早古(gu)生(sheng)代時(距今(jin)5.7億(yi)年前(qian)(qian)(qian)~4.4億(yi)年前(qian)(qian)(qian)),雷(lei)州(zhou)半島與(yu)海(hai)南(nan)(nan)(nan)島地(di)區是一(yi)個(ge)沉降帶。加里東造(zao)山運(yun)動(dong)(dong)使雷(lei)瓊地(di)區上(shang)升成陸(lu),形成以(yi)(yi)東北方(fang)向(xiang)為主的(de)(de)一(yi)系列斷(duan)裂褶(zhe)皺帶,使早古(gu)生(sheng)代沉積(ji)的(de)(de)地(di)層(ceng)發生(sheng)了質變(bian)。到晚古(gu)生(sheng)代(距今(jin)4.4億(yi)年前(qian)(qian)(qian)~2.3億(yi)年前(qian)(qian)(qian)),海(hai)南(nan)(nan)(nan)島陸(lu)塊相(xiang)對穩定。但印支運(yun)動(dong)(dong)又促使巖漿(jiang)活動(dong)(dong)強烈,形成海(hai)南(nan)(nan)(nan)島廣泛分(fen)(fen)布的(de)(de)花崗巖體,構(gou)成了山地(di),也筑成了海(hai)南(nan)(nan)(nan)島的(de)(de)基礎。后來的(de)(de)燕山運(yun)動(dong)(dong)和喜馬拉雅(ya)運(yun)動(dong)(dong)又使這個(ge)花崗巖穹窿發生(sheng)強烈的(de)(de)斷(duan)裂,形成幾條大(da)(da)(da)的(de)(de)東西(xi)向(xiang)斷(duan)裂帶,使斷(duan)裂以(yi)(yi)南(nan)(nan)(nan)大(da)(da)(da)約三分(fen)(fen)之(zhi)二(er)的(de)(de)區域抬(tai)升,稱為海(hai)南(nan)(nan)(nan)構(gou)造(zao)隆起,且1億(yi)多年以(yi)(yi)來一(yi)直在(zai)(zai)(zai)上(shang)升;斷(duan)裂以(yi)(yi)北發生(sheng)下陷(xian),稱為雷(lei)瓊凹陷(xian)。然而,在(zai)(zai)(zai)第四紀以(yi)(yi)前(qian)(qian)(qian)(250萬(wan)(wan)年前(qian)(qian)(qian)),海(hai)南(nan)(nan)(nan)島和雷(lei)州(zhou)半島還連在(zai)(zai)(zai)一(yi)起,在(zai)(zai)(zai)地(di)質構(gou)造(zao)上(shang)屬華夏地(di)塊的(de)(de)延伸部分(fen)(fen)。到了大(da)(da)(da)約更新世(距今(jin)250萬(wan)(wan)年前(qian)(qian)(qian)~1.5萬(wan)(wan)年前(qian)(qian)(qian))中期,由于火(huo)山活動(dong)(dong),雷(lei)州(zhou)半島和海(hai)南(nan)(nan)(nan)島之(zhi)間(jian)發生(sheng)了斷(duan)陷(xian),變(bian)成了瓊州(zhou)海(hai)峽(xia),才(cai)使海(hai)南(nan)(nan)(nan)島與(yu)大(da)(da)(da)陸(lu)分(fen)(fen)開。以(yi)(yi)后海(hai)平(ping)面(mian)多次(ci)升降又使海(hai)南(nan)(nan)(nan)島與(yu)大(da)(da)(da)陸(lu)多次(ci)分(fen)(fen)離和相(xiang)連,到第四紀冰期結束(shu),海(hai)平(ping)面(mian)大(da)(da)(da)幅度上(shang)升,才(cai)形成瓊州(zhou)海(hai)峽(xia)和海(hai)南(nan)(nan)(nan)島的(de)(de)形態。
地質(zhi)構造運動引起的(de)海(hai)南構造隆起是海(hai)南島(dao)(dao)中部不斷抬升,逐(zhu)漸形成了(le)海(hai)南島(dao)(dao)的(de)地貌特征;山地位于中央(yang),丘(qiu)陵、臺地、平(ping)原依次環(huan)繞四周。海(hai)南島(dao)(dao)平(ping)均(jun)海(hai)拔(ba)120米(mi)。500米(mi)以上(shang)的(de)山地占全(quan)島(dao)(dao)的(de)25%,100米(mi)以上(shang)的(de)平(ping)原、臺地占三分之(zhi)二。
也有(you)學者認為,海(hai)南島是2400萬年前開始從(cong)中(zhong)國(guo)北部灣分離旋(xuan)轉漂移(yi)出去的,海(hai)南島從(cong)原始位置逆時針旋(xuan)轉了約150度達到當(dang)前位置,仍在左(zuo)旋(xuan)向東(dong)南漂移(yi)中(zhong)。
海南島(dao)地(di)(di)質(zhi)構(gou)造(zao)形(xing)態在空間分布(bu)上,以各種不同的(de)(de)方向(xiang)、形(xing)跡和性質(zhi)的(de)(de)構(gou)造(zao)組(zu)合,形(xing)成(cheng)東(dong)西(xi)向(xiang)構(gou)造(zao)、南北(bei)向(xiang)構(gou)造(zao)、北(bei)東(dong)向(xiang)構(gou)造(zao)、北(bei)西(xi)向(xiang)構(gou)造(zao)等主要構(gou)造(zao)體系,成(cheng)為陸地(di)(di)的(de)(de)主要構(gou)造(zao)格(ge)局,控制著(zhu)島(dao)陸沉積建造(zao)、巖漿活動、成(cheng)礦作(zuo)用及晚近時期(qi)的(de)(de)山川地(di)(di)勢(shi)的(de)(de)展布(bu)。
海南島縱(zong)深地(di)質構造(zao)表現為(wei)(wei)地(di)幔(man)隆(long)起背景(jing)上的凹陷區,幔(man)凹中心在瓊(qiong)中至樂東一帶,幔(man)凹深度為(wei)(wei)30多公里。由于島內地(di)殼結構和(he)(he)深部構造(zao)的差異,在地(di)質構造(zao)、沉積建造(zao)和(he)(he)巖漿活動等方面,都呈現出許多不同的特征。
海南(nan)巖(yan)(yan)(yan)石有火成巖(yan)(yan)(yan)(巖(yan)(yan)(yan)漿巖(yan)(yan)(yan))、水成巖(yan)(yan)(yan)(沉(chen)積巖(yan)(yan)(yan))、變質巖(yan)(yan)(yan)3大類,遍布全省(sheng)各地。
海南島(dao)四周低(di)平(ping),中間高聳(song),呈穹隆山(shan)地(di)形,以五指山(shan)、鸚哥嶺為(wei)隆起核(he)心,向外圍逐級(ji)下降,由(you)山(shan)地(di)、丘陵、臺地(di)、平(ping)原(yuan)構成環形層狀(zhuang)地(di)貌,梯級(ji)結構明顯。
海(hai)南(nan)島(dao)(dao)地(di)貌以(yi)山(shan)(shan)地(di)和(he)丘(qiu)陵(ling)為(wei)主(zhu),占全(quan)島(dao)(dao)面積(ji)的38.7%。山(shan)(shan)地(di)主(zhu)要(yao)分布在島(dao)(dao)中部偏南(nan)地(di)區(qu),山(shan)(shan)地(di)中散布著丘(qiu)陵(ling)性盆地(di)。丘(qiu)陵(ling)主(zhu)要(yao)分布在島(dao)(dao)內陸和(he)西北、西南(nan)部等地(di)區(qu)。在山(shan)(shan)地(di)丘(qiu)陵(ling)周圍(wei),廣泛分布著寬窄(zhai)不一的臺地(di)和(he)階(jie)地(di),占全(quan)島(dao)(dao)總(zong)面積(ji)的49.5%。環島(dao)(dao)多(duo)為(wei)濱海(hai)平(ping)原(yuan),占全(quan)島(dao)(dao)總(zong)面積(ji)的11.2%。海(hai)岸(an)主(zhu)要(yao)為(wei)火山(shan)(shan)玄武巖臺地(di)的海(hai)蝕(shi)堆(dui)(dui)積(ji)海(hai)岸(an)、由溺(ni)谷(gu)演變而成的小港灣或堆(dui)(dui)積(ji)地(di)貌海(hai)岸(an)、沙堤(di)圍(wei)繞的海(hai)積(ji)階(jie)地(di)海(hai)岸(an)。海(hai)岸(an)生態以(yi)熱帶紅樹林海(hai)岸(an)和(he)珊瑚礁(jiao)海(hai)岸(an)為(wei)特點。
