predator that poses a damager to native species after its introduction or invasion. In its natural habitat, P. clarkii consumes Carassius auratus, however, whether C. auratus recognizes P. clarkii as a predator is not yet clear. In laboratory experiments, we investigated whether experienced and inexperienced C. auratus recognize P. clarkii as a predatory threat and the specific sensory modality used by C. auratus to respond to chemical and visual stimuli from P. clarkii. In the chemical stimuli experiment, two kinds of chemical stimuli were used, water from a tub containing P. clarkii previously fed with C. auratus （C. auratus diet cues） and water from a tub containing unfed P. clarkii （P. clarkii cues）. In the visual experiment, experienced C. auratus decreased activity, but inexperienced C.auratus avoided the predator compartment. When C. auratus diet cues were presented, both experienced and inexperienced C. auratus increased the use of shelter, decreased activity in the initial response phase. Compared with the blank treatment, experienced C. auratus responded to P. clarkii cues by decreasing activity; however, inexperienced C. auratus showed no reduction in activity. C. auratus appears to recognize P. clarkii as a predator both through visual and chemical cues. Further analysis revealed that C. auratus may recognize R clarkii visually through the disturbances caused by P. clarkii movement and chemically by detecting conspecific alarm cues in the diet of P. clarkii. The results also indicate that ex- perienced C. auratus can recognize R clarkii by innate chemical cues from P. clarkii, whereas inexperienced C. auratus cannot [Current Zoology 57 （3）： 330-339, 2011].