不同离海距离木麻黄防护林单木健康评价

单木健康评价是森林健康监测的重要组分。强烈的沿海梯度环境造成我国沿海重要的人工防护林出现不同程度受损,但因忽视在生态系统脆弱情况下生长的树木健康情况,使得单木尺度和不同离海距离的健康评价研究甚少。为此,本研究以沿海木麻黄防护林为研究对象,将其离海距离由近到远划分为5个梯度,建立了由根部受损程度、冠层落叶度、树冠透视度、树冠重叠度、树冠枯梢比重、树冠层比重和树冠偏斜度等指标构成的单木健康评价体系。结果表明：沿海木麻黄防护林单木健康情况整体较差,17.78%的林木处于不健康等级,仅有4.44%的林木处于优质健康等级;由海岸向林地内部,木麻黄防护林表现出明显的健康变化趋势,距海越远,木麻黄单木健康程度越高;第1梯度不健康等级林木达33.33%,显著多于第2梯度（P<0.05）,且没有优质健康等级的林木,而第5梯度不健康等级林木显著少于第3和第4梯度（P<0.05）,且健康及以上等级林木占比93.33%。研究结果为沿海木麻黄防护林的健康管理提供依据。

Single-wood Health Assessment in Casuarina Protection Forests at Different Distances from the Coastline

Single-wood health assessment is an important part of forest health monitoring. Coast protect forest is one of the critical plantation ecosystems in China, which is damaged to some extent in a strong variation environment with intense differences from the ocean to the land. But, at present the research on the assessment of forest health in a single-wood scale and in different distances from the coast line is so scarce due to overlooking the health of the trees growing in the weakness of the ecosystem. In order to make up the gap, we took different Casuarina forests as the study objects, divided their distances into five gradients from near to far, which was from the forest edge facing the sea to the forest interior, and established a single-wood health assessment system including the indexes of root damage, crown deciduous degree, canopy transparency, crown overlap, crown dieback, canopy weight and crown deviation. The overall health of single-wood trees in the coastal Casuarina forest was poor with 17.78% unhealthy and only 4.44% in good health. The different gradients of the coastal Casuarina forest showed obvious significant from the coast forest trees to the interior ones. The unhealthy grade trees in the first gradient were up to 33.33%, which was significantly more than that in the second one (P<0.05), and there were no high grade trees. The unhealthy trees in the fifth gradient were significantly less than that in the third and fourth gradients (P<0.05) with 93.33% of the health and above grades. The study would lay a basis for the health management of coastal Casuarina protection forests.