山地
海(hai)南(nan)(nan)島(dao)的山(shan)(shan)(shan)地位于島(dao)中(zhong)部(bu)偏南(nan)(nan),北(bei)界(jie)為(wei)光雅(ya)、儋州、仁興、屯昌、烏坡、龍塘,南(nan)(nan)界(jie)為(wei)長茅、田(tian)獨、保亭、光坡,東(dong)(dong)界(jie)至東(dong)(dong)升、軍田(tian)、興隆,西(xi)界(jie)達昌江、大田(tian)、尖(jian)峰等,面(mian)積8639平(ping)方公(gong)里(li),占(zhan)全島(dao)面(mian)積的25.1%。中(zhong)部(bu)山(shan)(shan)(shan)地在海(hai)拔500米以(yi)(yi)上(shang),是海(hai)南(nan)(nan)地貌的骨(gu)架,以(yi)(yi)中(zhong)山(shan)(shan)(shan)(800米以(yi)(yi)上(shang))為(wei)主(zhu)(zhu),面(mian)積6067.6平(ping)方公(gong)里(li),占(zhan)山(shan)(shan)(shan)地的7成強(qiang);低山(shan)(shan)(shan)(500~800米)只有(you)(you)2571.4平(ping)方公(gong)里(li),占(zhan)近3成。山(shan)(shan)(shan)體(ti)主(zhu)(zhu)要(yao)(yao)由花(hua)崗巖組成,山(shan)(shan)(shan)形高峻而圓渾。山(shan)(shan)(shan)脈大體(ti)分(fen)為(wei)3列,均東(dong)(dong)北(bei)—西(xi)南(nan)(nan)走向(xiang):東(dong)(dong)列為(wei)五(wu)指(zhi)山(shan)(shan)(shan)山(shan)(shan)(shan)脈,主(zhu)(zhu)要(yao)(yao)山(shan)(shan)(shan)峰有(you)(you)自馬嶺(ling)(ling)(ling)(ling)(ling)、五(wu)指(zhi)山(shan)(shan)(shan)、吊羅山(shan)(shan)(shan)、七指(zhi)嶺(ling)(ling)(ling)(ling)(ling)、馬咀嶺(ling)(ling)(ling)(ling)(ling)等;中(zhong)列為(wei)黎母嶺(ling)(ling)(ling)(ling)(ling)山(shan)(shan)(shan)脈,主(zhu)(zhu)要(yao)(yao)山(shan)(shan)(shan)峰有(you)(you)黎母嶺(ling)(ling)(ling)(ling)(ling)、鸚哥嶺(ling)(ling)(ling)(ling)(ling)、猴獼(mi)嶺(ling)(ling)(ling)(ling)(ling)、尖(jian)峰嶺(ling)(ling)(ling)(ling)(ling)等;西(xi)列為(wei)雅(ya)加大嶺(ling)(ling)(ling)(ling)(ling)山(shan)(shan)(shan)脈,主(zhu)(zhu)要(yao)(yao)山(shan)(shan)(shan)峰有(you)(you)雅(ya)加大嶺(ling)(ling)(ling)(ling)(ling)、霸王嶺(ling)(ling)(ling)(ling)(ling)和仙(xian)婆嶺(ling)(ling)(ling)(ling)(ling)等。
丘陵盆地
海南環(huan)山丘陵帶(dai)面積(ji)不大(da),僅占海南島面積(ji)的13.1%。丘陵地(di)中(zhong)也有(you)較高的齊頂(ding)面或和(he)緩的山頂(ding)面,常(chang)見的為(wei)450米、350米、250米三級。丘陵之間(jian)的盆地(di),如白沙盆地(di)、屯昌(chang)盆地(di)、樂東盆地(di)和(he)瓊海石壁盆地(di)等(deng),光、熱(re)、水(shui)(shui)、土(tu)及各種生態(tai)條件優越(yue),是(shi)農作(zuo)(zuo)物和(he)經濟林木生長的良好(hao)環(huan)境。海拔350米以下的低(di)丘、谷地(di)、盆地(di)內,有(you)充足雨(yu)量和(he)河水(shui)(shui)的滋潤(run),土(tu)質(zhi)很好(hao),又具(ju)備防風(feng)條件,非常(chang)適宜于(yu)發展天然橡膠(jiao)和(he)熱(re)帶(dai)經濟作(zuo)(zuo)物,因而環(huan)山丘陵帶(dai)成為(wei)海南橡膠(jiao)熱(re)作(zuo)(zuo)分布(bu)帶(dai),也是(shi)中(zhong)國(guo)最大(da)的橡膠(jiao)熱(re)作(zuo)(zuo)基(ji)地(di)。
臺地階地
海南(nan)島(dao)的(de)臺地(di)在各(ge)類地(di)貌中所占比例最大,約占全島(dao)總面積的(de)三分之(zhi)一。寬廣的(de)臺地(di)主要分布在瓊北地(di)區(qu),可分為海拔20米和40~50米2級,逐漸(jian)向海傾斜。
臺(tai)(tai)(tai)地(di)(di)(di)地(di)(di)(di)貌(mao)(mao)類型(xing)多樣化(hua),有玄(xuan)(xuan)(xuan)(xuan)武(wu)巖(yan)臺(tai)(tai)(tai)地(di)(di)(di)、花崗(gang)巖(yan)臺(tai)(tai)(tai)地(di)(di)(di)、紅(hong)巖(yan)臺(tai)(tai)(tai)地(di)(di)(di)、變質巖(yan)臺(tai)(tai)(tai)地(di)(di)(di),其中(zhong)玄(xuan)(xuan)(xuan)(xuan)武(wu)巖(yan)臺(tai)(tai)(tai)地(di)(di)(di)面積最大(da)(da),達(da)4159平(ping)方公(gong)里,占(zhan)臺(tai)(tai)(tai)地(di)(di)(di)總面積近四成(cheng)(cheng)。在玄(xuan)(xuan)(xuan)(xuan)武(wu)巖(yan)臺(tai)(tai)(tai)地(di)(di)(di)上,分布(bu)著典(dian)型(xing)的(de)(de)火(huo)山(shan)(shan)熔(rong)巖(yan)地(di)(di)(di)貌(mao)(mao),是由(you)于地(di)(di)(di)質史(shi)上新(xin)生代晚第(di)(di)三紀至第(di)(di)四紀的(de)(de)新(xin)構造運動(dong)(dong)時期,雷瓊地(di)(di)(di)區(qu)火(huo)山(shan)(shan)活動(dong)(dong)頻(pin)繁,并(bing)多次(ci)沿斷裂帶發生大(da)(da)規模的(de)(de)巖(yan)漿(jiang)噴發熔(rong)巖(yan)流動(dong)(dong),形成(cheng)(cheng)海(hai)南島北(bei)部(bu)遍(bian)布(bu)著成(cheng)(cheng)群(qun)的(de)(de)古火(huo)山(shan)(shan)錐及大(da)(da)面積覆蓋的(de)(de)玄(xuan)(xuan)(xuan)(xuan)武(wu)巖(yan)。