Impact of grassland contract policy on soil organic carbon losses from alpine grassland on the Qinghai–Tibetan Plateau

Carbon storage in the soils on the Qinghai–Tibetan Plateau plays a very important role in the global carbon budget. In the 1990s, a policy of contracting collective grasslands to smaller units was implemented, resulting in a change from the traditional collective grassland management to two new management patterns: a multi‐household management pattern (MMP: grassland shared by several households without enclosures) and a single‐household management pattern (SMP: grassland enclosed and used by only one household). In 2016, 50 MMP and 54 SMP winter pastures on the Qinghai–Tibetan Plateau were sampled to assess the differences in soil organic carbon (SOC) between the two management patterns. Results showed that average SOC was significantly greater under MMP than under SMP, with an estimated 0.41 Mg C/ha/yr lost due to SMP following the new grassland contract. Based on the government's grassland policy, four grassland utilization scenarios were developed for both summer and winter pastures. We found that if the grassland were managed under SMP, likely C losses ranged between 0.31 × 10⁷ and 6.15 × 10⁷ Mg C/yr across the Qinghai–Tibetan Plateau relative to MMP, which more closely resembles pre‐1990s grassland management. Previous estimates of C losses have only considered land use change (with cover change) and ignored the impacts driven by land management pattern changes (without cover change). The new data suggest that C losses from the Qinghai–Tibetan Plateau are greater than previously estimated, and therefore that the grassland contract policy should be reviewed and SMP households should be encouraged to reunite into the MMP. These findings have potential implications for land management strategies not only on the Qinghai–Tibetan Plateau but also other grazing regions globally where such practices may exist.     

11个葡萄品种在乐山地区的花芽分化规律

研究了11个葡萄品种3年生树在四川乐山地区避雨栽培条件下的花芽分化表现。结果表明,结果母枝的花芽分化率,魏可、维多利亚、黑芭拉多、金手指、金优2号和巨玫瑰6个品种的都高于50%,较易形成花芽;户太8号、巨峰、夏黑的在43%~48%;美人指和红指较难形成花芽。结果母枝不同节位的花芽分化率,多数品种在第3节位≥50%;结果枝上花穗着生节位在第3.8~4.9节,其中双花率以巨玫瑰、巨峰和户太8号较高,分别为83.45%、73.61%和73.06%。以结果母枝的花芽分化率≥50%节位作为冬剪的最低节位,则金优2号、户太8号、巨玫瑰、金手指、维多利亚5个品种在第3~4节,黑芭拉多和巨峰2个品种在第2~3节,魏可在1~2节。夏黑表现花芽分化率较低,为43.33%,可能与夏黑不耐弱光有关,设施栽培时应加强透光性。     

黔东南州打造全域森林公园的可行性研究

指出了建设全域森林公园是经济和社会发展的必然要求。在对黔东南州发展全域森林公园进行必要性和打造条件后认为:黔东南州在打造全域森林公园方面具有明显的政策优势,有着优良的森林生态环境资源,以及良好的林业产业基础等优势条件。通过不断完善相关的配套服务体系,已具备了打造全域森林公园的可行性。     

无核葡萄胚发育及早期离体培养的研究:Ⅲ.培养方式对离体胚发育的影响

对5个无核葡萄品种的试验表明,不同培养方式对离体胚发育的影响是很明显的,其中4个品种胚发育率液体培养高于固体培养,‘京早晶’在液体培养中胚发育率高达73.7%,是目前国内外胚发育率最高的报道;液体培养比固体培养胚的发育程度高,发育整齐,无畸形胚,易成苗.     

古柏赤枯病病原菌的研究

经Ｋｏｃｈ＇ｓ法则检验证明，ＡｌｔｅｒｎａｒｉａｔｅｎｕｉｓＮｅｅｓ（细链格孢霉）是北京地区古柏赤枯病的病原菌。它引起古柏针叶及嫩梢的大量死亡。２—３年生桧柏及侧柏苗经人工接种证明，该病菌有较强的致病力，它还侵染某些种类的杨树。该病潜育期为５—６天。对病菌生物学特性也作了研究。病原菌生长和孢子萌发最适温度为２５℃Ｆ相对湿度在９０％以上；最适ｐＨ值为６；葡萄糖、淀粉、蛋白胨、谷氨酸为该菌纯培养的优良营养源。     

SH系砧木及对应中间砧红富士苹果枝条水分输导阻力研究

为进一步揭示砧木的矮化机理 ,以SH系矮化砧木及相应中间砧红富士苹果为试材 ,在生长季测定砧木枝条及嫁接部位的水分输导阻力。结果表明 ,SH系砧木枝条及嫁接部位的水分输导阻力 ,随砧木矮化程度的升高而增大 ,表明水分输导阻力的增加 ,是导致嫁接树矮化的原因之一。     

红三叶的研究和利用

结合国内外有关红三叶研究和利用的科研成果，对红三叶的价值，品种分类，生长特性，混播和施肥技术及利用特点进行了综合分析，指出红三叶在我国，特别是南方地区具有很大的栽培推广潜力。     

CCC对葡萄试管苗生长的影响

ＣＣＣ对葡萄试管苗的茎叶生长有显著的抑制作用，茎的高度、节数及节间长度均有明显减少；ＣＣＣ对生根率没有明显影响，但对插段的生根数量有较大的影响，在一定浓度范围内（２０～８０ｍｇ／Ｌ）ＣＣＣ处理的生根数量有所增加，其中以４０ｍｇ／Ｌ时增加最多，为８．６７～８．９５条／段。但ＣＣＣ对根系伸长有明显的抑制作用，随着ＣＣＣ浓度的升高根长逐渐变短；从干、鲜重的变化来看，ＣＣＣ处理后墓叶的干、鲜重是随着浓度的升高而减少，但根系的干、鲜重在０～４０ｍｇ／Ｌ范围内呈略增加的趋势，４０ｍｇ／Ｌ以后则大幅度减少。     

非线性方程组拟牛顿法中线性搜索的一种改进

改进了Ｇｒｉｅｗａｎｋ（１９８６）提出了关于求解非线性方程组的一种线性搜索方式。在理论上保证了线性搜索的实现,使得算法是适定的,而且,在改进的线性搜索条件下,Ｂｒｏｙｄｅｎ算法仍具有全局收敛性和局部超线性收敛性。     

Carbon storage by urban tree cultivars, in roots and above-ground

Urban trees can favorably affect factors underlying global warming by storing carbon and by reducing energy needs for cooling and heating buildings. To estimate carbon stored in roots and above-ground portions of trees, data was collected consisting of whole tree sampling of Amelanchier, Malus, Pyrus, and Syringa cultivars. Roots were excavated using an Air-Spade^™. Regression analysis resulted in two equations for predicting total carbon storage based on height and diameter of trees up to 20 cm dbh: Y = 0.05836 (dbh²) for root carbon storage, and Y = 0.0305 (dbh² × h)^0.9499 for above-ground carbon storage, explaining 97% and 96% of the variation, respectively. Average carbon stored in roots of various cultivars ranged from 0.3 to 1.0 kg for smaller trees, those 3.8 to 6.4 cm dbh, to more than 10.4 kg for trees 14.0 cm to 19.7 cm dbh. Average total carbon stored by cultivars ranged from 1.7 to 3.6 kg for trees less than 6.4 cm dbh to 54.5 kg for trees larger than 14.0 cm. The data from these equations apply mainly to trees in nurseries and recently transplanted trees. Comparisons showed that above-ground estimates from previous studies using a sampling technique overestimated values obtained from actual above-ground weights.