火(huo)山(shan)(shan)錐有101個,噴火(huo)口(kou)有110多個,最典(dian)型(xing)的(de)(de)是瓊山(shan)(shan)西部(bu)的(de)(de)石(shi)山(shan)(shan)、永興(xing)一帶數十座火(huo)山(shan)(shan)口(kou)和遍(bian)地(di)(di)(di)流巖(yan)。玄(xuan)(xuan)(xuan)(xuan)武(wu)巖(yan)臺(tai)(tai)(tai)地(di)(di)(di)是火(huo)山(shan)(shan)噴發的(de)(de)熔(rong)巖(yan)在地(di)(di)(di)表流動(dong)(dong)、層(ceng)疊(die)而成(cheng)(cheng)的(de)(de)低平(ping)臺(tai)(tai)(tai)地(di)(di)(di),俗稱“石(shi)地(di)(di)(di)”,如(ru)瓊山(shan)(shan)羊山(shan)(shan)地(di)(di)(di)區(qu)、儋州(zhou)木棠、定安龍塘等地(di)(di)(di)都有大(da)(da)片這種地(di)(di)(di)貌(mao)(mao),土(tu)壤厚(hou)度小(xiao),但土(tu)質肥(fei)沃(wo)。熔(rong)巖(yan)地(di)(di)(di)貌(mao)(mao)還(huan)(huan)形成(cheng)(cheng)熔(rong)巖(yan)隧(sui)道(dao),如(ru)瓊山(shan)(shan)石(shi)山(shan)(shan)地(di)(di)(di)區(qu)已(yi)發現(xian)“仙人洞”、“臥龍洞”等隧(sui)道(dao)11條(tiao),一般寬10多米(mi)(mi),高2~4米(mi)(mi),最長(chang)的(de)(de)1200多米(mi)(mi),總長(chang)度達(da)3574米(mi)(mi),成(cheng)(cheng)為當(dang)地(di)(di)(di)的(de)(de)自然奇觀。還(huan)(huan)有不少臺(tai)(tai)(tai)地(di)(di)(di)是由(you)海(hai)蝕作用所成(cheng)(cheng),如(ru)樂東黎族自治縣九所東北(bei)的(de)(de)石(shi)門(men)嶺(ling)下花崗(gang)巖(yan)石(shi)蛋地(di)(di)(di)貌(mao)(mao)中(zhong),保留著明顯的(de)(de)海(hai)蝕地(di)(di)(di)形,如(ru)菌狀石(shi)、石(shi)柱、石(shi)詹(zhan)、石(shi)鍋、蜂巢狀海(hai)穴群(qun)、額狀崖等。
沿海平原
海(hai)南島沿海(hai)平原帶(dai)是海(hai)南島地貌環帶(dai)結構的最外一環,面(mian)積(ji)7800多(duo)平方公里,由海(hai)岸平原、潟湖(hu)平原、三角洲平原3種(zhong)地貌組成。
海(hai)(hai)岸(an)平原,由(you)多條沙(sha)(sha)堤(di)和于涸(he)低(di)洼(wa)潟(xi)湖沼澤(ze)相(xiang)間組(zu)成(cheng),地勢(shi)起伏,高(gao)處(chu)是(shi)沙(sha)(sha)堤(di),土質沙(sha)(sha)性,生(sheng)長耐(nai)旱植物(wu);低(di)處(chu)是(shi)灰黑色沼澤(ze)地,土質較(jiao)粘(zhan)。如樂東鶯(ying)歌海(hai)(hai)一帶,西(xi)岸(an)形成(cheng)南北(bei)走向(xiang)(xiang)沙(sha)(sha)堤(di)群,南岸(an)卻形成(cheng)東西(xi)走向(xiang)(xiang)沙(sha)(sha)堤(di),使鶯(ying)歌海(hai)(hai)沙(sha)(sha)堤(di)群由(you)2組(zu)不同走向(xiang)(xiang)的(de)沙(sha)(sha)堤(di)合成(cheng),呈三角形岬角突入海(hai)(hai)中,沙(sha)(sha)堤(di)內成(cheng)為一潟(xi)湖洼(wa)地。
潟(xi)湖(hu)平原(yuan),在海(hai)(hai)岸(an)沙(sha)(sha)堤后(hou)方(fang),以東海(hai)(hai)岸(an)的文(wen)昌(chang)、瓊(qiong)海(hai)(hai)、萬寧等沿(yan)海(hai)(hai)最典型。海(hai)(hai)南最大(da)的潟(xi)湖(hu)萬寧小(xiao)海(hai)(hai),是海(hai)(hai)灣被(bei)一大(da)沙(sha)(sha)堤隔開(kai)而形成(cheng)的,但尚未干(gan)涸成(cheng)洼地,故(gu)成(cheng)典型的大(da)潟(xi)湖(hu)。其他潟(xi)湖(hu)區(qu)多被(bei)風沙(sha)(sha)堆積填干(gan)而成(cheng)為平原(yuan),其表層(ceng)為沙(sha)(sha)土(tu)層(ceng),往下為粘(zhan)土(tu)層(ceng)、黑色潟(xi)湖(hu)粘(zhan)土(tu)層(ceng),以及部分泥炭土(tu)。
三角(jiao)洲(zhou)平(ping)原,在江(jiang)(jiang)河(he)出口處由泥沙堆積(ji)而成(cheng),但海(hai)南島山林茂密,河(he)流含(han)沙量不(bu)大,絕(jue)大多(duo)數(shu)江(jiang)(jiang)河(he)出口沉積(ji)物堆疊不(bu)厚,如昌化江(jiang)(jiang)、萬泉河(he)、陵(ling)水河(he)等河(he)口都僅停留在三角(jiao)洲(zhou)的(de)雛形或河(he)口平(ping)原狀態(tai),典型的(de)三角(jiao)洲(zhou)只有位于海(hai)口市的(de)南渡江(jiang)(jiang)口三角(jiao)洲(zhou),還(huan)有儋州西北瀕臨(lin)北部灣的(de)北門河(he)三角(jiao)洲(zhou)。
南渡江三角洲是(shi)海南最大的三角洲,是(shi)由南渡江口的古溺谷灣,經千萬年淤積含有(you)貝(bei)類的細(xi)沙(sha)泥等海相、河(he)相沉(chen)積物而成。
海岸
海(hai)南省海(hai)岸線(xian)總長(chang)1927.6公(gong)里,其中海(hai)南島海(hai)岸線(xian)長(chang)約1618公(gong)里, (新數(shu)據(ju)為(wei)1823)海(hai)岸線(xian)系(xi)數(shu)為(wei)0.0477。
海(hai)(hai)南島熱帶海(hai)(hai)岸地貌(mao)主(zhu)要有砂堤堆積、海(hai)(hai)灘巖、紅樹林海(hai)(hai)岸、珊瑚礁海(hai)(hai)岸、港灣地貌(mao)5類。
紅(hong)色(se)砂(sha)(sha)堤(di)堆(dui)積(ji),海(hai)南地(di)處(chu)熱(re)帶(dai),海(hai)岸(an)沙灘(tan)和砂(sha)(sha)堤(di)中的(de)鐵質氧化(hua)充分,使砂(sha)(sha)堤(di)成為(wei)(wei)赤紅(hong)色(se)堆(dui)積(ji)(年代屬晚更新世)。如(ru)陵(ling)水新村淌湖和黎(li)安(an)港(gang)之間(jian)的(de)紅(hong)色(se)砂(sha)(sha)堤(di),由鳳凰山腳延伸(shen)下來,披(pi)覆(fu)在白色(se)沙灘(tan)上(shang),并膠結成堅硬的(de)紅(hong)砂(sha)(sha)巖(yan)。樂東(dong)九所到(dao)昌(chang)江昌(chang)化(hua)一帶(dai)海(hai)岸(an)和文昌(chang)的(de)海(hai)岸(an)都有這(zhe)種(zhong)紅(hong)色(se)砂(sha)(sha)堤(di)地(di)貌。在正對(dui)著東(dong)北季(ji)風(feng)的(de)瓊(qiong)東(dong)北海(hai)岸(an),從文昌(chang)木蘭頭到(dao)抱(bao)虎港(gang)的(de)砂(sha)(sha)堤(di)上(shang),海(hai)岸(an)風(feng)沙堆(dui)積(ji)日益加(jia)高(gao)(gao),發育出風(feng)成砂(sha)(sha)丘巖(yan)層,砂(sha)(sha)堤(di)長達30多公(gong)里,最高(gao)(gao)點昌(chang)灑湖塘坡達58米(mi)多,其高(gao)(gao)大壯觀(guan)為(wei)(wei)全(quan)國所罕見。
沙灘(tan)上(shang)的(de)海(hai)灘(tan)巖(yan)(yan),在(zai)海(hai)灘(tan)上(shang)從灘(tan)面到海(hai)面,由(you)于陽光(guang)強烈照射,水(shui)中鈣質飽和析出(chu),把(ba)砂子膠結成(cheng)一(yi)層堅硬(ying)的(de)粗砂巖(yan)(yan)和礫巖(yan)(yan),厚度一(yi)般(ban)在(zai)2米以下。這(zhe)種鈣質膠結砂層即(ji)海(hai)灘(tan)巖(yan)(yan),巖(yan)(yan)層向(xiang)海(hai)傾斜,被風浪打碎后形成(cheng)巖(yan)(yan)石(shi)堆或巨大礁塊,是鮑魚棲(qi)息的(de)好地(di)方。若(ruo)海(hai)岸被沖蝕后退,海(hai)灘(tan)巖(yan)(yan)層能保存在(zai)離岸的(de)淺水(shui)中,例如樂(le)東(dong)縣鶯歌海(hai)岸外兩三百米處的(de)礁石(shi)。
熱(re)(re)帶紅(hong)(hong)樹(shu)(shu)林(lin)海(hai)(hai)岸(an)(an),紅(hong)(hong)樹(shu)(shu)林(lin)海(hai)(hai)岸(an)(an)是(shi)特(te)殊的(de)熱(re)(re)帶生(sheng)物海(hai)(hai)岸(an)(an)地貌,分(fen)布于港(gang)(gang)灣(wan)內靜風環(huan)境(jing)的(de)泥灘(tan)上,風浪大(da)的(de)沙(sha)灘(tan)不能生(sheng)長紅(hong)(hong)樹(shu)(shu)林(lin)。較發育的(de)紅(hong)(hong)樹(shu)(shu)林(lin)海(hai)(hai)岸(an)(an)主要(yao)分(fen)布在瓊山東寨港(gang)(gang),文(wen)昌鋪(pu)前港(gang)(gang)和(he)清(qing)瀾港(gang)(gang)內部、馮家港(gang)(gang)南(nan)北(bei),臨高(gao)新盈港(gang)(gang)內,儋州新英港(gang)(gang)內和(he)澄邁馬裊港(gang)(gang)等處。此外,在海(hai)(hai)口、瓊海(hai)(hai)、三亞、陵水等市縣也有小片分(fen)布。海(hai)(hai)南(nan)紅(hong)(hong)樹(shu)(shu)林(lin)種類多,樹(shu)(shu)型高(gao),生(sheng)長快,數量和(he)面積皆(jie)為全國之(zhi)冠,被譽為“海(hai)(hai)上森林(lin)”、“海(hai)(hai)岸(an)(an)衛士”。
環島(dao)(dao)珊(shan)瑚(hu)(hu)礁(jiao)(jiao)海(hai)(hai)(hai)(hai)岸,珊(shan)瑚(hu)(hu)礁(jiao)(jiao)是(shi)熱帶淺(qian)(qian)水造(zao)礁(jiao)(jiao)珊(shan)瑚(hu)(hu)蟲(chong)群(qun)體骨骼和其(qi)他石(shi)灰質生(sheng)(sheng)物(wu)(wu)遺體長期堆積而成(cheng),也屬(shu)(shu)典型的(de)(de)熱帶生(sheng)(sheng)物(wu)(wu)海(hai)(hai)(hai)(hai)岸地(di)(di)貌。珊(shan)瑚(hu)(hu)一般生(sheng)(sheng)長在(zai)(zai)海(hai)(hai)(hai)(hai)水透明(ming)、無泥(ni)、有浪(lang)的(de)(de)淺(qian)(qian)水域(yu),能(neng)在(zai)(zai)海(hai)(hai)(hai)(hai)岸上(shang)連(lian)成(cheng)一片礁(jiao)(jiao)盤(平臺(tai))地(di)(di)形,實際上(shang)是(shi)一個巨大的(de)(de)石(shi)灰質生(sheng)(sheng)物(wu)(wu)群(qun)體,在(zai)(zai)長期不斷的(de)(de)生(sheng)(sheng)長過程中,形成(cheng)特(te)殊(shu)的(de)(de)珊(shan)瑚(hu)(hu)礁(jiao)(jiao)海(hai)(hai)(hai)(hai)岸類型,厚(hou)度不過10米左右(you),下面即(ji)是(shi)沙泥(ni)層或基(ji)巖,屬(shu)(shu)全新世海(hai)(hai)(hai)(hai)侵相。珊(shan)瑚(hu)(hu)岸礁(jiao)(jiao)有保護(hu)海(hai)(hai)(hai)(hai)岸不受(shou)波浪(lang)侵蝕的(de)(de)作(zuo)用,又是(shi)魚類水產品集中生(sheng)(sheng)長的(de)(de)地(di)(di)點,故礁(jiao)(jiao)區生(sheng)(sheng)產力(li)比河(he)口(kou)區大,平均可(ke)達(da)4000克/平方米·年。海(hai)(hai)(hai)(hai)南島(dao)(dao)淺(qian)(qian)水造(zao)礁(jiao)(jiao)珊(shan)瑚(hu)(hu)種(zhong)(zhong)類多(duo)達(da)110多(duo)種(zhong)(zhong),環島(dao)(dao)海(hai)(hai)(hai)(hai)岸環境極適宜其(qi)生(sheng)(sheng)長,因而珊(shan)瑚(hu)(hu)礁(jiao)(jiao)特(te)別發育,生(sheng)(sheng)長帶可(ke)達(da)2000米寬,位居(ju)全國第一。
沙(sha)(sha)質(zhi)(zhi)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an),主要分(fen)布(bu)于沙(sha)(sha)壩(ba)潟湖(hu)和三角洲(zhou)平(ping)原沿岸(an)(an)(an)(an)(an)。在(zai)抱(bao)虎(hu)(hu)角~大(da)花(hua)(hua)角岸(an)(an)(an)(an)(an)段(duan),沙(sha)(sha)質(zhi)(zhi)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an)占絕大(da)部分(fen),約(yue)250公(gong)(gong)(gong)(gong)(gong)里(li)岸(an)(an)(an)(an)(an)段(duan)為(wei)沙(sha)(sha)質(zhi)(zhi)潟湖(hu)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an),集中分(fen)布(bu)在(zai)抱(bao)虎(hu)(hu)角至銅鼓(gu)咀、博鰲(ao)至大(da)花(hua)(hua)角兩個(ge)岸(an)(an)(an)(an)(an)段(duan)。在(zai)大(da)花(hua)(hua)角~梅山岸(an)(an)(an)(an)(an)段(duan),除巖(yan)石(shi)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an)外,其余(yu)基本上為(wei)沙(sha)(sha)質(zhi)(zhi)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an),總(zong)長(chang)(chang)近(jin)300公(gong)(gong)(gong)(gong)(gong)里(li)。梅山~昌(chang)(chang)化江口岸(an)(an)(an)(an)(an)段(duan),沙(sha)(sha)質(zhi)(zhi)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an)以沙(sha)(sha)堤(di)為(wei)主,總(zong)長(chang)(chang)近(jin) 200公(gong)(gong)(gong)(gong)(gong)里(li),幾乎連續分(fen)布(bu)于整(zheng)個(ge)岸(an)(an)(an)(an)(an)段(duan)。昌(chang)(chang)化江口~抱(bao)虎(hu)(hu)角岸(an)(an)(an)(an)(an)段(duan),沙(sha)(sha)質(zhi)(zhi)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an)線總(zong)長(chang)(chang)約(yue)340公(gong)(gong)(gong)(gong)(gong)里(li),其中昌(chang)(chang)化江口~洋浦岸(an)(an)(an)(an)(an)段(duan)長(chang)(chang)約(yue)100公(gong)(gong)(gong)(gong)(gong)里(li),儋州光村(cun)附近(jin)長(chang)(chang)約(yue)20公(gong)(gong)(gong)(gong)(gong)里(li),臨高角附近(jin)長(chang)(chang)約(yue)25公(gong)(gong)(gong)(gong)(gong)里(li),澄邁縣馬村(cun)至文昌(chang)(chang)縣抱(bao)虎(hu)(hu)角岸(an)(an)(an)(an)(an)段(duan)長(chang)(chang)約(yue)170公(gong)(gong)(gong)(gong)(gong)里(li),其余(yu)零星岸(an)(an)(an)(an)(an)段(duan)沙(sha)(sha)質(zhi)(zhi)海(hai)(hai)(hai)岸(an)(an)(an)(an)(an)長(chang)(chang)約(yue)25公(gong)(gong)(gong)(gong)(gong)里(li)。
海灣
海(hai)南(nan)(nan)島四面環海(hai),海(hai)岸線曲折綿長(達1584.6公(gong)里(li))(新數據為(wei)1823公(gong)里(li)),分布大小天(tian)然港(gang)(gang)灣(wan)(wan)(wan)(wan)(wan)78個(ge)(有大小港(gang)(gang)灣(wan)(wan)(wan)(wan)(wan)68個(ge)之說),較(jiao)大的港(gang)(gang)灣(wan)(wan)(wan)(wan)(wan)有北(bei)部的秀英港(gang)(gang)(又稱海(hai)口(kou)港(gang)(gang))、海(hai)口(kou)新港(gang)(gang)、東水(shui)港(gang)(gang)、鋪前港(gang)(gang)、馬(ma)村(cun)(cun)港(gang)(gang),海(hai)南(nan)(nan)灣(wan)(wan)(wan)(wan)(wan)、海(hai)口(kou)灣(wan)(wan)(wan)(wan)(wan)、澄邁灣(wan)(wan)(wan)(wan)(wan)、后水(shui)灣(wan)(wan)(wan)(wan)(wan)、白(bai)沙門等;南(nan)(nan)部的榆林(lin)港(gang)(gang)、三(san)亞(ya)港(gang)(gang)、鐵爐港(gang)(gang)、新村(cun)(cun)港(gang)(gang)、黎(li)安(an)港(gang)(gang),三(san)亞(ya)灣(wan)(wan)(wan)(wan)(wan)、崖州(zhou)灣(wan)(wan)(wan)(wan)(wan)、琊龍灣(wan)(wan)(wan)(wan)(wan)、海(hai)棠灣(wan)(wan)(wan)(wan)(wan)、陵水(shui)灣(wan)(wan)(wan)(wan)(wan)、南(nan)(nan)灣(wan)(wan)(wan)(wan)(wan)、香水(shui)灣(wan)(wan)(wan)(wan)(wan)等,東部的清瀾港(gang)(gang)、博鰲港(gang)(gang)、烏場(chang)港(gang)(gang)、潭門港(gang)(gang),石梅灣(wan)(wan)(wan)(wan)(wan)、日月灣(wan)(wan)(wan)(wan)(wan)、南(nan)(nan)燕灣(wan)(wan)(wan)(wan)(wan)、大花角等;西部的八所港(gang)(gang)、洋浦港(gang)(gang)、白(bai)馬(ma)井港(gang)(gang)、感城港(gang)(gang)、嶺頭港(gang)(gang),洋浦灣(wan)(wan)(wan)(wan)(wan)、北(bei)黎(li)灣(wan)(wan)(wan)(wan)(wan)、棋子灣(wan)(wan)(wan)(wan)(wan)等,港(gang)(gang)灣(wan)(wan)(wan)(wan)(wan)資(zi)源豐富(fu),環境條(tiao)件優越。其中(zhong)海(hai)口(kou)港(gang)(gang)、三(san)亞(ya)港(gang)(gang)、洋浦港(gang)(gang)、八所港(gang)(gang)和清瀾港(gang)(gang)為(wei)海(hai)南(nan)(nan)五大港(gang)(gang)口(kou)。
土壤分布
海(hai)南島(dao)(dao)土壤(rang)(rang)(rang)的水平地(di)(di)(di)帶(dai)(dai)(dai)性(xing)不明(ming)顯,地(di)(di)(di)帶(dai)(dai)(dai)性(xing)土壤(rang)(rang)(rang)為(wei)(wei)磚紅壤(rang)(rang)(rang)。因海(hai)南島(dao)(dao)地(di)(di)(di)勢中(zhong)(zhong)高周低(di),無論成(cheng)土條件(jian),或是(shi)土壤(rang)(rang)(rang)分(fen)(fen)布(bu)(bu),均以(yi)中(zhong)(zhong)南部(bu)山(shan)地(di)(di)(di)為(wei)(wei)中(zhong)(zhong)心向四周遞(di)變。土壤(rang)(rang)(rang)分(fen)(fen)布(bu)(bu)受地(di)(di)(di)形影響極為(wei)(wei)明(ming)顯,全(quan)島(dao)(dao)土壤(rang)(rang)(rang)分(fen)(fen)布(bu)(bu)成(cheng)若干個同心圓,圍(wei)繞(rao)中(zhong)(zhong)部(bu)山(shan)地(di)(di)(di)依次(ci)分(fen)(fen)布(bu)(bu):最外環(huan)(huan)圈是(shi)圍(wei)繞(rao)全(quan)島(dao)(dao)近代(dai)濱(bin)海(hai)階(jie)地(di)(di)(di)分(fen)(fen)布(bu)(bu)的濱(bin)海(hai)沙(sha)土,其(qi)海(hai)拔(ba)(ba)高度(du)僅在1米(mi)以(yi)內;次(ci)外環(huan)(huan)圈為(wei)(wei)地(di)(di)(di)帶(dai)(dai)(dai)性(xing)土壤(rang)(rang)(rang)——磚紅壤(rang)(rang)(rang),主要分(fen)(fen)布(bu)(bu)在階(jie)地(di)(di)(di)、臺地(di)(di)(di)和海(hai)拔(ba)(ba)在350米(mi)(或400米(mi))以(yi)下的丘陵。由于島(dao)(dao)北部(bu)沿海(hai)有較(jiao)(jiao)寬的階(jie)地(di)(di)(di)、臺地(di)(di)(di)和丘陵,因而,島(dao)(dao)北部(bu)土壤(rang)(rang)(rang)分(fen)(fen)布(bu)(bu)的環(huan)(huan)帶(dai)(dai)(dai)較(jiao)(jiao)寬。島(dao)(dao)南部(bu)因山(shan)地(di)(di)(di)位于正(zheng)中(zhong)(zhong)而偏南,甚至直逼海(hai)岸,土壤(rang)(rang)(rang)的環(huan)(huan)帶(dai)(dai)(dai)較(jiao)(jiao)窄。島(dao)(dao)中(zhong)(zhong)南部(bu)山(shan)地(di)(di)(di)為(wei)(wei)黃壤(rang)(rang)(rang),其(qi)海(hai)拔(ba)(ba)在400米(mi)以(yi)上。
植被分布
海(hai)南(nan)的水熱(re)條(tiao)件優越,植(zhi)(zhi)被(bei)的組成種類豐富(fu)多樣,屬熱(re)帶(dai)(dai)及(ji)熱(re)帶(dai)(dai)島(dao)嶼植(zhi)(zhi)被(bei)類型。據調查,海(hai)南(nan)島(dao)的植(zhi)(zhi)物(wu)有(you)259個科,1300多屬,4200種,喬木800多種,其中熱(re)帶(dai)(dai)種類占83%。1995年全省森林(lin)(lin)面積達(da)163.7萬(wan)公(gong)頃(qing),其中天然林(lin)(lin)83.9萬(wan)公(gong)頃(qing),人(ren)工林(lin)(lin)約82.7萬(wan)公(gong)頃(qing),森林(lin)(lin)覆蓋率已(yi)達(da)48.7%。
自然植被
海南的自然植被(bei)有熱帶季雨林(lin)、熱帶雨林(lin)、常綠闊葉林(lin)、紅樹林(lin)、針葉林(lin)、灌叢和草原等(deng)類型(xing)。
(一(yi))熱(re)帶(dai)季雨(yu)林
熱帶季(ji)(ji)(ji)雨(yu)(yu)林(lin)(lin)分布于周期性干、濕季(ji)(ji)(ji)交替(ti)的地(di)區,旱(han)季(ji)(ji)(ji)時(shi)或多或少是落葉的,而在(zai)濕季(ji)(ji)(ji)是常(chang)綠的,海(hai)南的熱帶季(ji)(ji)(ji)雨(yu)(yu)林(lin)(lin)又分為常(chang)綠季(ji)(ji)(ji)雨(yu)(yu)林(lin)(lin)和落葉季(ji)(ji)(ji)雨(yu)(yu)林(lin)(lin)兩種類型。
常綠季(ji)雨(yu)(yu)林,在原生林中(zhong)近似于熱帶雨(yu)(yu)林,但種(zhong)類外貌又(you)比雨(yu)(yu)林遜(xun)色,主要(yao)分布于海拔(ba)750米以下的(de)低山(shan)、丘陵(ling)和臺(tai)地地區(qu),尤以東(dong)南部丘陵(ling)低山(shan)為典(dian)型。主要(yao)珍貴木(mu)材(cai)有:青皮、荔枝(zhi)、蝴蝶樹、鶯歌木(mu)、油(you)楠、黃桐(tong)等。
落葉季雨林,主(zhu)要分布于海南的(de)西(xi)部(bu)(bu)和南部(bu)(bu)海拔500米以(yi)下的(de)丘陵、臺(tai)地上,群落比較低矮。常見的(de)植被有厚(hou)皮樹、麻(ma)櫟、白格、陸國、平脈(mo)稠等(deng)。
(二)熱帶雨林
海南(nan)(nan)島(dao)的(de)熱帶(dai)雨(yu)林(lin)(lin)實際上(shang)是(shi)溝(gou)谷(gu)(gu)(gu)雨(yu)林(lin)(lin)和(he)山(shan)(shan)地(di)(di)(di)(di)雨(yu)林(lin)(lin)。溝(gou)谷(gu)(gu)(gu)雨(yu)林(lin)(lin)分(fen)布于海拔900米以(yi)下的(de)山(shan)(shan)谷(gu)(gu)(gu)地(di)(di)(di)(di)區,如尖峰嶺(ling)(ling)、吊(diao)羅山(shan)(shan)和(he)卡法嶺(ling)(ling)等山(shan)(shan)地(di)(di)(di)(di),主(zhu)要樹(shu)種有:雞毛松、蝴(hu)蝶樹(shu)、母(mu)生(sheng)(sheng)、綠楠(nan)、海南(nan)(nan)楊桐等。山(shan)(shan)地(di)(di)(di)(di)雨(yu)林(lin)(lin),多(duo)分(fen)布于海拔750~1200米之間,在尖峰嶺(ling)(ling)、獼猴嶺(ling)(ling)、馬域嶺(ling)(ling)和(he)吊(diao)羅山(shan)(shan)等地(di)(di)(di)(di),面積較大,且(qie)多(duo)為原生(sheng)(sheng)性森林(lin)(lin),主(zhu)要樹(shu)種有:陸(lu)均(jun)松、稠木、坡壘(lei)、子(zi)京、花梨、油丹等。溝(gou)谷(gu)(gu)(gu)雨(yu)林(lin)(lin)和(he)山(shan)(shan)地(di)(di)(di)(di)雨(yu)林(lin)(lin)是(shi)海南(nan)(nan)島(dao)的(de)重要水源林(lin)(lin),同時又是(shi)熱帶(dai)的(de)珍貴用材林(lin)(lin)和(he)藥材生(sheng)(sheng)產基地(di)(di)(di)(di)。
(三)常(chang)綠闊葉林
常綠(lv)闊葉(xie)林分布(bu)于海(hai)南(nan)(nan)(nan)島的(de)山(shan)地(di)(di)上(shang),是一種(zhong)(zhong)山(shan)地(di)(di)垂直(zhi)分布(bu)的(de)類(lei)型,一般分布(bu)于海(hai)拔(ba)1000米以上(shang)的(de)山(shan)地(di)(di),可分為山(shan)地(di)(di)常綠(lv)闊葉(xie)林和山(shan)頂(ding)矮林。前者(zhe)的(de)樹種(zhong)(zhong)有:陸均(jun)松、海(hai)南(nan)(nan)(nan)楊(yang)桐、海(hai)南(nan)(nan)(nan)五(wu)(wu)針松、栲、黃背(bei)櫟;后者(zhe)的(de)樹種(zhong)(zhong)有:櫟子(zi)稠、五(wu)(wu)裂木、厚皮香、栲、冬(dong)青、海(hai)南(nan)(nan)(nan)杜(du)鵑等(deng)。山(shan)地(di)(di)常綠(lv)闊葉(xie)林和山(shan)頂(ding)矮林也(ye)是海(hai)南(nan)(nan)(nan)島重要的(de)水(shui)源林之一。
(四)紅樹林
海(hai)(hai)(hai)(hai)(hai)南的(de)紅(hong)(hong)樹(shu)(shu)(shu)林(lin)(lin)(lin)分(fen)(fen)為海(hai)(hai)(hai)(hai)(hai)灘紅(hong)(hong)樹(shu)(shu)(shu)林(lin)(lin)(lin)和海(hai)(hai)(hai)(hai)(hai)岸半(ban)紅(hong)(hong)樹(shu)(shu)(shu)林(lin)(lin)(lin)兩(liang)種類(lei)型。海(hai)(hai)(hai)(hai)(hai)灘紅(hong)(hong)樹(shu)(shu)(shu)林(lin)(lin)(lin)分(fen)(fen)布于淤(yu)泥深厚且(qie)較(jiao)閉塞(sai)的(de)海(hai)(hai)(hai)(hai)(hai)灣或河口,高(gao)潮線以(yi)下的(de)地帶,分(fen)(fen)布面積(ji)較(jiao)大的(de)是瓊山東寨港(gang),文昌鋪前港(gang)、清瀾(lan)港(gang),儋州新英港(gang)和陵水新村港(gang)等地。樹(shu)(shu)(shu)種有文紅(hong)(hong)樹(shu)(shu)(shu)、木(mu)欖、紅(hong)(hong)海(hai)(hai)(hai)(hai)(hai)蘭、海(hai)(hai)(hai)(hai)(hai)桑(sang)及木(mu)果楝。海(hai)(hai)(hai)(hai)(hai)岸半(ban)紅(hong)(hong)樹(shu)(shu)(shu)林(lin)(lin)(lin)分(fen)(fen)布于高(gao)潮線以(yi)上的(de)海(hai)(hai)(hai)(hai)(hai)岸地帶,常與紅(hong)(hong)樹(shu)(shu)(shu)林(lin)(lin)(lin)相連呈條(tiao)帶狀分(fen)(fen)布,面積(ji)很(hen)小。主(zhu)要樹(shu)(shu)(shu)種有:黃槿、海(hai)(hai)(hai)(hai)(hai)棠果、海(hai)(hai)(hai)(hai)(hai)芒果、水椰(ye)、草海(hai)(hai)(hai)(hai)(hai)桐、水莞花等。
(五)針葉林
海南(nan)(nan)島的針葉(xie)林(lin)純(chun)林(lin),面積不大,只見于丘陵和臺地(di)(di)上(shang)的南(nan)(nan)亞松和東部濱海臺地(di)(di)沙(sha)土上(shang)的竹柏林(lin),現狀植被中僅有(you)霸王嶺和瓊中縣的松濤等(deng)地(di)(di),保留有(you)天然純(chun)林(lin),樹種以海南(nan)(nan)松為(wei)主。在海南(nan)(nan)的自然植被中,還有(you)灌(guan)叢(cong)、刺灌(guan)叢(cong)和草原(yuan)等(deng)類型。
人工植被
人工植(zhi)被是(shi)人為(wei)經濟(ji)活動(dong)對(dui)土(tu)地(di)利用的(de)產物。海(hai)南島(dao)是(shi)我國熱帶經濟(ji)作(zuo)物發展的(de)主(zhu)要基(ji)地(di),栽培作(zuo)物種(zhong)類豐富,栽培群落多(duo)樣,并以熱帶性為(wei)主(zhu)。主(zhu)要樹種(zhong)有(you)木麻黃、桉樹,組成沿海(hai)防(fang)護林,1995年全(quan)省防(fang)護林約(yue)299萬公(gong)頃,主(zhu)要經濟(ji)林有(you)橡膠(jiao)、香(xiang)茅、胡椒、芒果、香(xiang)蕉等。1995年全(quan)省熱帶作(zuo)物種(zhong)植(zhi)面積(ji)(ji)達442萬公(gong)頃,占(zhan)土(tu)地(di)總(zong)面積(ji)(ji)的(de)125%,其中橡膠(jiao)種(zhong)植(zhi)面積(ji)(ji)有(you)368萬公(gong)頃。農作(zuo)物主(zhu)要有(you):水稻、番薯、木薯、花生和甘(gan)蔗等。1995年全(quan)省水稻播(bo)種(zhong)面積(ji)(ji)為(wei)394萬公(gong)頃,占(zhan)土(tu)地(di)總(zong)面積(ji)(ji)的(de)11.1%。
森林分布
在海南(nan)(nan)島,森林資源分布于(yu)中(zhong)部、西南(nan)(nan)部和東南(nan)(nan)部山區(qu),即集中(zhong)于(yu)尖峰嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、霸王嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、吊羅山和瓊(qiong)中(zhong)縣(xian)(xian)(xian)的(de)(de)(de)(de)五指山、鸚哥嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、黎母(mu)山、什寒山、白馬(ma)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、嘉積嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),白沙縣(xian)(xian)(xian)的(de)(de)(de)(de)南(nan)(nan)溪嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、南(nan)(nan)高嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、斧頭(tou)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),樂東縣(xian)(xian)(xian)的(de)(de)(de)(de)佳陽嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、抱由(you)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、卡法(fa)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),保亭縣(xian)(xian)(xian)的(de)(de)(de)(de)好梧嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、生(sheng)毛(mao)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、四方(fang)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、南(nan)(nan)林嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),三(san)亞市(shi)(shi)的(de)(de)(de)(de)抱龍嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、雅(ya)亮嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),東方(fang)縣(xian)(xian)(xian)的(de)(de)(de)(de)馬(ma)鞍嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、獼猴嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),昌(chang)江縣(xian)(xian)(xian)的(de)(de)(de)(de)保梅嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),萬寧市(shi)(shi)的(de)(de)(de)(de)牛土嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、銅鐵嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、六連嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、東嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)、尖嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling),瓊(qiong)海市(shi)(shi)的(de)(de)(de)(de)會(hui)山,儋(dan)州(zhou)市(shi)(shi)的(de)(de)(de)(de)鹿母(mu)灣,屯昌(chang)縣(xian)(xian)(xian)的(de)(de)(de)(de)黃竹嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)以及澄邁縣(xian)(xian)(xian)的(de)(de)(de)(de)仁興等山區(qu)。
海(hai)(hai)南島最重要(yao)(yao)的熱(re)(re)帶森(sen)林(lin)區有5個:①五指山(shan)熱(re)(re)帶原始森(sen)林(lin)區;②霸王嶺;③尖峰嶺林(lin)區;④吊羅(luo)山(shan)林(lin)區;⑤黎母山(shan)林(lin)區。這(zhe)些(xie)林(lin)區,森(sen)林(lin)資源豐富,珍貴樹種多。五大林(lin)區均為水(shui)源林(lin)和水(shui)土保持林(lin),對調節氣候(hou)、涵養(yang)水(shui)源、防御臺風等起著(zhu)重要(yao)(yao)作用。此外,海(hai)(hai)南島的人工林(lin)主要(yao)(yao)分布(bu)于(yu)環島沿(yan)海(hai)(hai)地帶和農墾局的各個國營農場。
海南(nan)島屬熱帶季(ji)(ji)風(feng)海洋性氣(qi)候。基本特征為(wei):四季(ji)(ji)不分明(ming),夏無(wu)(wu)酷熱,冬(dong)無(wu)(wu)嚴寒,氣(qi)溫(wen)年(nian)較差小,年(nian)平均氣(qi)溫(wen)高;干季(ji)(ji)、雨(yu)季(ji)(ji)明(ming)顯,冬(dong)春干旱,夏秋多(duo)雨(yu),多(duo)熱帶氣(qi)旋(xuan);光、熱、水(shui)資源豐富,風(feng)、旱、寒等氣(qi)候災害頻繁。年(nian)平均氣(qi)溫(wen)22.5-25.60C,年(nian)日照(zhao)時(shi)(shi)數1780-2600小時(shi)(shi),太陽總輻射(she)量4500-5800兆焦耳/平方米(mi),年(nian)降水(shui)量1500-2500毫米(mi)(西部沿海約1000毫米(mi))。
日照
海南島位于北回歸線以(yi)南,終年太(tai)(tai)陽(yang)高度角(jiao)大。夏(xia)至(zhi)前(qian)后有兩次太(tai)(tai)陽(yang)位于天(tian)頂,正午時(shi),太(tai)(tai)陽(yang)高度角(jiao)在84°45′~86°45′;即(ji)使在冬至(zhi)日,正午時(shi),太(tai)(tai)陽(yang)高度角(jiao)也在46°05′~48°05′。各地夏(xia)至(zhi)與冬至(zhi)的(de)晝長相差很小(xiao),因而,太(tai)(tai)陽(yang)輻射(she)能相當豐富,日照充足,年太(tai)(tai)陽(yang)輻射(she)總量為4600~5800兆(zhao)焦(jiao)耳/平方(fang)米(mi),年日照時(shi)數在1793~2590小(xiao)時(shi).為熱(re)帶氣候的(de)形成奠定(ding)了基礎。海南島位于東亞(ya)季(ji)風(feng)(feng)(feng)區,受季(ji)風(feng)(feng)(feng)影響較(jiao)為明顯。東風(feng)(feng)(feng)帶系(xi)統和西風(feng)(feng)(feng)帶系(xi)統對其(qi)均有影響。
氣溫
海(hai)南各地(di)的年平均氣(qi)溫(wen)(wen)為(wei)22.5~25.6℃,以(yi)中(zhong)部(bu)的瓊中(zhong)最低,南部(bu)的三亞(ya)最高。等溫(wen)(wen)線(xian)(xian)向南彎曲呈弧線(xian)(xian)分布,從中(zhong)部(bu)山(shan)區向四周(zhou)沿海(hai)遞增(zeng),23℃等溫(wen)(wen)線(xian)(xian)在(zai)中(zhong)部(bu)山(shan)區閉(bi)合(he)。由(you)于海(hai)洋的調節,海(hai)南氣(qi)溫(wen)(wen)年變差(cha)普(pu)遍(bian)較小,多數地(di)區為(wei)8~10℃,三亞(ya)最小(7.6℃)。普(pu)遍(bian)比中(zhong)國大陸地(di)區低5~10℃。
降水
海(hai)南(nan)各地的(de)年(nian)(nian)平(ping)均(jun)雨(yu)(yu)量(liang)(liang)(liang)為(wei)923~2459毫米(mi)(mi)(mi)(mi)。等(deng)雨(yu)(yu)量(liang)(liang)(liang)線呈環狀分布,中(zhong)(zhong)、東(dong)(dong)部(bu)多(duo)(duo),西部(bu)少(shao)(shao);山區丘(qiu)陵(ling)多(duo)(duo),沿海(hai)平(ping)原(yuan)少(shao)(shao);多(duo)(duo)雨(yu)(yu)中(zhong)(zhong)心位于萬寧西側(ce)至(zhi)瓊(qiong)中(zhong)(zhong)一帶,少(shao)(shao)雨(yu)(yu)區位于東(dong)(dong)方市沿海(hai)。多(duo)(duo)雨(yu)(yu)中(zhong)(zhong)心的(de)瓊(qiong)中(zhong)(zhong)縣(xian),年(nian)(nian)平(ping)均(jun)雨(yu)(yu)量(liang)(liang)(liang)為(wei)2458.5毫米(mi)(mi)(mi)(mi),年(nian)(nian)最(zui)多(duo)(duo)雨(yu)(yu)量(liang)(liang)(liang)為(wei)3759.0毫米(mi)(mi)(mi)(mi)(1978年(nian)(nian)),年(nian)(nian)最(zui)少(shao)(shao)雨(yu)(yu)量(liang)(liang)(liang)為(wei)1398.1毫米(mi)(mi)(mi)(mi)(1959年(nian)(nian))。少(shao)(shao)雨(yu)(yu)區的(de)東(dong)(dong)方縣(xian),年(nian)(nian)平(ping)均(jun)雨(yu)(yu)量(liang)(liang)(liang)為(wei)922.7毫米(mi)(mi)(mi)(mi),年(nian)(nian)最(zui)多(duo)(duo)雨(yu)(yu)量(liang)(liang)(liang)為(wei)1528.8毫米(mi)(mi)(mi)(mi)(1980年(nian)(nian)),年(nian)(nian)最(zui)少(shao)(shao)雨(yu)(yu)量(liang)(liang)(liang)為(wei)275.4毫米(mi)(mi)(mi)(mi)(1969年(nian)(nian))。瓊(qiong)中(zhong)(zhong)與東(dong)(dong)方直(zhi)線距離不足150公里,雨(yu)(yu)量(liang)(liang)(liang)相差竟如此懸殊(shu)。
海南島降(jiang)水的(de)季節分配很不均(jun)勻,有明顯的(de)多雨(yu)季和少雨(yu)季。每(mei)年5~10月是(shi)多雨(yu)季,總降(jiang)雨(yu)量(liang)(liang)1500毫米(mi)左右,占(zhan)全年降(jiang)雨(yu)量(liang)(liang)的(de)70%~90%,雨(yu)源主(zhu)要有鋒(feng)面雨(yu)、熱雷雨(yu)和臺風雨(yu);每(mei)年11月至(zhi)翌(yi)年4月為少雨(yu)季,僅占(zhan)全年降(jiang)雨(yu)量(liang)(liang)的(de)10%~30%,少雨(yu)季干旱常常發生。